Alright....we all know the story....

Wrecker engine was installed into a 97 k1500....

Engine was running great...now it is using quite a bit of oil....

There is no blue smoke coming out of the tailpipe at all....if you jab the throttle it will blow out clouds of grey/black/white....not really a blue tinge but the smoke will smell like burned oil...

There is absolutely NO blow by when you take off the oil fill cap....not even a hint of white vapor...

We have tried two different CDR valves with the same result...

There are NO oil leaks at all....

What we are wondering is if it is possible for a turbo seal to have gone bad (turbo has just under 400 000 kms on it and has been run starved of oil at one time in its recent history - turbo has also been run for a month with oil mixed with coolant from the cracked engine beforehand)...

If a turbo seal went bad, is it possible for oil to leak into either side of the turbo and get shot through the intake or burned in the downpipe?

We only have a week to get this sorted out before we have to let the wrecker know if we need a different engine....I have a hard time believing the rings are stuck on a cylinder because the engine runs like a top, has no blowby and does not smoke blue at idle...

We have a spare GM4 that we are going to put in place of the GM8 and see what happens...

Any comments/suggestions?

Diesel t\c's don't have seals like you're thinking of -

- no vacuum on compressor end, so 'seal' is centrifugal and Boost pressure

- always back-pressure on turbine end, so 'seal' is ebp, centrifugal, and a piston-type ring in a ring-groove

- if bushings and shaft are severely worn, all bets are off.

You can try the -4, but you made no mention of specific volume of missing oil

pull the upper intake and check for oil.

If it were coming through the cdr, you should see some oil on the intake side of the turbo if you pull the boot off.

Oil usage is 1L per hour at highway speeds.....

that sucks, chris! Are you sure it isn't leaking somewhere? (that's a lot of oil, if it was coming out the pipe, you would be seeing it, I would think)

So......in 3.79 hours you'd burn off a gallon?

And your fuel mileage hasn't increased dramatically?

There's a lot more btu in a liter of oil than in a liter of Diesel fuel.

And there's no smoke or dripping oil out the tailpipe?

As if it were exiting into the exhaust elbow.

That much consumption thru the intake has been known to cause surging and engine run-away - uncontrollable by throttle

If it's in the turbo elbow, then the turbine shaft must be leaking.

Pull the turbo to check for that - if not, pull the CDR tube for a test, plugging the inlet port.

Or give it few more miles to settle down - you can see haze better at nite in the cars headlites behind you.

So......in 3.79 hours you'd burn off a gallon?

And your fuel mileage hasn't increased dramatically?

There's a lot more btu in a liter of oil than in a liter of Diesel fuel.

And there's no smoke or dripping oil out the tailpipe?

As if it were exiting into the exhaust elbow.

That much consumption thru the intake has been known to cause surging and engine run-away - uncontrollable by throttle

If it's in the turbo elbow, then the turbine shaft must be leaking.

Pull the turbo to check for that - if not, pull the CDR tube for a test, plugging the inlet port.

Or give it few more miles to settle down - you can see haze better at nite in the cars headlites behind you.

fuel mileage is same as before....no huge increase...

no heavy smoke out of the tailpipe....at idle there isn't even a haze when the truck is warm.....smells like burned oil when the truck is shut off though....maybe I'm not looking hard enough...

no surging.....engine runs like a top...

will pull turbo and let you know....

You may also want to check the turbo oil drain tube, many overlook this item. It can cause a large oil consumption problem as well.

You may also want to check the turbo oil drain tube, many overlook this item. It can cause a large oil consumption problem as well.


It was cleaned out before install.....I don't think the tube would be stopped up....will definately look into it when the turbo comes off....

Wow....the turbo shaft in the GM8 is wrecked....there is a HUGE amount of play both side to side and front to back....the blades were contacting the housing and cutting grooves into it....

Needless to say - with the installation of the GM4 there is no more oil consumption.....

Thanks guys...

Good to hear that it's fixed!

Good to hear that it's fixed!


Mee, too ... I've been looking to the East for the last week, waiting to see the mushroom cloud.... all that work, and using lots of oil?

Would have been one unhappy flatlander, I'm thinking.

:eek:


:D

good to hear you got it fixed chris. I was wondering what else it could really be causing all that oil consumption.

I hear CR has a GM-8 thats been laying around for more than a year. Think he got that thing making 25 PSI pre-IC.

So ask the wrecker for a replacement GM8 turbo !!!!

The GM8 was on the engine that cracked.....we wanted a 599 block from the wrecker and the GM4 came attached to it....

Don't worry.....his truck is will never see any modifications to the extent that mine will....the small difference in the efficiency of the two turbos doesn't mean much to him....