Blowin by

[TPringle]

I recently purchased a 1992 standard cab truck that has had a dump bed put on some time back. I think I might have gotten "bitten" :{ on the deal, but not sure how bad. The engine is hard to start cold, but know at least part of the problem is the lack of a good battery. However, my other '92 will fire on the first spin, while this one needs to spin several times to light up. (No, I havent had the opportunity to ck the LP - yet)



It idles a little rough, but I wrote that off as a dirty injector & the need to be flogged. It smooths out when I bring it off idle. My thoughts were to have the injectors checked &/or rebuilt.



Now for the killer - this engine seems to have an awful lot of blow-by. There is a noticable stream of smoke coming from the breather hose & oil dipstick tube. The previous owner said it used some oil, but that didnt alarm me since my other 92 also uses some oil. The engine doesnt seem to smoke much from the exhaust (less in fact than my other '92), seems to run strong, carries good oil pressure and sounds good. The engine looks fairly clean and I dont see any oil leaks, other than dripping some from the breather hose.



I havent driven it enough to know how much oil it uses, how the fuel usage is or even know how many miles is on this truck. The odometer doesnt work, and it shows around 150k, but I am sure it is much more.



My worst fear is a broken ring/scored cylinder, but maybe you guys have had something similar and could shed some light. I havent been into one of these engines, and have wondered if it could be a bad head gasket. May not be any way to check without pulling the head. Havent done any compression readings or leak down tests...

 

[JLEONARD]

Cummins does have a blowby spec. I have the procedure in pdf but it's too large to post. You can e mail me at -- email address removed -- and I wll send it to you.

You can also change the way you vent the engine. Like this which is common in the marine world

 

[JLEONARD]

Let me also add that the Cummins "experts" on www.boatdesel.com don't panic to much about blowby. You can go to that site and do some reading as there is a current thread adressing it.

It might help you make a better decision on what to do... or not do.

Jay

 

[TPringle]

Jay, thanks for the advice. I visited this website, but have to have a membership to view the replies in there. It sounds like this may be a common problem (or maybe not a problem at all) with this engine. It alarmed me as compared to my other '92, as I can see the smoke coming from the breather, esp at night when I back up with the lights on. One response mentioned taking the oil tube off the turbo to see of the pressure is coming from the turbo or not. Honestly, this engine smokes more from the breather than the exhaust! For the record, I have rebuilt other diesel engines, but never been into a Cummins, so I dont know much about their quirks & failures.



Your photo says this blowby could be helped by rerouting the breather. Honestly this had crossed my mind to run this behind the cab or out by the exhaust. If this is fairly common/normal, then I will concentrate on getting it to smooth out at idle/low RPM, and reslove the starting issues.



I got a pair of batteries yesterday, which should give me about 1500 cranking amps to light the engine. I have to make a battery holder for the 2 batteries. I am also going to install an electric lift pump, and bypass the old mechanical one. Thanks for the advice, will keep ya posted.

 

[TPringle]

I think I may have found the cause behind the blowby on my engine. I was replacing the belt tensioner & thought I would see how plugged the air filter was. Any motorhead can imagine the feeling I had in the pit of my stomach when I saw the empty hole where an air filter shoud have been sitting!!!



I can only hope it was an emergency roadside 'repair' to get the truck home, then was forgotten about. You know, out of sight, out of mind. I cant imagine sacrificing an engine just to save a few dollars on a filter. The engine starts almost normal since I got the new batteries in, and aside from a lope in the idle, runs ok, but I am sure there is some damage to the cylinders & rings. It doesnt seem to lack power either. The biggest problem at the time is the "smokey" blowby from the vent hose. It is like having the exhaust run out the LF wheel well! Goes right up my nose! In fact, after a short test run, there was so much smoke I thought I may have blown a heater hose!



I dont have the time to rebuild the engine, so I need to find a way to live with it so I can use this truck for the reason I purchased it. Two thoughts. Run the breather under the cab to exit behind the back of the cab (then it can come in the rear slider window). The other is to run it over the the exhaust & let it exit there. The exhaust is straight piped & exits as a stack. Thought about welding a tube through right before it curves up at an extreme angle to go with the flow of the exhaust. The other thought if you think there may be too much exhaust pressure pushing back would to be to go to a dual stack & run it in the 2nd stack.



Anyone done this before? Any thoughts?

 

[JLEONARD]

Run the vent ito the air filter and the engine will burn it. That's what the boat guys do.

 

[PToombs]

Run the vent to the air filter and the engine will burn it. That's what the boat guys do.

All the new Case payloaders do this too. Only they run it in just ahead of the turbo. We had a few customers call for a service call just for me to tell them it's normal for the IC boots to weep oil like that. They weren't too impressed.

 

[cerberusiam]

All the new Case payloaders do this too. Only they run it in just ahead of the turbo. We had a few customers call for a service call just for me to tell them it's normal for the IC boots to weep oil like that. They weren't too impressed.

Ya think???



I hope this is not the new ones but the rode and put away wet ones you REALLY don't want to buy, right?

 

[JLEONARD]

If you look at the second picture I posted you will see that the vent hose leads around the engine and into the air filter.

The T at the low point lets the oily stuff collect into the catch bottle that is shown resting on the floor.

Therefore only the fumes get ingested. The liquid collects in the bottle.

 

[TPringle]

I guess if the boat guys can run the vent to the air intake, the truck guys can do it too! I just need to invent a way to connect it. May end up saving this rig after all!

 

[JLEONARD]

I just need to invent a way to connect it.

1/2 pipe tap and a barbed fitting into the air filter housing. Simple

 

[CToney]

My '92 I bought a couple years ago doesn't have a blowby problem but she smokes pretty good. Injectors helped some but it still is bad. When I put on my cooler tubz the old pipes had a lot of dirt in them. I hope most was stuck to the pipes. She starts ok and has good power and doesn't burn much oil. I have another good engine with 250,000 miles on her sitting in a parts truck so I am not too worried. If the engine doesn't work out by another for a few clams and throw it in.

 

[TPringle]

Do you think heater hose would work for this? I could probably put a "T" in the line with a small hose to drip oil out at the lowest point. Honestly, it is a little embarrasing to pull up somewhere and have all this smoke around the front end!

 

[JLEONARD]

Yes heater hose will work just fine. You could also use that clear hose with the support weave inside.