Boost leak test unearthed exhaust valve leak?

monster50iii

Member
Dec 5, 2014
329
6
18
I went to do a boost leak test tonight. I was having difficulties getting the system up to 25psi without emptying my compressor. I went to my exhaust tip and you could hear the air very loudly entering it. I've read the the dmax engines have zero overlap. I'm thinking, do I have a bent valve(s)? Are they just wearing unevenly etc and aren't sealing? Did they wear into the seats and have no valve lash? I bumped the engine a smidge with the starter and bam, I was holding 40psi in the system no problem..

The amount of air leaving the exhaust was a bit alarming. However, the engine shows zero signs of a weak cylinder. No odd starts, no misses or dead cylinders. Maybe the leak I heard isn't causing much of a fuss, but it sure is unnerving. The engine is now at 221k. Maybe a compression test one day? I read posts where others found a similar situation but it seems they chalked it up to a leaky egr.. maybe it was, maybe it wasn't, no one ever seemed to dig into it. Well, mine isn't there, so that leaves one way for the exit.

If lash is tight on both int and ex there is a possibility for some overlap to occur I would think. Im not sure how close to having overlap the stock cam is.

Thoughts?
 
Last edited:

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,065
4,734
113
Phoenix Az
A simple test would be to turn the crank and listen for the air leak to stop or change tune.

If compression/leak down test say cylinders are happy, it ain’t a burn exhaust valve.
 
  • Like
Reactions: MarkBroviak