dohc v6 Posted December 21, 2007 Report Share Posted December 21, 2007 I just did a compression check. I got 185-195 from the front 3 cyclinders, is this ok? Quote Link to comment Share on other sites More sharing options...
badassoldspower Posted December 21, 2007 Report Share Posted December 21, 2007 as long as they are all fairly close to eachother, you are fine, and just be sure to get good accurate measurements. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 Well I just put oil in the cyclinders, and the reading shot past 300, so I am guessing that either that happens when ever you put oil in the cyclinders or I have bad rings, got damn 2500 miles and already fried the rings. I guess I did not brake the motor in right. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted December 21, 2007 Report Share Posted December 21, 2007 Sup Kenny! /Hijack Quote Link to comment Share on other sites More sharing options...
badassoldspower Posted December 21, 2007 Report Share Posted December 21, 2007 Well remember DOHC that you cannot compress a liquid, so granted you are getting very high compression readings now. Also remember that no ring seals perfectly and you will always have leakage, but when you add oil, you reduce the size of the bore being measured, thus increasing pressure, and also the oil helps to prevent the rapid cylinder leakdown. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 Thats what I was thinking. I think that around 190 is pretty good, right? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted December 21, 2007 Report Share Posted December 21, 2007 yes. all the 3 readings between 185-195 are good Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 Ok well I thought that on a new motor I would have better. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted December 21, 2007 Report Share Posted December 21, 2007 doesnt matter new or old. There will be some variance between new and old but not a whole hell of a lot. cylinder pressure depends on certian things and the DOHC's just happen to have that much. Its motor to motor as to what it should have. Quote Link to comment Share on other sites More sharing options...
badassoldspower Posted December 21, 2007 Report Share Posted December 21, 2007 But if you do think you have a compression issue, you should really try to check the back 3 as well, I know they are a P I T A but sometimes it must be done. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 I am wondering with the other 3 in, that might have casue a little fluctionation in the readlings. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 WEll I did another check this morning. I got 200, 170-175 and 180 on the front 3. I am thinking that I will need to redo the rings. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 21, 2007 Report Share Posted December 21, 2007 WEll I did another check this morning. I got 200, 170-175 and 180 on the front 3. I am thinking that I will need to redo the rings. I disagree. the actual compression of an engine will fluctuate for a bunch of different reasons. temperature of the rings rotational position of the rings lifter bleed down. bore wear. the figures you gave are not significantly differing to be a problem. I think the allowable tolerance is 30%... so as long as your readings are between 200 and 140...... Your good as gold!!! Additionally, the proper way to do a compression test is to run the engine until warm, then pull the plugs and do the test. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 humm,ok Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 21, 2007 Report Share Posted December 21, 2007 p.s. I forgot to ask... how much oil did you dump into the cylinders? LOL Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 21, 2007 Author Report Share Posted December 21, 2007 quite a bit. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 21, 2007 Report Share Posted December 21, 2007 quite a bit. LOL probably the reason for exaggerated compression LOL Quote Link to comment Share on other sites More sharing options...
joey b Posted December 22, 2007 Report Share Posted December 22, 2007 I think my readings were in the upper 100s as well. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted December 22, 2007 Report Share Posted December 22, 2007 I just did a compression check. I got 185-195 from the front 3 cyclinders, is this ok? Entirely reasonable. Well I just put oil in the cyclinders, and the reading shot past 300, so I am guessing that either that happens when ever you put oil in the cyclinders or I have bad rings, got damn 2500 miles and already fried the rings. I guess I did not brake the motor in right. Not at all reasonable. Much too high. How much oil did you put in? WEll I did another check this morning. I got 200, 170-175 and 180 on the front 3. I am thinking that I will need to redo the rings. While I'd prefer to not have that much variation; it's not a "bad" result at all. I wouldn't "redo the rings" with readings like that unless you have evidence of oil coming up past the rings, or of compression going down past the rings. If it were me, I'd do a leakdown test if there were evidence of ring problems. Your compression is fine. And if the engine runs good, doesn't burn oil, and doesn't have excessive blowby--you're done. Drive it and enjoy. Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 23, 2007 Author Report Share Posted December 23, 2007 Sounds good, thanks guys Quote Link to comment Share on other sites More sharing options...
jeremy Posted December 23, 2007 Report Share Posted December 23, 2007 And if the engine runs good, doesn't burn oil, and doesn't have excessive blowby--you're done. Drive it and enjoy. he did say in another thread that he is getting smoke coming out of the dipstick tube now....so he might have a decent amout of blowby going on Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 23, 2007 Author Report Share Posted December 23, 2007 I drove the car on the highway tonight and got it to 90 then droped it into 3rd, brought the vac to 24. I did this like 4 times and the vac at idle went up to 18 from 17. I think that the rings are still a little in the break in period. So then I got off the hightwya and left it in 3rd, seemed to drive better and the vac stay steady at 18 at idle. I am going to drive like this for a while, hopefully it will help Quote Link to comment Share on other sites More sharing options...
dohc v6 Posted December 23, 2007 Author Report Share Posted December 23, 2007 oh, as far as the dipstick, when I took it out the car was hot as hell, and there was very little smoke in the tube, I just did not know if maybe something else was bad. But it was not smoking out, just a little haze in the tube, very little haze. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 23, 2007 Report Share Posted December 23, 2007 it all sounds like a normal engine to me. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted December 23, 2007 Report Share Posted December 23, 2007 I drove the car on the highway tonight and got it to 90 then droped it into 3rd, brought the vac to 24. I did this like 4 times and the vac at idle went up to 18 from 17. I think that the rings are still a little in the break in period. So then I got off the hightwya and left it in 3rd, seemed to drive better and the vac stay steady at 18 at idle. I am going to drive like this for a while, hopefully it will help Is this part of a normal, WFO/Idle break in procedure? You stand on the throttle in whatever gear is direct drive (or, with an automatic, give it as much throttle as it will take without dropping to a lower gear) until you get to highway speed, then release the gas so the car coasts down to ~40 mph or so, and then repeat until it stops being fun? It's not RPM that is going to help you, it's high cylinder pressures forcing the rings into the cylinder walls; and then high vacuum to pull a bit of oil up to wash away the wear particles. Quote Link to comment Share on other sites More sharing options...
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