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DISCUSSION => Engine + Driveline => Topic started by: AlphaVortex on April 25, 2011, 04:40:18 PM

Title: E36 M42 Overheating after Head Gasket replacement
Post by: AlphaVortex on April 25, 2011, 04:40:18 PM

Hey Guys... I'm not getting much love from 318ti.org, so I'm here begging for your help! Have mercy on an E36 guy! :D This is on a 1995 318ti M42 OBD1.

I have been trying for the past few weeks to get my car back on the road after a head gasket failure.

After all the work I've done, the car now starts right up and idles great. I can let it idle or even drive it, but eventually it will start overheating. The warmest it's gotten is to 3/4 on the gauge before I stopped it immediately. This has been only on trips around the block.

I've tried bleeding it at least 4 separate times at this point (using the instructions posted here, which include separate warm up and cool-down cycles on an incline), with and without water wetter. The coolant gets to a certain point, and just stays there.

Work Done So Far

Head Gasket change (this included new gasket, stretch bolts, other gaskets, etc. that go along with this)

Head taken to a reputable shop. Head was not cracked or warped, but did need a valve job.

New Water Pump and Thermostat (on my third thermostat at this point actually)

All new cooling hoses under the intake (including the plastic piece from the block)

Things to Note

The top coolant hose from the radiator to the thermostat is always hot, but the lower hose is cold. I tried removing the thermostat and running it, but it still wanted to overheat. With the stat out, the lower hose DID get much warmer.

There is NO smoke, and from what I can tell no oil in the coolant, and no coolant in the oil. I have pulled the spark plugs a few times and each time the cylinders were clean.

There were no obvious cracks on the block, but I did not have it professionally inspected.

I did have a stripped water pump bolt that I had to helicoil, and I was not able to tighten it QUITE as tight as the other bolts, but close. No leaking from the water pump.

There is a small amount of coolant coming out of the side of head/block directly above the plastic coolant piece and directly to the side of where one of the head bolts would be... this seems to leak only once the motor has gone to that 3/4 mark... until it gets to that point nothing leaks.

So off the top of your guys' heads... does this seem like a simple air trapping issue? A blockage in the coolant passages? Maybe the radiator? I'm honestly starting to get real stressed that maybe I cracked the block (perhaps I didn't manage to get all the liquid out of the head bolt holes?).

Any thoughts or advice from you guys would be great. I'm getting to the point where I'm about to call it a wash. :(

Title: E36 M42 Overheating after Head Gasket replacement
Post by: monty23psk on April 25, 2011, 09:35:22 PM

I would recommend doing a coollant pressure test to see if you have a leak first. Before going crazy replacing more parts, this will give you a real good idea of what you are dealing with. Then if you maintain pressure, you have no leaks and need to find out if you have trapped air or blockage.  I would start there. If you are located by me, I have a Stant coolant pressure tester we can try.

Title: E36 M42 Overheating after Head Gasket replacement
Post by: B318M42W on April 25, 2011, 11:50:28 PM

I'm thinking a failed water pump... impeller might be loose and only moves a certain volume before it slips, but not enough to keep it cool

Title: E36 M42 Overheating after Head Gasket replacement
Post by: mr.vang on April 26, 2011, 01:50:48 AM

check to see if all the water hose by the firewall is flowing the same direction..

Title: E36 M42 Overheating after Head Gasket replacement
Post by: AlphaVortex on April 26, 2011, 10:44:08 AM

Thanks for the suggestions guys! In a fit of rage I pulled the head back off, and low-and-behold theres a nice crack from a water channel into cylinder 2.

yay

Now to find me a used head. Any suggestions on the best places to get one for cheap?

Title: E36 M42 Overheating after Head Gasket replacement
Post by: gearheadE30 on April 26, 2011, 10:55:48 AM

ebay, junkyard, and these forums.

Interestingly enough, I have a similar overheating issue....looks like I'll be pulling the head too.

Title: E36 M42 Overheating after Head Gasket replacement
Post by: AlphaVortex on April 26, 2011, 11:00:03 AM

Well when this first started I checked ebay and there were like 6 up there, some for cheap! Of course now that I need one, theres ONE, and its for $400 before shipping lol.

Not many BMWs in the junkyards around here... crossing my fingers.

Title: E36 M42 Overheating after Head Gasket replacement
Post by: mr.vang on April 26, 2011, 11:44:56 AM

there is 4 m42 at my local picknpull yard. i can grab it for you if you paypal me 190 shipped. if they are gone i'll just refund you back the money.

Title: E36 M42 Overheating after Head Gasket replacement
Post by: AlphaVortex on April 26, 2011, 02:41:22 PM

Cool I'll let you know if thats something I need to end up doing!