Low compression across the board on fresh rebuild

[Burnett03]

Well, i put some compressed air to cyl 1. Nothing out the intake or exhaust, but you can hear it in the valve cover. Just basically confirms what i thought.

Plugs were oily on 1,2,&3, but 4 is clean. Same compression on all 4 though.

I know the webcams will bring it down just a little, but it is still sitting at 100 on all 4.

Breather tube is plumbed back into the intake tube.

I am still running a little rich at idle because of the low compression, so i dialed the afpr down another 5 psi. That brought my afr to @ 14:1. I am @ 15:1 off idle until boost hits.

Did another oil change today. Oil didn't smell of fuel, so i doubt it is washing down the cyl walls.

How many miles do you guys think i should go before i make the decision to try some new rings?

Any other suggestions?

atleast 500 before you pull it again.. mine was low on my last rebuild until around 600miles and it was up the high 150s

 

[tom04841]

One thing i forgot about was when i put my new head on , I had my CAS 180 deg out. It was misfiring pretty bad. I changed it the next day. Could this have caused the cyl walls to glaze or something to that effect.

I am just throwing out ideas and trying to provided the most accurate details i can.

 

[tom04841]

I checked compression again today. It is up to 120 across the board. This is giving me some hope The smoking is still random, but smoke more often then not.

 

[Forsakened]

If you decide to re ring it then you could also have your head pressure checked while its off to make sure the valves are sealing properly, swing by a machine shop they will usually do it right then. Can't hurt.

 

[tom04841]

If you decide to re ring it then you could also have your head pressure checked while its off to make sure the valves are sealing properly, swing by a machine shop they will usually do it right then. Can't hurt.

It was pressure checked by the shop i got it from before it was installed. Also when i did the leak down test, the was no loss from the intake or exhaust.

 

[Burnett03]

like i said before, ill say it again.. keep driving it, it'll go up.. lots of engine braking too

 

[tom04841]

like i said before, ill say it again.. keep driving it, it'll go up.. lots of engine braking too

With my luck lately, I tend to expect the worst.

To everyone, thanks for the help. I will keep updating, good or bad.

 

[95tsiawd6blt]

just beat the shit outta it, who cares what the compression is, dont take something apart that is running, you may end up with worse compression after u re ring it. i dont know why people worry so much about compression, you can still make plenty of power if your motor has 100 psi across. as long as all 4 are still going, just drive it.

 

[oldman]

just beat the shit outta it, who cares what the compression is, dont take something apart that is running, you may end up with worse compression after u re ring it. i dont know why people worry so much about compression, you can still make plenty of power if your motor has 100 psi across. as long as all 4 are still going, just drive it.

1. Please do not reply to subjects you seem to know nothing about.

2. Learn to use your shift key.

3. Complete your car profile.

 

[tom04841]

just beat the shit outta it, who cares what the compression is, dont take something apart that is running, you may end up with worse compression after u re ring it. i dont know why people worry so much about compression, you can still make plenty of power if your motor has 100 psi across. as long as all 4 are still going, just drive it.

You may not like your car, but I love mine. I will beat the snot out of it once it is ready to be driven hard.

Just another update.....Smoking is pretty much gone except for initial start up, and under vacuum @ 3000 rpms. There is no longer any air coming out the valve cover to intake tube vent line. I am going to do another compression check tomorrow at work and post the results.

 

[oldman]

I'm beginning to think the older compression tester is mor accurate than your new one, not uncommond really, I would go double check on that when you get a chance.

 

[tom04841]

I'm beginning to think the older compression tester is mor accurate than your new one, not uncommond really, I would go double check on that when you get a chance.

You may be right. It is a cheap one from autozone. I will check it with both tomorrow.

 

[tom04841]

Just another update.... smoking has pretty much stopped. couple puffs here and there. After 250 miles, compression is at 150 across the board I can live with that if it doesn't get any higher.

 

[T9S1i]

i told ya in your first thread not to check your compression until 2-300 miles, you could have saved yourself a headache!

Good to hear your compression is up where its supposed to be now. Sometimes i get like that with my car too, everything bad happens and you throw money at it and more shit goes bad. Then you put a motor in and you are so used to being f'd with by the damn dsm that you expect that to somehow not work out. But believe me, everything will be good with your new motor. My car has been solid ever since i dropped in a new motor. Probably since ive replaced so much stuff in my car that its practically brand new.

Good luck with the new motor man and happy boostin!

1 last question... did you use synthetic oil for your breakin?

 

[tom04841]

1 last question... did you use synthetic oil for your breakin?

No. I am still debating on whether or not to go synthetic. I only drive the car 3-4k miles a year, but do oil changes every 2 months. The motor is probably coming out next spring and a built motor is going in.