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1G Low compression new engine

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1GAWD87

15+ Year Contributor
80
35
Mar 8, 2009
milaca, Minnesota
Hey thanks for the post! Mods in profile. So last night i was getting things buttoned up on it lastnight, and i had noticed oil in my biss screw and around my tb gasket. Motor has 67 miles on it so far seated the rings moto man way. Ive been chasing an alternator problem and trying to fix broken ribbon wire behind gauge, got my check engine light back but no battery, coolant light. Compression test=120-100-120-120. Warm engine repeated twice. wot with all plugs ot no fuel or spark. Battery cranked it fine. Plugs looked good any advice would be appreciated. It was pretty late last night i will verify ignition and mechanical timing in a few hours when I'm off baby duty! Wyatt
 
Thanks for the reply. i don't have a leakdown tester. Maybe i can see if i can make a diy test, not going out much lately.... i didn't lasso the valves personally stock valves, my machinist installed them id imagine im sure he did? My lowest compression #2 also the cleanest piston
 
Take your compression tester and remove the schrader valve and hook it up to shop air. I forgot what I set my regulator to but definitely turn it down. Listen for air at the fill cap, dipstick tube and coolant reservoir. Set the cyclinder you’re testing to tdc
 
Ok thanks! Baby duty for 2 more hours tuning in a few days.... found receipts from the sho . Clean and grind valves lap seats. Also i should mention i needed a catch can in a hurry my buddy brought a morooso -10 atmosphere canister style. One from pcv and partner side of vc and plugged the vaccine off of canniste . No vacuum from can to head, i was wondering if that was the culprit
 
Ring gaps too large, too much PTW clearance, rings gaps not spaced 2/3rds of a turn apart are all ways to not have good compression on a new motor. A clean piston almost indicates it is getting "cleaned" by something. Was the motor decked and the head completely flat and true? Just things that could cause the problem, not sure how to cure it. Put some oil in the low cylinder and retest compression. The oil will help the rings seal if they are leaking. I would have thought it would have more pressure than 120 on a new engine, but it is within service limit.
 
I am wondering if the head gasket is leaking a bit into #2, steam cleaning it? Check the torque on the head bolts/studs for proper torque.
Any pictures?
 
I am not stock so I can't compare but the Red Talons motor was 10:1 and was 200 across the board and my Blue Talon is a 9:1 motor and has 185 all across it.
 
I am not stock so I can't compare but the Red Talons motor was 10:1 and was 200 across the board and my Blue Talon is a 9:1 motor and has 185 all across it.

You should give me some :aha::)
 
Test was inconclusive new o-ring in tester cranking slow still around 100. My brother just brought my other gauge cluster hopefully that will solve the other headache. What pictures would you like? Also wasnt to add 2nd set of plugs bpr7es ne . Put then in 30ish Mike's ago torque to crush washer when i removed them last night they were dang near hand tight only? My understanding was the L19 shouldn't have to be re torqued but il definitely do s . Thanks
 
Test was inconclusive new o-ring in tester cranking slow still around 100. My brother just brought my other gauge cluster hopefully that will solve the other headache. What pictures would you like? Also wasnt to add 2nd set of plugs bpr7es ne . Put then in 30ish Mike's ago torque to crush washer when i removed them last night they were dang near hand tight only? My understanding was the L19 shouldn't have to be re torqued but il definitely do s . Thanks

English only please...LOL jk. Hard to follow what your're saying at times. What did you torque your head to?
 
Sounds to me like your ptw clearance or cylinder wall finish is the issue. The 4g63 is a very forgiving engine, headgasket sealing issues etc etc don’t usually come in to play until you start throwing serious boost at them. Those number are low for a new motor.
 
Hey thanks for the post! Mods in profile. So last night i was getting things buttoned up on it lastnight, and i had noticed oil in my biss screw and around my tb gasket. Motor has 67 miles on it so far seated the rings moto man way. Ive been chasing an alternator problem and trying to fix broken ribbon wire behind gauge, got my check engine light back but no battery, coolant light. Compression test=120-100-120-120. Warm engine repeated twice. wot with all plugs ot no fuel or spark. Battery cranked it fine. Plugs looked good any advice would be appreciated. It was pretty late last night i will verify ignition and mechanical timing in a few hours when I'm off baby duty! Wyatt
Not good.:toobad:, rings are likely trashed.
 
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