C12 front cover leaking oil

C12's are pretty good as far as seals, so there's not really a "common" leak. Fuel pump, power steering pump and air compressor are about the most common. Clean and pressure wash it it really good and see what area it's coming from. The crank seals on C12's are bolt on, so no special tools needed if that's what's leaking. If you send me a PM with your email, I can send you a .PDF manual so you can see what your in for if you decide to tackle it yourself.

 

Sorry I didnt respond earlier I did notice the power steering(I THINK) is leaking now that it is colder. Ive got to get it pressure washed theen go from there. I think it is also leaking oil, it doesnt use maybe a couple quarts every 10,000 miles if that. I think the fan makes it look worse than it is. Im not gonna do it myself right now, I dont have anywhere to do it, we are looking for a house now that i can at least bring my tractor home so I can do some of these little things without dragging tools to the truckstop. I park at Dallas Pike TA on 70 at WV, Pa line.

 

Sorry for taking so long to reply. And yes it does get ya kind of angry after you keep up with the thresd and the guy trying to fix his truck just goes away with no conclusion, lol.... I guess they just get excited and get back to work. Your right it would cut down on repeated threads.

 

Reviving this old thread because of the complaints about people posting problems, but not following up with findings and fixes.

I too developed a front cover leak, which turned out to be a crack in the aluminum front cover between the A/C bracket and air compressor. CAT says this was a common problem caused by the A/C bracket not being sturdy enough to support the front cover with the compressor mounted to it, and they had to beef up the bracket. I did have the beefed up bracket, so I was perplexed about why it cracked. CAT quoted me between $5500 and $7500, depending on whether they had to pull the camshaft if they couldn't get the cam gear off. I kind of feel like I shouldn't be responsible for paying the extra labor because they didn't engineer the cam gear properly, but I digress...

So yesterday I removed the air compressor and A/C bracket, thinking I would drill the end of the crack to stop it from progressing, then mill it out and TIG weld it. After getting everything disassembled and cleaned, I determined that the cause of the crack was actually the air compressor vibrating. The two spacer studs on the back of the air compressor had loosened slightly and fretted, with one of them breaking off in the housing, causing the compressor to vibrate and crack the front cover. The crack ran all the way across the top of the cover just above the compressor, then halfway down the side, ending in the compressor mounting bore. The far side of the crack wasn't visible without using an inspection mirror. That will be almost impossible to weld with the cover installed on the engine, so that's not an option.

My plan is to seal it up with silicone gasket maker to stop the leak, then install a new compressor. I don't trust the bolts on the old compressor to remain tight due to the amount of threads that have been worn away from the fretting. If the leak continues, I'm going to have to replace the cover. For the amount of labor cost involved, I'm considering doing the work myself. It may be more cost effective in the long run to have CAT do the work though.

 

That crack is caused usually by not having the rear brace installed on the rear of air compressor. Shady mechanics some times leave the bracket off or steal it. So when that bracket is missing, all that weight from the compressor not being supported causes that. Was your bracket on there when you removed it? Or was it missing? If it was missing, I have the part number for you in my parts manual and location. Also, yes you can clean that crack up real good and use jb weld. It will hold for a good while as long as you install the rear compressor bracket, that mounts to block

 

The bracket was there, but as I stated in my post, the stud / spacers that attach the bracket to the rear of the compressor had loosened due to fretting, and one of them had broken off inside the compressor body. Those spacers / studs don't seem to be available as separate parts. Also, the threads in the holes are worn down from the vibration, so I'm going to go ahead and replace the compressor as a preventative measure.

I've slathered the crack with gasket maker / sealer (I think JB Weld might not be flexible enough to hold up to the vibration), and I'm going to see if it holds up and for how long. This is a 1999 build engine with 1.6M miles, and 150k on an inframe that I did myself 2 years ago. If it starts leaking again, I'm probably going to hand it over to CAT and have them replace the front cover. Still cheaper than a new truck with ELD, payments and a VGT / EGR / SCR and DPF to maintain.

 

ten 4

 

Key numbers 26-38 are the nut and washer attached to the part that failed. That part isn't specifically called out in the diagram, so it's probably not available separately. Even if it was, the holes in the compressor body are too worn for me to trust the threads to hold. I'd have to drill and install inserts. The compressor is probably old enough that it should be replaced anyway.

 

everything is available and have the part numbers.I have more diaghrams if the numbers arent pictured. I also have the thread and pitches for the exact bolts you need. Kinda sounds like you are good to go though. If you need to helicoil, tell me what exact bolt hole it is, and i will tell you the helicoil kit size so you can retain same bolt. Helicoils work as good as new on these motors. Need to use exact torque with torque wrench on the cats as well. I have all those specs if you need them.Need any help just holler. If not, good luck driver

 

The bolt you are pointing to with red is M12x1.75x40mm. The washer is13.5x25.3x3mm
That gets blue loctite and then torque 75+15 for a total of 90 foot pounds. Those are cat specs.
The compressor seal part number is 129-2181. Cost is 16 dollars through cat.

Here is an example helicoil kit you need to retain same bolts pattern and size
https://www.amazon.com/Perma-Coil-3...2x1.75+kit&qid=1618168997&s=industrial&sr=1-2