Did another long back country drive, finding new and wonderfully twisty roads off the beaten path. Even on a Sunday, when motorhomes and pickup trucks with dirt bikes clog the roads heading back from the desert, there are still a few roads to be explored. About half way through this drive, the little voice in my head asked, “Do you smell something?” Me: no.
A bit later, “Are you sure, it smells like oil.” Me: Yeah, but it’s really faint and probably isn’t even coming from my car. It could be a truck and I don’t see any smoke. As I neared home, however, the oil smell had become unmistakable.
Pulled into the garage and the line of oil down the street delivered the message in no uncertain terms that something was up. The bottom and back of the drivetrain, and all the suspension and the rear of the car were covered in oil, so the immediate goal was finding the source.
Started it up and there it was, coming from around the oil-to-coolant heat exchanger. After cleaning up the mess to get under the car without taking an oil shower, a closer look found it was coming from the inlet fitting on the oil cooler. The -12 AN fitting wasn’t loose; it was the bolt-on adaptor it was screwed onto that was leaking. Oddly, the Torx screws were tight, so it seemed like the gasket must have given way after, what, five years?
After removing the fitting, it turned out that it’s sealed with an O-ring and it seemed like it had gotten pinched – or so I thought. It wasn’t until I pulled it out of the groove that I found there were two O-rings! The only thing I can think of – given that there’s only room for one O-ring – is that the assembler must have reached into a bag of O-rings and not noticed that two were stuck together. Amazing that they remained sealed for as long as they did.
I’m going to call the seller to see if they’ll give me a free replacement gasket set if I casually mention that the only reason I didn’t trash this engine was the 8 quarts of oil in the dry sump system. When the tank was drained before removing the fitting, it was a bit shocking to see that only about two quarts of oil were left. I think the leak started very gradually which is why it didn’t become suddenly obvious. Seeing the solid line of oil down the street, I doubt it would have lasted another 20 minutes. Yes, the ECU should catch the low oil pressure with a rev-limiter and a warning message, but I don’t want to test that. Close call though.
While looking at the broken exhaust, the brace from the engine block that supports the turbocharger was found broken as well. I think I know when this happened. I was leaving a driveway and accelerated hard and may have caused a “PIO” (Pilot Induced Oscillation) with my foot inadvertently getting on and off the gas due to the car accelerating and decelerating so hard. The result was a violent back and forth action similar to ignition cut. I say I may have because the ECU failed to log it (again). Anyway, the turbo support bracket was repaired – though I noted that some bonehead had left it tack-welded, no surprise it failed.
As a temporary fix, the failed stainless bellows was welded back together instead of being replaced. That’s because even before this happened, there’s been a plan afoot to adding a muffler (again). The intent is to both reduce noise and unwanted attention, and to just be more pleasant. Besides, the car has so much power that if I lose 10 hp by adding it, so what. It’ll be installed so that it takes about a minute to remove for track event.The downside is more weight and heat, which will likely lead to something else that been on the back burner, a cold air duct running from the side vent to an enclosed air filter. As it is now, the open air filter sucks hot air in straight from the engine compartment, decreasing power and increasing the chance of preignition. Adding the duct may well make back whatever power the muffler takes.
In other news, a bit more information was found regarding CS-130D alternators. Apparently they contain a temperature sensor, though it’s unclear what for. It might be to reduce output to protect the alternator as it warms up, or maybe it’s to maintain output instead of it dropping off with temperature – I suspect the former.
Also alternator related, it was noticed that at idle, the alternator vibrates some. Suspecting something was broken, it was disassembled again but nothing was found, so the mount may simply be flexing. Might have to make a new one using thicker material, or double up the material that’s there now. It was reassembled with a new bolt and after putting it all back together, turning the alternator pulley now turns the engine (apparently it had to wear in) so belt tension’s off the list of suspects.
Right now I suspect it’s just how these alternators work, varying the output with temperature. An experiment would be to warm up the alternator with a drive, then while idling, cool it with compressed air to see if the output voltage jumps back up. My brother reminded me of something I intended to do, measure battery voltage with a good DVM instead of taking the dash/ECU’s reading as fact. Good idea, because the dash reads about 0.2V low, further lessening my drive to fiddle with this issue much longer.
Took the alternator out and found it’s a CS130D model – I thought it was the previous generation, the CS130. The “D” version has more output, larger bearings, and better ventilation, though it is a bit larger.
It appeared to be in good condition so a cable connecting the alternator directly to the battery was fabricated, in addition to connecting the previously-unused “sense” wire to make sure the voltage is monitored directly at the battery.
At initial cold-start, battery voltage immediately went to 14.5, higher than before, but like before, after about 30 minutes of driving, it had decreased to 13.5-13.7V. The odd thing is that later during the same drive, sometimes it would go back up to 13.9-14.0V. If it slowly sank and leveled out, I’d think it was a temperature-sensitive voltage regulator and that would be the end of it, but this, huh.
A possible contributor might also be belt tension. Some sources claim that a serpentine belt is tight when you can just turn the longest span 90 degrees. Another source says that the belt should be tight enough that the engine can be rotated by turning the alternator pulley with a wrench. If it’s the former, I’m fine; if it’s the latter, I’m not. If the belt is slipping though, I’d expect it to get worse when a big load like the radiator cooling fan is switched on, yet when I did so when the alternator output was 14V, it didn’t drop much, implying that belt slip isn’t the issue.
The alternator might be defective, or maybe they all do this. The belt might be slipping, or it might not be. The alternator is mounted in the only place it can go due to the required reverse-rotation of the water pump. Because of the mount’s geometry, mechanical leverage increases as the belt is tightened. This would be a good thing if there was more space but there’s a chassis tube not far away, so there’s only a limited range to get it tight, and the next shorter belt won’t fit. Another possibility is to switch to the slightly smaller CS130 (though it’s only about 0.3″ smaller) but may still not allow getting the next shorter belt on.
Yet another variable is the pulley ratio. An aftermarket alternator manufacturer claims their alternators are good to 18,000 rpm, though I’m not sure whether OEM units are the same. The ATI crank damper is 5.5″ diameter and the alternator pulley is 2.7″ (68.6mm) – an odd size regardless of units. Alternator speed is scaled by pulley diameter, so if the engine’s spinning at 8200 rpm, the alternator’s spinning at (5.5/2.7)*8200, or 16,700 rpm, so there’s a bit of wiggle room left. The math says that the alternator pulley could be reduced to 2.5″ to increase charging at lower speeds. The thing is, the belt routing is sort of like the letter “B”, such that it nearly touches itself as it passes over the water pump pulley. If the alternator pulley diameter is reduced, the belt surfaces may touch and greatly accelerate wear. Maybe a pulley could be added to increase spacing, but messing with pulley diameter is sort of besides the point since sometimes the voltage output is fine. Further muddying the waters is how sometimes, when I’d rev the engine up, battery voltage would increase, implying it’s a pulley ratio problem – yet other times it wouldn’t make any difference. Ugh.
Summed up, I’m not sure where to go with this, leave it alone and keep an eye on it, or chase it down until root cause is identified. Lastly, this article is really helpful in understanding alternators.
In other news, I was wondering why my exhaust pipe was suddenly pointing off to the side. Turns out that the flex joint in the exhaust has completely cracked through. That’s nice, but it didn’t ruin my 100-mile drive through the back roads!
Whether or not the alternator gets swapped out, it looks like its wiring needs revisiting. The alternator connects through the fuse box to the battery. The catch is, I added a battery cut-off switch upstream of the fuse box and bad things can happen if the switch is opened with the engine running. At best, the engine quits as it should, though I now think it won’t. Since the alternator feeds in downstream of the switch, it would likely self-power the system and the engine would keep running. At worst, not only would the engine keep running, but with no voltage reference, the alternator could generate voltage spikes high enough to damage the ECU. I’m too chicken to try it and find out.
The alternator feed-in point needs to be moved directly to the battery. As a related issue, the wire connecting the alternator to the battery is way too small (I blame the Painless Wiring kit but should have known better). It’s 10-gauge but needs to be much larger; the PowerMaster site claims that a 7-ft wire running 125 amps requires at least #6, if not #4. Yes, 125A is extreme, but having everything on in stop-and-go traffic with a flat battery could get there, albeit briefly. Wire size doesn’t seem like it could be the sole cause of the voltage drop, but it can’t be entirely ruled out either. Copper has a positive temperature coefficient, meaning the hotter it is, the more resistance it has, which causes voltage drops with current (this is why a hot starter won’t crank an engine). Still, air temperature rising only 20C wouldn’t be enough to account for the problem… only there’s more to it. The alternator wire runs down the center tunnel, sharing space with the coolant pipes. There’s a fair chance that it’s seeing around 60C or so, increasing resistance by around 16%. That still doesn’t fully explain the situation because the wire temperature in the center tunnel likely doesn’t vary much. Guess I just have to try it to see; right now I still think there’s still a good chance the problem is an overly-sensitive voltage regulator in the alternator. Regardless, the alternator wire needs to be upgraded no matter what alternator is used, so this is a cheap experiment before spending money on other things.
Received the replacement coolant temperature sensor and finally checked its calibration… well, let me back up.
An authentic Honda coolant temperature sensor is roughly $45 online, and me being a cheapskate, looked for alternatives. Found one on Ebay for about $8, with the picture showing the sensor next to an authentic Honda part bag with the correct number on it. I knew better than to think it was actually what the picture portrayed and bought it anyway. Sure enough it arrived in a plain box with no markings whatsoever, so no surprise it’s a knockoff.
Boiling water in a Thermos was placed in the engine compartment where the wire harness could reach. The new sensor was plugged in, and it and an accurate mercury thermometer were submerged in the hot water. The sensors were allowed to settle for several minutes and then the temperature read; the thermometer settled out at 91C, while the sensor read 77C. Sigh, it wasn’t expected to read exactly right but this is kind of ridiculous. To be fair, I don’t know how accurate an authentic Honda part is, but doubt it’s that bad. We’ll see since a “real” sensor has been ordered.
Took Midlana and the granddaughter to the new Cars and Coffee location, currently at the Outlet San Clemente mall (one can only wonder how long it’ll be before they get thrown out from there as well, which seems to be the fate of the event, for noise, exhibition of speed, etc). This was the first time she’d been to any car show and, it went about as expected, not much interest, but the point was to expose her to it at least once so she knows they exist and what it’s about. I told her that I’d be happy to take her again but she has to ask – I won’t pester her to go.
No good deed goes unpunished and the traffic for the 50-mile trip home was brutal. The clutch was used about a million times because even at idle in first, Midlana wanted to move along faster than traffic. Being around 28 C didn’t help but it was a good test of the updated cooling system; coolant got up to around 90C but no higher. On the way up it was the exact opposite temperature-wise, dipping as low as 6C, brrrr. With such low temperatures, engine coolant only got up to about 80C.
Speaking of that, I’ve been watching how alternator voltage varies with temperature. In cold weather, charging voltage is 14.1V, perfect, and turning on the radiator fan caused it to drop to about 13.5V, still pretty good. On the way home in the heat though, charging voltage slowly dropped off to around 13.6V and dropped to 12.9V with the fan on. I was going to check to see whether the Chevy pickup alternator I’m using has an “S” input (Remote Sense). As I type this though, I just realized it doesn’t matter if it does or not. If there was a voltage drop problem at higher air temperature, it would still be there in cooler weather, but the problem is only during warm weather, ruling that out. It’s not like the alternator is being overheated either; right now there’s neither an engine cover nor belly pan. Also, since this is a cross-flow engine with the alternator on the intake side, it’s not near anything hot. I suspect the built-in alternator regulator just isn’t very good over temperature.
I could try running a cold air hose from the side vent to the alternator, but related to the above, since it’s already fairly well ventilated, there’s a good chance that the “cool air” being fed to it through a hose from the outside isn’t much lower than the air already swirling around the engine compartment. Of course, zooming way out on the problem, I’m not sure how much it matters. That is, it’s been this way for years and hasn’t been an issue, though I do keep a battery tender on it when in the garage. Then, during the endless traffic jam yesterday, I managed to stall it once and forgot the radiator fan was still on; when cranking, the battery clearly wasn’t happy at all about having to run both (sounding like a run-down battery). So there’s several approaches: do nothing, get the aftermarket alternator and hope it’s less temperature sensitive, or set up a cooling air duct for the existing unit and hope the outside air is a lot cooler than engine compartment air.
Finished the radiator ducting, though it still needs paint before being permanently mounted. It was assembled with temporary rivets and Midlana was taken out for a drive, again confirming a 2-3 degree C decrease in coolant temperature under all conditions.
Twice now the same cylinder head exhaust manifold bolt has backed out, the first time completely and the second time about a centimeter. Not sure why since it’s torqued to Remflex’s recommended 20 ft-lbs. It was okay after today’s drive but if it does it again it’ll be safety-wired.
Went on a longer test drive into the back country, up “my” Palomar Mountain “test track”. This time there was an interesting mix of events.
At the base of Palomar Mountain, they were fishing a balled-up sportbike out of a ditch, the driver nowhere around. Heading up the mountain I got stuck behind a cruiser Harley where the rider was apparently still learning to ride. That’s fine, except he was going between 22 and 32 mph, I checked. At first I was polite – everyone starts somewhere – but after a while it got kind of annoying as he kept passing places he could have pulled over. And then…
After ruining about 80% of my ride up, a Harley was coming down the hill the opposite direction and correctly assessed my situation in a flash. It was quietly hysterical what he did, first tapping his helmet and then giving a palm-up gesture toward the Harley, like, “dude, how long you been holding him up?” I don’t know if the Harley ahead of me finally noticed me, or if the guilt worked, but he immediately pulled over. I had a very hard time to not laugh as I gave him a thank-you wave.
After I passed the Harley I went tearing up the rest of the hill, trying to make the best of my shortened “course.” The new tires are, well, amazing. The old ones had really lost their stick because these new ones are pretty incredible. I haven’t even managed to slide the car yet because doing so means going into a turn fast enough that if it does become unstuck, I’d likely end up in the ditch along with the sportbikes. Speaking of that, came around a turn and there was a second sportbike being retrieved from the rocks. Not far away, a cop was making an accident report but heard me coming and had a good long look at me as I came by… I waved to acknowledge, “yes, I know you see me and are thinking ‘how can that be legal’, and that I’m cutting it close.” Thankfully all I got was the look.
All the way up, coolant temperature stayed lower than it had on previous drives – I’m happy. Drove around the top of the mountain a bit then headed back down. This time I had a Harley behind me who wanted to play. I let him pass and once past the cop, we had some fun heading down the hill. I’m curious how I would have done behind a real sportbike, but that puts us both in a situation where things get serious. I previously wrote that I always wanted a car that could keep up with sportbikes heading up the hill and I may well have that. The thing is, there’s a small chance that one or both of us might go off (as said above, two bikes already had). If he went off with me right behind him, I’d stop, and then things could get really interesting, like, would he sue me because I was pressuring him, him hoping to avoid his share of responsibility?* Would the cops arrest us for street racing? Serious thoughts – or maybe I’m just old. I passed a group of sportbikers at the base of the mountain, apparently grouping for another “assault”, and sure enough, they got all excided when they saw Midlana. I waved, but decided that stopping and getting involved might not be wise.
Oh, I got my very first thumb’s-up from a Harley rider, the first out of the 500 or so I’ve passed over the years. Meanwhile, sportbike riders give enthusiastic thumbs-ups about 30% of the time – I have theories.
On the way back, passed the local university and a car pulled up alongside with several hot and crazy college girls, screaming how “sick” my car is. Ah, if I were but young and single…
During the weekend’s drives, the alternator may or may not have been acting up. It normally stays mid-13Vs, which is a little low and is why I’m considering an aftermarket adjustable unit. It’s as if my alternator heard my thoughts because now it’s charging at around 14V, which it’s never done before. Also different is that with the radiator fan on, a few times at least, voltage sagged down into the 12.XV range, which was new. Checked for loose wires and found nothing.
No bites on the transmission, but at $4000, it’s not surprising that it may take a while. The price is what it is because of the work done to ensure it’s as close to “new” as something used can be, so for now I wait. We’ll see if and when my idea of its worth matches anyone else’s!
I have all the parts to start building the rear wing, and at some point I also have to figure out airflow in the proposed location (how high it needs to mount to be in clean air). There are various ideas, one involving smoke bombs… that could be interesting…
Lastly, I tried fixing something that’s low on the annoyance scale but there nonetheless – the perpetually-crocked steering wheel. It’s because the splines on the steering wheel adaptor are fairly course, so it’s either wrong in this direction or that direction, take your pick. I finally realized that the Miata splines further down the steering column are more fine-pitch, probably around double, so I tried offsetting it by one spline, and it’s much better now.
*There’s currently a lawsuit between a sportbike rider and Laguna Seca Raceway. He had gone off-course and hit some sandbags, which threw him off. He’s claiming that Laguna unnecessarily made the track dangerous and caused him to lose control. Well, what was he doing off course if he hadn’t already lost control, but anyway, people sue for all sorts of reasons.
Went to the local hot rod show with my brother. He wanted to talk to Tremec, his transmission builder, about how the front of his case has cracked, something that’s reportedly happened to other people as well, but wasn’t much satisfied with their answers, which were a little wishy-washy. I told him the right ($$$$) solution is to suck it up and buy their next model up in strength, else the probably may well happen again. The first picture with my hand on the gears is one of their upper models. Yeah, those gears look like they could handle some pretty good torque.
The rusty white truck had a turbo about twice as large as mine, with an air cleaner about 8 times smaller than mine – yeah, it shows signs of collapse.
The yellow and red show car looks like something the Simpson’s or a few Minions should be driving.
The green truck had a complete 425 (or 455) c.i. Oldsmobile Toronado in the truck bed. The picture from the side shows just how compact the drivetrain is, with the engine sitting directly over axle centerline. Compact yes, light, nope.
That tire? A “405/25-24”. I fear tires are still heading up in size.
The engine with the bluish valve covers isn’t anything remarkable, but the fuel and nitrous plumbing was “noticeable.”
There were a few rat rods, and then there was what appeared to be a very old stock vehicle, but it turned out he’d created it from authentic odds and ends from that era, including a V12 out of something. Another car had a V12 in it as well; the header fabrication would have been a fun project.
The light blue/silver car was amazing, kit or otherwise, as was the period correct engine in another car.
And then we come to our favorite, the ratty-looking pale green Chevy truck. We’d have walked right by it had we not just seen it at the autocross. Watching it approach the first turn we both said out loud “he’s never going to make that”, and then did. The thing was flat-out amazing, beating about 90% of everything else. The secret is its Corvette chassis, suspension, and drivetrain, but you couldn’t tell from the outside, though the huge brakes are a hint. The interior looks much like an old 1960’s truck, albeit with racing seats. He’s looking forward to taking it to a trackday, and it would be pretty funny seeing him pass “real sports cars.”
Went for a couple test drives to get more comfortable with the new transmission and the close ratios. Something else though, came to light during the drives that consumed my attention.
Ever since the engine was retuned I noticed that coolant temperature seemed a little higher. It wasn’t a lot though and since coolant temperature is affected somewhat by outside air temperature, it was never really clear if it really was or not.
As mentioned before, Midlana has always had this somewhat odd trait where when idling with the fan on, coolant temperature is fine (mid-80s, C of course), and when on-track and driving hard, coolant temperature is about the same. But then there’s just plodding along on the freeway at 65-75 mph. One would think in that low-power situation, coolant temperature should again be about the same, only it isn’t. Given enough time, the temperature very slowly creeps its way up to around 90C, and this weekend on the freeway while going up a long incline, it hit a new record of 93C. If it was the middle of summer it wouldn’t have been as big a deal, but outside air temperature was only 17C.
There’s about a dozen things that could be going on, and in no particular order: radiator too small, weak electric water pump (or plumbed backwards(!), mechanical water pump turning the wrong way(!), defective coolant temperature sensor, air going around the radiator, big air bubble in the cooling system somewhere, engine timing, a collapsing hose or obstruction, low coolant, or maybe something I’m missing.
First, a back story regarding pumps, which involves Kimini, predecessor to Midlana. Kimini’s new owner added an electric water pump to help move coolant from the mid-mounted engine to the radiator and back. It apparently worked well enough that he stopped paying attention to coolant temperature, because soon after, the engine was destroyed due to severe overheating. Turns out that he’d wired/plumbed the pump so it was moving coolant the opposite direction as the engine’s mechanical pump! This caused very interesting symptoms – had he noticed. At idle, the electric pump probably won the tug of war regarding flow direction, so it stayed cool. At freeways speed, the mechanical pump, now spinning fastest, probably won the fight, moving coolant the opposite direction. But consider the case of driving at some magic lower speed where the flow generated by the mechanical and electric water pump perfectly balances. At that speed, coolant flow through the engine is zero – end of story, and end of engine.
As a sanity check, both pumps were checked for proper rotation; the mechanical pump because I’d rerouted the belt, and the electric pump, just because. Both were fine, so they’re off the list.
To keep from wastefully replacing stuff, the car was warmed up to an indicated 80C, then the radiator cap on the header tank removed and the temperature measured with an accurate mercury thermometer, which read about 68C. At first it seemed like “ah hah”, but probably not because the header tank is filled by two bleeder hoses, a small one from the cylinder head, and a larger one from the top of the radiator. It’s likely that the header tank will always be somewhat cooler than the coolant measured by the sensor itself inside the cylinder head. That said, I’m going to buy a new coolant sender anyway, plug it into the harness outside the cylinder head, and put it and the thermometer in a heated container of water. The reason is because an inaccurate calibration of one of the ECU manufacturer’s default Honda sensors has already been identified. I’ve never tested the coolant sensor so this would be a good reality check.
Another reason the header temperature might be inaccurate is because coolant flowing from the engine to the radiator flows first through an oil-to-coolant heat exchanger, which can add or subtract heat depending upon oil temperature.
Because of the bleed lines, I don’t believe it’s possible for a big air bubble to be trapped in the cooling system; it’s self-purging by design so that’s off the list. The radiator being too small doesn’t fit either, since it works fine under hard use at the track. Coolant level is fine; I don’t think (without proof) that there’s any obstructions because I only use distilled water and Water-Wetter. That leaves air going around the radiator… hmm.
As a quick test, rags were stuffed around the radiator where I could reach and another test drive performed. Well huh – taking the very same route, at the same speeds, and in the same weather, coolant temperature struggled to reach 90C, and when I let off, it dropped faster than before. This leads to the theory that at idle with the fan on, air gets sucked through the radiator by the fan, so the gaps around the sides don’t matter. At speed on-track, there’s so much air coming in that even with the leaks, there’s sufficient air flowing through the core that cooling is sufficient. That leaves the freeway situation. Here, there’s less air coming in the nose and maybe half (a big guess) is going around rather that through the radiator and providing insufficient cooling. It’s just a theory but seems to fit the facts. So first thing was to cut off the support for the horn (it sticks around the side of the radiator and makes sealing it in that area impossible). The horn will be relocated behind the radiator. Paper templates are being made for aluminum panels to extend from the inside of the nose cone to the forward face of the radiator, with foam between the two. This is so when lifting the front cover, the panels sealing the radiator will move away from it without snagging on anything.
So things look promising, though it’s something I should have done back when the car was built. Of course back then there was a big push to get it on the road, so some things got pushed off.
Oh, and there’s one other variable – ignition timing. From my understanding, timing really affects how much heat gets pushed into the cooling system. The tuner noted that he advanced timing quite a bit, so it may well be that that’s the source of the higher coolant temperatures.
Lastly, I’ve been trying to find what the normal coolant operating temperature is for a Honda K24, something that’s surprisingly vague and variable. It seems to be somewhere between 80-95C, so it’s not like the engine is overheating. This motivation to get to the bottom of this came from seeing temperatures it had never reached before, so adding the radiator ducting is the right thing to do, regardless.