Possible Causes Of Blow By

[washout996]

I have an 03 dually with the 5.9 Cummins and 6 spd manual. There is some blowby, not bad but enough to notice it when the truck is idling and you look under the front. I found some seals and an open ended ring in the dash pocket when I bought he truck, I wonder if the turbocharger seals were changed and not put back right, and if that is causing my blowby. (See the bottom cause in the chart)

 

Anybody have any thoughts on this ?

 

[mopartechnician]

Blow by is caused by worn piston rings or scored cylinders. There will be some blow by. Turn the oil fill cap upside down over the fill hole, if it blows off you got too much blow by. Why do you think the turbo was rebuilt?

[joecool911]

There are video demonstrations on YouTube about blowby on cummins motors. In extream cases, blow by will shoot the cap into the air. Less dromatic cases it will just flutter a bit. Best case is no action at all.

[mopartechnician]

This is a scored cylinder from driving a truck too much with a sticking injector

Edited February 3, 2014 by mopartechnician

[joecool911]

Short of pop testing is there a way to evaluate injector performance?

[mopartechnician]

I cant get my video to upload off my phone. You can do injector return and compression test but the return wont be an indicator here. Compression is going to tell you the most. Injectors have to be sent off to test.

[joecool911]

So starting a newly acquired truck with injector testing my be advisable. Then any noticeable change in performance would indicate possible trouble. I'm just going to replace mine with 50-75+ injectors and be done with it for a while. Are new injectors pop tested for matching purposes?

[mopartechnician]

No 3rd gens arent popped tested since they are electronic. They test spray pattern, spray volumn, return, and some other stuff. Gotta be careful on which injectors you buy, there are lots of junk rebuilds out there. The only ones i use are bosch rebuilds (rebuilt by bosch) or i am going to start pushing the big bang injectors since they are completly brand new

[washout996]

I just found a website that claims to have a product that will fix Blowby without ever turning a wrench. This is my first Diesel engine, and I'll be the first to admit that I know nothing about them. Any Thoughts ?

 

http://shop.certechgels.com/category-s/1822.htm

 

 

[mopartechnician]

Uh thats called snake oil.

[hex0rz]

Hmm, thats weird!

 

http://shop.certechgels.com/product-p/4-and-6-cylinder.htm

 

I would try it on a lawnmower engine or something first before I ever considered putting it in my cummins!

[Mopar1973Man]

If I thought there was excessive blow by this thing I would do is take all 6 injectors out and have them pop tested being 99.9% of all CR engine cylinder issues are from injector failure. Then while the injectors where out I would do a compression test and see if you can reach a normal 450-475 PSI worth of cylinder pressure.

[mopartechnician]

Min. compression is 350 and all cylinders should be within 20%. The last two pickups I did were all around 380

[Mopar1973Man]

Heck... That seems low. I know the Dodge FSM doesn't state a number.

 

But when Pepsi71Ocean did his it was 425-450 PSI for a 16.3:1 ratio SO 24V engine. I know the CR engine are better compression over the 24V.

[mopartechnician]

Thats what my 06 fsm said. Ill look later at other ones.

[mopartechnician]

My 04 fsm says the same thing about compression. I couldn't find it in my 01 fsm though.

 

Here is a video I recorded of blow-by on a 05 cummins. I can't remember what the readings are but I was thinking one cylinder was around 100-150psi.

video-2012-01-02-20-21-23Converted.wmv

[Mopar1973Man]

Thats what my 06 fsm said. Ill look later at other ones.

 

 

Great. I love when there is some factual information. Now if we can get it for the older series say 24V and 12V...

[washout996]

I was about ready to shell out 5 grand for a complete engine rebuild, so I figured Why Not ? and I popped for the $177 bucks for Cer-Tech Gels kit. I followed the instructions to the T, adding 1 tube of Gel, driving about 100 miles and then adding the other 3 tubes. It's been a little over 900 miles now, and the blowby is gone. No more white smoke coming from underneath my truck, No more burnt oil smell when I shut it down and open the door to slide out. You might ask how long it will last ? That's a good question. The rep I talked to at Cer-Tech when I bought it claims it will last up to 100 thousand miles, but it will take years for me to put that many miles on my truck so the jury will remain out for now. If your dealing with Blowby, your going to have to make the call on your own on this one, but I will tell you that it seems to have worked for me.

[hex0rz]

Awesome! Its definitely not a conventional thing to consider, but atleast you have stepped up to the plate and took the dive. It will be useful to see how it works out!

[mopartechnician]

Ya i think it would be cool to see the before and after. My concern would be if it fixed a scored cylinder than did it plug the cooling nozzles on the pistons? I still cant believed it fixed it. I guess its worth the shot if you are gonna spend money on a rebuild.

Edited February 23, 2014 by mopartechnician