Engine/Transmission (1994 - 1998) Chasing blowby

[TRCM]

OK. I've had a blowby issue since I got the truck.



I've been told it can be any of the following:

1) head gasket

2) turbo seals

3) rings

4) bad injector

5) bad exhaust valve guides





I ran a manometer test (home made variety) and got about 2. 5 times the normal readings. The engine doesn't use oil, but it does have a LOT of blowby. When you stop at a light at night, it looks like someone is pouring oil on the exhaust manifold.



I just got the results of my lastest oil analysis yesterday. I called them today, and asked them some questions and below are their answers based on the analysis.



1) head gasket - none of the tests indicate any kind of leakage unless it is possible for it to leak compression without getting antifreeze in the oil

2) turbo seals - IF the turbo seals are letting pressure get by and into the crankcase, this could fail to show up in the analysis

3) rings - none of the tests indicate abnormal wear at all. Chromium was only 3 ppm, and iron was 55 ppm. The tech said if there were any wear issues (like bad rings), the numbers would have been a lot higher

4) bad injector - this may be an issue, but there is no fuel dilution (< 1% vol)

5) bad exhaust valve guides - again, none of the analysis seem to indicate any abnormal wear of the metal components in the engine.





The only abnormal things were high silicon and a slightly higher than normal viscosity. The high silicon may be from my sampling, or from antifoam agents, as it was kind windy that day, and some dirt/dust may have gotten in the sample. No signs of any air filter issues elsewhere.



Below are the results, if anyone sees anything that concerns them, please let me know. This was with 3200 miles on the oil, and 138k on the engine.



iron 55 ppm

chromium 3 ppm

lead 3 ppm

copper 2 ppm

aluminum 9 ppm

silicon 97 ppm

boron 38 ppm

sodium 10 ppm

magnesium 94 ppm

calcium 2480 ppm

phosphorous 1163 ppm

zinc 1358 ppm

molybdenum 7 ppm

tin, nickel, silver, barium, titanium, vanadium, potassium 0 ppm



fuel 1% vol

vis @ 100 C 20. 44 (15w40 castrol, diesel rated)

water 0% vol

soot/solids 0. 2% wt

glycol neg

tbn 5. 7

f-soot 0. 2



Their comments said excessive wear is not indicated, and said nothing else but to change the oil if not done at time of sample.





Any advice on what may be causing the blowby is begged for. After this, I amnot sure if the rings or head gasket or valve guides are the culprits.

 

[Johnstra]

I'd be worried about the high silicon reading - 97 is a lot. But given your decent wear numbers it doesn't look like the silicon is doing any significant damage. Still, I'd check out your air filter assembly - maybe put a dab of grease somewhere behind the filter and check it periodically for dirt getting past your filter.



I suggest getting an accurate manometer test and if it reads high doing a compression test. You could have a dusted engine.



Good luck to ya.



-john

 

[Mundgyver]

Just out of curosity, how many miles on the engine (oops sorry I missed that and see it now) and have you ever had the head off or done any kind of work on the pistons



I know that when you install rings in a gasser that you make sure the ring splits are 120* apart and do not line up. Compression and blowby seem to be affected if they are. I would assume this would be the case in a Cummins also. So if any engine work was done in the past, could this be a factor. Miles on the engine and normal wear, maybe the amount of blow by you are seeing is normal for the amount of miles on the engine.



I am just throwing out ideas here as food for thought.

 

[Forrest Nearing]

you can try loading up about 30k lbs behind it and pulling the dog snot out of it to try to get a better ring seat...



or you could hone it and put new rings in it...



or you can just keep driving it... that's what I did with my truck... well... that and keep feeding it oil



seriously though, mine would paint the tailgate and the underside of the truck w/ oil vapor on the highway... truck ran great and laid down just shy of 450rwhp, got great mileage, etc. just had a good amount of blowby.



The truck currently has about 250k on it, and the new owner is enjoying the heck out of it.



it was embarassing leaving oil spots on the ground though!

 

[TRCM]

to my knowledge,the head has never been off.



the blow by is NOT normal, I've seen 250,000 mile trucks (no rebuild) that you can't even tell there is blowby on.



And the air filter better not be bad. it's a new bhaf with a new outerwears cover on it.



maybe I'm too picky, but I don't like the fog that surrounds the truck at a stop light.



kinda like would you let a mech work on your car if his smoked all the time ? I mean, if ha can't fix his own, how can he fix yours ?

 

[Forrest Nearing]

mine wasn't so bad that the vapors were visible at idle or anything...



and I didn't say it was normal, I just said that you could ignore it if you wanted to

 

[TRCM]

not you Forrest, someone else asked if it was normal.



yes, mine are visible. When I pull up to a stop light, it looks like someone just poured a cup of oil on the exhaust manifold.



but it does not seem to be using oil.



I don't want to live with it, but kinda have no choice until I can find out the cause. I really don't want to start throwing money at in the form of 'it may be this' parts replacements.

 

[Vaughn MacKenzie]

I have 385,300 mi and very little coming out my blowby tube.



Another commong cause for high apparent blowby and oil usage is a problem with the vacuum pump. It exhausts into the crankcase so if there's a vacuum leak it blows a lot more air through the crankcase.



A lot of blowby at idle probably means it's not the turbo, a bad seal becomes a problem at high boost or when an exhaust brake is employed.



Vaughn

 

[Evan A. Beck]

Compression test results?

 

[TRCM]

hopefully that will be this weekend or next week.



I'm putting an htt exhaust manifold on it to replace the warped & leaking stocker, and a new SBC next week, and plan on the compresson test being done then.



The blowby is mainly smoke, no oil on the underside of the truck.



I'm going outside right now to check for vacuum leaks on the chassis side of the vac pump.

 

[TRCM]

I just got done testing the vacuum system (in the cold rain no less). Seems to be fine. The vac pump will pull 25+ inches at idle, and the system (chassis side) only lost 1/4" of vacuum in an hr... went from 27 1/4" to 27". I also saw no noticeable change in the blowby with the pump connected or capped.





Now, I did look at my turbo, and it has me concerned. I have between 20 and 30 thou of side to side play (maybe more, I'm guessing here since my dial indicator wasn't long enough to get in there), but it doesn't hit the sides of the case that I can see.





The blowby is bad at idle, but it is the worst when you come down from higher rpm. It seems to be fairly constant, not really pulsing like it would if it was a single cylinder or two causing it.

 

[TXDSLSHOP]

I would not worry about a little side to side play on the turbo, only end play and leaks. As long as the vanes don't contact the housing. When it has oil pressure to the bearing the oil film tightens the play up.

 

[TRCM]

I agree, but on a precision part that spins at 50,000 plus rpm, I'd have thought it have been a lot less, like < . 001"

 

[PHedge]

we had a 24 valve in a school bus that did the same thing. The blow by was visible at idle but not to bad. Then if you would take and drive it the motor would start blowing alot of oil out of the tube. If you would put a catch can on it the thing would strart pushing gaskets out. We ran a compression test on the motor but there was not much difference between the cylinders. The biggest difference was about 50psi. When we finally ran out of options we tore it down and it ended up all of the top rings were shot,. Hope this can help you

 

[TXDSLSHOP]

"The shaft in my turbo feels loose. How much freeplay should I have?"



" While this specification does vary from one brand to another and rule of thumb is less than . 030" radial freeplay and less that . 002" axial freeplay.

This amount of freeplay is required to allow the bearings to "float" in a pressurized film of oil while the engine is running. The flow of oil through the clearance around the bearings is what helps the bearings stay cool. This oil film around the bearings also help dampen vibrations that occur to the rotating assembly as it moves through it range of RPM. Ball bearing turbochargers do not have this pressurized film of oil around the bearings; this is why they are somewhat more noisy than floating journal bearing turbos. " - taken from a turbo performance website. Maybe it explains it better than I did. Jeremy.

 

[Forrest Nearing]

I agree, but on a precision part that spins at 50,000 plus rpm, I'd have thought it have been a lot less, like < . 001"

try 150,000 plus!

 

[pwerwagn]

Well, I must say, im glad I read this thread. I've been following it because for the last month or so, my tailgate is always coated in oil. I kinda figgered id do what forrest did and just keep adding oil, (I do the 30,000lb-dogsnot pulls regularly enough... ) and go to the car wash once a week and wash the oil off.

well, after reading the last few posts, I just freekin realized I have a vaccuum leak. when I put the clutch in, i musta forgot to hook up one vaccuum line because my front end doesnt engage when i put it in 4-wheel and I have no floor or vent in the HVAC, only defrost (which is default when there is no vaccuum... . ).

so I must say thanks to you guys for helping me realize my stupidity.

-Jeff

 

[TRCM]

When we finally ran out of options we tore it down and it ended up all of the top rings were shot,. Hope this can help you

HA... not exactly what I wanted to hear... ...

 

[Vaughn MacKenzie]

I take it by your first post you haven't had the truck that long. Any idea of its history? A Cummins is pretty young at 138k, but all it takes is one bad air filter or a lot of flogging running the pyro to max and beyond to do in a good engine. I know someone posting awhile ago having to rebuild their motor by 200k 'cause it had too much blowby, but it had been driven real hard all its life.



I don't know how good a compression test is. Mine ran 500-520psi when checked at 355k mi, with a . 010" over head gasket. But I think my rings have seen better days.



Vaughn

 

[TRCM]

Only had it since late july, and from what I've found out & seen, the previous owners didn't know how to spell maintenance very well (or do).



It had close to a qt of oil spilled on it from spillage during filling, the wrong fuel plate for the other mods, no boost elbow (they broke the one that came with the plate), front d/s was literally hanging by a bolt from the tcase, wastegate was so loose I could actuate it by hand, major vacuum pump leak (not the source of the qt of oil tho), all valve covers leaked, low fluid levels everywhere, broken and welded (not very well either) tbolts on the downpipe clamp, pyro was loose on the dash (sticky tape was no longer sticky) and these are just a few of the issues I have found.



I suspect the K&N filter that is in the stock airbox that came with it is a good part of the turbo looking bad on the impeller.