badly need help, burnt valve ?

[greasemonkeyjmj]

as many of you know, i have been fighting demons, well with my constant CEL code of P0302 i was doing some troubleshooting. i decided to check the compression. well its doesnt sound good. number 2 cylinder shows to have 50 pounds less than the other cylinders do. is burnt valves a likely thing on a stock pt with 47k miles. if not does anyone have other ideas of a cause .

[CREWZIN]

Some more stuff to read.....


re: Why low compression on one cylinder?

leaking valves, low compression one cylinder.. . - Cadillac Owners Group

What will a compression test tell me? — Yahoo! Autos

[greasemonkeyjmj]

hi crewzin. i understand all about how to test for low compression and the burnt valve tests but what i was wanting to know was, is this a common thing with a pt having that low of miles ? my thinking was that burnt valves were not that common of thing any more......thanks

[CREWZIN]

IF you do have a burnt valve, it's the first one I've read about in all the forums I go to. Not to say there isn't another one or more but nobody has come to the forums and told us about it. Probably one or two of the mechanics on this forum have seen them in the shop.

[greasemonkeyjmj]

well that makes me feel a bit better anyway. does the pt's have adjustable valves ?

[CREWZIN]

You need some of our technical members for the answer to that.

[greasemonkeyjmj]

hi crewzin with my luck, ill have the first one that you have heard about. the pt is idling at approx. 600 rpm and the #2 cylinder is hitting, but not hitting as solidly as the other cylinders, when i test them by pulling the plug wires.the engine runs strong when on the road, it doesnt really run bad at idle, has just a bit of vibration/shakyness to it.

[GALVANIZEDYANKEE]

The 2.4 L engine has hydraulic valve lash adjusters. Burnt valves are now a rarity. Thirty years ago it was common. Metallurgy has advanced, and most engines use sodium filled exhaust valves. These valves withstand high operating temperatures. Make sure your problem is a valve. A cracked ring will also give low compression. That will cause excessive blow-by. Check you air cleaner and make sure the PVC filter is not oil soaked.

[greasemonkeyjmj]

hi yankee. i have had the filter out several times over the last few days, and everything looks fine. as far as i know. my pvc valve hose runs into my intake behind the throttle body. i pulled the hose off a few days ago and started the engine up, and didnt see any blow by coming from the pcv valve.and i also had the oil filler cap off earlier tonight with it running and there didnt show to be any smoke......thanks

[greasemonkeyjmj]

ok i got another compression guage today. 3 cylinders show approx 170 lbs and the week cylinder shows approx 120 lbs. i can add oil to the plug hole and it will build up to approx 170 lbs like the rest.