Leaking valve
Leaking valve I've been doing a dod delete on my ls and I got my cylinder heads redone at a shop while it was apart. The valve springs I chose where not right for the cam. So I ordered new ones but I had already installed the heads so I am having to install them with the compressed air method. When I got to the number 6 cylinder the intake valve leaked really bad but I don't understand why because it's a brand new valve job from a reputable shop so what could be going on here?
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Joined: Jan 2019
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Could be leaking around the stem or valve needs lapping. Nothing major. Take it off and have it tested.... the valve seal needs replacing. More than likely a simple fix.
**** happens, a seals got pinched hopefully.
**** happens, a seals got pinched hopefully.
I would contact the shop that did the heads and see what they have to say.
You could try opening the valve a few times and see if it seals.
From your description I don't see the valve stem seal being the issue.
You could try opening the valve a few times and see if it seals.
From your description I don't see the valve stem seal being the issue.
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if they reused your stock valves, you may need one replaced. sometimes you find one that looks like it seats but is actually slightly bent. they should have checked that if they were rebuilt, though.
could also just have crud on the seating surface and needs to be cycled a few times with the spring pressure pulling the valve against the seat to really seal it, so having the rockers on and rotating the engine over a few times would help.
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Teching In
Joined: Apr 2017
Posts: 42
Likes: 0
From: Western NC
With the rockers off on the leaky cylinder, put compressed air on that cylinder via the spark plug hole, then tap the valve stem with a plastic mallet.
If the leak clears up great. If not then give the shop that did the work on your heads a call.
If the leak clears up great. If not then give the shop that did the work on your heads a call.
Agreed. If the spring is still on the valve, whap the top of the valve with a plastic or rubber hammer a few times, to help the valve seat. Make sure piston is down the hole of that cylinder some or you could potentially bend the valve from interference with the piston top. Very common procedure actually. I do all of my valves this way, head on a fixture, before I install the heads on the engine, just for an extra “because”. Had an engine builder that did all of my dry sump circle track engines in the early 2000’s, that would not lap a valve to save his life. He used the “tap” method which basically is what I’m suggesting you do here, but different...
Agreed. If the spring is still on the valve, whap the top of the valve with a plastic or rubber hammer a few times, to help the valve seat. Make sure piston is down the hole of that cylinder some or you could potentially bend the valve from interference with the piston top. Very common procedure actually. I do all of my valves this way, head on a fixture, before I install the heads on the engine, just for an extra “because”. Had an engine builder that did all of my dry sump circle track engines in the early 2000’s, that would not lap a valve to save his life. He used the “tap” method which basically is what I’m suggesting you do here, but different...
