Engine compression

FORDSMB454

MEMBER
2005 CHEVROLET TRAILBLAZER
4.2L
V6
2WD
AUTOMATIC
130,000 MILES

I conducted a compression test on my dad's vehicle listed above. I did each cylinder dry and wet test cylinder 2 read a 90 rest cylinders were at 175-185 dry did cylinder 2 wet with tiny bit of oil nothing changed. I assume the valves are broken or stuck I threw some air in the cylinder 2 with it being on almost compression stroke hear ait coming through the air intake I assume the intake valve is stuck or something? Any help be great thanks any ideas?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,872 POSTS

Hi,

If the oil made no difference, then you are likely correct, it's related to a valve not seated fully or damaged.

I assume this test was done due to a misfire. Were there any other symptoms you noticed such as white smoke from the exhaust, or any overheating issues? It could be a head gasket issue, but that is a big difference in cylinders.

Take a look through this link and let me know if anything mirrors something you remember:

https://www.2carpros.com/articles/head-gasket-blown-test

If not, the next thing to do would be to remove the valve covers and see if there is anything pointing to a stuck or damaged valve.

Let me know.

Joe

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Tuesday, May 10th, 2022 AT 8:14 PM

FORDSMB454

MEMBER
40 POSTS

Yes, kept throwing cylinder two misfire code truck was running rough and my dad said he would stall at redlights with A/C or he have to put the truck in neutral otherwise it stalls no smoke though no white smoke no sounds nothing taping nothing. Just think it's the intake valve I think it may be bent or stuck.

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Tuesday, May 10th, 2022 AT 8:47 PM

JACOBANDNICKOLAS

MECHANIC
109,872 POSTS

Hi,

I would remove the valve cover on that side of the engine and see if there is anything indicating a problem with the intake valve. I say intake valve because you mentioned hearing the air come through the intake.

Let me know if I can help in any way.

Joe

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Tuesday, May 10th, 2022 AT 9:00 PM