Air leaking into LIM while doing a Valve job?

**Pure2sin** · 05-03-2011

I still have a bunch of other stuff to add before I put it all back together. Mainly an intercooler. I wonder if I could have blown the valve seal when I first added pressure to the cylinder. I will have to recheck it tomorrow because now it has new valve seals and new springs and retainers and locks.

**FETGYK06GP** · 05-04-2011

Originally Posted by Pure2sin

I wonder if I could have blown the valve seal when I first added pressure to the cylinder. .

When you say valve seal are you referring to the guide seal? More likely to be a burnt valve or seat. Or if your are lucky just carbon build up on the valve keeping it from fully closing. If it was leaking into the intake then its the intake valve and you should be able to see it on a vacuum gauge. How did the spark plug for that cylinder look?

**BillBoost37** · 05-04-2011

This is normal. A valve leaking air from the cylinder into the intake or exhaust is common. When I do springs, I put air to the cylinder and any ones that are leaking a little, I tap with a rubber mallet. Usually helps them seal much better.

maybe a valve was open, glad it didn't drop in on ya,

Not with the rockers off. All the springs hold the valves completely shut when the rockers are off. If a valve was open when the cylinder is pressurized with air, the air would run right out. He had a small air leak.

i bet you got a bad valve seal,

The valve seal keeps oil from the rocker area getting down the valve guide and into the cylinder. It does nothing to seal the compression chamber.

**Scottydoggs** · 05-04-2011

Originally Posted by BillBoost37

This is normal. A valve leaking air from the cylinder into the intake or exhaust is common. When I do springs, I put air to the cylinder and any ones that are leaking a little, I tap with a rubber mallet. Usually helps them seal much better.

The valve seal keeps oil from the rocker area getting down the valve guide and into the cylinder. It does nothing to seal the compression chamber.

your right bill. it was late and i was sleepy, i was referring to the valve not being seated to the head, the mallet trick works well.

**FoSHO99** · 05-04-2011

Sometimes it takes more than a few taps with the mallet to get them seated properly, I'm surprised you only had trouble with the one. And obviously never do the tapping with the spring off.