How to replace hyd tank sight gauge? - Cat 931B

[OzDozer]

G'day All - I have acquired a Cat 931B in pretty sad shape, and one of the things that is currently annoying me is the hyd tank sight gauge has been sandblasted by some previous idiot owner or sandblasting operator.

I bought a new sight glass and sealing grommet from my Cat dealer, and I expected that I could get access to the bolts that hold the sight glass via the hyd filter housing.
However, to my surprise, I find the filter housing is a solid tube, with no way to reach inside the hyd tank.

I have the service manual on microfiche, but I can't find any section dealing with sight glass replacement. I did find the section detailing how to remove the hyd tank.

Can anyone with any 931B experience tell me how to replace the sight glass? Is there an access panel hidden on the front of the tank, somewhere, behind the hyd control valves?

Please don't tell me the access is via a removeable plate bolted to the bottom of the hyd tank! - and you have to remove the tank to get at it!
After owning and working on much bigger Cats, I'm already a bit sick of the tightness of fit, of everything on the 931B!

 

[DB2]

Unfortunately I believe you answered your own question. My father was a Cat field service man and was never fond of the 931, 910 wheel loader or the D3. Had the same complaints as you.

 

[Welder Dave]

Yes, everything is a tight fit. Thankfully my sight glass is good. Maybe this will help. Looks like a cover on the front of the tank but the hyd. valve and/or some lines may have to be removed to have access.

https://avspare.com/caterpillar/sebp1247/sebp1247034/#SEBP12470345

 

[OzDozer]

Thanks, guys. Welder Dave, I missed that cover in the parts diagrams when I looked before. I believe you've nailed it, that 6S6439 cover is a circular access cover, common to many traxcavators, loaders and IT machines.

I'll have to pull that cover guard in front of the tank to see what's involved. I already have the tank drained to fix a holed suction line to the hyd pump, so now is an ideal time to do it, if it doesn't involve several hours work. The tractor is 90kms (55 miles) away from my shop, so I can't afford to start relatively minor repairs that will take hours, where it is.

I'm trying to get the engine to fire up, but I found chunks of what looks like piston in the bottom of the oil pan, so I'm going back today with a borrowed borescope camera to see how bad the damage is.
If I can get the engine to crank up - even with a damaged piston, it will make it a lot easier to move it.

The people on the farm where it's located told me the previous owner had it running in March 2017, but then started arguing amongst themselves as to whether it was missing, when it was running. One guy said it kept missing, another guy said it cleared up.
The main problem is the previous owner killed himself when he got drunk and rolled his car, only days after he collected this tractor, so I have no first-hand knowledge of the engine condition.
I inserted the borescope camera into the engine intake, and into the rocker cover weeks ago, and everything looked fine - but I still suspect a piston is breaking up.

 

[Welder Dave]

Hopefully all the hyd. lines to the valve aren't a nightmare. They are on my machine and a couple had been repaired by O/A welding or brazing before I got the machine. No leaks there so I'm happy. I did have one of the larger steel lines made up but it was easy to access.

 

[OzDozer]

O.K. I did find that cover plate today, it was buried in dirt and half-hidden behind the plate that holds the control valves.
Doesn't look like a job I'll be placing a lot of priority on, because there's a lot more important things to be done on this machine, first!

The good news is, I got the engine running today. The bad news is, it's making a LOT of piston noise - and the water pump has seized up solid!
I tried for about 15 mins to get it to loosen up, but no joy. Looks like my next trip back there, I get to find out how easy 931B water pumps are to work on!

 

[Welder Dave]

Water pump isn't bad. If I recall there's a bleed screw or something to get the air out of the system quicker. Been quite awhile since I did mine.

 

[OzDozer]

Is it economic to rebuild the water pump? I find cheap aftermarket water pumps in the U.S. (USD$109 on eBay), but shipping to Australia is substantially more than the pump cost. It ends up about AUD$500 (USD$350) when it lands here.

Local aftermarket suppliers will want to make a big killing on the aftermarket pumps, I expect they will want around AUD$700 (about USD$500), and I'm pretty sure a couple of bearings, a seal and maybe a shaft rebuild will work O.K. for me. But I find that Cat no longer stock the water pump seal, so that's a bit of a problem. Not sure if a local bearing supply house could supply a seal, they can usually supply most water pump seals.

 

[Welder Dave]

I'm not sure about rebuilding but they are fairly simple. Be careful if you go aftermarket. I did the water pump the first time and a few years later the the fan was wobbling around because the hub got loose. I got a better aftermarket and it has been good. Sorry not sure what brand the good one was but most likely IPD. I got it from the same place that did my engine with IPD 3 ring pistons. They are an IPD dealer.

 

[OzDozer]

Yes, I like IPD parts, I've used them for years with no problems. There's certainly a lot of dodgy Chinese knock-offs out there. I recently got a new oil pump for a Toyota 4 cyl diesel (1Z) in a forklift, and the rotor to housing clearance was .009"!
On top of that, the gear teeth were cut at a different angle to the (genuine Toyota) original! I had to swap the gears (the original was still good), and take .006" off the alloy housing of the new oil pump, to get a more satisfactory level of rotor clearance!

I like to know what's going into stuff I rebuild. Chinese bearings are pretty notorious for dodgy material quality levels, and poor QC.

I'm going to be looking for an in-frame engine kit soon, is there any one supplier who provides the best aftermarket parts at good prices?

 

[Welder Dave]

I'd use IPD if you can get it. They have the 3 ring pistons that are a big improvement over the Cat 2 ring pistons. They make oversize up to .040" so you can bore the block if required.