Replacing exhaust manifold gaskets on M103

[Rahulio1989300E]

Hello,

The exhaust manifold gasket on cylinder number 4 for my M103 cracked. i can see a black trail power on my cylinder head from it.

I have the gaskets already, I know the simliar 5 go on cylinders 1 to 5 and the last 3 holed gasket goes on cylinder number 6.

I will need to buy a torque wrench for this job...

So, I have 3 questions for you all.

1. What is the size of all the nuts? I need to replace all of them since there is some rust on each one.

2. At what ft/lbs should I torque them all to? The online service manual says 25Nm. What is the conversion? Is it 18.5 ft/lbs?

3. How do I go about doing this? Do I remove all nuts attaching the exhaust manifold to the cylinder head or do I have to remove more than that?

Thank You for your help

[wbain5280]

Originally Posted by Rahulio1989300E

Hello,

The exhaust manifold gasket on cylinder number 4 for my M103 cracked. i can see a black trail power on my cylinder head from it.

I have the gaskets already, I know the simliar 5 go on cylinders 1 to 5 and the last 3 holed gasket goes on cylinder number 6.

I will need to buy a torque wrench for this job...

So, I have 3 questions for you all.

1. What is the size of all the nuts? I need to replace all of them since there is some rust on each one.

2. At what ft/lbs should I torque them all to? The online service manual says 25Nm. What is the conversion? Is it 18.5 ft/lbs?

3. How do I go about doing this? Do I remove all nuts attaching the exhaust manifold to the cylinder head or do I have to remove more than that?

Thank You for your help

1. Get out your sockets and test fit until you find the right one, figure 10, 12 or 13. I did this, can't remember which one.

2. It's about 3/4's, don't overtorque.

3. Actually, since the pipes are connected further down, you might as well unbolt both manifolds and replace all the gaskets. You mau want to unbolt the support piece by the trans to let the pipes swing out. Inspect the bolts and W shaped clamp before you start. Get replacements if they look rusty, mine broke, yours might too.

On mine, one of the rear paired studs had already pulled out so I'll fix that with a Helicoil when I finally do the head gasket.

[richard28]

Warren, do you have any suggestions on unbolting the manifold at the pipes. I tried and the bolts were rusted pretty good, and access from the top was almost impossible. Must this be done from underneath?

[S-Class Guru]

The bolts are 12mm. The torque is 25nm x 0.73 = 18.25 lb ft.
Spray penetrating oil on the nuts and let them sit overnight.
Unless the manifold-to-pipe connectors are leaking, probably best
to leave them alone - they get pretty frozen. But, yes, they must unbolt
from the bottom.
But do unbolt the pipe support bracket down by the tranny, to give a little
movement to the pipes. Then just unbolt the manifold nuts and it will slip away from the head with plenty of room to remove the gaskets.
very easy job actually, just use that penetratin oil to avoid any issues.

DG

[Strider]

You need to use multiple applications of penetrating oil, and rap and tap the studs.

Don't be alarmed if a stud screws out instead of the nut screwing off the stud. This can be fixed. Also, I seem to recall not being able to fit a socket over all the nuts, and that the EGR valve may need to be disconnected...

[danwatt]

If you do have an EGR valve be sure to get a new gasket for that as well. It's going to have to come off. Be careful, some of the nuts might be frozen to the studs, in which case the whole stud will come out.

[t walgamuth]

heat might be needed too.

tom w