truck is idling funny from time to time. at first start up it doesnt idle quite smooth and i notice vaccum is only 9. my motor normally is 10. now after awhile of driving it idles fine. this is as long as i dont go into boost. now if i go into boost then let off the truck then idles funny. I dont see any ECTs out of ordinary. If i continue to drive around stoich and not get into boost truck runs fine and at idle vaccum is 11 which is a plus. after driving truck tonight i opend the resivor cap and i noticed it being pressurized. does this seem like a lifted head issue? i checked all valves for being bent and they are straight. I was going to do a compression test tomorrow and thought of applying air to the cylinders to see if i can hear or see bubbles in the resivor. this was first time running truck after the rearend breaking and motor spiking to 19psi


im also gong to check and see if possibly damage happend to the fast with the spike. id much rather have gasket go bad on fast then head gasket

 

I vote head gasket. Check your oil btw, before you lose the whole thing.

 

If you lifted a head you will push water out the overflow, and or between the head and the block.

 

Doesn't sound like a lifted head to me, but I don't have any other suggestions

 

I'd say a leakdown test could be your friend here....but the compressed air with no gauges is a definite start. gauges will show if its leaking down....then its a matter of listening to where (exhaust, intake, coolant, crankcase)

 

oil is still color of oil and no milk issue. coolant is still the color of coolant. I dont have access to a leakdown tool but i do have a compression guage and ill do thta along with compressed air. also the exhaust has no trace of smoke either

 

you sure it ain't something stupid like a minor vacuum leak?

 

thats what im going to find out. i might of blown out the seals inside the Fast. i sure hope its that. i dont want a hurt motor. just odd it acts funny right after boost. but i read on tech that a lifted gasket acts normal once it seals again but isnt going to hold the same after that.

 

this stock heads/mls gaskets/bolts etc??

if so the odds aren't in your favor for those head gaskets being too happy...

 

they are stock MLS gaskets and stock head bolts. thats why i think i lifted the heads. before the spike to 19 when the rear broke. eariler that day my boost controller malfunction and motor spiked 25 at 50% throttle. but the truck drove fine after that. its just now im seeing issues after getting the rearend fixed.

if i find an issue with the gaskets, im just going to pull the 10psi spring and just run wit hte 5psi so i can limp it for now till im ready to fix it.....if its intake ill either fix the fast or toss on my LS2 intake