Just checked the Compression & Results are in

AA_Ezra · 09:20 AM

Checked the compression a few days ago, Still debating to put in the newer head and cam i got from the 85.5 in ( got lifter noise). I let the vehicle warm up to normal operating temp, Cranked over about 4 or more times Heres what i got

Cylinder #1 179 psi

Cylinder #2 181-182 psi ( hard to tell exactly)

Cylinder #3 120,150,170, Finaly 175 psi ( psi kept rising)

Cylinder#4 179 psi

After the first 2 I thought i was in good shape, Cylinder #3 gave me problems b/c my bater died the first 2 reading. Recharged the battery and kept the charger on batter Cranked over about 5-6 times and got 170, I still thought that was too low but results got better. Last time Cranked over i dont know how many times but i got it up to 175. Battery got low again.

Heres my thought: Cylinder #3 on the cam is about where i can hear the ticking noise, So the lifter not firming up is causing the Valve(s) to stick delaying my psi buildup? Or i got some Carbon buildup and need to run a Injector cleaner. Or maybe its both?

What's everyones 2 cents?

Regards
J

scheistermeiste · 07-19-2006, 09:35 AM

you can do a leak down test to confirm if you have a valve thats staying open

AA_Ezra · 07-19-2006, 09:42 AM

Yeah, I guess i should do that too. I just made my own leakdown tester the same day i tested it. But got the Compressor at dads house. With a sticking vavle i should be able to hear it hiss or somethign like that right?

scheistermeiste · 07-19-2006, 05:32 PM

that i wouldnt know, ive never had a car with a valve that stuck open. a collapsed lifter wouldnt cause a valve to stay open though, only to open later than it should.

Razorback1980 · Razorback1980's Garage

Hey Jaime,

Doesn't seem too bad on the compression. Key is to have them all pretty close to the same numbers and I would say yours are close enough. Number 3 is a bit concerning, but I think the thing to do there is let it sit over night and charge the battery and go try it again in the morning. If the compression tests low, the the lifter is probably flat and needs some oil to start working properly. If you turn an engine over enough times with a starter, it may build up enough oil pressure to fill the lifter with oil, just not sure. If you start with number 3 in the morning and a fresh battery, that will tell the story. If it were mine, I would test the compression after it's set over night and then put the plugs back in and drive it for a short while and test again. If the reading is low the first time and much better the second time, then I would guess your lifter is leaking the oil out and needs to be replaced and is more than likely your ticking sound.

If you have a lifter leaking off, then it will not cause your valve to stick but what it will do is not open the valve enough so when the piston goes down on intake, it will not take in enough air and when the piston comes back up to compress it, there isn't enough air there to compress causing you to have low compression. Of course as the engine puts oil pressure to the lifter the lifter stays up and opens the valve as it's suppose to and the cylinder will then bring enough air in to give you the compression you are looking for. Could very well be what's happening.

AA_Ezra · 07-19-2006, 08:28 PM

i'm gunna have to do both the compression test and leak-down my next few days off.Thanks for the input thus far guys. I'm leaning towards the lifter(s) are giving me the problems of a low psi reading. Looks like i'm going to have to run another bottle of Marvel mystery oil as it has made the lifter noise a bit quiter Even with just the Mobil 1 in it now.

scheistermeiste · 07-19-2006, 08:48 PM

if it is a lifter why dont you just replace it? ive never been on the inside of the 944 engine (only learned about stuff after i got rid of my 924S), but i know that on a chevy motor replacing a lifter is cake. Although i noticed from pelican the price of one lifter is almost as a set of 8 for chevy...

AA_Ezra · 07-19-2006, 10:32 PM

yep the lifter isen't cheap from what i remember. If it comes down to it i'll replace the whole cam/housing with the used one i have laying around. I'm just hoping my Compression on #3 is due to only a lifter.

hpaulb · 07-22-2006, 07:09 AM

Wrote a procedure a little while ago on testing lifters. Quite easy. Submerge in a light penetrating oil and push center pin in several times to wash out the oil. Should go from whatever condition to soft. Blow or pump it out till clear then submerge in oil and pump. Should feel it go from soft to hard as it fills. If it does it's good. This way you can easily test used one's and replace without having to spend a fortune on new ones.

AA_Ezra · 07-22-2006, 02:00 PM

I hear ya. The set in my back-up cam i soaked in some Purple Power Cleaner/Degreaser for a few hours an watched the deposits ooze out of the lil lifter holes. I'll have to check that write up I bearly remember that right up. you/somone used Marvel mystery oil to soak um in.