Excessive Blowby

[cjones]

I would like some advice on what constitutes 'bad' blowby. My 98 Suburban 6.5 Turbo has a constant flow of white smoke from the oil fill tube and obvious white smoke from the oil dip stick tube. I've done the CDR test and confirmed that there is negative vacuum at 1500 rpm so the CDR should be good.

About a week ago I just finished swapping out injectors, I had them rebuilt. About a month ago I replaced the water pump, flushed the radiator, after a radiator/heater line ruptured.

The rig is actually running fine, I haven't noticed any excessive oil consumption, loss of power, or coolant loss, although I'll be watching for these closer now. I'm hesistant to do a compression test because of the cost.

In one week, I'm planning on using this rig to haul about 10K to New Mexico....should I be worried. I'm not opposed to adding oil or patching things up along the way, I just don't want to be stuck in Podunk, UT for a week.

My question is: When should I be worried about blowby? How long, avg, will the engine run normally like this? Any other tests to narrow this down?
Thanks in advance, Chris

[Robyn]

With the oil fill cap off, its not uncommon to see some white vapor.

With the cap off, the vapor should go away when the rpm is raised to about 1500

As long as its not Huffing, not to worry too much.


Missy

[cjones]

Thanks Robyn, that checked out good. Needless to say I've been a bit anxious to see how these rigs will tow...in August....in the southwest. The 98 seems to have the power if needed on the hills with the load but overheating is my worry. I'll put on the pyrometer/tranny temp sensors Monday....I guess the worse thing that will happen is we'll drive slower. Thanks for the help.

[DmaxMaverick]

It's really quite simple, and I think you get it. If your truck is healthy, you use it to it's potential, or get more truck if you think you need more. Drive slower, or get more truck. Slower is not such a bad thing, and you won't lose more than a minute or so at the top of the grade. If you want to drag race, get (pay for) a capable truck.

[More Power]

Diesel engines generate considerably more combustion pressure than a gasoline engine, so they also generate more combustion gas leakage past the rings. That's why the engine oil darkens due to soot sooner than the oil in a gas engine, and is what determines the oil drain interval. Soot is mildly abrasive.

It's somewhat normal to see wisps of whitish/greyish vapor with the engine idling and the oil fill cap removed. The vapor should be translucent in a normal and healthy engine. If, on the other hand, the vapor is opaque, there could be a problem. If the vapor appears as opaque puffs, like Robyn mentioned, you may have a damaged piston. Yours doesn't sound like the latter.

Jim

[Robyn]

50k miles after I rebuilt the engine in our 94 Burb, there was zero vapor at the fill cap at idle.

I had a factory new 2500 club cab that had a ton of slop at the fill cap when it was near new.

The blowby depends on how good the rings sealed right off the git go.


Missy

[greatwhite]

Are you seeing oil smoke coming from the dipstick tube with the dipstick in or out?

Out isn't a really big surprise, in is a sign of potential problems.....