More bloody overheating!!

[dogger]

Took my 1989 325 up to my mums over xmas, about 160 miles, cruised at a good pace as its motorway 99% of the way. Got there, switched off and before i got out the car i could hear it gurgling loads and it was throwing water out of the expansion tank all over the road but id not seen the temperature creep up.
The week before the coolant light had come on and it took about a litre of water to top up.
I called the RAC as i needed to get home the next day and he said the thermostat was jammed- i replaced it last year with a cheap one, so i got towed home phoned BMW and got a genuine one- lesson learnt i thought- replaced it and its still the same!
I can drive two miles and no more before the needle is right thru the red.
Any quick and cheap ideas as im hoping to part ex the car before the weekend???

[Brianmoooore]

You've overheated the car with the duff thermostat, and that once could well have been enough to cause permanent damage. If you drive it now and it overheats, you will almost certainly cause damage if it hasn't happened already.
If the car overheats that quickly, you probably have an air lock. Does the heater give out heat up to the point you shut it off?

[dogger]

Ive got no mayonaise in the filler cap or dip stick and did a quick compresion test earlier and got 10 bar on cylinders 1 to 4 and 9 bar on cylinders 5 and 6.
Yeah the heater is still giving out heat. Ive not driven it since it over heated but need to get shot now, i did wonder about an air lock as i had great fun trying to get all the air out when i did the thermostat last year but got it eventually. the car is jacked up as high as i can get the front at the mo to see if that helped as it seemed to last time

[Brianmoooore]

If the heater is working, then there's no airlock.
Do the radiator pipes get hot at all? Are the rubber O rings present on the coolant pressure cap?

[dogger]

yeah both o rings are there, the water is going down the little overflow hose.
none of the 4 big hoses at the front get hot, the two off the rad and the other two- all the big sort of inch and a half size ones- all cold

[kam-325i]

Id check the thermostat again......

[dogger]

yeah i know what your saying- is a brand new genuine bmw one tho!
and it went in the same way round as the old one- in fact i dont think you can fit them the wong way round can you, coz of the shape of the housing

[Brianmoooore]

Id check the thermostat again......

There doesn't appear to be any appreciable circulation, so there's something odd going on at the front of the engine!
Stat? Water pump rotor? Blocked radiator?

[dogger]

if i get chance tomorrow i might try running it without the thermostat just to see if i can get any flow, and maybe try pullinf one or two hoses off and cranking the engine to see if the water pump is going or not, cheers guys

[kam-325i]

Thinking about, thats how mine started.

It turned out the be a leaky waterpump. It was leaking from the front of the pump, just behind the pulley.

The bearings had given up the ghost and the impeller was shot....

Ended up cracking the head.

[dogger]

the pump is definatly pumping coz i took the hose off and cranked it and i can see it spinning, ive taken most of the main hoses off and the radiator is in great condition and ive had my fingers in a few holes and all seems pretty clean.
Am thinking its got an airlock in it so ive started pulling hoses off and filling slowly from several points, will see what happens

[anton89]

Have you sorted it out yet? I had corrosion in a waterway which was causing a blockage in the system resulting in alot of back pressure, more pressure more heat. solved it by draining the system and refilling with a chemical that dissolves calcium deposits. let it sit over night and then drained it. reffilled with distilled water and coolant now sits a couple of degrees under half even when I tracked it. Have you tested the thermostat? I place it in a pan of cold water with a thermometer and the heat the pan taking note of the temperature at which it opens.

[bjg16v]

did any water appear in the passenger footwell ?

[Tay]

to put my 2 penth in!!! i would have to say the water pump is shot, you may have one of the models with an aux pump on the heater?

usually what happend is that the impeller will spin when the engine is cold, however once it gets hot it expands and stops spining while the spindal obviously still has drive. certainly worth checking.

hopefully you haven't cracked the head as what is common when these engines go into the red a couple of times!!!! but that is worst case!

[dogger]

hey bjg16v- ive had a look and the passenger footwell carpet is soaked, never noticed as the mats are so big- what does that mean? is it a good sign lol?
all the hoses and in the rad where ive pulled stuff off and had a good look or a poke around seem really clean tbh, but obviously it could be something inside the engine.
i poked my finger in the water pump and couldnt turn it but it definatly goes when its cranked, but it is only cold like you say, hope theres no serious damage!

[Tay]

if your carpets ar wet then more than likely the heater matrix is gone, you can replace it without taking the dash out but it's a pain in the arse!!!!

[bjg16v]

dooger,ive replaced my entire cooling system over the last 2 weeks but it was still the same overheating possibly air locking.

so i turned my attention to the matrix and spent an afternoon taking it out yesterday.
turns out the end cap on my matrix has a split in it all the way along ! thats the problem

its not such a bad job to get to the heater matrix just time consuming if you have any questions feel free to pm me ive got photos on my phone i could send you + ive got mine in bits still whilst i await a new one and im only down the road from you if you fancy taking a look.

[dogger]

right i've pulled all the panels off and with the engine running i can see nothing leaking round the matrix, not even a drop, my wet carpet could be the little round panel on the floor pan which is quite rusty!
it got hot but i was getting not hot air out of the heater - so thats an airlock isnt it?

[dogger]

and as i didnt have the filler cap on after it started to get warm the water was bubbling out of the filler hole

[dogger]

im thinking more head gasket than anything else right now, but i seem to be changing my mind every hour.
have re-fitted the heater matrix and im happy that its fine, but ive got paperwork which says the head gasket and water pump were replaced in oct '08 and its only done 11000 miles since then? could they still be the problem?

[Tay]

possibly the waterpump but you don't know who did the head and how they did it!!!???

[dogger]

no i changed my mine since then!!
poked my finger in the water pump and turned the engine by hand and couldnt feel anything turning so i decided it was that- 4 hours later and the pump is off and its definatly not that!
have already paid for a new one at ECP so i'll fit that tomorrow then i guess i'll have to buy myself a head gasket whilst im there

[Brianmoooore]

Have you checked that the vent pipe from the top of the radiator to the coolant bottle is clear?
You should be able to see a steady stream of coolant flowing into the bottle at any revs. above idle.

[dogger]

ive just had a quick blow down i and its clear

[dogger]

can head gaskets leak one way only, i mean can coolant get into the combustion chambers but not the other way?
ive got no sign of mayo on the filler cap or the dipstick at all, not even a hint, but have got all the other signs

[dogger]

More good news- the head gasket WAS ok!! fuck!

[Rtaylor2208]

Having read through the thread can you confirm \ deny a few things as its not so clear now with everything thats been tried.

1. Your heaters are working?
2. When bleeding from the bleed nipple do you get any water or air bubles comming out.
3. Are you loosing coolant?
4. Have you tried removing the rad and flushing through with a hose to make sure its clear?
5. Have you tried the new theromstat in hot water to make sure it opens?

Just a bit of a summary of what has \ hasnt been confirmed as working it might be easier to give you further help.

[Tay]

So you lifted the head in the end!!!! I'm a bit stumped at this one without looking at it!!! If you have lifted the head would definitely worth checking for cracks and the flatness of the head??? They usually have avisible crack along the underside of the cam from the rear.

It only takes a tiny air leak to throw the whole coolant system out! Worth checking all the hoses especially the one on the back of the head, waterpump gasket and any others,

There is obviously something stopping the coolant from circulating! And it's hard to diagnose if you can't see!

[dogger]

yeah i know what you mean about trying to diagnose something over forums, quick summary-

the heater wasnt working when i checked again
had a fair amount of air out the bleed point but then just water, by which time its got v hot and is throwing water out the expansion tank so i have to switch off- its hard to top up the system when the water is pouring out the filler cap
coolant was definatly going somewhere but this is only very recent, last two trips out
tried flushing thru the rad and any hoses/ pipes i took off, rad was pretty clean
both the new and old thermostats opened fine in a pan of water
old water pump was fine, all intact and twirling away, new one on now tho

when i changed the 'stat about a year ago i had massive trouble bleeding it and was driving irratically to try and loosen any trappped air, parking it up banks on the side of the road to bleed it so i know what a pain they can be, but this seems different

gonna strip the head this morning- did notice the holes in the head gasket along one side for the water were about 6mm diameter and on the other side they were only about 2mm!! is that normal? not clogged, just made that way

[Tay]

mmmmmmmmmmmm they are usually only about 2mm sounds like the gasket has gone? you should be able to see a blackening around one or more of the cylinders on the head where the gasses have been blowing passed? give it a good check for cracks between waterways and cylinders/vaves and under the cam, shouldn't be any need to pressure test as they are usually prominent! and check for flatness on the face of the head too!i would expect to see it blowing on the back 2 cylinders. check for corroson on the head too!!!!

[dogger]

just to finish off- all seems well now its back togther. might have been the head gasket and i couldnt see the damage possibly, some bits pull apart as you lift the head off so maybe, but its sorted now, thanks for all the help guys