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Ralphjenner 11-05-2012 07:54 AM

'87 316 M10 overheating with new parts
Hi all. have had a look but can't find another thread on this. Sorry if I have been thick.

I have a 316 m10 1.6 '87.

Since a rad broke I have had a mystery problem. Car overheated and was trucked home.

Engine ran fine, no signs of head gasket issues. So the car has had a new rad, 'stat, fan coupling. Hoses are new.

After the rad change she was fine for two weeks and then boiled her water. Stat worked in a pan but clearly stuck in the car. Short circuit too hot to touch, bottom hose cold. would overheat within two miles

Changed stat. Now the car will run for 10 miles fine. Then it starts to boil and throw coolant. bottom hose is warm but easy to hold. Top hose to rad v hot. Short circuit hoses n stat very hot, rad boiling.

About the only unchanged part is the pump which is six years old.

I have heard that you should fit the 'stat hot from a pan of boiling water, ram the hoses on and drive, adding water after some minutes, and fasting up the clips at this point. Can't find any other reference to this on the web so hesitate to boil a new stat. Pump is not weeping or squeeking.

Any ideas ? I am starting to despair and I love this car.

Thanks, Ralph

hornhospital 11-05-2012 03:16 PM

Take a peek at the pump impeller. I'll guess that it's shed it's fins, or is loose on the shaft.

Short version: change the pump. Should have been done with the rest of the work. :rolleyes: I hope you haven't hurt the engine.

downhiller 11-05-2012 05:00 PM

+1, sounds like the pump is bad or youve been putting the tstat is backwards. pump is a more reasonable answer

BMWFatherFigure 11-05-2012 05:02 PM

Hi Ken, That sound like a fix. I would check for impeller parts in the radiator too. CS.

Ralphjenner 11-06-2012 04:00 AM

Thanks guys. Will get into the pump as soon as rain stops. I have a nasty feeling that a leak from the head gasket is pumping air into the system.
BUT has any one heard of this "boil the 'stat before fitting" caper ??? The advice comes from my parts supplier who has worked with BMW s since the sixties. Quote "It often takes to or three goes as they are hell to bled"

Did not fit a whole new system in a one er due to the fact that she was ok with a new rad for a couple of weeks, THEN the 'stat seemed to stick one day...... ho hum

Anyway a nice engine to work on so if the head has to come off it comes off !

Ralphjenner 11-06-2012 06:44 AM

As an aside I have been examining the rad cap. It seems a bit ropey, with the rubber seal perhaps not seating all the way round. Looks a little melted too . Hmmm. If , when the rad is pressurised water can get by the seal it will be lost via waste ,no ? I will be checking this too. Wish I had a nice pile of parts to swap about. Will wait 'till pump looked at and then change it I think.

BMWFatherFigure 11-06-2012 04:57 PM

See if you can install a coolant recovery system. Works better than a 'vent to atmosphere' system.

downhiller 11-06-2012 05:13 PM

if the rad cap is bad, then yes youll loose fluid which gives you what youre talking about. forgot about that bugger

Nick323 11-07-2012 12:04 AM

It mazes me how few people look at this part costing under 10 USD

downhiller 11-07-2012 03:59 PM


Originally Posted by Nick323 (Post 7180667)
It mazes me how few people look at this part costing under 10 USD

the pressure cap? yea, its forgotten alot. sneaky lil bastard

BMWFatherFigure 11-07-2012 04:50 PM

Still try for the coolant recovery system. Keeps oxygen out and slows corrosion.

Nick323 11-07-2012 11:53 PM

coolant recovery system

coolant recovery system
All our 323, 325 etc came with that standard :thumbup:

_Ethrty-Andy_ 11-08-2012 12:07 AM

sorry missed this post before, and already decided it was likely to be the radiator cap before finding that solution further down the page. Is the radiator after market? the carb'd 316s used an all metal radiator right? BMWs run a higher pressure cap than most traditional cars, but whether it applies to your 316 im not sure. never the less they are a good car, i know a guy with an E21 with the same engine

BMWFatherFigure 11-08-2012 06:23 PM

I know the larger engines have recovery system but he has a 316/318. I dont know if factory parts would retro fit. If not after market is available, even a system from wrecker would do the trick.

Ralphjenner 11-09-2012 08:30 AM

Ok. Had the pump off. It is still like new. The car having had a new ?stat, rad, & fan It is felt that it is time for a new head gasket. I suspect that air is entering the system and forcing out coolant, causing locks etc. I have just changed the head on my 6cyl Nissan Jeep which did the same thing. IT has an expansion bottle so I could see the bubbles....

The view through the pump mounting is of a VERY clean and un rusted cooling system. The engine is at around 100,000 miles so a new gasket will do it no end of good.

I'll keep ya'll posted , and thanks for all the sensible replies.


Ralphjenner 11-13-2012 07:18 AM

Ok. Pulled the head off yesterday. Nice easy job on the m10, mind you I had good help. Result, a nice clean head with no pitting. Three pistons with normal carbon and one, No 4 nearest firewall, clean as a whistle. Gasket had just started to go round No.4 . So head is off getting skimmed, gasket set on the way. We'll stick some new stem seals in as we go. So all good news. A nice overhauled top end/cooling system will be the result, and not too expensive either. Worth noting here that my last two gasket problems have NOT resulted in coolant loss, or oily water , symptoms are overheating under load, and failing to respond to other fixes, ie fans, stats etc.

Thanks again for all the good advise , Ralph

BMW318i_ 11-13-2012 03:36 PM

Wow nice job I hope this does the trick

Sent from my HTC Sensation Z710a using Bimmer App

Ralphjenner 11-22-2012 08:06 AM

Great. Runs well now with a new gasket. Heater works now too due to not being filled with air.

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