Exhaust manifold heat shield bolt
 

Hi - I removed the 1/2-20 bolt that was threaded into the rear exhaust manifold which was the location of the fixed orifice EGR takeoff. In FI cars it's just a bolt that holds down the heat shield. Anyway when I pulled it out the thread insert came with it.

I've encountered this exact scenario before on a Series 3 and I'm wondering if the thread insert is as it came from the factory or if it's just a common issue of the original threads in the cast iron coming apart when that bolt/take-off is removed (seems unlikely) being repaired with a heli-coil.

On the Series 3, I just retapped the hole for 9/16-fine and installed that. I had no problem with it but the car was driven exclusively in Florida so the exhaust manifold metal never encountered a wide temperature range... As in going from freezing cold to engine-running hot in a few seconds. I mention this because I'm wondering if it might be the reason for the helicoil insert if it came from the factory that way...?

Now I live in New Jersey so I have to worry about extreme temeratures plus I want to be able to remove the bolt if I have to. My other thought was that the thread inserts are typically made from superior quality metal or stainless so maybe it's there to allow it to be able to be removed even after years of cold-hot cycles and rust.

Does anyone know for sure if this thread insert was installed by the factory?

Thanks,

Every Ser III I've worked on had the threaded inserts. Fair bet that they were all factory installed, IMHO

Cheers
DD

Hi Doug - have you ever had occasion to replace the insert? Will a standard helicoil 1/2-20 insert go into the original threads?

No, and I don't know :-)

Sorry

DD

in my 1984 I've removed that ½" bolt several times and it never came out with a helicoil, the hole looked threaded, no insert, unless it didn't show its face. The first time I had the manifolds removed, blasted, and repainted, and again, no helicoil did I see. I applied anti-seize the first time I replaced the bolt so it came off easily the second time when I had the shield treated with Jet-Hot coating. But I am not saying the holes do not have those helicoils from the factory, I'm saying I didn't see one. As far as I know, helicoils are used to repair damaged/stripped threads.

b

Hi Jose - Weirdly the first time I removed the EGR takoff and replaced it with a bolt mine didn't come out either. I think you might have been lucky and smart enough to use anti-sieze the first time. Judging by Doug's experience with several and my 2 it must be a factory thing.... probably stainless steel so it can be removed easier.

Thread inserts are sometimes used to create threads in soft metal from the factory - it's a little strange to see it in cast iron but Jaguar must have had their reasons.