malohnes
Well-Known Member
- Joined
- August 8, 2009
- Messages
- 903
- Reaction score
- 16
- City, State
- SE Alaska
- Year, Model & Trim Level
- '91 xl m5 4x4
As an FYI for those chasing the various crazy to diagnose oil leak our rigs develop, I just discovered the cause of one of mine I'd like to share.
When replacing the heads, with new aftermarket heads, and all the gaskets, I failed to notice that the LIM gasket fit a little skewed so that one edge on one side stuck out into the joining surface where the valve cover goes over the head and onto the LIM. On the opposite head, there was the tiniest of valley that was more receptive to RTV, such that there wasn't any leaking I could discern. When I used rubber, not cork valve cover gasket, the part sticking up caused just enough of a gap to allow oil to seep and over time to spew oil out the rear of the engine when running, especially under load.
Consequently, I was getting a consistent leak over time that would make a real mess of the tranny, and everything below the engine when viewed from the engine compartment, but when driving only. Idle conditions, especially at start up did not yield any evidence of where the leak was originating from.
I cured it buy shaving the gasket down ever so slightly with a razor knife and X-acto knife and then RTV'ed it and carefully cleaned and reused the rubber valve cover gaskets that are 6 months old. So far so good.
2 tips I found helpful:
One - before working on engine, warm it up, then allow it to cool down some so that by the time you remove all the parts to get to the area to address there is still some heat in the block to aid the curing of the RTV.
Two - don't drive right away, even a hour afterwards. Give a few hours minimum before driving to promote curing of the RTV.
This leak actually contributed to the death rattle (knock or detonation) our trucks are prone to in that I had oil in the combustion chamber as evidenced by reading the #6 plug. Once I cleaned the plug, fixed the leak., the rattle disappeared.
I hope this helps you guys out as this was a tough one to figure out, despite all the excellent threads and advice form various posters.
When replacing the heads, with new aftermarket heads, and all the gaskets, I failed to notice that the LIM gasket fit a little skewed so that one edge on one side stuck out into the joining surface where the valve cover goes over the head and onto the LIM. On the opposite head, there was the tiniest of valley that was more receptive to RTV, such that there wasn't any leaking I could discern. When I used rubber, not cork valve cover gasket, the part sticking up caused just enough of a gap to allow oil to seep and over time to spew oil out the rear of the engine when running, especially under load.
Consequently, I was getting a consistent leak over time that would make a real mess of the tranny, and everything below the engine when viewed from the engine compartment, but when driving only. Idle conditions, especially at start up did not yield any evidence of where the leak was originating from.
I cured it buy shaving the gasket down ever so slightly with a razor knife and X-acto knife and then RTV'ed it and carefully cleaned and reused the rubber valve cover gaskets that are 6 months old. So far so good.
2 tips I found helpful:
One - before working on engine, warm it up, then allow it to cool down some so that by the time you remove all the parts to get to the area to address there is still some heat in the block to aid the curing of the RTV.
Two - don't drive right away, even a hour afterwards. Give a few hours minimum before driving to promote curing of the RTV.
This leak actually contributed to the death rattle (knock or detonation) our trucks are prone to in that I had oil in the combustion chamber as evidenced by reading the #6 plug. Once I cleaned the plug, fixed the leak., the rattle disappeared.
I hope this helps you guys out as this was a tough one to figure out, despite all the excellent threads and advice form various posters.
