cooling

ok i been looking first in case someone posted that before but couldn't find anything.

we changed the thermostat yesterday on my 1996 2.5dei bmw engine.
it was the original - not blueprint part - as it came faster as the aftermarket one. - i just didn't want to wait..

so we taken the old one out, put the new one in after cleaning the housing and surrounding.
refilled water.
blotch....... it leaked.
hmmm.

all back apart and try again.

leaked.

so we made a gasket from heat resistant rubber 1mm thick.
all back in and no leak.

i drove about 30 miles home. - when it was cold refilled about 2 litre coolant.
today i did a roundtrip in 28 degree for about 80 miles. cross country and heavy traffic in town.
temperature staid steady.
when i came home after it cooled down i had to refill another 1 1/5 litre.

but there is no leak. no temperature rising or anything.

chocked oil and water etc. no wet inside the cabin.

just wondering - dos the coiling system on the 2.5 dei need a lot water ?
and / or is there any gaskets other used because of the leaking problem after exchanging the thermostat.
( all i found was one for the petrol engines, and inclined getting one and just put it on. but is some kind of paper seal? )

i always checked when i stopt for a while of any water under the car but nothing ( over paranoid ) . - unless it is going somewhere i don't know ?

( and yes as i had suggested i checked island 4x4 and rimmers for any available seals. both saying the 2.5 only has the rubber o ring. )

There should be a rubber o ring with the thermostat, bid the new one have a small bleed hole in the outside ring.

Yes. The o ring didnt prevent the leak. Lol.
It dos fit how it should but for some.reason it was leaking .

And yes the small thing is there.

There is a kind of Alan key on the thermostat housing but we didnt open it because the fan is in the way. Lol
So we did bleed it the way we would any other car.
Pressing pipes.and wait till refill then test drive.

If you have booked the system properly and the level keeps dropping then you have a leak. Either into the cylinders or to the atmosphere. If it leaks onto somewhere hot then it could be evaporating instead of making it to a puddle on the floor.
Have you got a pressure tester? It's a great way to find leaks

Nope. I dont.
I may know someone.

I dont know much about diesel engines sorry. I always had petrol.

There is water in the pipes but they not hard as it would be on a.petrol even when it's cold.
You can hear the water flow.

No smoke from the exhausts if that's what you mean with going in cylinders.

Coolant system on a diesel is much the same as a petrol, water jacket round the engine, pipes, radiator, expansion tank. The same rules should apply.
When it's cold, there shouldn't be any pressure and you should be able to squeeze the pipes easily, but there should be some pressure when it's at normal running temp
Are you filling to the correct level when the engine is fully cold?

Yes.
Yes that's right. You can squeeze the pipes and hear the water in the overflow.
When the hot the have pressure.
And yes correct level


I may just been paranoid because of the second time.to refill after I done a day out.

It's just the fact of not sealing the housing as it should according to the repair manuel.
That was.my worry.
Not sure if that is normal at this age.

It’s a sealed unit. Shouldn’t require topping up after it’s settled.
They do need good burping with the hoses, I park mine front right corner up hill for it. (Rhd)

There is a U-pipe at the back of the head RHS sometimes rots out that people miss

Ok. I'll check that pipe.
And I park him overnight up hill. My drive is up hill anyway.
Good idea. Thabks.

Only slightly lol
As opposed to dead level

Right. Result.
Parked.slighcup hill over night. Buried got another 5 min. A bit water top up.
140 miles today.
All sound. No more water / coolant to top up.
And checked that pipe. Previous owner must have changed it. Is brand new. Lol

Good news