RE: Exhaust manifold "expansion"
Quote:
Originally Posted by
Reddirt204
When I replaced the head gasket I found 3 studs snapped off. Went through and replaced them all with longer ones, I drilled out the manifold holes as well. I used an angle grinder and a cutting disc to de-web the manifold along with a die grinder to clean it up ( as others have said, use what you have) personally I don't think it's the manifold expanding that is the problem, more like the LACK of expansion compared to the aluminium head, but anyway, when I refitted the manifold I used some spacers on the longer studs ( this is similar to how my Prado is setup from factory)
The Disco has now covered about 20k so far and no issues.
Cheers
Redd
Have had one TD5 exhaust manifold warp, and was advised to replace exhaust manifold studs with 10mm TDi300 studs (but not to change the centre 2 studs as drilling these out goes into coolant area in head), which required drilling out the holes in exhaust manifold to take 10mm.
Faced manifold, changed out to larger studs and that did work well, but was a lot of fiddling with drilling and tapping out for larger studs.
Next TD5, I drilled out the manifold holes to take 10mm and had the manifold ceramic coated (to dissipate heat better), BUT I did not change the studs from the 8mm.
I was thinking that the warping might be due to the manifold expanding but not having anywhere to expand to, and that by having some space in the holes around the 8mm studs, that might allow for expansion without warping.
So far I have covered over 50K and no issues as far as warping, which might be down to either the ceramic coating, the larger holes in the manifold, or both, but it seems to be working and I drive long hauls in hot areas, so it would be getting pretty hot in the exhaust department.
