Caterpillar 930 Loader - Mechanical fuel pump leaks diesel out of weep hole

Cat930 · Jul 10, 2016

Hello there,

I got here a leaking mechanical fuel pump on a 3304 PC engine. First symptom was diesel in engine oil and eventually constant fuel leaking out of weep hole. Dealer suggest pulling the pump out and sent in for rebuild. Nearest Cat dealer quoted $3500 - $5500. New pump would be $8000 plus. I am just curious if I could get away with just replacing the front lip seals of the mechanical fuel pump without disassembling the whole pump. Next opportunity I will get to pull the pump would be in couple weeks due to my work schedule. Any recommendation of where I could buy a refurbished or used pump. Part number for new Pump group is 7N-0009. Thanks in advance from Alaska.

kshansen · Jul 10, 2016

Cat930 said:
Hello there,

I got here a leaking mechanical fuel pump on a 3304 PC engine. First symptom was diesel in engine oil and eventually constant fuel leaking out of weep hole. Dealer suggest pulling the pump out and sent in for rebuild. Nearest Cat dealer quoted $3500 - $5500. New pump would be $8000 plus. I am just curious if I could get away with just replacing the front lip seals of the mechanical fuel pump without disassembling the whole pump. Next opportunity I will get to pull the pump would be in couple weeks due to my work schedule. Any recommendation of where I could buy a refurbished or used pump. Part number for new Pump group is 7N-0009. Thanks in advance from Alaska.

Is there any chance of a picture with a pencil or finger pointing to the "Weep hole" area? Just want to be sure I have a good picture of the style of pump. Also a full S/N would help, for engine if it is different than the loader.

Right off I'm thinking this should not be that big a problem but would like to know 100% which of a few different pumps you are dealing with.

Cat930 · Jul 10, 2016

Serial number is 78P60421. AR # is 7N1522
Sorry I don't have a picture of it. It will be a while before I get back to where the loader is located. But it seems like that there is a spacer plate between the pump and front housing where the whole pump is bolted to. There is a drain tube connected to the weep hole on the spacer plate. When I called the dealer they say that there are 2 style of fuel pumps and he told me that I have the screw type.

Cat930 · Jul 13, 2016

Cat930 · Jul 13, 2016

Where the arrow is pointing is the weep hole and there is a plastic tube connected to it. Just from looking at the pic above, it looks like there is a lip at the end of the camshaft just before the cone where it might be impossible to pull the seals out that way. I screwed up saying its a "screw type" earlier, but its actually Sleeve Metering Fuel System. I will take pics and keep you guys posted.
*Update: Called the dealer and they said that there is no new fuel injection pump or reman. It has to be sent in for rebuilt if I can't just replace the front seals or if I see a groove on the shaft where the seal rides. These older style uses fuel for lubrication.

kshansen · Jul 13, 2016

Took me some looking till I realized that little drain nipple was in the transfer gear pump and not part of the actual injection pump. Did not have many sleeve metering pumps on our equipment and the last one was probably 10 years ago.

Anyhow does not look to be too bad a job, once the whole pump and governor assembly are off the engine. Then the biggest thing is getting the pump back on and timed, I'll have to look into that later. For now I'm hoping I can attach the instructions on removing and replacing the transfer gear pump. If that work and you elect to have a go at it I should be able to supply any other information needed like how to time it.

View attachment 930fuel transfer pump.pdf

Cat930 · Jul 14, 2016

Thanks for the info kshansen. It really doesn't look too bad to replace the lip seals. I just have few questions:
1. On the pdf attached, 2H3740 Bolt (B) is the same bolt that holds the drive gear to the shaft?
2. To put the engine on #1 TDC it says I need turning tool group 5P7307. Do I necessarily need this? or you know another trick to turn the engine? (other than bumping the starter) Just on a budget here, hate to buy special tools just for one time use. Its almost $500 here at my nearest dealer.
3. I already have a puller, but the info I have here says I need a 8B7560 step plate to be used with the puller to loosen the gear? Do I have to get this step plate too?
Sorry for asking too many questions.

PAcattech · Jul 14, 2016

Cat 930 No Bolt "B" is not the same one that holds gear on Its 5/8 fine thread youll need, You do not need engine turning tool , lot of time if the fan belts are tightened correctly you can turn engine by pulling on fan if not socket and ratchet on the front crank pulley will work . you wont need that step plate either Just loosen the bolt that holds gear back it out couple turns and put puller against the bolt head , What you will need is a timing pin to time fuel pump before you take it off. cant find part number of timing pin sorry its late I'm almost certain the shank end of a 1/4 '' or 5/16 drill bit will work for pin.

Cat930 · Jul 14, 2016

Thanks for answering my questions PAcattech and kshansen, I appreciate it. I will try to get this done in couple weeks. Ill be back for an update.

kshansen · Jul 14, 2016

Cat930 said:
Thanks for answering my questions PAcattech and kshansen, I appreciate it. I will try to get this done in couple weeks. Ill be back for an update.

Glad PAcattech stopped by with some first hand knowledge, I've worked on more than a few different Cats over the years but no recent experience with the sleeve metering pumps. Cat can make somethings sound like you need all kinds of special tools to do some jobs but if you understand the basic idea of what the tool is actually doing one can improvise most of the time. Like PA says use a drill bit that fits nice and snug in the hole to set the timing or grab the fan to turn engine. Sure if you are doing the job 10 times a week the factory tool might make it a little easier but for a once in your life job it's not worth it to pay for the tool.

Cat930 · Aug 22, 2016

Update: pulled the pump and tried to replace the lip seals on the transfer pump, but it still leaked. Normal wear on the camshaft and I didn't think it needed a speedi sleeve. I was able to get an used pump off another loader and got the loader back to work. I am just wondering if you guys have any info on how to rebuild a whole pump. Nearest dealer quoted $6k, a bit too much for my budget. TIA.

Cat930 · Aug 22, 2016

1/4 drill bit shank fitted perfectly on the pump timing hole. 3/4" fine thread bolt to pull off the cone from the camshaft. I also went ahead and changed the injector tips and body (pre-combustion) it was very easy, thank goodness the tips came with new O-rings.

thepumpguysc · Aug 22, 2016

A rebuilt pump from a fuel shop in the lower 48, costs about 1k.. and takes about a week to turn around..
About 40% of the cat pumps I do need speedi-sleeves..
IF its just leaking at the supply pump and the pump is off already..
take the SP off and have a fuel shop press in new seals.. there are special stepped tools for the process.. and new seal updates..
For that matter>> take the pump in.. with the SP removed and get a speedi-sleeve put on.. THATS something you don't want to mess up..

Cat930 · Aug 22, 2016

Would you rebuild the pump for $1k? I'll pay shipping.

thepumpguysc · Aug 22, 2016

ANY OTHER TIME I would jump at it..
BUT I'm sidelined w/ 2 ruptured disks in my back.. and headed for surgery in a few weeks.. Sorry.

Cat930 · Aug 22, 2016

All good thepumpguysc, good luck with your surgery

Caterpillar 930 Loader - Mechanical fuel pump leaks diesel out of weep hole

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