924Board.org

[Dr. Don]

HELP!!
I need help replacing my exhaust manifold on a 1981 924 non-turbo. It's cracked.

I am replacing the entire exhaust system, but cannot seem to figure out the best way to get the manifold off, short of removing the entire engine. I do not want to do that. I do not have an engine lift.

What manual(s) describe best how to approach this project. I cannot find any that talk about it. Anybody do it out there?

I am in the Grand Rapids, MI area. Any shops specializing in do this type of work without charging a small fortune? Any advice would be great. DJM

[eturbo924]

Did a bolt crack or did the manifold just crack?

If the bolts are ok. I suggest you soak and soak and soak the bolts over night. Then maybe apply some heat to them... becareful with this depending on the penetrant an amount you use. Actually forget the heat. Just use good penetrant. Then carefully begin taking the nuts off the studs. Apply more penetrant as nessesary. What you will likely find is that the studs will come right out since the nuts will be frozen. You should get under the car and take the down pipe off the manifold first. This will do two things. Give you much more room to work and take weight/stress off the manifold and thus the bolts.

Eri

[coconutcowboy]

I have a spare 924NA manifold from an 80 for sale.

$50 usd and shipping or trade for parts.

post here or email me at coconutcowboy@hotmail.com

Try mousemilk penetrant works great on aircraft exhaust studs cooked into alloy heads.

Sean Ross A@P

_________________
porsche924 in georgia

[ This Message was edited by: coconutcowboy on 2002-06-13 07:49 ]

[Dr. Don]

I have a replacement header that will go into its place. I have a cracked manifold that I want to remove altogether.

What is this milk penetrant? I am not familiar with it? I have used Kroil namebrand and "Rust Remover" penetrant? Is the milk the same type of product? Where can I get this milk penetrant?

As far as the other person's suggestion, If I keep working the nuts and studs, are you saying that the studds will come out of the head without breaking? Is this common to have the studs come out of the head rather than the nut off the stud? DJM

[marky522]

Hey, its good to see another michigander!!! I'm in port huron!!! Good luck on the project!!!

Mark

[gohim]

On 924 heads I haven't broken any exhaust studs, but a fair number have unscrewed and come out, instead of the nuts coming off of the studs. A few have also come out, while puking out the threads as well.

Since you are replacing the entire exhaust system, do yourself a favor, and use the final muffler (exhaust system from the cat to the tailpipe) from a 944, with the 944 cat/downpipe.

What you do is cut the 944 downpipe to match the flange/joint where the headers or original downpipe are/were connected to the 924 cat adapter. Use the flange from the old 924 cat adapter pipe on the 944 downpipe.

This modification is suppose to yield 8-10 horsepower.

[Dr. Don]

I originally bought a Bosal high performance sat-back system that I got at wholesale pricing through my consulting business vendor accounts (with the price of Porsche parts, it's nice to have contacts).

I have all the parts sitting in my garage. I originally wanted to just replace from the cat back. The previous owner of this car cut off the flange on the two-to-one pipe that sits between the manifold and the cat. I am trying to get the car to a more reliable state so that I can have some fun with it. I want to do the job right myself without investing a small fortune to garages.

I like the fact that others have done this job and the studs come out of the head without breaking. That gives me hope that I will do this without potential snapping and/or redrilling. Still looking for information on the milk penetrant mentioned earlier.

The person that commented about "puking the threads." What do you mean by that? As the studs come out, are the head threads ruined and thread inserts need to be added? Please explain. DJM

[gohim]

Yes, The exhaust studs usually won't break when they come out with the exhaust nuts, but sometimes the threads in the head will rip out when you tuen out the nuts/studs.

There isn't much you can do, when that happens, except repair the damage.

Just do you best to avoid the problem, soak the exhaust hardware with whatever lubricant/penatrator you choose for at least a couple of days before you attempt to remove the exhaust manifold.

For a late model exhaust to crack up like yours did, ther must have been something seriously wrong with the turing setup, or engine. Don't be surprised if there are other repairs necessary to get the engine into good running condition.

Porsche made major mechanical improvements on the 80 and later cars. The 81 and later cars have some fastener sizes, and types of gaskets were changed. Make sure when you order parts that you specified that you have an 81/82, and check the fit of the parts, before you try to install them.

Example: The size of the studs on the exhaust manifold to downpipe/collector were changed from 8mm to 10mm, and the gasket from a flat gasket to (2) aluminum crush sealing rings with a 930 part number to improve exhaust sealing. the 8mm exhaust nut cost around $1 each, and the 10mm exhaust nuts are about $12 each. The flat exhaust gasket is about $5, and the aluminum crush sealing rings are about $20 each.