Can't seem to get my E36 M3 coolant system bled correctly

Nose in the air, heater on high, squeezing both hoses, revs up. Finally got hot air out of the vents. Heat cycled it in my garage and topped up each time.

Thought I had it so I drove to a friends house today, VDO water temp gauge read 20 degrees higher than before. Got to his house, engine off, cracked the bleed screw and got a steady stream of coolant, no bubbles.

Let it cool, had to add just a small amount. Drove home, same temps, getting really hot air out of the interior vents. It's cooling in my garage right now.

WTF? Thought if I got hot air out of the interior vents that meant I'd gotten all the air pockets out?

Have you tried the magic yellow funnel?

https://www.amazon.com/Lisle-24610-Spill-Free-Funnel/dp/B001A4EAV0

I dunno specifically about E36 M3s, but it works well on other cars. It seals to the radiator fill cap, you pour a bunch of coolant in it, run the car for a while to burp it, then you add the plug to seal it, take the funnel out, and put the cap on.

I have the same problem with my race car. Very frustrating. Try jacking one side up in the air instead of the nose. Seems easier to get the cap way higher than the head. You can also try cracking a fitting in the head area to relieve any pockets of air there. The other thing I do is use an oil suction gun with a rubber hose on the end and force coolant into the head under pressure.

This is not really useful, but nobody on the planet can make a cooling system harder to bleed than a German.

Except Nissan.

Trick I was told was to jack it up, squeeze hoses, etc and then let it run and leave the cap off. After a little while the Coolant will start to drop out of a pin sized hole on the inside of the filler. Once that gets a steady stream it should be good

Hmm, I've bled lots of E36s and never had much of a problem. I usually jack up the front, remove the plastic bleed screw on the top, and fill the over-flow until a steady stream comes out the bleed screw (no bubbles). I typically drive it for a bit and then rinse and repeat, so to speak just to be safe. Last track weekend, I did it a few times (long story, pin-hole leak in a hose that I was struggling to find).

my old 318ti had a small leak (later discovered to be my brand new water pump)and I had to refill and bleed it every two weeks.. never had the issues you are having

wake74 wrote: Hmm, I've bled lots of E36s and never had much of a problem. I usually jack up the front, remove the plastic bleed screw on the top, and fill the over-flow until a steady stream comes out the bleed screw (no bubbles). I typically drive it for a bit and then rinse and repeat, so to speak just to be safe. Last track weekend, I did it a few times (long story, pin-hole leak in a hose that I was struggling to find).

Pretty much this, but with the hose squeezing trick thrown in for good measure. I have been told that side to side oscillation is also a good idea, but that is pretty much impossible to do with any sort of front jacking system, save for NASCAR style pit crews. I've never had an issue with the above method though, so maybe you've got a small air leak somewhere up high that's not pushing everything out?

Yeah, been doing the jack up the front, squeeze hoses, ad nauseum. I have a persistent air bubble in the system somewhere.

Friend is coming over tonight with a pressure tester, we'll use that to force all the air out...

docwyte wrote: Yeah, been doing the jack up the front, squeeze hoses, ad nauseum. I have a persistent air bubble in the system somewhere. Friend is coming over tonight with a pressure tester, we'll use that to force all the air out...

I've owned and raced S52 powered cars for a long time they are not difficult to bleed and you are doing everything correctly.

You either have a pinhole leak allowing it to suck air in, or you have a failing head gasket pressurizing your cooling system. Replace the coolant cap first. It's the #1 culprit closely followed by cracks in the overflow bottle.

Then, if not fixed, pressure test test the cooling system and look carefully at the radiator and water pump. If you have a leak you can't find bubbling at a hose, connection or bad casting on an aluminum water neck... short the hoses going to the firewall (heater core) and test again. Failing that - open the oil cap and put your ear to it. If you get here, it's time for a compression and leak-down test. They typically breach a head gasket between 4 and 5. If the car was ever overheated - skip all the rest of the diagnosis except the new cap and start with the HG.

All that stuff is new. New expansion tank, new cap, new hoses, tstat, water pump, radiator, etc, etc.

Car never over heated, I replaced all this stuff due to maintenance.

We'll be pressure testing it this evening, I really hope its not a head gasket, hard for me to believe it is as the car was fine before I replaced all this stuff and started to bleed it...

docwyte wrote: All that stuff is new. New expansion tank, new cap, new hoses, tstat, water pump, radiator, etc, etc. Car never over heated, I replaced all this stuff due to maintenance. We'll be pressure testing it this evening, I really hope its not a head gasket, hard for me to believe it is as the car was fine before I replaced all this stuff and started to bleed it...

If you just touched all that stuff - I am a firm believer in Occam's Razor so ... it's either a faulty new part or a leaky clamp.

Good luck!

A leaky clamp would make my day