Cat D7F 3306 making engine oil (suspect fuel from transfer pump)

[LCA078]

Engine Serial: 08Z94098
Engine Arrangement: 5R8357
My 'new to me' D7F military surplus dozer appears to be dumping fuel into the crankcase. Oil level was slightly high when I got it but it's rising fast and has the typical diesel smell. I might have put 2 hours on it since I got it a few months ago from the military surplus sales so no idea of how long this was going on. I sent an oil sample out for analysis and I'll cut the filter open when I get some downtime in the next few days. Hopefully there are no main bearing flakes or other metallic bits in the filter....

After reading thru the forum it appears the common issue is oil coming from the fuel transfer pump. Looking at the diagrams in my military parts manuals (attached in this post), it looks like a simple replacement of o-ring #3 part no: 4J8997 will fix it but asking the experts here to verify that's true. If I replace that o-ring, is it worth to do a field re-build of the transfer pump and replace all o-rings and such inside? I want to order all the right parts so they're sitting at the Cat dealership when I do some family travel these holidays....

 

[tctractors]

What you need for your engine is a new fuel transfer pump, these are really just a simple fuel lift pump and cost only a few $$$$, the down side is what damage has unrolled to your crank, Diesel fuel in the oil takes out the main bearings and in the worst case will spin the mains and destroy your block, this lift pump is fitted to the intermediate fuel system and is common for this trick, you can roll in new main bearings in frame if you think something might be happening wrong, the thought of changing a few 0 rings is not the route to take just swap the pump and always check your oil level BEFORE you start up the engine, don't check it at the end of the days work as the fuel has all night to drain off in to your engine. p.s. your number 3 4J8997 will fix nothing chap.

 

[kshansen]

Engine Serial: 08Z94098
Engine Arrangement: 5R8357
My 'new to me' D7F military surplus dozer appears to be dumping fuel into the crankcase. Oil level was slightly high when I got it but it's rising fast and has the typical diesel smell. I might have put 2 hours on it since I got it a few months ago from the military surplus sales so no idea of how long this was going on. I sent an oil sample out for analysis and I'll cut the filter open when I get some downtime in the next few days. Hopefully there are no main bearing flakes or other metallic bits in the filter....

After reading thru the forum it appears the common issue is oil coming from the fuel transfer pump. Looking at the diagrams in my military parts manuals (attached in this post), it looks like a simple replacement of o-ring #3 part no: 4J8997 will fix it but asking the experts here to verify that's true. If I replace that o-ring, is it worth to do a field re-build of the transfer pump and replace all o-rings and such inside? I want to order all the right parts so they're sitting at the Cat dealership when I do some family travel these holidays....

I think I would at least order the following: #3-4J8997, #7-3D2824, #10-6J2419, and #12-5P8215.

Then again not knowing what the pump looks like inside it could need more that seals? But like tctractors says a new transfer pump would be cheap insurance against the cost of major engine damage!

 

[Mquinista]

naa... one bit of diesel will not kill the caps,(assuming it still has oil, Hehe) worst problem is a runaway... that dear friends will kill it.
replacing the lift pump is the best option... as it might cost 10USD more than the seals...
Good luck

 

[kshansen]

I just took a look at prices of those pumps. At local dealer a new 1W1695 pump is listed at $755.00 a re-man 0R3537 is listed at $543.00. Now if you feel lucky I see a off-brand pump for $89.13 or best offer.

Now if it was mine I would be at least tempted to take it off and disassemble and see if the seal rings were the only problem. But that is because I'm pretty confident I would be able to determine condition of "hard parts".

But then if downtime was critical..............

 

[LCA078]

Thanks for the quick responses. Downtime is not an issue as it's a ranch dozer. Cat SIS didn't offer a breakdown of parts and I could only order a whole transfer pump for ~$800 out the door. That's why I sent the stuff from my military manuals. But I remembered reading on the forum about replacing o-rings to fix the issue but maybe that was for a different style transfer pump. The funny thing I went ahead and ordered all the o-rings and check valves earlier today (just like kshansen suggested) for about $35. I had other parts for my 325BL excavator to order so I just tossed these in the mix. I can't believe a transfer pump would be that hard to rebuild but I'll take a look at it when I get some time to go to the machine and wrench off the pump. Might be a bit due to family stuff and the holidays but I'll keep all informed.

And yes, tctractors- I read a lot of your posts about trashing the main bearings so I'm curious what's in the filter.... more to follow.

 

[Nige]

Here's the breakdown of the 1W-1695 Transfer Pump as fitted to engines of Serial Number 08Z87550-Up. All the individual parts are available.
Also the D&A in case you want to pull it apart.

 

[LCA078]

Thanks, Nige- that's helpful.

 

[LCA078]

I was able to get the filter open for a look inside. The ribbon is about a third of the filter so it's a lot of pics to see all of it. I'll add a few more of the same areas but at a different angle

 

[LCA078]

A little closure but at a different angle to find any glittering shiny bits. There a few brassy flakes but not much.

 

[LCA078]

Last pic is running my finger down the pleats. All I could get out was a bit of brassy dust. The magnet didn't pick up any ferrous material. Thoughts overall?

I'll also keep the filter media in case anyone asks for a closer look at anything

 

[LCA078]

So I went back out and played with the contaminates a bit and realized the brassy stuff was probably yellow paint as it was mushy when I probed it. You can see the other non-ferrous flakes better in this picture too.

 

[Coaldust]

You could even have a leaking fuel nozzle, but the transfer pump is the culprit. I wouldn’t stress about the crank, too much. Run it and start scheduled oil sampling. Monitor

Or, go Asperger about it and drop a main and a rod. Take a look. Roll a set of bearings in the old girl. It’s a sweet tractor.

 

[OzDozer]

They're a pretty tough engine, and diesel in the oil doesn't cause bearing problems like antifreeze does.
Diesel is still a lubricant, unlike many other contaminants. It just reduces oil viscosity, so the danger lies in high operating temperatures and heavy engine loading operations.
You certainly don't appear to have been working it long and hard under hot conditions, so I wouldn't stress about the fuel dilution too much. The filter looks fine to me.
I seem to recall about 6% fuel dilution is still an acceptable number. The 3306 holds plenty of oil, unlike some engines, where the oil quantity is marginal.
Remember the bearings are tin-overlay aluminium, so if there's serious bearing damage you'd see a highly visible level of aluminium flakes in the filter media.

 

[LCA078]

always check your oil level BEFORE you start up the engine, don't check it at the end of the days work as the fuel has all night to drain off in to your engine.

I couldn't agree more about doing a thorough check on all items before cranking the engine. My time in military aviation gave me some pretty anal pre-flight "check every fluid, pivot point, and overall look for any oddities" behavior that carried over onto my old iron. This is how I saw the oil level rise more than an inch, almost two inches, on the dipstick since last time I used it so I realized something was up. I just dropped the filter and took it with me full of oil since I didn't have my oil sample bottles with me at the time. After reading a bunch of threads of 3306's making oil I figured it was the transfer pump like you pointed out many times. I didn't realize it may even leak down when the engine is sitting which is good news to me since it may mean I didn't run it that much with the high levels of fuel in it.

They're a pretty tough engine, and diesel in the oil doesn't cause bearing problems like antifreeze does.
Diesel is still a lubricant, unlike many other contaminants. It just reduces oil viscosity, so the danger lies in high operating temperatures and heavy engine loading operations.
You certainly don't appear to have been working it long and hard under hot conditions, so I wouldn't stress about the fuel dilution too much. The filter looks fine to me.
I seem to recall about 6% fuel dilution is still an acceptable number. The 3306 holds plenty of oil, unlike some engines, where the oil quantity is marginal.
Remember the bearings are tin-overlay aluminium, so if there's serious bearing damage you'd see a highly visible level of aluminium flakes in the filter media.

I agree diesel is still a lubricant. The old yellow sulfur smelling syrup diesel I grew up is probably has some lubricating properties but today's 'clean' stuff bothers me so I agree with TC that even minimal fuel dilution is something to be worried about. As for the bearings, I thought mains had copper/bronze/brass in them which is why I got a little concerned about seeing gold flecks in the filter. When I realized it was probably yellow paint, I felt a bit easier. But I'll monitor.

I just got this dozer recently from military surplus so even thought it's got a lot of years on it, I don't think it has many hours. I only put a couple hours on the fuel pump hour meter since I had it floated in and most of those two hours was not under load pushing dirt. Those two hours were from getting her home, working a frozen pedal and a few other items straightened up before putting her to use. And then some family items kept me from spending time clearing our land so it's just been mainly sitting for a few months. Hopefully that's when most of the fuel infiltrated the crankcase.

You could even have a leaking fuel nozzle, but the transfer pump is the culprit. I wouldn’t stress about the crank, too much. Run it and start scheduled oil sampling. Monitor

Or, go Asperger about it and drop a main and a rod. Take a look. Roll a set of bearings in the old girl. It’s a sweet tractor.

Agreed not stressing too much on it. I'm leaning towards getting the transfer pump fixed and doing an aggressive oil sampling. Thinking even cutting open a filter in another 2-3 hours and maybe at 10 hours just to see what's going on as I really don't have a lot of history on this machine. Once I get situated on some family matters and able to get busy pushing dirt. I bet I'll only put 2-3 hours of work on her at a time (and that's maybe 3-4 times a month) as it's an evening/weekend thing clearing brush on our land. (Is that about a tank of fuel per month? LOL!) Maybe I just need to build up my confidence and use her like she was built to be used. She is pretty sweet.

 

[tctractors]

2 Points of interest here, the first one being that in the U.K. we can buy those lift pumps for low coins as in CPD and ITR parts that work very well and can be changed 10 times for the price of a pucker CAT part that was most probably built in China so get a grip, the pleats of your oil filter show flakes of White Metal so how brave do you feel???? you might want to change out the oil and filter and see how it fairs, but be warned all the rotating mass of the Crank, Flywheel etc, Rods and pistons are all weight that is running on the Main bearings that has no fun running in Diesel, people can all say it will be fine and those few bearing flakes are nothing and mean nothing, I am just saying in the last 6 years I have had to do big rebuilds on CAT engines due to fuel in the oil, if its only been run for 20 mins it might be worth the risk but don't think the bullet has been dodged, if the dilution is / was 10% or less the motor might hold up, I have pulled these engines open that showed about 2 1/2" of oil above the stick and the mains were scrap and the rear crank seal allowing fluid to pass into the transmission, this engine was running but what a din it made with no interest on running on it's own oil, you might be lucky I prey that you are with the fact that you have not really given it a hard shift, as you are going to monitor the oil and filter you need to forget oil sampling just cut the oil filter top off and look at the oil content of the remaining bowl then cut out the full length section of the pleats to check, the oil sampling is to long and drawn out for this type of issue, besides they will only say monitor at next oil change or something of little interest, best of luck.

 

[d9gdon]

I've had 3306s that had this happen in 100 degree weather and I just fixed the pump and changed the oil and rolled on...your filter looks good to me.

 

[Nige]

A thought..........
This tractor was ex-military. What are the chances that it sat for so long after the SLEP programme was done on it and before that The OP bought it that the seals in the transfer pump hardened up through lack of use.?

 

[Welder Dave]

Leaking due to sitting for a long time makes a lot of sense. It's always a concern with older low hour military machines. I remember a while back there was a thread about a really low hour military D7G and if it was worth $77K or something like that. Dried up seals was brought up.

 

[LCA078]

Hi Guys-
Just a quick update as I've been consumed with a number of family issues the past month. In short, yes I'd love to find a reliable aftermarket transfer pump but haven't had the bandwidth to chase one down yet. And yes, I do believe dried seals on the transfer pump were the cause but of course I can't tell until I pull it off and look at it. As far as the engine goes, SIS shows the engine to be new in 1996 and the hour meter on the fuel pump only shows 423 today (it had 422 when I received it). I know the military changes hour meters without concern but I think this is the original because of the way the paint looks (no cracks/chips on the mating surfaces to show removal). Either way, I still need to determine if I replace the mains or not...just won't be a decision on my radar for a bit though. All the great advice (especially TC's) is highly appreciated so thanks for the input so far.