Heavy Equipment Question
 

Hey, there's always someone who knows something on a forum.

I have a heavy equipment/diesel question. I'm using a Cat 931 track loader to build the pad for my new building. I'm sure there is some water in the fuel. It loses power and I see puffs of white smoke when it happens. At first I had visions of a high temp sieze as it died and wouldn't turn over the first time on Saturday, but that was due to a dead battery. Whew! Temps were all in the green when it happened.

Anyway, the owner also thinks water in the fuel. I had no problems at all on Monday (4 hours running) and I ran it 5 hours at least on Saturday before it happened the first time. There is a valve on the bottom rear of the fuel tank that I assume is to drain water. I opened it and it must be plugged because all that I am getting is slightly damp fingers, no stream so not going to work to drain without disassembly. It's not mine, so I don't want to tear into it.

Is there a water separator/filter on these things? I don't see one but only looked through the oil cehck access door on top.

It seems to run fine if I have over 1/2 tank. Does it sump fuel from the bottom or is there a floating draw tube? If so, I'll just keep it full to finish the job. It happens when I get down to 20-30%.

Finally, is there a "water remover" additive that I can add to the diesel to help?

If you so much as THINK there MAY be water in diesel fuel, don't operate the equipment. Running water through an injection pump is a really, really, really good and fast way to trash it. The internal clearances are really, really tight, and require the fuel as a lubricant/coolant- water will just evaporate and you wind up with metal/metal contact.

There should be a water separator in the fuel line, typically part of the fuel filter/fuel filter housing. This *usually* has a probe in it that tells you when it's full/nearly full so you can drain it, but not always. Some heavy equipment simply has clear bowls on the filters/filter housings for a visual check.

That being said, white smoke is typical of unburned diesel. Give it a whiff if you feel like it- white smoke/sputtering when running could be an injector hanging open, injection pump going bad, or (worse) an injector that's going "stream" rather than "spray"- a sure way to melt/burn holes in pistons.

Don't know much about that specific model, so just giving you general diesel stuff.

I have never worked on construction equipment, but have had plenty of diesel experience on semis.

Almost all heavy duty diesels have a water seperator on them. Trace the fuel line you should find the filter then between the filter and the tank a seperator. Make sure it is drained, if it has a drain. From talking with a few mechanics if you have a little water in the fuel it will still run, but will be under powered. If you are seeing white smoke 80% chance of a blown gasket or cracked head. Cats are notorious for cracked heads.

If you pm me an equipment serial number I can possbily tell you where the seperator is. At my dealership we are an authorized Cat retailer :D


Edit: Talked with my Cat guru. The 931 does not have a fuel seperator. And he told me that the 931 was notorious for blown head gaskets. As the engine is simular design to the 3208 cat which loves to blow head gaskets.

Good luck

Change the fuel filter(s) first. I work for a heavy machinery dealership and customers change fuel filters monthly in some cases. Fuel quality is always a problem. There is always water (which the filter(s) will typically separate out) in older diesel tanks to contend with. If the drain on the tank is clogged blow compressed air through the petcock to try to clear it. Catch what comes out so that you can see what is in there. If the drain is clogged, you've certainly got a "crap in the fuel" problem anyway. So change the filters and fill them with diesel before replacing them so you don't have as much air to bleed from the system. Do you know how to bleed the air out?

And yes, the Cat 3208 engine is a known piece of shit from the word "go." Some Cat designs are decent and some are "WTF were they thinking" bad.

EDIT: BTW every NAPA should have filters for that thing.

Never had to deal with water in the fuel, but I would guess changing the filter MIGHT help. But if water is in the filter/separator then there is probably still some in the tank that is just waiting to get back into the system. See if you can't syphon some of the fuel/water off the bottom of the tank and see what it looks like. Not familiar with that specific model, but if its like the others I've worked on, it probably has a flat bottom tank, so maybe its all spread out evenly on the bottom. Another fun fuel system fix is bleeding the system after running the tank empty, so don't drain it and try to start it (of course). Fortunately I did't have to work on much equipment, I just mostly operated it.

Water is such a common problem in diesel fuel that most fuel filters are combo water separators as well and most have drain petcocks right on the filters for draining off water and sediment. I've known guys who got a batch of bad fuel and had to change three sets of filters in one day before the machine would run right.

And yes, water will destroy an injection pump in short order.

Are there any additives that help with water in the fuel? I recall we used to run additives in every tank, in both our road driven trucks and its aux fill up tanks and in our equipment. I don't recall in years ever having bad fuel cause us to lose work. Perhaps it was luck, or maybe the additive.

I think Stanadyne has an additive for water in fuel. We used to sell the stuff by the case when the old idi diesel Fords were popular.

http://www.stanadyne.com/docs/puba/W...For%20YOU!.pdf

Thanks for the replies. I did some research and it appears to be a later model - 931B with the 3024 engine. It is a 25Y designation for 3 speed forward 1 speed reverse. Trying to locate filters locally. I assumed that id had them, but I couldn't locate them on my inital look.

The tank drain is on the bottom rear and yes it is a flat tank but I can put the bucket down and lift the tractor and put the tank on at least a 10* angle so getting the drain to the bottom isn't a problem. The problem is getting at the valve to clear it as the access hole is only about 4" in diamteter.

Also, I'm familiar with bleeding the filter if it has the bleed screw at the top like my tractor.

EDIT:

Called the local dealer and they have fuel filters in stock and there is a hand pump near the transfer pump to prime and a bleed screw on top. There isn't a water separator, though, so I don't know how much good it will do but doing it anyway. Coudn't believe a Cat filter from a Cat dealer was only $8.19.

Cat has become very reasonable in there filters. They want average Joe customer using there filters. So they sell that at a loss to make the public happy. :D

BTW Cat filters are made by Baldwin if you were ever curious

Yep. The Baldwin plant is just down the road 100 miles from me.