When taking the m20 exhaust manifold out

[xavier]

When taking the bolts off of the exhaust manifold, is it best to access the bolts from under the car or above. Any helpfull hints other than lots of WD40?

[sweep]

warm them up if needed.

[Brianmoooore]

Manifold to downpipe nuts are accessed from underneath. Manifold to head nuts from above, but if the head is coming off, leave the manifold attached until it's on the work bench, and then work VERY carefully, so as not to break any studs.

[xavier]

I am not intending to take the head off. I have a ticking sound, which I think indicates a dodgy stud. I will soak the studs and nuts with WD40 each night for few nights leading up to the Job. I think buying new studs and nuts is the best plan(and new gaskets of course). By warm them up, do you mean the bolts with a small hand held gas torch?

[daimlerman]

Your problem is steel studs into an alloy head.

A ticking sound would tell me it's already too late,you have a broken stud.

If you are very lucky,it's at the front of the engine where access with a power drill is just about do-able.
But most are at the bulkhead end.....

[Topblag]

Your ticking sound might just be your tappets. I changed the manifold earlier this year on a 325i and started off with a 3 days of soaking them in wd40, then used a 1/4" drive ratchet, so as not to put too much torque into removing the nuts. Most came off with that setup, a few needed. 3/8 drive.

I'd recommend new studs and nuts across the board.

Double nut trick for getting any studs out.

Be gentle, last thing you want is them snapping, this is really is a job to take your time with and work in silence so you can hear any 'stud is about to snap' noises.

[xavier]

What is the double nut trick? I fear googling "double nut trick" in case I get directed to web sites in Thailand.
Is it worth taking the head off before I even start to loosen the nuts? I have never taken the head off of this engine. Are we talking weeks off of the road, or a weekend of swearing and spannering?

[daimlerman]

Double nut trick.

Winding two nuts onto a stud and tightening them together will enable you to use the lower nut to wind the stud out.

Snapped exhaust studs are difficult to remove,the one's that snap within the head are the most difficult as these can only be drilled out.Given that the engine sits at an angle,it is very tricky to get a drill bit started with the cylinder head in place.
If there's still a chunk of stud showing,it's often possible to weld a bigger nut onto the remains of the stud.The heat generated by welding also helps to free the little swine up as well.

The main cause of snapped studs is the manifold going 'banana shaped' over time,thus putting extra load onto the studs at each end of the head.
E34's that used the M20 engine had a two piece exhaust manifold to eliminate this problem,but I have never tried fitting one to an E30!My choice of an Hottuning stainless steel manifold was partly down to a warped casting.

Time to remove a cylinder head?
A couple of hours or so,it's the 'whilst I have the thing in bits' syndrome that takes the time,you will probably want to fit new valves/rockers/cam!
Plus you will need the head skimming to ensure a nice flat surface for going back.

[Grrrmachine]

My engine came with the e34 two-piece manifold, and three broken studs...

[daimlerman]

My engine came with the e34 two-piece manifold, and three broken studs...

But yours is wrong side drive,on right side drive the exhaust manifold needs to share the same space as the steering shaft!

[BenHar]

Plus Gas or equivalent penetrating oil is much better than WD40.

The clue is in the name.

Ben

[xavier]

I bought spare steel manifold of bloke who lives near by. the only thing is, I think the joint to the down pipe may be different. The the spare one is a 4 bolt and I have the early 1984 323i m20 b23 set up, which I think the E30 wiki says is a bit different. I will need to climb under the car at the weekend and have a look. if it is the same I will get the spare manifold cleaned up and price ceramic coating.
I have had the joy of removing a snapped stud on a different motor once before. I went through the whole progressively larger drill bit method, which realy needs to be done on a bench. Lordy, lordy what a lot of hassle for one stud.

[falkor]

PBBlaster is friendlier than wd40

and, I have been successful with a crank bolt snapping (cheap torque wrench), with using a dremel and a thin metal grinder to make a standard screw driver cut...which the broken bolt came right out.

whether it was from the vibrations of the tiny grinder with the PB-Blaster, or not, i don't know, but that bolt was flush with the pully, and a pita for about 30 minutes.