Coolant and Compression Issues (Overheating? Thermostat? Electrical? Headgasket?)

[chriso]

Hey Guys,

I'm new here. Having a lot of issues with my E30. Ranging from Overheating to simply identifying the model.

Its a 1986 325E (2.7 ETA) but the cluster revs to 6000 (Redline 5000-5500)

Anyway, on to the specifics...

It starts cold, and revs between 600 and 1000 RPM at idle, bouncing back and forth until it's warm. This happens even when it's 95 degrees outside sitting in the sun.

Once it's warm, it runs great, but after about 5-10 minutes of driving, the coolant temperature gauge is in the red. Tapping the gauge causes it to drop to the 3/4 mark, but it slowly will climb into read until I tap it again.

There is no smoke from the exhaust, and no bubbles or foam under the oil cap.

The other day, I noticed my coolant was low, and I found a leak where the upper coolant hose connects to the coolant reservoir. I tried replacing the clamp, and tightening the clamp made it worse. There did not seem to be any cracks in the hose. (It's the original OEM BMW hose).

I bought a new set of upper and lower hoses, and I could only find hoses that supposedly matched the 325E, and while they're molded to the same size and length as the OEM hose, they are larger is diameter. Not by much, but it makes it so they're loose around the ends of the reservoir and the radiator without a clamp. I haven't installed them yet.

I did a compression test, and the cylinder closest to the occupants tests low at 120PSI. All others tested at 150 on the dot. Should I be worried?

Could it all be as simple as a vacuum leak in the upper radiator hose?

[chriso]

I replaced the coolant with a different brand and mix yesterday, as well as the Coolant Expansion Tank hose.

What's confusing now is, the coolant temperature gauge goes into the red after 5-10 minutes of driving still, but 5-10 minutes after that, it drops to normal operating temperature.

Could this be a thermostat issue?

[101]

It could be a thermostat sticking closed, but my money would be on air in the cooling system as a result of it being low on coolant from the leaky hose. I'd replace the thermostat just for piece of mind and give the cooling system a proper fill and bleed.

You may have a secondary issue with a loose connection on the temperature gauge in the cluster.

[chriso]

Well, I found a leak on the Expansion Overflow Tank. A new hose didn't fix the leak, so it could only be the tank, right?

Ordering a new one later on ($66!?).

I'm assuming the low compression on Cylinder 6 is a separate issue?

There is definitely air in my coolant, I bleed it daily and it leaks air for about 30 seconds to a minute, and I'm trying to track down where it's coming from (assuming it now the Expansion tank, since I found that leak).

[101]

yes, the expansion tank could have a hairline crack that is leaking coolant / letting air in. You did clean up any mineral deposits that were on the plastic nipple before putting that new hose on, right!

Compression is probably a separate issue - but keep an eye on the oil and coolant to make sure they are not mixing in the engine indicating a head gasket failure. If the engine has not been overheated, its more than likely the beginnings of piston ring / bore wear or an intake / exhaust valve not making a good seal. Monitor it and see if it gets worse - or perform a leakdown test and see what results that gives you.

[chriso]

yes, the expansion tank could have a hairline crack that is leaking coolant / letting air in. You did clean up any mineral deposits that were on the plastic nipple before putting that new hose on, right!

Compression is probably a separate issue - but keep an eye on the oil and coolant to make sure they are not mixing in the engine indicating a head gasket failure. If the engine has not been overheated, its more than likely the beginnings of piston ring / bore wear or an intake / exhaust valve not making a good seal. Monitor it and see if it gets worse - or perform a leakdown test and see what results that gives you.

So, I did clean the nipple, reattached the new hose, still leaked, drained to almost empty, refilled it last night, and it is still full today. I haven't checked to see if it's still dripping.

What I noticed is, if I let it run for a while before driving it, it never over heats, and stays around mid point on the coolant temperature gauge.

So, if I let it idle past blue before driving at all, it's fine the whole day of driving.

It's weird, and every time I think I found an issue, it seems to either fix itself, or something else appears to be wrong.

As I mentioned before, I haven't found any issues with coolant mixing into the valve cover. No bubbles or foam that I can see. It does smell sweet when I initially start it in the morning, but it stops smelling sweet almost instantly, and then doesn't smell sweet anytime while driving. I just wrote it off as coolant that was splashed onto the engine overnight, and it burning on the outside, as there's no other signs of coolant burning internally.

I drove about 25 miles today so far, and it has not overheated at all, but I have been letting it idle for a lot longer before driving.

I wish it was just a simple solution to fix it. Seems like the best solution is just to rebuild it from the head up, I'm just trying to not replace a head gasket until I find a nice 885 head to put on the 2.7 block.

[goldenbb]

Welcome to the indeterminate loss of coolant nightmare, also known as an M20. Mine's the b25 and it has a similar mystery--new head gasket, re-worked head, and yet I am still mysteriously losing coolant and have that "hot coolant" smell after the car is parked in the garage. I see no signs of coolant in the oil, but where the heck is it going?

Some notes:

1) If the system is low on coolant, the gauge will not read "hot" so you could be overheating and the gauge won't tell you. So be careful.

2) The lines don't usually leak when the car is off, but mainly when the system is pressurized.

I'm thinking my own problem is maybe one of the smaller lines underneath that drips right on to the road when I'm driving. I notice a tiny bit of wetness, but overall nothing that I can point to that is my leak. Having gone through the head gasket project, I continue to second-guess whether I effed up the install. I did everything the way it is supposed to be done, but maybe outcomes can still not be good.

I have considered replacing my head gasket a second time, or just buying another whole damn engine. Then I get in to the "how do I know the engine I'm buying is good? They're all 20+ years old!"

I have come to hate the smell of antifreeze. Can't stand it, can't stand it on the floor of the driveway.

[chriso]

Welcome to the indeterminate loss of coolant nightmare, also known as an M20. Mine's the b25 and it has a similar mystery--new head gasket, re-worked head, and yet I am still mysteriously losing coolant and have that "hot coolant" smell after the car is parked in the garage. I see no signs of coolant in the oil, but where the heck is it going?

Some notes:

1) If the system is low on coolant, the gauge will not read "hot" so you could be overheating and the gauge won't tell you. So be careful.

2) The lines don't usually leak when the car is off, but mainly when the system is pressurized.

I'm thinking my own problem is maybe one of the smaller lines underneath that drips right on to the road when I'm driving. I notice a tiny bit of wetness, but overall nothing that I can point to that is my leak. Having gone through the head gasket project, I continue to second-guess whether I effed up the install. I did everything the way it is supposed to be done, but maybe outcomes can still not be good.

I have considered replacing my head gasket a second time, or just buying another whole damn engine. Then I get in to the "how do I know the engine I'm buying is good? They're all 20+ years old!"

I have come to hate the smell of antifreeze. Can't stand it, can't stand it on the floor of the driveway.

I've found my cause of the leak to be my expansion tank. While I don't see a crack anywhere on it, I figured I'd replace it since it's faded and impossible to see the coolant level in it anyway, so a new one is just a nice solution.

I have new hoses, and next week I'll be replacing my thermostat, thermostat housing, and expansion tank. Anything else I should look at replacing while I'm in there?


RELATED, this morning I tried to start my car, and it wouldn't turn over. It took 3-5 cranks of the ignition to get it to start, and then it ran fine. Then, my coolant light was on, and it leaked coolant over night onto my driveway. Luckily work is 1 mile away, but, is the low coolant the cause of it not starting? Or is it related to low compression on Cylinder 6?

[Dirty325ix]

Chris it sounds like you have multiple problems that are all independent from each other
if your loosing coolant fluid that is either from a cracked reservoir, ripped coolant hose (if they are the originals just change them), leaky water pump, maybe a cracked radiator, or worst of all a slight headgasket leak(if this is the case than you can test your coolant for exhaust fumes) but in general the coolant system is the easiest part of the e30 to keep leak free so you shouldn't have this hard of a time (mine is leak free and pieced together 100% from free junkyard parts)

as for the 1 cylinder that is at 120 that is out of spec so that would mean you be thinking at some sort of engine rebuild in the next few years (it won't leave you stranded but your missing out on Moar power)

As for the surging idle that is most likely cause by vacuum lakes so just get a smoke test done at a garage and fix everything that leaks (probably leaking everywhere)

And in general don't drive your car around with the temperature needle in the red and if you think your Guage is broken then fix that before you use that same broken Guage to diagnose your problems