My D8N 9TC02252 was getting exhaust in the coolant. Pulled the head and the head gasket fire ring was blown out on #6. Sent it it to be resurfaced, magnafluxed and valves replaced. The liners had no crosshatch left so we were hopeful of getting away with an inframe. We dropped a rod and a main cap and the bearings were pretty rough and the crank had a few minor scratches so we decided to do a complete rebuild. Still waiting on word on the crank. Hopeful for just a polish. Just looking over the oil pump gears and they have an abnormal wear pattern to them. This has the two section pump setup. The rear 1/3 to 1/2 of the gears in the main pump body have more wear than the forward portion of those gears. The scavenge pump gears appear to have more uniform wear. I can still see the machining marks on the gears except for where they are polished. They are smooth and look good otherwise. Just wondering if the abnormal wear is anything to be concerned about? Also seeing as I have the torque converter out is there anything I should check or replace on it while it's out? Was running good when we took it down. It's my first time dealing with one so I'm a little unsure. First pic is of our fun so far. I think we reached the end of our troubles hopefully. Second is a scavenge pump gear. Third is a main pump gear. Fourth is a rod bearing. Think we were on borrowed time. Thanks
First question - how many hours on the engine and the converter and has either of them ever been rebuilt before.?
Hi Nige. The hour meter says 12,500. I bought it two years ago and have put about 600 hours on it. Not sure if the meter has been changed as that seems too low. I don't really have any history on it. The engine bearings were OEM and don't have a date stamp so I'm unsure if they've ever been replaced. It was odd in that the main bearing caps weren't numbered so I assume they haven't been off? There was paint on the gasket edge between the block and flywheel housing and no chipped paint on the external bolt heads so I don't believe the crank has been out of it before. The head had no paint so it has been replaced or rebuilt some time previous. Not sure about the status of the converter. I didn't see any obvious signs of it being replaced/ rebuilt. Not sore what an average life span of one would be? I bought it as kind of a project. The undercarriage was nearly shot and it was hard starting. I put all new Cat rails, idlers, rollers, segments and several bogie pins on it a year ago. It was a fair bit of fun to pull the engine and TC so I'd like to do this right and really appreciate all the experience such as yourself on here. Thanks.
I used to always to do a tear down and inspect on the converter when I had the engine out. I’ve found the vanes on the stator starting to loosen and change their angles. The oil wasn’t heating yet but was close showing a big problem. It doesn’t take long to tear them down and bearings and seals aren’t that expensive. The three critical and expensive parts are the impeller, turbine and stator.
I’d agree with John. The converter is out, tear into it and reseal it at the very least. Maybe new bearings as well. If you look at the back side of the crank bearings you should find a 6-Letter Code. It might look something like UNDDNN. Post that code and Information is available to date the bearings. With that and the date of manufacture of the tractor it should be possible to determine if the bearings are original or not.
I would at least reseal converter and inspect metal seal ring retainers closely. Those oil pump gears don’t look bad but watch out for wear in the bearings and shaft surface of the oil pump. While you have the trans pump drive shaft off now would be the time to at least replace the trans pump input seal.
I couldn't find a 6 letter code on the bearings. On the rod bearings I found a 5NMOO O On the main bearings there's a 5 NEOO 13 (lower half) 5 NROO 3 (upper half)
At least nice and clean, bearing shell erosion usually indicates coolant in oil(Acidic metals removal to cavitation erosion(Steamoff), doing it right full out of frame and cannot agree more converter is out go thru it.
Thanks guys. I read through the converter disassembly and reassembly and it doesn't appear to require any special tools. I don't think my micrometers are big enough for measuring the stator flange and impeller wheel flange. Should I be finding some larger ones?
If you can see machining lines on edges of mating surfaces you probably wont need to measure them.
Didn't know what to expect or look for as I've never opened one up before. Thanks for the tip.
Hi,we had a lot of trouble with #6 piston seizures on the early D8N, at one stage we were using a different part number piston from memory than what the parts book indicated Cat later put out a service bulletin covering this topic and what to do about it. i don't have the resources any more to see if this is still a problem but looking on SIS there are still references to this issue Mark
The oil pump shafts look good yet. The bushings show some scuffing so I'm going to replace them. The transmission pump looks to have been changed fairly recently. The couplers on the transmission pump drive shaft are cracked so I'm going to replace them. And a bunch of hyd hoses that are original yet I believe. Thanks.
Just 3 small bolts gets you the input seal holder and bearing off the pump. I’d still check the lip seal if I were you.
Funny you mention that #6 was giving issues. On mine #6 had a head gasket blow out and the piston rings were broke in a couple pieces yet the other 5 pistons were good. I'll have to check with my machine shop as far as what piston/liner assemblies they ordered. Did you upgrade them to dual piston cooling tubes? Thanks for the heads up.
Sounds simple enough maybe I'll add it to my parts order and do it just to be safe. What part of Sask are you at? I'm an hour west of Edmonton. Thanks.
Regarding Date Codes on the crankshaft bearings, they are marked with only month and year rather than day, month, and year which is what I was originally thinking would be the case. NEOO translates as March 88, NROO as April 88, NMOO as February 88. With the build date of the tractor being May 1988 I am of the opinion that these are the original crankshaft bearings.
Thank you. I definitely learned something today.
I fitted a new complete oil pump to my D8R motor even though the one in it wasn’t the worst I’d seen. Cost about 1000 US dollars from ITR non oem. I also fitted all new Cat hoses that run from the tank down the chassis to the front. Another 1000 but well worth it while you have acess
Agreed. For the value of everything else that's will be installed in it a the cost of a replacement engine oil pump is small beer in comparison.
It may be too late but the Service Magazine Mark250 posted above (post #12) regarding cylinder packs an updated version with new information was published yesterday. I came across it while looking for something else. Copy attached.
Hi guys. I appreciate all the info. Unfortunately I've been dealing with some personal stuff and this project got on the back burner for a bit. I was preoccupied when my machine shop finished checking the crank and cam, rebuilding the head and reshimming the counterbores. Seeing as he had all the internal components and I had no time at that point I got him to assemble it. I'm not sure which cylinder packs he ended up going with. He's on holidays now so it will be a while before I can ask him. Just got started on this again a few day ago. I opened the torque converter. I was hesitant as I've never been inside one before but it was fairly straight forward. The bearings showed wear so I replaced them and the seal rings. The turbine, impeller, and stator all had machining marks yet. The sun and planet gears showed some wear so I replaced them. I replaced any of the hydraulic and transmission lines that were easy to get at. Also the engine oil pump too. Finally got the engine and torque bolted in. The shelves of parts are starting to get smaller so it feels like we're making headway. Hoping to get her buttoned up this week. Thanks for the help.
Question, those added cleats on grousers, Ice Cleats?
$$$$$$$$$$$
Yes. We call them "corks" here but it's the same difference. Pretty much necessary from Nov-May here.
Congrats on what you're done so far. Kudos for replacing the engine oil pump as well. I think if it was mine I'd want to establish the Part Numbers of the cylinder packs and piston cooling jets that went into the rebuild before I turned the key. In fact I don't think I'd be doing any more assembly on the machine just in case that engine has to come back out again. For the amount of money spent on the rebuild it would be a shame to have something go South just for want of making sure the correct parts went into it.
Did you recheck crankshaft end play after you installed the torque converter? It only takes about a minute but if the torque converter pushes the crank forward, that check could save you thousands.
Took some time but I finally ascertained my machine shop used the updated 20R-1115 cylinder packs and 290-6567 piston cooling jets. He's a very meticulous German who takes pride in his work. But this does make me feel a little better too knowing that everything is up to snuff. What would you recommend for a start up procedure? I filled the transmission and hydraulic reservoir to slightly over full. Do I need to fill the torque converter or will the transmission charge pump do that? I oiled all the bearings and seal rings when I assembled it. As far as the engine I've usually just started in the shop and monitored oil pressure and check for leaks for 10-15 minutes then out the door and put to hard work. Thanks for all the advice.
Well I'm still just shy of $30k in parts. That is Canadian pesos mind you. Includes a lot of "while we're in here lets do it" stuff. There's a few grand just in hoses because they look like originals yet. Not sure what this would have cost at a shop. I stopped counting hours a couple days in. Lol. Good thing I work for cheap.
Thanks for the heads up. Wouldn't have crossed my mind. Just checked and its at .012". Which is in the middle of the spec. Thank you.
Always liked an 8N with a u blade for grubbing
Time to poke the bear: Did not Know you were a Ford farm tractor and Drag Bucket aficionado there CE!!!! And you DID toss that clay bird for all to see!!!
Forgot the D. I don't have an 8N, but I do have a tea20. No attachments for it, just a fixer upper that belonged to my grandfather
No offense intended Just a little fun! TO20 and 8n about the same Good for light work
None taken. I had to stop and think how you got ford tractor out of 8N, then it hit me
Finally got everything hooked up. Went to start it and she cranked real slow and some smoke signals from the starter. My dad who usually operates it had mentioned the starter was getting weak but it slipped my mind. Open the starter up and it was a carboned up mess inside as the seal was leaking and the brushes were shot. Quick run to town for a new one and she spun over way better. Had oil pressure after just a few seconds. Had her primed and running after maybe another 40 seconds of cranking total. Have 60 psi engine oil pressure at an idle and no leaks. The coolant flow alarm was going off. Finally traced it down to a bad ground wire on the sensor circuit. Still haven't quite figured out the purpose of it though? Seems kind of redundant with a coolant temp gauge and warning light. Just need to install the hood, canopy, c frame and blade. Thanks for the help.
Be sure to post a video of her first blade full.
Consider the coolant flow indicator as just another insurance policy. If you lose a fan belt or a water pump impeller or something like that the coolant flow is going to be the first alarm to go off. Like car insurance, always good to have it and not need it than need it and not have it, especially when you consider how much $$ you put into the engine rebuild.
Agreed. Sometimes those Temps can sneak up on you. I find when I'm grading, I tend to neglect the gauges, especially on our maintainer graders as they are over my head. One night, I pushed the snow banks back on 4kms of road with the loader. Back and forth, back and forth all night. Warning light and buzzer went off as the trans temperature was up and I hadn't noticed
Well I figured it's time for an update. She has 100 hours and no surprises yet. I have a pic of when I hauled it to the 1/4 we're clearing bush on but haven't been back to see it till today as we had to replace a broken pin on the brush rake. My dads cousin has been running it and he's the kind of guy who you just have to tell him which direction you'd like the brush piles and he's off. He's got it all walked down and about 30 acres piled so far. I'll try and post a video but I've never done that before. Thanks for all the help.
Always nice to hear a success story, although it was touch and go for a while it was "All Right on the Night". Protect your investment and get some regular oil samples from the engine if you haven't already. You need to establish a trend in the various "trace elements" present in the oil for future reference. Post any results you get here for comment. 100 hours and you should already have taken two samples - at 50 & 100 hours respectively.
I also hope you’ve already changed the engine oil & filter at least once by now.
Hi Nige. Yes I have changed the oil at 70 hrs. I have used oil sampling in the past to verify issues such as fuel dilution previously. With all the work that went into this rebuild I'll look at starting sampling it. What kind of schedule would you recommend? I'm just actually troubleshooting an issue with hyd oil leaking into the transmission I believe. But I'll start a new thread on it. Thanks.
Sampling should be done in the window between 50 and 250 hours. When in that window depends on your circumstances. If you're only running 250 hours/year then consider 50 hour samples. If you're a 24/7 operation then 250 hr sampling is appropriate. Whatever you decide, the key is consistency. Chose your routine and stick to it give or take 10 hours and use the same sampling method every time. Fluid analysis is a trending tool and not really intended for one-off diagnosis.
Wot he said........ ^^^^^^^^ The only thing I'd be doing on a recent rebuild is some early "out of sequence" samples (not changing the oil/filter though), more than anything looking for something spiked way out of whack compared to all the others. Also as a check on the Silicon numbers that the engine in not pulling dirt into the intake through a loose clip or a damaged hose. That can ruin your day big-style and in short order. Silicon should walys be in single digits as far as I'm concerned.
Forgot to say the 250 hr maximum interval applies to engines. Power train and hydraulic systems usually recommend 500 hr sampling intervals but again, it depends on the circumstances.
I suppose one could postulate the value of oil analysis as follows: - How much is the machine currently valued at, especially in view of all the recent wok done on it.? How expensive does a $35 oil sample analysis look compared to the value of the machine.?
Thanks guys. I'll get a sample soon. It usually runs 6-800 hrs a year and 250-300 hrs on an oil change so I'll aim to do a 150 hr interval.
I think I'd do it every 100 hours if you are making 300hr oil & filter changes, at least for the first couple of rounds. Then go to 150hr after that. It's surprising how fast SOS history builds up. As I said before, keep a close check on the silicon which is an indicator of the health of the air induction system.
I found the sampling period was cost effective at oil change intervals. The first oil after a rebuild is always going to have run in metal in high doses and you end up losing lots of sleep. I usually ran an engine less than a hundred hours and drop the oil. Start sampling at the next oil change at two hundred fifty hours.
I agree 100% with that john. However as far as I'm concerned the early-hour samples are more to check for the presence of silicon, fuel, glycol, & water in the oil. I'm not worried about a spike in iron or copper for example. Also, given the info the engine has just been rebuilt, any good (that's a kicker right there) oil analysis lab would pick that up as normal break-in numbers and say so in their interpretation.
Good points as well. I guess I never worried about those things as I knew they wouldn't be my problem on a startup and run in after rebuild. They usually showed up between six months and a year later.