exhaust manifold bolts coming loose.

[Darren1983]

Hi all,

When I got the turbo refurbished I noticed that the bolts where really loose on the manifold, obviously when I put the turbo back on I tightened it all up and put some locktite on too.

The car seemed loads better for a few weeks and then the lack of power/boost slowly crept back in, I went out last night and just had a little mess around cleaning sensors checking for splits etc and then I checked the manifold bolts which were really loose again!! tightened them up an car feels better again now so im guessing this has been one of my main issues all along.

now the problem is rectifying this so they don't come loose again, Read a few posts and some people say that putting some sort of nord lock washers on will sort it. My only problem is I don't have a clue which washers are needed.

has anyone else had this problem and would you be able to shed any light onto how I sort this.

Thanks
Darren

 

[carlcall]

Are they bolts or studs?

 

[Darren1983]

Studs with nuts on mate

 

[joinerman]

Is it the studs or nuts coming loose ?

 

[Darren1983]

4 of the studs and one of the nuts.

 

[joinerman]

Are the studs that are loose long enough to get two nuts on & lock together then tighten the stud & put spring washers under all the nuts.

 

[SDHA4SLine]

Have they been over tightened and stretched the threads maybe? If that's the case this may answer why they're coming loose

 

[adamss24]

Cannot really over tighten the studs as they usually strip the threads in the head... I had high EGT do that to turbos and some gtb2260vklr keep snapping bolts on a mates a4 tdi... We had to drill and tap for larger bolts and also thread locked all the studs and used new coper locking nuts and still have a few odd ones snapping or coming loose...

 

[SDHA4SLine]

Cannot really over tighten the studs as they usually strip the threads in the head... I had high EGT do that to turbos and some gtb2260vklr keep snapping bolts on a mates a4 tdi... We had to drill and tap for larger bolts and also thread locked all the studs and used new coper locking nuts and still have a few odd ones snapping or coming loose...

Didn't specify which thread would stretch (head, nut or stud), its possible threads in head could be stretched before they're stripped. No matter just a thought anyway.

 

[B5NUT]

Did you buy new reuse the old nuts?

 

[adamss24]

Didn't specify which thread would stretch (head, nut or stud), its possible threads in head could be stretched before they're stripped. No matter just a thought anyway.

I wasn't contradicting you entirely just what I found on few occasions - based on my experiences ! Anyway, high thermal stress make the bolts expand on a much higher rate hence they usually come loose or snap altogether. I found using metal spacers stops it to some extent however they are still coming loose or snap eventually ! I am talking highly strung Diesel engine and I am sure petrol ones do exactly that as they run higher EGT...

 

[Darren1983]

update.

so I re-tightened the bolts and the performance didn't seem as good as before.

when I previously did this when I felt a noticeable difference I also cleaned the map and maf sensor at the same time so I suppose it is a possibility that it was cleaning them that did improve performance.

it looks like I may need to look into the maf and map sensors further and see if I need new ones.