Well I bought a 1996 12 valve 3500 recently. I love the truck. When I test drove it I crawled underneath it with my creeper and looked at the breather hose and there was no blowby. I took the oil cap off and there was VERY little haze and no real blowby. A couple days after I got it home I ran drove the truck and shot a video and there was very very light hazing through the oil cap.



I just did my KDP fix and changed the oil. I used Valvoline Premium Blue 15-40 like they sell at the Cummins service centers. The last few days when I run the truck for a few minutes I get some blowby from the oil cap. Today I was going for a good 3 hour drive to get the truck up to speed and really get some highway miles on it to see what it was like on a road trip. When I started out I had some blowby and blowby from the breather hose. For what it’s worth it was drizzling. After my long drive while the truck was hot I took the cap off and had quite a bit of blowby. I’m concerned and ******.



Did I just get hosed on my truck? Did the previous owner put something in the oil to hide a blowby issue until after the sale? Do I need to go back to Abilene and hunt this old man down? (kidding)



When you start seeing blowby what happens next? It gets worse until the truck explodes and kills me? (kidding) but really how long before this thing is done?



Here is a video from this morning………..

 

Bueller? Bueller? Bueller?

 

Not good. Pull your injectors and bore scope it. Also check for fuel or anti-freeze in the oil or oil in the anti-freeze.

 

Have you checked for major vacuum leaks in the system yet?

 

Kudos brother. I did check the vacuum lines and found a broken vacuum line under the driver’s side battery….. probably broke it when I was pulling my radiator and shroud. Ok I have a little bit of an update. I checked around the engine bay today and found a tiny vacuum line with a break in it. I repaired it and the blowby went away…… for the most part. There is still a little hazing at the oil fill and none under the truck at the breather hose. WHAT A RELIEF! It’s a wonder how much blowby you can get from a tiny little vacuum line. I would advise anyone who is panicking about blowby to check your vacuum lines. Thanks to you guys for sharing your knowledge. I did a lame quick video that hopefully helps someone else with the same issue. I also gave the forums some credit. Cheers

 

That’s your cruise control servo under the battery. Glad to hear you found the source of your problem

 

So now my Cruise Contrl might work?? I’ll give it a try! THANKS

 

Enjoy the hamburger in Blanco.

Glad I could help with the vacuum leak . I have seen a leak like that make a lot of blow by on my own trucks before.
Gotta love those cheap and easy fixes.

 

Thanks brother. Yeah I’m learning a lot in the weeks I’ve had the truck. You can’t beat the relief of a potential disaster turning into a simple solution ha. I once had a Mercedes E500 that was sagging at the rear wheel. It had factory air suspension and I thought it was a pump that would cost me $3500. Had it towed to Ben’s Workshop and it turned out to be a $1 fuse. What a relief. How did we ever get anything done before forums and Youtube??

 

I bought a '98 12V 5 speed 4x4 QCSB outta Texas in '19. I flew out with the plan of driving it the 2000 ish miles home.

The truck checked out pretty good when I bought it. The next day headed to Arkansas I pulled over to fill up the diesel tank. I had a massive blow by issue. Oil was slathered all over the transmission and frame under the truck. I was a little worried as I was about 3 days drive from home...

It was later that day I realized I had no brake lights, and it instantly blew the fuse when you swapped one in.

It was a long road trip and I learned a few things in a bunch of Napa parking lots on the way home. Bought a bunch of tools I had at home too.
Making memories I tell you....Haha

 

How did we used to get things done before you ask?

The same way you just did - asking someone who has been there and done that before.

 

I’ve been talking to a guy out of state about a pretty beat up 2nd gen 3500 4x4 12 valve. It is rough. I drove it. 2nd and 3rd grind… the clutch is on it’s way out…… but I really want to have my girlfriend drop me off next time we are visiting her parents and I’ll drive it back….hopefully. I’d take tools with me. I have this idea that it would be a great adventure to take back roads across 3 states back to Austin. I watched a video of this guy who did the same thing with an old Cummins and it just looks like a blast. In reality I may end up stranded but if I can get my girlfriend on board I may try it. I may get a couple guys’ numbers from the forum so I have roadside assistance along the way haha.

 

Yep it just took a LOT longer to get information and parts and I could have never gotten it from a guy in Vermont