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

[Mquinista]

Just a thought,
Based on my experience i never seen a main bearing set failed in a diesel engine due to lubrication issues, (unless it was due to contamination) Main Rods bearings yes, Hoo yes , usually they throw rod´s out of the block if u hear them knock and insist on running them.
Recently i had my Mercedes OM606, with this type of problem, engine oil was going up instead of going dwn, replaced lift pump plunguer seal (more or less same system as CAT) and its fine now. I do not plan to look at the Crank mains or Rod bearings.
If u wan´t to go that road, its a precaution, but look also the main rods, thats is where the system is weaker.
regards

 

[Mobiltech]

I don’t like the looks of the flakes of grey / white material in that filter. Looks a lot like bearings to me.
I would be investigating further.

 

[56wrench]

In these cases, an ounce of prevention is worth 10 lbs of cure……

 

[LCA078]

I've been working hard to bite the bullet and embrace reality that replacing the main and rod bearings is the right (and only) thing to do. I don't have easy access to a shop so this may be a field fix. Called the local Cat dealer to see if they were interested and they said they are shying away from field work and would need to pull the engine anyway to get all the bearings because of the equalizer bar being in the way. At first I thought it was just Cat being Cat but I took a look at the equalizer bar area and agree it would be a bugger to get back there to remove the oil pan bolts. Not even sure if there is enough room to back out the oil pan bolts to get the oil pan off so coming back here to hear your thoughts on rolling in new bearings in the field. Does the engine need to come out or can it be done in frame without a lot of special tooling, cussing, and extra hands?

 

[Dave Neubert]

Costex has it for $85.00

 

[OzDozer]

The bearings can be rolled in without the engine having to be pulled out. Yes, the rear oil pan bolts are a PIA to get out and replace, but it can be done. I did several inframe engine overhauls in my D7F's.

 

[LCA078]

Thanks, Dave. I'm setting up an account with CTP as I have a feeling I'll be using them more in the future.

Oz- Thanks for the input on the inframes. I figured that was the case but the Cat mechanic made it sound otherwise. Once I get the belly pans off, I'm sure I'll be able to get to everything.

One lesson I learned the hard way was to work on the difficult bolts first. Going after the easy ones first only to find there is one bolt in a back corner requiring a special tool is frustrating to say the least. Always hate putting everything back together because I couldn't get that one last bolt out...

 

[tctractors]

Just a thought,
Based on my experience i never seen a main bearing set failed in a diesel engine due to lubrication issues, (unless it was due to contamination) Main Rods bearings yes, Hoo yes , usually they throw rod´s out of the block if u hear them knock and insist on running them.
Recently i had my Mercedes OM606, with this type of problem, engine oil was going up instead of going dwn, replaced lift pump plunguer seal (more or less same system as CAT) and its fine now. I do not plan to look at the Crank mains or Rod bearings.
If u wan´t to go that road, its a precaution, but look also the main rods, thats is where the system is weaker.
regards

We are poles apart here as I have totally the opposite experience with fuel mixing into the engine oil, the Big End bearing seem to suffer nothing while the Main Bearings have spun in the cylinder block, it might be the case on an 0M606 but I have never touched one of these engines or even know what they look like, on the CAT 3306 the effect of Diesel fuel mixing with the engine oil the results are near always the Main journals take the Hammer, we all do things and think things our own way and I am basing my comments on what I have found many times, I don't get the easy jobs in this game only the knacker jobs so have seen some wrecks.

 

[tctractors]

Thanks, Dave. I'm setting up an account with CTP as I have a feeling I'll be using them more in the future.

Oz- Thanks for the input on the inframes. I figured that was the case but the Cat mechanic made it sound otherwise. Once I get the belly pans off, I'm sure I'll be able to get to everything.

One lesson I learned the hard way was to work on the difficult bolts first. Going after the easy ones first only to find there is one bolt in a back corner requiring a special tool is frustrating to say the least. Always hate putting everything back together because I couldn't get that one last bolt out...

The engines in the D6 and D7 are simple to do an in frame to, the oil pan and sump (that is the Plate) are not hard to remove, its more fun to get them back up without damaging the gasket, the Main Bearings will roll out and back in but you might need a hand to turn the engine to get the back 2 cylinders, I use the engine turning tool that fits into the starter motor location it is slow and steady, so use your brains, the Vee belts would need to be eased off as that can hinder the front bearings moving, always check and double check the thrust washers for the correct way out, CAT have made this task near fool proof on the later blocks, the torque set is the same for both Main and Big end bolts so nip up the Tang side first on all caps, on the Mains I do the ft lb bit first then the deg' turn set going from front to back on 1 side then across on the back cap from back to front on the opposite side.

 

[LCA078]

Thanks, TCTractors- I appreciate the input and confidence on keeping this simple. Here is what I found in my Army manuals for replacing bearings in a D7G which should be the same 3306 in my upgraded D7F. Granted these procedures are for an engine removed and completely broken down in clean shop environment but I'm guessing they should also be useful when laying on my back and having dirt and oil fall in my eyes.

Any special tools to rolling/prying out the old bearings? I've seen the little tee looking thing that goes in the oil port but I'm guess even a homemade pin will work. I'll look for the barring tool you mention but sure would be nice to just crank on a nut/bolt in the front pulley or such.

Looks like the main and rod bolt tightening spec is to take to 33 ft-lbs then crank another 90 degs. I assume I can this by myself with a 3 ft breaker bar or will I need another person with a cheater? I have a decent cordless impact wrench but I don't like using impacts on these kind of jobs unless you think it's fine.

 

[Old Growth]

Ok, let me see if Im following along correctly,,,


You have an engine that runs FINE.

You have a leaky fuel pump diluting the oil.

You have ONE hour experience on this machine.

Now the internet has talked you into rebuilding the engine in a perfectly fine machine????


WHAT?????


Just change/rebuild the lift pump, change the oil and RUN the machine. Watch the oil pressure and forget any of this happened, until another oil change and analysis tells to you be worried.


Ive seen a ton of engines get fuel in them. Then be repaired and live LONG and HAPPY lives. With the same ol bearings they had beforehand.

 

[oarwhat]

Ok, let me see if Im following along correctly,,,


You have an engine that runs FINE.

You have a leaky fuel pump diluting the oil.

You have ONE hour experience on this machine.

Now the internet has talked you into rebuilding the engine in a perfectly fine machine????


WHAT?????


Just change/rebuild the lift pump, change the oil and RUN the machine. Watch the oil pressure and forget any of this happened, until another oil change and analysis tells to you be worried.


Ive seen a ton of engines get fuel in them. Then be repaired and live LONG and HAPPY lives. With the same ol bearings they had beforeh

Old Growth I agree with what you say and have done it a few times. But TC tractors is the best when it comes to these machines. He's been spot on for a few problems I had in the past. I do see the flakes he's talking about in the filters. Fix the fuel problem first then I think there's two ways to deal with this.

1 Run it and open up the oil filter every 50 hours to monitor.
2 Replace the bearings and not have to worry and wonder if it will blow.

 

[Nige]

The other factor to throw out there is that this machine was parked for an indeterminate period of time before it was sold in a military surplus auction. What that might have done, or how it was treated before being put into the auction, could also be a factor. It looks like what is basically a good machine and the OP wants to keep it that way.

 

[OzDozer]

A new bearing roll is a cheap solution to prevent a whole lot more, and a whole lot higher, set of expenses down the track, such as having to install a new crankshaft.

Listen to tctractors, the mans got the track record behind him of being inside a multitude of Cats over many years.

 

[56wrench]

At the very least, i would recommend checking all the bearings. The mains will show the most wear on the bottom halves and the rod bearings will be worn more in the upper halves. Not knowing how much it was run with the crankcase dilution is the real question as to how much, if any, damage has been done to the bearings. In the future, a spun bearing will cost you a hell of a lot more than checking them or changing them now

 

[LCA078]

You have ONE hour experience on this machine.

Exactly. That's what worries me.

If I owned her for the last couple hundred hours and was confident the fuel leak just started to happen in the last hour or two, then yes- I'd just replace the transfer pump, change the oil and run her hard.

But no, she was delivered fresh from the Army where she probably sat and sat for 20+ years with minimal usage after a complete rebuild by Cat. I distinctly remember looking at the oil when she was delivered and thinking it was a fresh oil change because there was still a bit of straw color to the oil. It was also a bit high (maybe 3/4" above full?) but that didn't bother me too much. It was less than a couple hours of running (most at idle when I was cleaning out the mud in the winch cable) did I see how fast the oil level was rising. It was over 2" high above full so who knows when the transfer pump started to leak and how long the crank turned with diluted lube. It could have been leaking only a couple hours at little to no load with me or over a few hundred hours pushing berms at the Army.

So yeah, rolling in new bearings is either a) a waste of my time, b) good insurance or c) preventing an expensive failure turning into a catastrophic failure. We'll all find out when I get into her....

 

[tctractors]

Ok, let me see if Im following along correctly,,,


You have an engine that runs FINE.

You have a leaky fuel pump diluting the oil.

You have ONE hour experience on this machine.

Now the internet has talked you into rebuilding the engine in a perfectly fine machine????


WHAT?????


Just change/rebuild the lift pump, change the oil and RUN the machine. Watch the oil pressure and forget any of this happened, until another oil change and analysis tells to you be worried.


Ive seen a ton of engines get fuel in them. Then be repaired and live LONG and HAPPY lives. With the same ol bearings they had beforehand.

Old Growth, I totally agree with every word you have printed, but the poor chap who has paid out big for a very fine Tractor that is New Growth in CAT fettle is caught in a tight spot, the Tractor has no history in regards how long it has been suffering a Diesel sump, or how long it has been running with this fuel addition, the chap has the Brains to to find a real neat Tractor that will go a good bit for him, also the Brains to not be scared to safeguard his capital investment, if it was my Tractor I would have the sump off in a flash as I can pop those bearings out and fit new easy in a day and a half ley in the crap on Site, I hope the bearings are found to be like Brand New and any comment I have made is Total Rubbish, the owners mind will be glad that he checked the Crank but annoyed that it was all a waste of time, all it would cost is a lower structure gasket set and fresh oil and filter that has to be changed anyhow, there would be a time cost but it's his Tractor and his time and he seems to have the right minerals to tackle the job, how do you balance things and just because the Tractor runs well and sounds like a CAT it means nothing at this point, if he had been running the Tractor himself and noticed the oil up the stick one morning it might be worth the risk, all these comments about Big Ends and rods through the side mean nothing to me as it's the Main Bearings supporting the rotating mass that suffer in this case, I hope I have not offended you in any way and give you total credit for shouting out a Key Board Midland Banker, but the Tractor is worth the effort.

 

[Old Growth]

Old Growth, I hope I have not offended you in any way and give you total credit for shouting out a Key Board Midland Banker, but the Tractor is worth the effort.

Dont ya worry. Its takes much more than the internet to offend me.

Its good advice.

Ill share my experience. I live less than 10 miles from JBLM. One of the largest military installations on the west coast. Ive bought/scrapped/salvaged and sold TONS of military iron.

It comes in two forms. Its either royally screwed, or its abundantly rebuilt and about like brand new, but been sitting a long time.

My bet is that this machine was pristine when it was parked. The seals dried up (possibly more seals also that he has not discovered yet) and recently started leaking fuel into the pan. Then the military stated the auction/liquidation process about a year ago. The machine was woken up and shuffled around till the new owner got it and that more than likely how long its been leaking.


OP, whats the MFG date on the batteries that were in the machine when you bought it?

 

[LCA078]

Old Growth- You're spot on. I have a bit of experience purchasing military surplus and I know you can get a gem almost as much as you get junk at these auctions. Being patient at these auctions is a virtue to not get bent.

The dozer I picked up was original in the early 70's but went through rebuild, probably in the mid- to late-90's. I'm only guessing the rebuild date since the upgraded 3306 under the hood was made in '96 per SIS. But it's in really good shape so I took a chance and bought it knowing that things like seals, rubber hoses, and other non-metal bits would be the gotcha's. If popping on a new lift pump and rolling in a few bearings are my only issues for the next 500 hours, then I'm happy. But let me open her up and see what's inside. I'm with TC on this one hoping it turns out to be a non-issue.

The dozer came without batts so I had to drop in a couple Cat 31's where those ridiculous 6T's sat. But that would have been a safe bet to at least determine when the last bit of decent preventive maintenance took place. Best I can tell is probably 3-5 years ago by the amount of fading on the oil and fuel filters. No rust, just not shiny like new.

JBLM- it's a great place and I've been there a few times. Was just there this past summer. Even took a nice pic of the scenic backdrop since it was so clear. Definitely a great place to live.

 

[Welder Dave]

That looks like the pic. on a beer can but can't remember what brand.