m42 running hot

[ibatic1]

Hello im new to the forum, but on my second e30 vert with the m42. The PO told me the motor had been rebuilt from the bottom up. Until recently i felt like the car was flawless with of course all its little flaws or "Personality Quirks" now 2 weeks after owning it i'm noticing more and more. The car doesn't overheat but it runs around the 1/2 to 3/4 mark depending if i'm sitting or driving. I also saw signs of water in the oil via the dipstick, however the milky oil is higher on the dipstick about 1-2 in from where the oil level is. Which is right under the max. The car has also been blowing a pretty light smoke that doesn't really look like a head gasket leak, and just smells like a normal exhaust. The car also blows hot air. I know these cars need attention and i don't want to end up with another cracked head. I plan on doing the water pump, thermostat, and a coolant flush soon. Just looking for advice or any help on the issue. Maybe the thermostat gauge is off?
Between work and life i don't get a whole lot of time to investigate. I am driving this car about 30 miles to and from work though and just want to be able to trust it. I am open to any and all suggestions. Will post pictures soon. Thanks in advance and hello to all on R3V.

[e30davie]

1st step: forget everything the previous owner said.

Then I would do the following as you allude to;

Radiator flush.
Check thermostat works by putting it in some hot water
Compression test
Coolant system prrssure test.
Confirm ignition timing

See if anything comes of those tests eh.

[jaredmac11]

I wonder what percentage of PO who say they replace the HG actually did it right, or actually tested the head to make sure it wasnt warped or cracked?

Replacing a HG on a warped or cracked head does nothing to resolve the actual issue. a failed HG is often a symptom of a larger issue. If he has no receipts, assume the worst here.



Start with Davie's advice and hopefully its resolved with new coolant and maybe a new thermostat but something tells me its gonna be more than that. If its possible for you, it may be worth it to turn this to a project and get a more reliable DD for your needs.

[ibatic1]

Thanks for the answers. I've never done a compression or leak down test but i guess the best way to learn is to do. Unfortunately I made a dumb and uneducated decision to sell my DD. Sucks to put faith where it doesn't belong. Good thing I've always learned from doing things the wrong/hard way.

[jaredmac11]

When is the car overheating? Idle or drive? Have you done a complete oil change yet? If its just half up the dipstick, it could just be condensation.

[e30davie]

Replacing a HG on a warped or cracked head does nothing to resolve the actual issue. a failed HG is often a symptom of a larger issue. If he has no receipts, assume the worst here.

Its amazing when you see advertisements for cars that say "headgasket needs replacing, have quotes for gasket $100 - cheap easy fix". What that is code for is "shes had it mate, needs $2k spent on it"

I once left the head bolts loose by mistake, i didnt go back and re-toruqe and they were so loose when I removed them, like finger tight. So i had a "blown" head gasket but it wasn't the heads fault. haha. Man i learnt a hard lesson that day. Luckily it was on a suzuki sierra/samurai 8v engine so was a 2hr job to change the gasket and off i went wheeling again.

Also perhaps question the gauge firstly. I know alot of people have faith in OEM gauges, but on older project cars the first thing I do is install a VDO temp gauge. Its just nice knowing the exact temperature on an unknown engine and they are like $40 so its cheap insurance.

[ForcedFirebird]

3/4 on a stock gauge doesn't mean overheating. The e30 normally runs at about 190-205f with the t-stat open, which is half on the gauge. Red on an e30 gauge is in the neighborhood of 225f+ and the left sweep can be as much as 150f in the blue area, so it's not linear. I would start with the fan clutch and test it with the magazine/newspaper trick. A bad fan clutch will see 3/4 at stop lights after a long stretch (or high speed/AC on, etc), normal most of the time.

The old BMW engines suck the PCV straight into the throttle boot. It's not uncommon for a daily driver to see some slight milkshake on the back of the oil cap and/or slightly on the dipstick, but be wary, the 4 valve BMW heads like to crack from the chamber to the outer coolant passage. A DIY check is to purchase a coolant combustion kit, flush the system, fill with fresh water, run, dip the tabs in the coolant. A more expensive kit is a coolant pressure test kit (may be able to rent/borrow on, though). Fill the system to the top, pressurize and remove spark plugs while waiting. If the system looses pressure, keep filling with air and take note of any water buildup on the top of the pistons.

Any other symptoms? Are you loosing coolant? Do the hoses feel abnormally tight when at operating temp?

[ibatic1]

As of now i bled the system a bit and with the heater on and driving the gauge stays a little past the 1/2 mark, but like you're saying with ac on it gets hotter. Also want to say that the smoke out the exhaust was because of the weather because last night and today there was none. My tach and thermostat gauge also keep messing up and usually straighten up when i give the dash a good thump so i do believe ill be getting a new gauge for the car. The hoses from the radiator don't seem super hard which makes me think there is a little air in the system still. No leaks or anything though. This friday ill be doing the thermostat, water pump, fan clutch, oil change, and a radiator flush. Ill keep y'all posted. I don't think its as severe as a HG, but only time will tell. Tips on how to fix the dash will be extremely helpful as well. Ie if i just need to pull it out and make sure the connections are solid. Thanks a lot to everyone for sharing there thoughts and knowledge with me.

[Balleristic31]

Clean/tighten the ground nut on the back of the temperature gauge. I believe it takes a 7mm socket. I had one loosen up on me and my gauge read about 3/4 at normal operating temp.

[ibatic1]

System has been flushed and its running better. The thermostat gauge is staying just barley past the 1/2 mark after idling for a solid 30 min and a put around the block. In the process of burping the air out of the system with the heater on out of nowhere the air completely stopped and now no longer turns on... Also noticed that after being parked a while there was a coolant stain on the ground. seemed like it was coming from under the radiator on the drivers side. Ill keep this updated with what i find out later. Still accepting any and all advice/tips and tricks lol. I just want some piece of mind.

[ForcedFirebird]

Did you test the fan clutch yet?

[ibatic1]

just replaced the fan clutch and can definitly tell the difference. The top coolant hose gets super hot and hard. Still seeing very lite smoke from the tailpipe along with some water or condensation on the first start. idling at 500rpm so i sprayed the icv with carb cleaner and it did not make any difference. Cant wait to be problem free.. just hope i dont need to rebuild to get to that point. Ill be looking for another motor to rebuild in the houston area.

[ForcedFirebird]

Did you test the fan clutch, though? I've had so many come bad right out of the box, I test them, even when brand new.

Get to operating temp, and stick a rolled up newspaper, or cardboard in the fan. If the fan stops, clutch is bad.

[e30davie]

Compression test done yet? It will at least give you some co fidence in the engine if the results are good.

[ibatic1]

oil in the sparkplug holes.... about a table spoon in each. I know i need to have that done or can i do the compression test myself?