Pressure in cooling system

[David]

Hi,
Im having a problem with my e34 524td, the cooling sytems builds up a lot of pressure, it is just imposible to squeeze te upper radiator hose, engine temp stays normal though, but such pressure can't be good I think.
I've bled the system several times, but that doesn't help.

I was thinking that the headgasket was blown, but coolant looks clear, also no steam from the exhaust.

Any sugestion?

[Kyle in NO]

Is it rock hard or just quite firm? It should hold about 12-15 psi of pressure or so....

[David]

Its rock hard......

[markx]

Cracked or warped head....maybe blown headgasket. Are you losing coolant too or is there just an abnormal pressure in the cooling system? I had a cracked head too and it started with pressure buildup in the cooling system......no mixing of fluids or other abnormal effects .....then it gradually got worse during an interval of about one year and the gas buildup got so bad it would kill the circulation and force coolant out of the reservoir cap valve and eventually caused overheating problems. Ended up replacing the engine altogether.

[David]

thanks for the reply's guys,

no, no losing of coolant yet...

So you guys think its safe to drive the car for a few month???

Maybe i'm allready driving like this for a long time, I never noticed the pressure till recently.

I'm gona replace the reservoir cap next week, maybe I get lucky and solve the problem with that.

[Kameix1]

this happens to e34's alot, the expansion tank is mounted to the firewall right?? if so, on the passenger side of the tank there is a drain hose, pull the hose off, take off the cap and run a drill bit into the hole making is slightly larger, then put the cap on and try it again. It usually happens to 535i's here in the states.

[slave2school]

Maybe you can go ghetto and use a headgasket with some RTV on it if funds are tight (till a proper replacement can be had).

[twin55]

Maybe you can go ghetto and use a headgasket with some RTV on it if funds are tight (till a proper replacement can be had).

If that don't work then maybe you can try the Red Neck Way-- Take your .22 pistol and shoot the radiator.
Once all water/coolant has drained, patch hole with duct tape.
Refill Radiator with 2 parts coolant to water.

Normal way:

Take vehicle to an Auto Repair shop and pay them do the job properly..

[David]

yep, its mounted to the firewall.

Il try it first thing tomorrow, thanks!

[David]

Maybe you can go ghetto and use a headgasket with some RTV on it if funds are tight (till a proper replacement can be had).

If that don't work then maybe you can try the Red Neck Way-- Take your .22 pistol and shoot the radiator.
Once all water/coolant has drained, patch hole with duct tape.
Refill Radiator with 2 parts coolant to water.

Normal way:

Take vehicle to an Auto Repair shop and pay them do the job properly..

haha, think a .44 Magnum wil work??

I refuse to go to the bmw stealer, they charge 55euro's per hour

Il do the job myself..

[slave2school]

Maybe you can go ghetto and use a headgasket with some RTV on it if funds are tight (till a proper replacement can be had).

If that don't work then maybe you can try the Red Neck Way-- Take your .22 pistol and shoot the radiator.
Once all water/coolant has drained, patch hole with duct tape.
Refill Radiator with 2 parts coolant to water.

Normal way:

Take vehicle to an Auto Repair shop and pay them do the job properly..

I thought the redneck way would be to just crack the coolant cap, seems cheaper than even wasting a bullet

[twin55]

Maybe you can go ghetto and use a headgasket with some RTV on it if funds are tight (till a proper replacement can be had).

If that don't work then maybe you can try the Red Neck Way-- Take your .22 pistol and shoot the radiator.
Once all water/coolant has drained, patch hole with duct tape.
Refill Radiator with 2 parts coolant to water.

Normal way:

Take vehicle to an Auto Repair shop and pay them do the job properly..

haha, think a .44 Magnum wil work??

I refuse to go to the bmw stealer, they charge 55euro's per hour

Il do the job myself..

x1

[Aquaworksllc]

retorque the head bolts in the proper sequence 1/4 turn on all and this will likely fix your problem.

[David]

Ok, I'm gonna try that, do I retorque them when the engine is warm or cold??
Thanks.

[slave2school]

Generally speaking torquing anything engine related should be cold. When I did the headstuds in the Golf it was after it sat all night.

[ISO_524td]

I would say you would want to re-do the last step of the M21 torque procedure which would be to do it when its warm.

I would reccommend to break the headbolt loose first with a 1/4 turn CCW. Then come back 1/2 of a turn.

I just did this on another 524td I have. To get back up to factory torque specs with the old hex heasbolts, I needed to go another 1/4 to 3/8 of a turn CW. I was expecting at any minute to break the headbolt though......

Dale, how's that cylinder head coming along? Thanks!

[slave2school]

Are the stock bolts TTY?

[David]

hi guys,

I took the valve cover of today and I saw that one head bolt broke completely of

I ordered one new head bolt today, so how do I tighten it?
Is it better to loose al the bolts 1/4 turn and then tighten all the bolts to spec?

I know the best thing right now would be to pull the head and do everything the good way but i'm on a tight budget this month and I need the car.

[slave2school]

First does the Bently say if the bolts are one time use or not? If one broke maybe the others are close to the same state and should be refreshed.

[markx]

Them bolts are for one time use only.....retorqueing a used set is likely to overstress and break them.

Replace all of the head bolts with NEW ones and torque to specs by proper procedure. That is the least you can do......proper thing to do would be to pull the head, have it straightened and replace the gasket too. A set of bolts will cost ya around 40-50$. That ain't a breakneck compared to replacing the whole head due to warpage or cracks.

[muuris]

Try replacing expansion tank cap. Helped on mine.

[bashibazouk]

hi guys,

I took the valve cover of today and I saw that one head bolt broke completely of

I ordered one new head bolt today, so how do I tighten it?
Is it better to loose al the bolts 1/4 turn and then tighten all the bolts to spec?

I know the best thing right now would be to pull the head and do everything the good way but i'm on a tight budget this month and I need the car.

I understand the tight budget aspect, but it might be false economy to try to do this on the cheap. You're likely to have to do it all again or even risk catastrophic failure if the other head bolts let go.

For what it's worth, I recommend Raceware studs instead of the bolts. No stretching-- reusable. Not cheap, but if you have to take your head off a couple of times, they've paid for themselves. Plus, I think they're less likely to spontaneously break.

Josh

[johnnye23]

Fwiw you may be wasting your time not replacing all the bolts. Call Haygood and see what a set will run you . Once stretched you will not get an accurate torque on the bolts when re-using them.

[David]

Hi guys,

Today I replaced the headbolt, I just did that bolt only, didn't touch the other head blots, I followed the 3 step procedure, first 50nm, ---> 90° ---> 15 min. idle---->another 90°

It worked , no more pressure in the cooling system. I'm happy again

Think I can leave it like this for a while?

I'll go for the studs if it ever gives problems again, just need to find a place to buy them here in Belgium.

thanks a lot for all your help guys!

[slave2school]

If someone would be kind to post the length and thread pitch of the oem bolts (and a picture of the head) I would love to look around for a suitable stud, perhaps a bit less pricey than raceware.

Any help much appreciated, I will pass on any info I get on this to the rest of you guys.