Inlet manifold studs

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LennyK

LennyK

Member
Posts
39
Location
Tasmania
Hi everyone. Just a quick question. I've found plenty of advice on stripped exhaust manifold studs but on removing the inlet manifold on my Td5 to clean the oil out from a blown turbo I found 3 studs had been striped and just about fell out. Is it safe to drill them out oversize and tap them for larger studs? I dont wont to damage anything internally in the head on that side. Cheers
 
Hi Magicgrotto. Have thought about that but I would still have to drill out the original stud holes. I'm worried about damaging some internal structure if I do. Cheers
 
There should be enough meat in the head to enable you drill out 10.3mm, tap and fit M10 Helicoils with an OD of 12.5mm
Failing that you could always drill out to 10.2 and tap M12, and open out the holes to 12.2 in the manifolds, clamps and gasket.
 
I've got a helicoil holding my head to the block and another holding the rocker shaft cap to the head.
No issues 4 yrs later. (200 TDI).
 
Oldseadog said:
There should be enough meat in the head to enable you drill out 10.3mm, tap and fit M10 Helicoils with an OD of 12.5mm
Failing that you could always drill out to 10.2 and tap M12, and open out the holes to 12.2 in the manifolds, clamps and gasket.
Click to expand...
Just wondering did you try stud extractors (easy outs to an old fitter) ? would be good if you could stay standard.
I took one of mine out, then I opened up the clearance in the manifold stud holes and had a good friend take the manifold and mill a slot in the webs between each manifold port apparently it lets the manifold flex a fraction.
Some people mill the webs out completely but i didn't want to do that.
 
Flossie said:
I've got a helicoil holding my head to the block and another holding the rocker shaft cap to the head.
No issues 4 yrs later. (200 TDI).
Click to expand...
Thanks Flossie. Do you think there's an advantage then to the Helicoils? The steel coil fixed into the head and the bolt then into a steel thread.
 
raywin said:
Just wondering did you try stud extractors (easy outs to an old fitter) ? would be good if you could stay standard.
I took one of mine out, then I opened up the clearance in the manifold stud holes and had a good friend take the manifold and mill a slot in the webs between each manifold port apparently it lets the manifold flex a fraction.
Some people mill the webs out completely but i didn't want to do that.
Click to expand...

Thanks Raywin. No extracters needed as the bolts are on the Inlet side and are stripped out of the block. They just about fell out. The inlet manifold is not warped and it looks like some kind of grease was used when they were installed, something like Nickel Coat. Wouldn't surprise me if this was the cause. There can be a significant difference in the tightening torque between a dry and greased thread depending on the metals involved. They might have pulled the threads out of the alloy if the torque setting was for dry threads. Can't remember exactly....was a long time ago
 
LennyK said:
Thanks Raywin. No extracters needed as the bolts are on the Inlet side and are stripped out of the block. They just about fell out. The inlet manifold is not warped and it looks like some kind of grease was used when they were installed, something like Nickel Coat. Wouldn't surprise me if this was the cause. There can be a significant difference in the tightening torque between a dry and greased thread depending on the metals involved. They might have pulled the threads out of the alloy if the torque setting was for dry threads. Can't remember exactly....was a long time ago
Click to expand...
Sort did not read Inlet manifold seems like this old fitter is getting careless.
The TD5 is famous for busting exhaust manifold studs especially when people tweak the performance a bit.
Still glad to hear it went well, I sgree about greasing studs iveeven seen where people damage castings forcing them in with oil or grease in the hole.
 
LennyK said:
Thanks Flossie. Do you think there's an advantage then to the Helicoils? The steel coil fixed into the head and the bolt then into a steel thread.
Click to expand...
Definitely! The aerospace industry use them for alloy parts.
A helicoil in alloy is stronger than the alloy itself.
 
Thanks for the input there Jamesmartin. Was thinking that might be the case. They're not much different to inserts you see already in aluminum that are put under angular loads.
 
Screen Shot 2017-10-19 at 07.44.41.png
Dont forget to deweb the manifold, plus drill all the holes out a mm or two larger, apart from the very end one on each end also worth searching out some of the m8 nuts with built in washers as they allow the whole thing to shuffle about in use.
Bet you a pint it will also need skimming as it will be warped, pic os the manifold cyl number 5 end and you can clearly see the warp, ****e design.

Std metric threads straight into alloy arent much cop, much older landrovers used UNC threads which are much coarser.
 
lynall said:
View attachment 133704 Dont forget to deweb the manifold, plus drill all the holes out a mm or two larger, apart from the very end one on each end also worth searching out some of the m8 nuts with built in washers as they allow the whole thing to shuffle about in use.
Bet you a pint it will also need skimming as it will be warped, pic os the manifold cyl number 5 end and you can clearly see the warp, ****e design.

Std metric threads straight into alloy arent much cop, much older landrovers used UNC threads which are much coarser.
Click to expand...
I think you are reading this the same way I did. The problem is with the inlet manifold not exhaust.
I had the problems you describe and solved it the same way.
 
jamesmartin said:
also with the helicoil type some force is applied side ways, holding the helicoil tighter and giving more strength than just the threads in parent material would give
Click to expand...

Shifty1962 said:
Helicoil would be my choice as once in place the threads are much tougher than tapping direct into ally.
Click to expand...

That's nice to know, I had always assumed helicoils to be a bit of a bodge. Not that I need to use the system at the moment, but if I do I'll be happy about it.
Cheers chaps.
 
frog hopper said:
That's nice to know, I had always assumed helicoils to be a bit of a bodge. Not that I need to use the system at the moment, but if I do I'll be happy about it.
Cheers chaps.
Click to expand...
The exact opposite. They were initially designed for critical use in ally parts where the base material is not hard enough to take a thread subjected to high torque or repeated use. They are commonly used on aircraft and aerospace technology and well proven. I have used them on several occasions with no problems.
 
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