LS1 Sounds

iTrader: (11)

A buddy's H/C/TH400 WS6 started smoking a week or so ago at the track. We began working on it Saturday to find the cause. He was thinking a broken ring or something, but we wanted to do some checking before shopping around for short blocks.

The first thing I noticed was a puddle of oil in the throttle body. We fired it up and it was pulling SERIOUS vacuum under the valve covers, it almost sucked the oil fill cap out of my hands when I was taking it off. The vacuum is only present under the driver's side cover though, and he also mentioned that one spark plug was coated in oil when he pulled them at the track (same side of the engine).

We pulled the PCV lines and valve and there were no problems there, so were thinking the intake valve seal is hosed on that same cylinder with the oil-fouled spark plug. This could explain how oil is getting into the chambers and also what's causing the vacuum under the valve covers.

Any other ideas? Thanks!

oange ss

iTrader: (50)

could be valve seal or need to reseal rocker arm bolts...pcv system is pullin vacuum thru valve cover, check to see if you have vacuum on the drivers side too, if you dont you could have a leak in the crossover hose

jaberwaki

reseal rocker arm bolts???
what do you mean?
if those were loose wouldn't the rocker arm be loose?(they were not)

the crossover hose is fine.

oange ss

iTrader: (50)

use teflon thread sealer on the intake rocker bolts

REDWS6ROCKET

iTrader: (4)

sounds like a valve seal if you have a oil fouled plug. i would look into that first just a suggestion.

LS1 Sounds

iTrader: (11)

Valve seal is our main suspect too.

The vacuum was mainly coming from the driver's side valve cover. IOW, when I removed the crossover tube from it, there wasn't much suction on the tube but there was tons in the VC hole. This was the same side with the fouled spark plug, btw.

FiveSevenEagle

between a piston ring and a valve seal , ive been in this 2 times before ,

how many miles on the engine ?

how heavy is the smoke ?

any misfires ?

did u the compression test ?

maybe i can help , just let me know ,

1fastWS6

iTrader: (3)

If it was a ring, you'd be getting a bunch of blowby and also crankcase PRESSURE not VACUUM.

I've had bad valve seals before and it only takes 1-2 bad ones to pull a quart of oil in the cylinder in 500 miles or so. Smoked like a B!TCH at idle. Very noticeable on the plug ceramic part that faces the intake valve.

DaddySS

Hmmm....valve seals usually show up as smoke on deceleration and first start up, not under power. Valve seals also need to be really bad to foul plugs. For step #1, I'd disconnect and plug the PCV line then see what kind of blowby if any you're getting.

1fastWS6

iTrader: (3)

Good point.

I'd do a leakdown test after checking blowby.