97 LX450 Good spark, fuel and air and still no start (1 Viewer)

[GearHeadGunGuy]

Couple of ounces per cylinder, enough to completely coat each piston top (so the oil is forced to drip off onto the sides), OR if you have a way to 'fog' the cylinders....all the better. The idea being we want to let the oil coat the cylinder walls (as much as they are exposed right now) AND seep down onto the rings overnight. We've seen this low compression thing before on engines that have sat. After cranking and lubing....a good number of them can be revived. But you don't want to crank DRY cylinders and rings ( I know you know).

IF that fails to bring up the compression, then you're looking at pulling the head to see what the trouble is .

Thank you.

 

[flintknapper]

Thank you.

De Nada....hope it works for you. I know you'll get to the bottom of this It's clear you are an accomplished mechanic by the steps you've already taken.

 

[60 toy ota]

Thought it'd be worth mentioning, as your experience is mostly with diesels (though I'm sure you probably already know) to be at WOT during compression testing

 

[GearHeadGunGuy]

Thought it'd be worth mentioning, as your experience is mostly with diesels (though I'm sure you probably already know) to be at WOT during compression testing

Forgive me, I don't know the acronym for WOT.

 

[Speedytech7]

Forgive me, I don't know the acronym for WOT.

Wide open throttle

 

[GearHeadGunGuy]

UPDATE:

So, fogged all 6 cylinders and did another compression test. Got 4/6 cylinders over 120psi but the other 2 stayed at 30-40psi with no change. I was able to get it running but have misfires in the two cylinders with no compression. I ran my bore scope into the cylinders but was unable to see any definite signs of problems. I have ordered a leak down test kit from my local snappy guy. Until then I am leaning towards putting on a new head.

Thanks for all the help so far ya all.

 

[flintknapper]

UPDATE:

So, fogged all 6 cylinders and did another compression test. Got 4/6 cylinders over 120psi but the other 2 stayed at 30-40psi with no change. I was able to get it running but have misfires in the two cylinders with no compression. I ran my bore scope into the cylinders but was unable to see any definite signs of problems. I have ordered a leak down test kit from my local snappy guy. Until then I am leaning towards putting on a new head.

Thanks for all the help so far ya all.

Are the two cylinders with low compression side by side? IF so....then likely a blown head-gasket between cylinders.

Leak down test (you are already on it) is the next step. Listen closely for escaping air anywhere.

Good job.....you are narrowing it down in a methodical fashion.

 

[lelandEOD]

^ This.