Trailblazer 250 can't get compression...

[wolf trail]

Hi Everyone. I have a 2000 Trailblazer 250 I am having compression problems with. New piston & rings (gap is .010) clean honed bore from machine shop, and rings seem to be tight all the way around. All I can get is 60 psi on a gauge and it will hold it for a day with no pressure loss. No visible cracks or damage on head. Any ideas or something else I can try?? Thanks!

[Gear_Head]

wrong head gasket?

[wolf trail]

It looks right and fits the motor. How else could you tell?

[Gear_Head]

Originally Posted by wolf trail

It looks right and fits the motor. How else could you tell?

Thickness of it could be off. If you are relatively sure the piston and rings are correct, the only other thing that could effect the compression is the head and gasket. Sounds like your leak down test was great.

Was your compression tester fairly reliable til this test?

[wolf trail]

Ok, so I read another link on how to do a leak down test on my 2000 model 250. Evidently it was only my gauge that was holding pressure! Duh!! So, I capped exhaust and intake , then put air to it, and air started coming out around the magneto wires!?! Should the crankcase be pressurized?? or... do I have another problem? Rings not sealing? Thanks for any help!

[Gear_Head]

Originally Posted by wolf trail

Ok, so I read another link on how to do a leak down test on my 2000 model 250. Evidently it was only my gauge that was holding pressure! Duh!! So, I capped exhaust and intake , then put air to it, and air started coming out around the magneto wires!?! Should the crankcase be pressurized?? or... do I have another problem? Rings not sealing? Thanks for any help!

yes the crank case is going to be pressurized, this helps find the leaks it seems you may have. Best thing to do after having done a 2 stroke rebuild. helped me find a small leak on mine I never would have found otherwise.

$17 Leak Tester (2-Stroke)

Sounds like you may have a crank seal leak, if the stator wires are where I think they are. I know when you do the pressure test on my engine, the piston is to be in the down position. Hope this helps.

[wolf trail]

Thanks gear head! That is actually the link I found and built my tester from! A crank seal leak, huh? So... will that affect / be the cause of the low compression? Thanks again!

[Gear_Head]

Originally Posted by wolf trail

Thanks gear head! That is actually the link I found and built my tester from! A crank seal leak, huh? So... will that affect / be the cause of the low compression? Thanks again!

I gotta be honest, I don't think that would cause low compression, however can cause disaster for the engine and cause problems for you. I personally believe the compression would be an issue with piston and above.

Hopefully someone will chime in and help a little here.

[Diesel man 03]

With a new piston and rings and hone job you will not get real good compression until those parts break in a bit, are you able to get it started and yes if air is leaking out around stator wires youn have a seal leaking.

[bikersayings.com]

Wolf trail,

I need your help. I just had my friends blazer bored and honed and it now has 62 psi compression. What was your solution? Thanks,

Rob