Welder Dave
Senior Member
Replace the oil pump. My oil pump spec'd. as new but 16 1/2 hours after rebuild one of the gear teeth that drives it broke off. PIA to have to pull the engine and trans again.
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Cat 3204 overhaul - which bolts are critical to replace?
- Thread starter OzDozer
- Start date
OzDozer
Senior Member
Dave, surely your oil pump rotor must have already been cracked when it was replaced?
I find it hard to believe that it would do 16.5 hrs before it broke up, if it appeared to be in good serviceable condition, and met Cat re-useability guidelines, when it was put back in?
I find it hard to believe that it would do 16.5 hrs before it broke up, if it appeared to be in good serviceable condition, and met Cat re-useability guidelines, when it was put back in?
Welder Dave
Senior Member
Yes it measured good. A tooth on the outer gear that drives it broke off. I asked about having the bigger gear that drives it replaced too but they said it was still as good. I think it was an oddity that the gear broke. I have in an old truck. I'll try to remember to take a pic. when I go out to my property tomorrow. There is a Canadian National MX event on the weekend and 1 of the riders contacted me about practicing at my track tomorrow. Hopefully a few riders come out. It would be great publicity for my track, especially if they did good and made the podium. I still have a few stickers they could put on their bikes or trucks/trailers.
Welder Dave
Senior Member
OzDozer
Senior Member
Yow, that's some serious gear stripping! - not just one tooth!! Was that a genuine Cat rotor, or an aftermarket one?
Here's photos of my rotor. There's only a few tiny marks on about 3 teeth, and I reckon they are the result of corrosion, I think there was some water in there sometime.
I can barely feel the depth of the marks with a fingernail. All the other teeth are perfect, and I've checked carefully for any tooth cracks with a magnifying glass, and looked for corrosion at the roots of the teeth - and they're perfect.
The rotor has some tiny scratches in the face, you can't even feel them with a fingertip or fingernail. They're essentially just light marks on the face surface.
The tops of the rotor lobes have about .001" - .002" wear. The maximum gap between the rotor lobes, installed, is .009". But the bushing that supports the outer rotor is worn .008".
I have a new bushing to go in, and I estimate when the new bushing is installed, the gap between the rotor lobes will come back to around .005" - .006" maximum.
I reckon that gap is quite satisfactory, it's a satisfactory gap for many crank bearings in many engines.
Here's photos of my rotor. There's only a few tiny marks on about 3 teeth, and I reckon they are the result of corrosion, I think there was some water in there sometime.
I can barely feel the depth of the marks with a fingernail. All the other teeth are perfect, and I've checked carefully for any tooth cracks with a magnifying glass, and looked for corrosion at the roots of the teeth - and they're perfect.
The rotor has some tiny scratches in the face, you can't even feel them with a fingertip or fingernail. They're essentially just light marks on the face surface.
The tops of the rotor lobes have about .001" - .002" wear. The maximum gap between the rotor lobes, installed, is .009". But the bushing that supports the outer rotor is worn .008".
I have a new bushing to go in, and I estimate when the new bushing is installed, the gap between the rotor lobes will come back to around .005" - .006" maximum.
I reckon that gap is quite satisfactory, it's a satisfactory gap for many crank bearings in many engines.
Attachments
Robert61
Well-Known Member
I would be scared of those gears, please send them to me for proper disposal.
(Sarcasm)
(Sarcasm)
OzDozer
Senior Member
I'd have to opine Welder Dave's gear stripped all those teeth, simply due to some foreign object that came up the suction line, and jammed the oil pump rotors.
Engine reconditioners failing to properly clean out oil galleries and lines has led to some major misery.
My nephew runs 38 machines, mostly Cats, and his guys installed a full out-of-frame overhauled engine into one of his D9R's about 6-7 years ago.
It took them 3 days to do the engine swap, they hit the starter, and the "new" engine locked up solid within 30 seconds!!
Someone in the engine reconditioning shop had failed to clean out an oil gallery, and the oil pump promptly pumped the trash into the bearings, and the engine was history.
It cost the engine reconditioner a lot of money for another rebuild, but the nephew still ended up out of pocket, as he never got compensated for the engine swap time.
Engine reconditioners failing to properly clean out oil galleries and lines has led to some major misery.
My nephew runs 38 machines, mostly Cats, and his guys installed a full out-of-frame overhauled engine into one of his D9R's about 6-7 years ago.
It took them 3 days to do the engine swap, they hit the starter, and the "new" engine locked up solid within 30 seconds!!
Someone in the engine reconditioning shop had failed to clean out an oil gallery, and the oil pump promptly pumped the trash into the bearings, and the engine was history.
It cost the engine reconditioner a lot of money for another rebuild, but the nephew still ended up out of pocket, as he never got compensated for the engine swap time.
Welder Dave
Senior Member
I'm pretty sure it was the original Cat oil pump. I think the hour is correct and if had less than 5000 hours at the time. The shop that did the engine does lots of Cat engines. They even hot tanked the block but I guess it's possible something jammed the oil pump. I don't think they'd seen that before but after seeing it won't reuse oil pumps any more. They were baffled by what would cause it. The larger gear that drives it they said had very little damage and wouldn't replace it on warranty.
I was running the machine and out of the blue heard a bang and saw I lost oil pressure so shut it off. It's odd, I was in a soft spot when it went bang. About 2 minutes before that I stopped on my driveway, I think to see how wet it was where I wanted to work. I can't remember if I left it idling or shut it off. I do remember looking at the oil pressure gauge and it showed good oil pressure. Thankfully my neighbor knew another guy who happened to have D7G who was doing some work on the other side of his field. He walked the D7 across my neighbors field and pulled my 931B with the backhoe on out. I did remove the the 4 in 1 bucket off the front. It was too soft for any kind of rubber tired vehicle to get in there. He towed it to a dry spot on my neighbors field beside the road. Cost me $100 and I cleaned his tracks out. I was able to lift the loader boom up with my skid steer since the bucket was already off. A field mechanic from the shop drove out and verified the oil pump didn't seem to be working. Out comes the engine and trans. again. Sadly it had to come out a 3rd time because the rings didn't seat. The shop did it that time after I got a deal to get it hauled to them. $300 well spent in my opinion. It has been running great since then thank God.
I was running the machine and out of the blue heard a bang and saw I lost oil pressure so shut it off. It's odd, I was in a soft spot when it went bang. About 2 minutes before that I stopped on my driveway, I think to see how wet it was where I wanted to work. I can't remember if I left it idling or shut it off. I do remember looking at the oil pressure gauge and it showed good oil pressure. Thankfully my neighbor knew another guy who happened to have D7G who was doing some work on the other side of his field. He walked the D7 across my neighbors field and pulled my 931B with the backhoe on out. I did remove the the 4 in 1 bucket off the front. It was too soft for any kind of rubber tired vehicle to get in there. He towed it to a dry spot on my neighbors field beside the road. Cost me $100 and I cleaned his tracks out. I was able to lift the loader boom up with my skid steer since the bucket was already off. A field mechanic from the shop drove out and verified the oil pump didn't seem to be working. Out comes the engine and trans. again. Sadly it had to come out a 3rd time because the rings didn't seat. The shop did it that time after I got a deal to get it hauled to them. $300 well spent in my opinion. It has been running great since then thank God.
OzDozer
Senior Member
You can hot tank a block, and still have metal trash in oil galleries. You need to blow air through them, run a bottle brush through them, and physically check that all the galleries are clear.
I have yet to remove the screen from the oil pump suction line in my engine, it looks pretty cruddy, and I suspect the etching showing on the bearing metal has been caused by cavitation.
I don't know what else I'm going to find in that suction pipe, but it's going to get a good cleanout, and a thorough inspection!
The early 1100 series and early 3200 series had problems with oil pump cavitation, especially at startup on cold mornings, when the oil was thick.
I believe Cat increased the size of the oil pump suction line in the 3200 series engines around the late 1970's.
A trucking friend installed an 1155 Cat engine in his IH R190 truck in the late 1960's, and he always had problems with oil cavitation at startup on cold Goldfields mornings.
He was a careful operator, and he always noted when the oil pressure hadn't picked up, right after startup. He'd shut the 1155 down and restart it, and it was all O.K., then.
I have yet to remove the screen from the oil pump suction line in my engine, it looks pretty cruddy, and I suspect the etching showing on the bearing metal has been caused by cavitation.
I don't know what else I'm going to find in that suction pipe, but it's going to get a good cleanout, and a thorough inspection!
The early 1100 series and early 3200 series had problems with oil pump cavitation, especially at startup on cold mornings, when the oil was thick.
I believe Cat increased the size of the oil pump suction line in the 3200 series engines around the late 1970's.
A trucking friend installed an 1155 Cat engine in his IH R190 truck in the late 1960's, and he always had problems with oil cavitation at startup on cold Goldfields mornings.
He was a careful operator, and he always noted when the oil pressure hadn't picked up, right after startup. He'd shut the 1155 down and restart it, and it was all O.K., then.
Acoals
Senior Member
Generally speaking a rebuilder who screws up isn't going to run out and say "wow, I guess I messed that one up"
They are going to stand there and be puzzled and talk about strange random failures they have never seen before until the customer goes away ....
They are going to stand there and be puzzled and talk about strange random failures they have never seen before until the customer goes away ....
Doing a post-mortem on a failure like that should not be rushed because its easy to overlook the cause. Do not just slap a new gear in the oil pump and call it good. There are reasons parts fail. Even the best mechanics are not infallible and sometimes get complacent regarding cleaning or assembly procedures. The old ‘ I’ve been doing it this way for 40 years and never had one fail’ may not be the best way to approach a new situation.
Welder Dave
Senior Member
It seems odd it would happen 16.5 hours after the engine was running. If something jammed the oil pump it can't have been sudden or only a couple teeth would have been sheared. It seems like maybe something partially stopped the oil pump and then locked it up a second later. It still seems bizarre. Could the rotor have seized on the shaft from not being lubed on assembly?
OzDozer
Senior Member
I would think it highly unlikely the rotor would seize on the shaft after 16.5 hrs in operation. It would have been getting lube oil within seconds of startup, as the rotors picked up the oil from the crankcase.
The fact that multiple teeth sheared off indicates a catastrophic event that brought the outer rotor to a grinding halt - and the only thing that I can imagine that would do that, is a foreign object becoming jammed between the lobes of the two rotors.
The fact that multiple teeth sheared off indicates a catastrophic event that brought the outer rotor to a grinding halt - and the only thing that I can imagine that would do that, is a foreign object becoming jammed between the lobes of the two rotors.
Welder Dave
Senior Member
It is interesting because they also replaced the oil pick up tube and screen. They said there was a crack in the tube from when the root went through the oil pan. I'm wondering if there's a way the gears could have not been aligned right or if it's possible the oil pump wasn't timed right? With the screen on the pick up tube what else could cause the gear to have the teeth sheared off?
Welder Dave
Senior Member
True enough but they did warranty it.
OzDozer
Senior Member
It's extremely unlikely the gears could not be "aligned right", they run on bronze and aluminium bushings which provide good alignment support.
No need to time the oil pump, only the camshaft and fuel injection pump need timing.
Despite there being a screen on the pickup tube, if there had been a piece of metal left in the tube, it could have been stuck to the side of the tube by some heavy sludge that wasn't cleaned out.
The screen is a piece of mesh in a circular shape slid into the pickup tube, and then a section of the end of the tube is deformed to hold the mesh in position and stop it from falling out.
It's important that the tube deformation is straightened out and the mesh screen removed, and both the pickup tube and screen cleaned spotlessly.
Your engine reconditioning guys may have overlooked this crucial little job first time around.
A lot of repair people get focused on "major" points such as bearing fit and clearances - but it's the little, seemingly unimportant jobs such as ensuring no trash is left in oilways that rate just as highly as bearing fitment.
Unfortunately, these "clean-out" jobs are often left to junior repairers/apprentices, and if their work is not checked by a supervisor, then that's when the problems start.
No need to time the oil pump, only the camshaft and fuel injection pump need timing.
Despite there being a screen on the pickup tube, if there had been a piece of metal left in the tube, it could have been stuck to the side of the tube by some heavy sludge that wasn't cleaned out.
The screen is a piece of mesh in a circular shape slid into the pickup tube, and then a section of the end of the tube is deformed to hold the mesh in position and stop it from falling out.
It's important that the tube deformation is straightened out and the mesh screen removed, and both the pickup tube and screen cleaned spotlessly.
Your engine reconditioning guys may have overlooked this crucial little job first time around.
A lot of repair people get focused on "major" points such as bearing fit and clearances - but it's the little, seemingly unimportant jobs such as ensuring no trash is left in oilways that rate just as highly as bearing fitment.
Unfortunately, these "clean-out" jobs are often left to junior repairers/apprentices, and if their work is not checked by a supervisor, then that's when the problems start.
Welder Dave
Senior Member
The pick up tube and screen were brand new and I believe OEM Cat. I think the actual rebuilding was handled by 1 mechanic who was quite familiar with 3204's. The 16.5 hours and then a bang seem really odd. If there was something in the pick up tube it should have been sucked up way before 16.5 hours.
New parts have to be cleaned just like used ones. There can be contamination from manufacturing that can easily be missed. It could have been a small metal particle or slag from the tube manufacturing process. I have seen mechanics use new parts without cleaning. Thats just asking for trouble. Gerotor style pumps do not tolerate as much contamination as spur gear pumps
OzDozer
Senior Member
O.K. - so I pulled up the 3204 oil pump specifications and the book says normal rotor tip clearance is .002" to .009", and maximum allowable rotor tip clearance is .011".
I reckon my rotors have minimal wear, are still within the specs - and I'm still choking on the new rotor prices (even the aftermarket ones - and a new aftermarket one at AU$1000, probably only has the same reliability as my old one) - so the old rotors are going back in.
I reckon my rotors have minimal wear, are still within the specs - and I'm still choking on the new rotor prices (even the aftermarket ones - and a new aftermarket one at AU$1000, probably only has the same reliability as my old one) - so the old rotors are going back in.