2002 2.2L cavalier vin 4
first thank you for listening to my question, even though i think i know my own answer. just looking for confirmantion i guess. ive been a quality mechanic for more than 20 years, owning my own business for over 5 years, currently working in the parts side of the auto world now. with that said, let me say i dont know everything, and i know asking questions is not a bad thing.
have a 2002 2.2L vin 4 cavalier with about 115k miles. only had this car about 2.5 weeks now. it ran with a pretty bad miss, but seeing that no appearent maitnance had been don to it figured as a used car it would need reg tune up issues, some brakes, ect. well after only about $150 in neccities, working on the tstat, which turned out not to be there, and a bad fan relay, i started to wonder. hummm?? well it still has a miss. all inj harness were checked with noid light, injector resistances were all within ohm specs, voltage referances are good. dry comp ck w/ w/o throttle, and leak down tests , not so good.
cyl 1 = 150 / 25% leak down
cyl 2 = 115 / 60% leak down
cyl 3 = 115 / 60% leak down
cyl 4 = 65 / 95% leak down
mostly you can hear leak through intake. took rockers off # 4 to make sure valves were closed as much as possible, and tapped on valve stems to see if possibly a carbon build up issue was there. no change.
question is , cyl head replacement?
fyi on new related new parts / ac delco irid. plugs, plug wires, #4 coil, fuel filter, ign module, temp sensor, flushed cooling sys and new tstat.
codes = p0300 / p0304 / older snapon scanner
You need to locate the source of the leakdown before proceeding. Valves, rings, head gasket. Could be any one or all of those.
forgot to mention. no overheating and coolant is not overflowing, and no signs of air (no bubles) in tank when doing a leakdown test. minoe air noise from exhaust/barely moves smoke from match.
What made you do the leak down test? Did you do a compression test with bad results?
If so what were the results and when you did the leak down you did it on the compression strokes, not the exhaust correct?
My father is 62 and I'm 24. My questions are asked solely due to the fact that working around my father has showed me how much things have changed from the mid 90's, which is when he stopped working on cars, to early-mid 2000's, when he picked it back up, when I started working on cars. Plus the amount of change in the 10 years I have been turning a wrench. If by some odd chance you are accidentally testing on the exhaust/intake stroke you could be catching some valve overlap, or a loose timing chain could be causing the valve to not shut at tdc.
thanks for your responses. the tests were done on the compression stroke, yes. and removing the rockers should have eliminated the timing chain issue you mentioned when doing the leakdown test. besides i would think a timing chain problem would create other running problems. yes bad results on the compression tests as in my initial post. leak appears to be through the intake. i am believing that a previous owner overheated the enging and either damaged valves or cracked a valve seat or the head itself. i find out more ill let you know. thankyou again
A loose timing chain could cause the symptoms you describe not necessarily the cylinder 4 specific but the crappy running and the multiple random cylinder miss, and that's the only reason I asked. You did the test the exact same way I would have. You throw out there cylinder head with a ?. I look at it this way, pull the cylinder head and have it tested. If its leaking get a rebuilt one if its not leaking go from there. If you say its leaking into the intake then, something wrong in the head, is the only exlpanation because its the only thing connected to the intake.
do a wet vs dry compression test to attempt to rule out piston rings. If the wet compression test doesnt change the numbers drastically then its probably head, valves, or head gasket.
#4 cracked valve seat and 2 more burnt valves in the 2 & 3 cylinders. can only assume the lack of maitnance and overheating by previous owner lead to this. i know its just a car but why not take care of what you have, or why people dont ill never understand. oh well. had head resurfaced, checked, new valves and seats. car runs fine now. thankyou for all your help. steven