I’ll add pictures Friday, forgot to take some today. E30 made it down and back to the vintage again this spring with zero issues (technically +1 because I bought a new coolant level sensor at the swap meet portion and repaired that longstanding issue while down there!). Was a ton of fun, and running the dragon this year with the entire group was a ball. Sooo many BMW’s, everyone there was wondering WTF was going on.
I then parked it for part of June (no A/C makes for a hot commute), then lent it to a friend for his wedding getaway car in mid July. Well, it proceeded to nuke its 1yr old rebuilt alternator on the morning of his wedding day, super fun to find that out when I arrived that evening. Whoops. Got it back, pulled the alternator, had the shop rebuilt it again (needed to rob the rotor out of a spare I had), put it back in, and all is fine. Right?
Wrong. It then started to show that it was overheating, at least according to the gauge. It never smelled hot and I couldn’t get it to ever show crazy temps anywhere, but the gauge would slowly fluctuate between middle and 3/4, never going beyond 3/4. I later found that electrical load could cause it to shift almost a full quarter of the gauge. It all just seemed bizarre since the cooling system is pretty much all 2-3yrs old, and is running through a beefy all aluminum radiator with an electric pusher fan augmenting the clutched engine fan. I’m wondering if it’s a gauge issue partially - the ground nuts on the cluster are tight, but I suspect my SI batteries are dying because my tach occasionally drops out for a split second, and the econometer works like 20% of the time. Probably time to have it rebuilt, it’s a good winter expenditure I think.
Regardless, I knew I had a slight thermostat housing leak where the two halves meet, so I figured I’d fix that to narrow things down, and toss in some new temp sensors while I was there (the ECU sensor was leaking thru the connector). Swapped in a fresh thermostat, o-ring, and housing cover/bleed screw while I was there too, and drilled a little hole in the top of the tstat to help with bleeding. I filled it and fired it up tonight, and the odd gauge behavior resurfaced for a few minutes but then appears to have gone away. It didn’t seem to correlate with bleeding or an air bubble. Hard to say really. Expecting something like this, I bought myself this thing as peace of mind and a troubleshooting tool:
https://e30clusters.com/product/vent-gauge-3-indicators-fahrenheit/
It’s pretty simple to install, looks awesome, works well, and showed me that I had a rock solid coolant temp of 180F at idle even after 20min. Hoping that carries over once I put the car back down and take it for a test rip. I will update when I do so! I had a nice surprise when installing too - apparently some of tbe M20 thermostat housings (maybe just replacement ones?) have 4 bungs for sensors vs the original 2, so all I had to do to add the sender was remove a plug and screw in the new sender with a fresh crush washer. The added bonus is that it’s still reading in the main thermostat housing cavity, so I have an accurate picture of what the temp is doing vs something in the upper rad hose that won’t show an overheat if your thermostat sticks closed. I’ll maybe hook up the oil temp sender over the winter, but for right now I’m not worried about it. I might even repurpose it for a second water temp sensor to monitor temps in the return hose from the radiator or something. Either way, super cool product and I’d highly recommend.
