Oh no! BMW's infamous cooling system strikes again it seems....

Scania

Scania

Scania

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25 Nov 2004
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On the road....
My e36 328i decided to overheat last night on the way home, well, I noticed it was 3/4 on the temp guage where normally, it would be bang in the middle.

I stopped and let it cool down and then rather stupidly :o removed the expansion tank cap!.

One shower of hot coolant later, I filled it back up and drove it gently back home the temperature stayed half way as per normal with no problem.

I've driven it again gently to my parents today (with the temp guage not moving beyond 1/2) where I've had it on flat ground and been bleeding the thing - I live on a hill - , lots of bubbles coming from the bleed screw when its removed and the car seems to have taken an awful lot of coolant.

I went out to get yet more coolant and the temp went back upto 3/4 yet almost immediately went straight back to 1/2 ! :confused:

I'm wondering if either I have a water pump thats starting to fail, or possibly a dodgy thermostat?

It will be into the garage asap to get this sorted, theres definately something wrong, its had a habit for a while of losing nearly all of its coolant after a real hard hoon but the overheating is a new issue, bar giving it a bit of right foot to get it upto motorway speed on the sliproad last night, I was driving it gently following an HGV in the middle lane.....

The car has been pressure tested with no fault found.

Iirc, Invader had a similar problem which killed his M52 engined 328i, does any of this ring a bell mate? :(

Catch 22, need to get the car fixed asap but equally need the car...... :(

Tempted to take it down a quiet lane & torch it ..... :D j/k

Any thoughts appreciated.
 
Check the thermostat in a bucket of boiling water, and take your waterpump out to make sure it's a metal impellared one.

Bleeding these systems is almost impossible, my old 325i is still being refilled/rebled by its current owner a few times a month (proven HG not failed by garage), most of the issues are caused by air locks rather than HGF, although if you get an M52 too hot, you WILL warp the head.

Next time you bleed it, make sure that you have the front end jacked slightly (otherwise the heater matrix is actually the high-point in the system).

What is your bleed process anyway?
 
MikeHunt79 said:
Hmm, fist thing I'd check is the coolant hoses, and maybe check the rad also to see if it has a leak?
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The hoses are soft to the touch and the rad is less than 6 mths old (was replaced by the garage that supplied the car) theres a bit of what looks like limescale around the waterpump assembly (well, I think thats what it is!) I'll take a picture if it'll help? - I had said deposits investigated by a local garage that I trust (the same poeple who pressure tested it) and whilst they agreed that it had been leaking at some point, it seems that the coolant is not being lost from there any more.


paradigm said:
Check the thermostat in a bucket of boiling water, and take your waterpump out to make sure it's a metal impellared one.

Bleeding these systems is almost impossible, my old 325i is still being refilled/rebled by its current owner a few times a month (proven HG not failed by garage), most of the issues are caused by air locks rather than HGF, although if you get an M52 too hot, you WILL warp the head.

Next time you bleed it, make sure that you have the front end jacked slightly (otherwise the heater matrix is actually the high-point in the system).

What is your bleed process anyway?
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Cheers for the tips paradigm. :)

My bleed process involves removing the bleed screw, starting the engine & filling the rad with coolant until bubbles stop appearing from said bleed screw appeture, replace screw & cap, drive car & repeat.

Done this about 5 times this after.....

It behaved itself on the 12 mile or so trip back from my parents although the expansion tank level had gone down considerably (just above the sender) on my return home.

Topped it up again doing the same bleed procedure, again, lots of bubbles initially and then they stopped.

I was using hot water in my coolant mix btw, not chucking in cold....
 
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when my e39 did this turned out to be the pump on the way out aswell as a blocked radiator and a blocked hose where someone had used some radweld or whatever its called.

So check the pump and rad for blockages or signs of white gunk.
 
Piccys...

P1010105.jpg


P1010106-2.jpg


P1010107.jpg


P1010108-1.jpg

^^ Bleed screw to the left of the rad cap (with a cross on it)
probably as much help as a chocolate fireguard, sorry. :o
 
Firstly, when doing the bleed, heaters on, full. You want to wait until the temp guage hits mid-point, then hold the engine at around 3,000RPM for 1-2 minutes, cycle through this until you start to get hot blow through the heater. Top up as necessary once you have no more air bubbles through the bleed nipple.
 
Sounds similar to what mine did after the rad pipe snapped, it really is a pig to fill up, problem I had with mine though is it blew a hole in the head so water would come out when it got a little bit warm resulting in the high temps and removal of coolant.

It was never obvious with the escaping water, till it was low and mostly steam in the system.
 
Egg won't help the leak if there is one.

Make sure the thermostat is good, that's what aided in the death of my 328i, combined with the viscous unit of the fan being duff too, it wasn't locking up at high temps so was doing minimal cooling...in hindsight, it's well worth the £60 the unit cost. :(
 
InvaderGIR said:
Egg won't help the leak if there is one.

Make sure the thermostat is good, that's what aided in the death of my 328i, combined with the viscous unit of the fan being duff too, it wasn't locking up at high temps so was doing minimal cooling...in hindsight, it's well worth the £60 the unit cost. :(
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? using an egg is a well-established means of fixing a radiator leak :confused:
 
NickXX said:
Be very careful tightening that bleedscrew up. It only needs a quarter turn to seal it (especially with your heavy hands :p).

I managed to snap mine off (it's a plastic screw) and get covered in hot coolant.
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I tightened it up using a piece of brittle plastic which broke as soon as it was tighter than finger tight if you see what I mean. I managed to crack the expansion tank cap on my Scania by overtightening it a few days back.... :o:o:o:D


InvaderGIR -Thanks for the info mate,very much appreciated. :)


InvaderGIR said:
No, it's a way that can sometimes temporally fix a leak that was used in like the 80s.
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True enough, these days a few doses of radweld does a far better job, not to mention your coolant won't stink to high heaven after a few weeks.... :D
 
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