So i just picked up an lb7 with 220k miles all stock. it has exessive blow by where you can see it during the day. No tailpipe smoke at all and still runs strong. I just had a compression test done on it and came back lowest at 662 and higheat at 670! Is this correct? Ive been reading the min is 300 and everyone seems to be at mid 400s. Previous owner said it got a new turbo a few years ago and the injectors were done right after 100k. No fuel or coolant in oil.Stumped on what the blow by could be shop says maybe valves.?? Any input would be appreciated thanks.
Exessive blow by help!
- Thread starter ws6woody
- Start date
Compression test was not done properly... healthy is 400ish.
How much blow by are you getting out of the oil filler neck with the cap off?
How much blow by are you getting out of the oil filler neck with the cap off?
Those numbers are way high. Not sure what or how the compression test was done though. Valve guides and seal could be the culprit for blow by ....could be rings as well. Depends on how the truck was used or abused
The truck was pretty much just used on occasion to pull a 5th wheel and took it easy the rest of the time. I got it from a neighbor an old guy and he put 70k miles on it it 8.5 years. If it was the rings wouldn't it smoke out the exhaust? Sorry for the newbie questions im kinda new to diesel.
Check and make sure you PCV hose or PCV reroute hose isn't plugged, that could cause blowby. Not sure why you have 600+ psi for compression test but somethin's wrong with that reading. I suspect injectors are bad, leaking fuel during compression test. Is the crankcase oil diluted with diesel?
From the filler and the vent on passenger side on engine its a steady puff puff puff whitish smoke. I noticed the passenger valve cover leaking quite a bit also could this have anything to do with the blow by if the engine isnt completely sealed properly?
The puff puff would lead me to think it is a single cylinder issue... I would have the compression test redone by someone who knows what there doing and go from there.
How close are you to Van? Josh has a shop there. http://www.duramaxdiesels.com/forum/forumdisplay.php?f=156
How close are you to Van? Josh has a shop there. http://www.duramaxdiesels.com/forum/forumdisplay.php?f=156
Mine had blowby and quit, guessing valve seals got hot on mine, weird but it quit.
If yours is puffing it's probly a single cylinder that is washed or bad rings, someone correct me if I'm wrong but could be a bad set of valve guides or seals on a single cylinder making the cover leak and the puff as well?
If yours is puffing it's probly a single cylinder that is washed or bad rings, someone correct me if I'm wrong but could be a bad set of valve guides or seals on a single cylinder making the cover leak and the puff as well?
Ok i finally spoke to the tech that worked on the trk the guy i spoke to didnt know shit jst read notes lol. so the 600 numbers were the cylinder output from the gm scan tool. He never did a compression test so being that they are that close together and efficient i can rule out rings. He is stating maybe oil seals on turbo or valve stem seals. Tuesday he will do a leak down and compression test on it ill update then. Thanks fellas