Engine/Transmission (1998.5 - 2002) Question about compression check and leakdown test.

[Blacksdieselhp]

I have a few stupid questions. I purchased the snapon compression adapter that goes in the injector hole. And I have a 0-1000psi compression guage. But it doesn't have a one way valve. Anyway, my first question is do you leave the exhaust rocker off to do the compression check or put it back on? I put it back on and tried it, but the guage would only go to about 200psi and back to 0 as soon as I stopped turning the engine. So then I put a one way valve in the line on the guage and it would go up to 300 and leak down to 0 in about 30-45 seconds I'm guessing. Am I doing something wrong here? I wanted to check compression and leakdown because the truck is missing on one hole, and pours white smoke out. I think it may have a burned piston. I loosened each injector line one at a time and it dropped rpm with each line. So I'm not sure what to do next. It has a fairly new injector pump and supply pump. It doesn't sound like a bad injector pump either. It has 145,000 miles on it. The guy says it ran fine, then he stopped to fill it up and it happened about 80 miles after he filled up. Any help will be greatly appreciated.

 

[Mhannink]

the compression seems a little low for static. i have no idea what time is allowable for leak down. my bet is its an injector miss

 

[Partyat33]

You should be seeing about 460 psi after you crank it over a few times.

 

[Blacksdieselhp]

The most I seen on any of the holes was about 320. They all are starting out very low and bilding up as I crank it. I just feel like the guage isn't exactly right. The truck ran fine and strong with no oil consumption or anything right before this happened. One weird thing though, every time I turn the engine over someone says that it smeels like kerosene. I just wander if they put kerosene in it on mistake. My nose isn't good enough to tell, but that would explain the problem I guess.

 

[Misenheimer]

I put kerosene in my back hoe one time and it ran terrible till it got fresh diesel back to it. White smoke also.