Compression issues on a 1000 mile engine built low 100 psi on cylinder 2 Please Read

[garputo2]

I have around 1000-1500 miles on my 2 g engine that was built new crank rods pistons bearings ect I have noticed a decrease in power in the car decided to check the compression and 134 all have 150 # 2 has 100 when I add oil #2 goes to 120 psi. I think its something with the rings on that cylinder problem I have is I have run premium oil did a 500 mile break in at 1000 miles I started to tune the car got it at about est 300 hp the clutch was slipping so i never got a chance to tune anymore but was still able to handle pulling just no launching. But now my question is what happened everything is premium wiseco manley acl ect all done by machine shop what went wrong and is this whats causing the loss of power maybe I was thinking one of the rings is broken and its increasingly getting worse or maybe its something else all feedback is appreciated.

 

[donniekak]

Do a leakdown test.

 

[dsm8883]

Do a leakdown test.

I 2nd that

 

[garputo2]

I cant get ahold of the tester at the moment. Is there any other way to do a leak down test without the leak down tester?

 

[donniekak]

Unscrew the adapter hose from the gauge of the compression tester. Screw it into the sparkplug hole. Put an airhose fitting on the other end, hook it up to a compressor. This can show you where you are leaking, but won't give you the percentage reading a leakdown tester will.

 

[white92talontsi]

Unscrew the adapter hose from the gauge of the compression tester. Screw it into the sparkplug hole. Put an airhose fitting on the other end, hook it up to a compressor. This can show you where you are leaking, but won't give you the percentage reading a leakdown tester will.

Dont forget that whichever cylinder you are leak testing with the compressed air method that you have to make sure that the valves are 100% completely closed on that cylinder(piston at TDC). or you will get false information.

 

[garputo2]

But even if I do a leak down test if my compression is changing based on the fact I add oil doesnt that automatically mean we have a problem with the rings? This engine has around 1200-1500 miles ran really well just the other day then I noticed a decrease thats why I noticed this. My problem is if it was a valve issue wouldnt it not be running very good at all I mean the car still runs pretty well just loss of power I am getting a leak down tester tomorrow but I just want to know what I have to look forward to.

 

[Tanro]

Sounds to me like your piston rings did not seat properly.

 

[Calan]

What he said ^

How did you break it in? How long did it idle before you started seating the rings?

 

[white92talontsi]

But even if I do a leak down test if my compression is changing based on the fact I add oil doesnt that automatically mean we have a problem with the rings? This engine has around 1200-1500 miles ran really well just the other day then I noticed a decrease thats why I noticed this. My problem is if it was a valve issue wouldnt it not be running very good at all I mean the car still runs pretty well just loss of power I am getting a leak down tester tomorrow but I just want to know what I have to look forward to.

Correct. Rings did not seat correctly. When you get it fixed during the next break in drive the car harder. Dont baby it.

 

[garputo2]

i made a tester and it seems that cylinder 2 which is the one with low compression has possible leak thru exhaust when tested

 

[white92talontsi]

i made a tester and it seems that cylinder 2 which is the one with low compression has possible leak thru exhaust when tested

Make 100% sure that #2 is at TDC and that when you put the air in the cylinder the engine doesnt rotate and slightly open the valve.

You can makeshift you a valve that way you have a way to regulate how much air you are putting into the cylinder also.

Usually when you have a valve that isnt sealing you will get a slight misfire at idle that will go away as you rev the engine up.

 

[garputo2]

I have 272 cams and crower springs so it has a rough idle anyways but I made sure and know there is leakage on the # 2 for sure 3 is questionable. My prognosis is maybe when I installed this ebay catchcan which pushed all the blow by back thru the engine causing puffs of black smoke out the back may have blew shit down there causing the valves not to seat all the way just some buildup of crap on the seat of the valve. The car still runs and drives good though but not under load its just missing power under 20 psi when it was going like a champ. I am going to get a leak down tester but if there is a valve not closing all the way do you think I can run some of that gas cleaner thru see if it breaks down the crap on the valve? I really dont want to rip the head off at the moment 100 head gasket in the toilet. I am hoping something stupiod is causing the valve not to seat all the way thats a easy fix.

 

[JusMX141]

i made a tester and it seems that cylinder 2 which is the one with low compression has possible leak thru exhaust when tested

Then you definitely have exhaust valve sealing issues on that cylinder.

 

[donniekak]

Was the head rebuilt? Sounds like you may have a slightly bent exhaust valve, or worn seats and valves. Try lapping the valves in by hand, then filling the ports with solvent to check for leaks.

 

[white92talontsi]

With the engine running and a vacuum hose off the intake, rev the engine to around 1500-2000rpm. Start pouring water into the intake slowly until it starts to misfire and quit. Do this a few times. If there is any carbon build up on anything this will usually get rid of it. But dont go all crazy with the water.