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2006, 48K miles on it. Low pressure on cranking, about 275 PSI. Rigged up an air test going in through the ICP with about 100 PSI. Leak sound is coming from the passenger side valve cover. Pulled the stand pipe and the dummy plug, and it just doesn't look right.
I worked on gas engines for 50 years. This is the first diesel I have ever owned, so I don't know what these things are supposed to look like. They must have been done because they are 12mm Allen.
Are they supposed to look like this? I m going to pull the oil rail for giggles and also check the nipple seals.
Last edited by bajadudes; Dec 28, 2025 at 05:14 PM.
That’s a monster thread that I have been enjoying for the past 1.5 hours while looking for an answer on my situation. Yeah that dramatically overlapped one does not look right at all. I’m tempted to get a new diesel site set and put the Alliant D rings on there. I’m trying to understand how that dramatic an overlap can happen on that washer?
I should probably finish that thread. I’m surprised those guys aren’t in a clean room with surgical suits on. Very impressive and informative.
2006, 48K miles on it. Low pressure on cranking, about 275 PSI. Rigged up an air test going in through the ICP with about 100 PSI. Leak sound is coming from the passenger side valve cover. Pulled the stand pipe and the dummy plug, and it just doesn't look right.
I worked on gas engines for 50 years. This is the first diesel I have ever owned, so I don't know what these things are supposed to look like. They must have been done because they are 12mm Allen.
Are they supposed to look like this? I m going to pull the oil rail for giggles and also check the nipple seals.
This is not your pressure issue / leak. Do a pressure test through the IPR valve port.
Leaks under the oil rail are mostly the top injector o-ring (often rail installation issue) or injectors itself, not the nipple cup o-ring.
When you install the oil rails, use M6 studs to ensure the nipple cups are pressed into the injector exactly vertically. On new injectors, the inner diameter at the upper injector o-ring is 0.2 mm smaller than on used injectors.
Did the air test leak at the IPR but still could not pinpoint the air leak. I pulled the rail and cleaned out the oil from the injector top seal holes and to my untrained eye the look good. Perhaps the back most one may look a bit disfigured but it’s hard to tell. The nipple cup on that one moves rather easily in the oil rail. Not like flick of your finger easily but with two fingers you can move it around. The others in the oil rail are firm and seem solid. The injectors look fairly new and so do the standpipes and dummy plugs. Do you guys think I should replace just the injector top o-rings or do the nipples, standpipes and dummy plugs rings while I have it apart?
@Hartwig using M-4 studs to guide the oil rail down is a great tip. Once in place do you remove them and use the regular stock bolts or you just spin down a washer and nut onto them?
@Hartwig using M-4 studs to guide the oil rail down is a great tip. Once in place do you remove them and use the regular stock bolts or you just spin down a washer and nut onto them?
This is not your pressure issue / leak. Do a pressure test through the IPR valve port.
Leaks under the oil rail are mostly the top injector o-ring (often rail installation issue) or injectors itself, not the nipple cup o-ring.
When you install the oil rails, use M6 studs to ensure the nipple cups are pressed into the injector exactly vertically. On new injectors, the inner diameter at the upper injector o-ring is 0.2 mm smaller than on used injectors.
Hartwig, what length studs do you use? I'm definitely doing that next time I'm doing an injector, which is looking like sooner than later!
Three to four inches are good. I use studs to align anything that goes together in registration, even when it has dowels. Front cover, rear cover, heads, rails, even exhaust manifolds. It easier to install even when it doesn’t need the alignment.
