Head Gasket R&R in M30 engine

[NJe23junkie]

How difficult is a Head Gasket replaement in the old M30 (3.5L big six) engine?

My level of functionality:
1) I have replaced the final drive (diff & CV boots)
2) removed a driftshaft
3) change Oil, plugs, acessory belts, etc...

But I am a bit nevous about undertaking the head gasket w/o some direction.

Thoughts & insights appreciated.

ERT

[webmasterz]

Hi NJe23junkie

It is not that difficult if you take your time and work methodically.
There are a few awkward nuts n bolts waiting to skin your knuckles, but if you are prepared to give it a go its achievable.
I replaced mine on my E32 last weekend total time including tea & cigarette breaks about 12 hours.

[NJe23junkie]

Thanks Webmasterz,

I have nothing but time so 12 hours isn't too bad.

Especially considering the alternative, paying someone else for 12 hrs of labor + parts and only coming away with my pockets a wee bit lighter.

Is there anything tricky that I should look out for? Bolts to purchase instead of reusing (or because one tends to strip them), seallent, lines to replace while there, etc?

[webmasterz]

OK well its like this!

Because the lower inlet and exhaust manifold bolts need someone with flexible arms beyond whats normal. If you can get away with unbolting the exhaust downpipe and with some help lifting it all off in one go.
You can allways replace inlet and exhaust manifold gaskets on the bench if need be.

I couldnt undo the downpipe nuts (rounded off) so removed both inlet & exhaust manifolds insitu. But I was using a mates workshop with a fine collection of snap-on swivell head sockets and the like.

32mm thin spanner to remove the viscous fan

ensure cam timing is correct.

Any more info?

Tony

[NJe23junkie]

I attempted to remove an m30 engine from an euro wreck and ran into some problems, (ie removing the exhaust man bolts). I was able to get 5 of six of each and i could get the downpipe bolts because they had rusted and rounded off.

....Don't get me started with the fan! I have the wrench and I have been turning for days with no effect. Next I thought that I could take the fan blades off (ah duh) not a chance ...

So after this experience i was just seeking any assistance in the form of pre-screw up notes because this is the "good engine".

[webmasterz]

The fans a reverse thread - a sharp blow with a hammer to the spanner should see it off.
The trick is to Shock It

Re the nuts If you can hammer an under size socket on (7/16" !) often the stud will come out as well, not a problem because you can put a new one in on the bench

[NJe23junkie]

Ok, maybe I am the village idoit (and I just might be), becasue the fan turns freely clockwise ("righty tighty") and nothing is coming off!



The next item you mentioned was the down pipes. You are right about this being another point of difficulty. I rounded and/or could not get a clean grip to remove these. Maybe I could have driledl them out from above?!?



So I thought I could be a wise guy and work around removing the down pipe and just take the manifolds off... Getting 5 of 6 bolts will frustrate you worse than being a Philadelphia sports fan!
(And I am a die hard Philly sports fan).




PS: Yes, I like to keep pictures of my defeats as well as my victories. If I can learn for the next time it is worth and angst of seeing them over again in the "BMW projects folder".

[prairieman]

if you're still having difficulty with the fan clutch nut, leave it.

fan removal is not necessary to remove and replace the cylinder head on the M30.

Brad
1979 635CSi
1981 745i
1991 M5
1992 735i

[NJe23junkie]

Update: The exhaust manifolds are off as well as the upper timing chain cover. I am at the point of attempting to remove the upper sprocket & chain so that I can remove the valves and expose the head.

I have removed the 4 bolts to the spocket and I am currently seeking a source for a 41 mm socket to fit the nut that appears to hold the sprocket in place.

(After this my tool box will be quite a bit more extensve.)

[webmasterz]

You only need to remove the 4 bolts to get the sprocket off!

[NJe23junkie]

So what is holding it on then?!?!?

Is the metal ring in the center a retainer of some sort?
(Bentley talks about the ring not being used anymore.)

Is there a hidden clip of some sort?

[NJe23junkie]

Ok guys,

Forest Gump of the garage just applied a bit more force and the gear came right off...

I don't see any pitting in the valves and the both the valves & heads or BLACK.

I'll send pictures of progress.


Thanks again!

[snowman]

Check on the head bolts. On some of these the bolts are stretch bolts. That means only tightened one time and then they get throw away. Some may say its not necessary to replace them. DO not beleive this. These are the same people who have repeat head gasket failures.

Also, this is very important, do not let anyone resurface the head. If it is warped, first check and see what if any thicker head gaskets are avilable. There may not be any. In that case the head should be straightened by a special proceedure. The proceedure involves bolting the head to a flat plate and temp cycling it in an oven many times. Many so called head resurfacers will do these heads are ruin them. They must be done by someone who can do them to BMW specs and guarentee it to meet BMW specs in writing, it not don't let them touch it. The problem is removal of material from the head changes the cam timing.

Cleaning up the block and head surfaces deserves special attention. Hard wooden scrapers are suppested for the head. The latest is to use green wooly 3M pads on a die grinder. These can safely remove gasket material without removing metal. Maybe someone could show some photos of these pads and what the cleaned head should look like.

[Jared at Pelican Parts]

Pelican carries the oversize gaskets.. If the car blew the head gasket, you have to have it checked for warping, you'll save yourself a lot of trouble.. If you're in Los Angeles, I reccomend Engine machine Service in Inglewood

[NJe23junkie]

Before I started on this trek, one of my neighbors tried to convince me to used this product called Bar's engine block and gasket sealant...

For the amont of time and having the confidence that the problem would be fixed, and done correctlyversus being masked until nother less optium time...

Thank you to everyone for their assistance.

[Jared at Pelican Parts]

Oh, is he talking about Bardahl's?

Dont put any sealant on the head or the block. Have it checked for warping, and have it machined if needed. Be sure that the machine shop knows exactly how much can be removed.

[prairieman]

no ... his neighbor has the correct name.

Bar's stop leak has been around for generations. It's added to the cooling system via the radiator. As stop leak products go, this one has a good reputation - regarding effectiveness.

Having said that, it is obviously not the solution to a blown head gasket. For that matter, I would only use a stop leak material in an old tractor, or in an emergency situation to get home if stranded somewhere with no other options.

Brad
1979 635CSi
1981 745i
1991 M5
1992 735i

[snowman]

BMW heads must be machined for both flatness AND parallelness to the top of the head. That is the top of the head has a cam in it and if the bottom of the head is warped then the cam bearings are also in a bind if you don't compensate for them. In other words the head basically has to be straightened without machining! Any machining is just to clean up the surface. Remember this or you may have a very short lived rebuild. Also some bmw heads do not have any, I mean any thicker gaskets available, check before you machine.

Finally DO NOT DISPAIR!! they can be repaired. you just have to find a competent machinist and they are out there. There are competent bmw machinist that can do everythine I have mentioned and give you a good solid product that will last another 200.000 plus miles for about the same price that the incompetent ones will charge.