Hello. I am new to this forum and heavy equipment. My wheel loader overheated the other day so after it cooled I added coolant and went on my way. The next time that I used it, when I pulled the dip stick, I noticed coolant on the stick. There was also creamy oil coating the back side of my oil fill cap. My thoughts are head gasket, water pump or oil cooler. Any advice on diagnostics to determine the issue would be greatly appreciated. Cat 950 Serial 81J8051 3304 PC Serial 78P20298 Arr. # 4N3975
Welcome, and kudos for posting Serial Numbers. Most new members think that model years mean something. Do you have any traces of oil in the cooling system.? It often appears as a rainbow effect on top of the coolant in the radiator.
the fluid was down below the fins a bit so I drained some into a bucket. I couldn’t tell if it’s just extremely dirty or oily so I let it set for a while and I don’t see any oil trails on the top.
Drain engine oil-leave drain plug out for now, pressurize cooling system let set under pressure for several hours see if any coolant drains from oil pan. Put at least 10 psi on the cooling system. One thought, one opinion.
if it was over heated I would bet the oil cooler is fine, unless by some fluke it decided to give up at the same time as over heated. 3304's and heat don't go well together, my buddy who is a old Cat guy preaches a good water temp gauge and to watch it like a hawk, he even went as far to say if you have untrustworthy people using it to wire a oil pressure switch and a temp switch to a backup alarm in the cab to really get your attention! Usually they just cook the head gasket but its possible to cook the liner O rings so do yourself a favor and pressurize the coolant and see where its coming from, pulling the oil pan in the machine is easy and worth doing to have a good look. If you don't do that you will have a very bad day if you go through all the work of just doing a head gasket only to find it was the liner's and you have to undo the work you just did and buy a 2nd head gasket. also if the engine has ever been dug into before which chances are good with these old machines, for the little effort it takes I'd check the liner protrusion. Once again it might save you from having to do a 2nd head gasket, I learned that lesson the hard way! cat sells shims in various thickness's that normally you install while building the engine, but I've successfully installed them in an assembled engine by splitting the shim. trouble is pulling the liner up, I machined a tool to do it which was comprised of 2 disks slightly smaller then the bore diameter with a disk of really soft rubber sandwiched between them. drill and tap everything accordingly so you have 3 or 4 bolts to compress the rubber squeezing it out and grabbing the liner, and a center hole for a puller of your preferred flavor. brake cleaner on the cyl wall really helps with the rubber grabbing and not slipping.
This would be a very good first step.