brian andrews

Just picked up this 90 cummins and dude never changed the fluids. Oil looked muddy almost and felt tacky and thick. Changed the oil and it looks like this. When you touch it with your finger it comes off yellowish but on the stick it looks straight black. Couldn't be a head gasket could it? Have new injectors on the way that should fix it running rough. Any ideas guys?

brian andrews

Kinda hard to see in pics but looks like really small bubbles. Oil cooler maybe? Not too experienced with diesels just yet

patdaly

I would be tempted to run it till warm, then drop and change just the oil and see how it does the second time around.

You might be dragging all the much up into the oil.

How long has that oil been in it?

bigragu

Did he actually tell you he NEVER changed the fluids? Hard to believe it still runs if the fluids have never been changed... Now if the owner before him used some type of Lucas product, such as the oil stabilizer, it does feel sticky to the touch somewhat

mknittle

It is also kinda thick when cold.

brian andrews

Yes his words were, " it could probably use some fluid changes, cause I don't do that stuff " Lol and the pics were taken right after doing the oil change and running it for a minute. I have new injectors on the way and that should fix how it's running, if not I know I have another problem

dan123dbl

Did you use 15w40 oil? It is normal for the oil to turn black quickly. Mine takes over 1000kms to get black but I've heard of others turning black as soon as they start the truck after an oil change.

You might want to check the valve clearances if the engine has some miles on it and hasn't been maintained properly.

j.fonder

get it warm, drain it, change filter, fill it with full synthetic.

j.fonder

btw, excited to see another 1st gen owner in Jacksonville! we'll have to get together sometime

brian andrews

Heck yeah man!

And yes fresh shell rotella 15w40 conventional. If these injectors get it on the road I planned on putting 500ish miles on it and doing another. I'm not concerned about the color as much as the bubbles. I've heard bubbles means bad things

j.fonder

i'd say as long as it's not foamy/frothy i wouldn't worry too much about it.

i recommended the synthetic because it will clean up things that conventional will leave behind. which sometimes is good or bad.

thrashingcows

I agree with the others...if it had been neglected for a long time there is most likely a lot of sludge in the motor. It's going to blacken up super fast!

I'd change the oil like you suggested, after a 500 mile trip. Then I'd do it every 3 months for the next year or so, or until the oil starts looking more "normal".

My 89 motor I had in my crewcab used to turn the oil black within a 1000miles or so, but my 93 motor I now have in the crew will just start to turn slightly brown-sih, from clear oil, at 5000km's.

signature600

Here's something we did when we had a programming problem on some new Common Rail engines back in 2006-2007. They would root the oil up WAY too fast, and would cause valve bridge and rocker arm wear like you wouldn't believe. This was a Sisu Diesel sanctioned fix, that I have used many times in the past, and since then.

Fill the crankcase half full of diesel, and half full of oil...and for good measure, install a manual oil pressure gauge in the filter head just to be sure.
Fire it up, and run it at 1500-2000RPM until the oil pressure drops to 20psi, or the light comes on...Drain.
Repeat this 3 times.

Fill with new oil, change filter, and go. This does an excellent job of cleaning out a LOT of old sludge from the engine.

You can use it if you like, just throwing it out there for you.
Chris

thrashingcows

New filter every time you fill with oil/diesel?

BlueW250

On a neglected engine that sludge probably is your seals. The method will work but you will likely see some new leaks.

Thank you,
BlueW250