Blown intake manifold gasket

[E30_318i 0]

Once again, exactly a year (to the week) after my 525i blew an intake manifold on the 6th cylinder, it happens again. I have just over one week of doing nothing before I go off to the navy, so thought I might give it a try. I looks like a rather straight foward fix, but for those who have done this, are there any hidden, annoying suprises when removing and replacing the manifold?

Does the throttle need to be adjusted when the manifold is off?

I assume it is a good idea to replace the hoses that need to come off as well?

Also is there any reason why it has blown the gasket twice in one year on teh same cylinder? I have been told the manifold could be warped.

My E30 Bentley manual doesn't have any info on this job, the closest it comes to is R/R of the throttle housing (looks like where all the hassles/fiddly sh*t lie).

Other than that I have to rely on internet boards, already searching an E34 one, quite helpful.

Cheers.

[topless 13]

what motor does your 525 have?

[E30_318i 0]

The ol M20

[topless 13]

It is a fiddly job rather than a difficult one because of all the bits that are in the way of getting it off.

It is possible the manifold is warped. Check it with a straight edge when you get it off. If it is warped it is probably cheaper to buy a secondhand one then get it machined. Also, check the studs around where it is blowing, one may be pulling free of the head allowing the gasket to loosten. When replacing the gasket, put a thin layer of a good gasket compound on both sides. (I hate silicon, I use a Loctite product..)

The only tricky bit in removing /replacing the manifold is to depress the oil return tube that joins the manifold to the sump and keeping it depressedwhie you remove or replace the manifold... use a waterpump pliers and twist it downward. It will mostly stay down but some will not. It has to be held down to get the manifold free. If it is one that does not stay put, when you have the manifold off, slightly deform the bit that goes into the block so it is a tighter fit. Also replace the o-ring at the top. After replacing the manifold, make sure this tube is properly seated into the manifold. Twist it upwards with the waterpump pliers and check that the o-ring has seated itself properly.

You also have to remove the thermostat housing with the manifold unless you can manage to remove the temp sender units with it in place, a difficult job!

Check the hoses out, replace if brittle/cracked and don't forget to do the fuel lines!!!

While you have the manifold off, check that the throttle position switch is in adjustment, the Bently E30 manual has a good description of how to do this.

Hope this helps you.

Edited January 5, 2006 by topless

[Gus 5]

and don't drop anything into the oil return....ask me how i know.

albeit i did it while off the car, but will is right, more fiddly than difficult

[E30_318i 0]

Thanks a lot. Have gathered some info off E30 boards aswell and will give it a shot in a few days

Now it has a broken engine or g/box mount :banghead: