Cat 235c / 3306 Bad Oil Leak

Hi, my father-in-law has a 1990 Cat 235c with a 3306. SN: 5AF00998.
I help him when I can, but we don't have a great amount of knowledge about these things, and don't have a manual for this excavator.

He tells me that this machine has an oil leak (which he estimates at about 18 quarts an hour). It's leaking oil at the point between the engine and the transmission. The best I can figure is the rear crankshaft seal needs replacing. Given the quantity of oil leaking, is that a reasonable assessment, or is there something else that could be going on? Also, once it's open to change the seal, what else would you look at to maybe save a trip back in later? I see that Cat has a tool to install the new seal, is there a diy method that might also work? Any other help or suggestions is appreciated. If anyone has the section of the manual covering this, might I look at it please?

Thank you for your help!

NEW INFORMATION: I'm sorry, I misunderstood (my f-i-l's 1st language is not English). The fluid that is leaking is hydraulic fluid from the transmission, it appears to be coming from the junction between the engine and the transmission, and he estimates that it's leaking about 18 quarts every 2 hours. I'd figure to change the rear crankshaft seal since it'll be available anyway, so: is there a seal up there that could cause that bad a leak? Thanks for any help and any other information you can give.

Well to start with that machine don't have a transmission. But it do have a pump drive and three pumps and they may well be above your pay grade to repair Get a service manual and study it closely .
Bob

Couldn't make my sisparts ID the pump, so got pics from elsewhere.

That much leakage indicates a pump drive shaft seal is leaking. The problem could be age related and the seal just cooked hard and a groove in the drive shaft or it could be excessive case drain creating pressure and blowing the seal out. Then you have to try to guess which pump is leaking and the usual fix is to go through all of them at the same time. Sounds like a lot of work and hefty parts costs.

Good Luck

The quote he got was a little over $20k. How's that sound?

I'd like to say that sounds about right but I haven't been into one of those in many years. Fixing that old of a machine is like opening up a casket. You might find a lot of bones and little else.

Cat reman...new one is reman price plus core. Does that mean $7k in labor and oil?

heymccall said:

View attachment 178498 Cat reman...new one is reman price plus core. Does that mean $7k in labor and oil?

Click to expand...

That's for one there are two of these plus a tandem gear pump and a pump drive.
Bob

average used price on a working 235 is about $25,000..altho most are used up by now they are good machines with some care applied as you go.

I would pull it apart and see whats going on before Ide drop 20K with CAT.

if you just want to get it back up and working, a good used pump drive could be had on the secondary market. Maybe pull yours as vetech63 said and see just how bad it is..bearings and seals,maybe a pump seal? while its on the bench.

I would suggest doing the labor of removing and installing yourself. And then letting a hydraulic pump shop make your repairs instead of using a Cat dealer. You will save allot that way.