operating temp

[jrobie79]

pretty sure I have a stock (88 C) thermostat in my car...however I notice the temp gauge barely creeps above the 1/4 mark. maybe 1/8" over the line.

I thought the temp needle was supposed to be at or slightly below halfway, any ideas?

[roguetoaster]

Thermostat could be stuck or inop, or even in backwards. Temp gauge could be faulty, maybe check your IC ground. Bad mix of coolant, or an always on fan could be other culprits, although those are a stretch.

[e30s50dan]

Must have tool. $30 at harbor freight

[jrobie79]

Must have tool. $30 at harbor freight

I have a one of those thermometer guns - where would I take a reading from?

It's all brand new coolant - BMW blue even (50/50 with distilled water)

The fan is brand new and wired correctly, the whole car has been restored, its an e36 m42 engine, but I dunno that that would make a difference, and I believe when I painted my instrument panel needles I tightened all the nuts down in the back because of the erratic conditions loose ones cause (the needle never jumps around, just warms up to 1/4)

The only other thing I can think of is an incorrect thermostat, I'll check the temp with the gun and report back

pic for attention

[irish44j]

If you want the temp gauge to be accurate, go aftermarket. My stock one basically sat at halfway during regular operations, then would quickly climb to 3/4 when idling in grid at races, then quickly drop back to 1/2 when my Spal fan kicked on. It certainly wasn't linear and I wouldn't trust it any more than anything else in the e30 gauge cluster (which is to say, very little). And btw mine never was below 1/2 EVER except when the engine was cold.

I use a VDO standalone gauge for oil and water temp, which reads actual temperature and not a vague range.

Mine generally runs at about 205* during hard driving, and 210* at the end of rallycross runs (when my fan kicks on). I think the M42 is supposed to run right at 200* during regular light-throttle cruising though.

[Dust2glory]

That's exactly where my 318is runs at - 1/8 inch past the 1/4 line. I have a completely refreshed cooling system. I think your car is running properly and from talking to others, it is common for them to run in that area of the gauge.

[irish44j]

That's exactly where my 318is runs at - 1/8 inch past the 1/4 line. I have a completely refreshed cooling system. I think your car is running properly and from talking to others, it is common for them to run in that area of the gauge.

IDK, I think the stock gauge is just lousy. I know for a fact that my car operates at the correct water temp (due to both direct readings and my VDO gauge), but it never, ever, ever was below 1/2 on the stock gauge except when the car was cold.

I also have a completely refreshed cooling system and running a larger M3 aluminum radiator to boot, along with water wetter.

YMMV though. There are easy ways to find out what the actual temp is. Just saying that reliance on the stock gauge is not the best idea.

[irish44j]

curious thought: is your fan clutch working correctly? If it's not, the fan will be on all the time and may be keeping the water temps lower than they necessarily should be. The fan clutch should be disengaged during most regular driving, and only engage when at idle, or during hard driving, etc...

[anthonymax007]

Maybe give this a try: Take out your cluster, there's a nut behind the gas gauge and one behind the temp gauge. Take the nut off and try cleaning it and the area it mates to. Put the nuts (deez nuts!!!) back on and give it a whirl. I did this when my gauges were acting up and it helped a lot.

[TobyB]

A little over 1/4 corresponds to 180f at the outlet of the water neck on mine...

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[jdt10768]

Mine stays at 12 noon dead center, verify thermostat is correct, pull cluster and clean posts with fine steel wool, reinstall deez nuts tightly

[varg]

Good advice ITT, just wanted to add to the list of people whose temp gauge needle stays near vertical. It might move slightly past vertical once in a while if I'm running my AC and driving the car in traffic, at which point my MS readout says coolant temp is around 210. I have seen as high as 215 while autocrossing. My radiator is behind my intercooler though, so airflow isn't the best, and my car is far from stock.

[packratbimmer]

- temps can vary from brand to brand with thermostats ( I have found that Wahler runs cooler and Behr Thomson runs closer to spec)
- pressure cap good and correct psi?
- air leaks in system?

[RCtheRed]

Sounds like a thermostat problem, you said you are pretty sure it's a 88C one, you are positive there is one installed? Seems like a case of coolant circulation at all times of operation and the only logical reason why the car doesn't warm up to operating temp.

[jrobie79]

sorry to jump on this, i never responded...there is 100% a thermostat installed, I believe it's from Autopart International, maybe I'll swap the brands, and verify operation in boiling water before installation.

My clutch fan runs all the time, never stops, right after startup to idling for 5 minutes, it's always spinning. It stops with slight pressure tho, so the clutch is probably toast, I guess I can change that. I have R&R'd the cluster - cleaned the post and the nut threads.