Good Morning,

First and foremost I just wanted to say hello and how excited I am to finally be a dues paying member of this club!

Okay now to dive in as the title says I have a D6-8u that my family has owned for the last 40+ years in service on our family ranch in Eastern Oregon. For the last 20+ years she has been in basically retirement mode only doing the odd job here and there, as she was replaced by a D7E (sadly the 4 cylinder model). Anyway I would like to begin the restoration project on her as this was the first machine I learned on and spent a good portion of my childhood jammed in the seat with my grandpa or my father, and running a cable dozer made me certainly appreciate the hydraulics on the newer machines. My goal if feasible is to give her a second lease on life so that my son who loves dozers can have something to learn on and appreciate. 

Alright moving on first of all can someone please help me get a year on her I know she is a later model but that is it. 

Second question as you can see in the pictures it is spewing oil from around the valve covers. The gaskets were changed a couple of times back in the day at least that is what my father remembers but unsure. He seems to think the valve covers were warped but I’m not sure. 

Last question for now. It has a miss in the number 5 cylinder at least I believe that is the one. When you loosen the fuel line at the injector pump it tends to disappear. Hopefully my videos we load and be clear enough(okay I need to figure out how to compress or just take audio). My question is am I looking at rebuilding injectors? Or replacing injector pumps? 

Thanks and looking forward to sharping knowledge and memories. 

Nice looking old D6. Parts are getting harder to find, but generally speaking you can still find about anything to rebuild a 8u or 9u D6.

I think your serial number makes it a 56 year model.

I have had valve covers on the D318 engine ( what is in your D6) that where warped. I think I got them flattened enough to stop leaking with a new gasket. But I may have used a different set finally. I have always had better luck by tightening them just a little at time.

I have replaced injector nozzles when I have had one cylinder missing, but never a pump yet in 40 years. But who knows how much better they might run with rebuilt pumps. I think the "new cleaner fuel" will cause more trouble with gumming and rusting than the old fuel with sulfur in it ever did.

First things First!
Clean that machine up around the valve covers, fuel pump, filter tower, etc - in short anywhere that dirt and grunge can enter the engine. DIRT IS THE ENEMY when working on machinery.

After you have gotten the "grunge and grime" off you can determine where the leaks are and a suitable fix.
There are many products out there now that will cover large gaps and take temperature too. The advent of silicone type sealants has changed everything as we knew it.
Neil is correct - find out which corner is bent and if the flanges are indeed cracked.

Cracking an injector line at the pump (bleeding the fuel off) will cause a missfire - the injector does not get the fuel. If that is indeed what you are doing and it makes no difference in the engine sound, you have found the cylinder that is the problem child. Try each injector line, one at a time and compare the "squirts" of fuel as you run through them.
They should be pretty even. Keep your skin and eyes protected, that fuel is under high pressure leaving the pump.

Nice looking machine, some TLC and it will be purring!
CTS

for most gaskets a dressing i use is loctite aviation n03 form a gasket they also have hardening one that is a paste and a non hardening paste.
there is also "stag" jointing paste its hard setting designed primarily for pipe fitting but also works on gasketing (dad used heaps of it doing water bore and irrigation pump work)

loctite also make a couple of anerobic gasket makers i use 515 master gasket a fair bit too it can be used as a dressing or on its own.

a word of warning about rtv silicones only apply the amount needed any excess squeezes out and goes places you dont want like oil galleries cuasing problems. and often much superior products are available.

a loctite product guide has lots of helpful info. thier MRO product guide is very useful.

any good injection shop should be able to rebuild those pumps and injectors for you. and yes todays fuel doesnt lube the same as the old fuel did so a diesel fuel conditioner is helpful. i use flash-lube's product in our equipment works out pretty cheap insurance as 5 litres will treat a thousand gallons since the mix rate is 1 ml per litre of fuel.

Hey thank you everyone for your replies and great info! First thing I’m going to do is get her a good bath and get ready to dive in. I’m not far from general gear in Boise Idaho so I may just zip down there for some other parts and see if they have any valve covers. I found the valve rebuild kits fairly cheap on the web and I might call the old cat store and see what they would charge. However at least now I have a starting point and Ray54 my dad tends to agree with you on the pump. He was telling me from when he was a kid they had a 3T and the then old timer said usually never have a problem with the pump. But if you mess with it make sure you don’t mess the timing and that was in the early 60’s.

Welcome to the club! Boise eh? Our resident Caterpillar fan lives in Ada County, Mr. D4e; Maybe when he isn't hanging out in the local doughnut nook or making snowmen, you guys could meet up. The U series D6s are some of my favorites. They sound great and handle nicely. Hope to see more pictures of your tractor. JM

Okay new question as the search function on the forums is not my friend apparently. Is there anyway without the engine data plate to figure out what series of the D318 is in it? I wanted to try and find the Manual for it so I had a reference but I’m coming up blank. Thanks again everyone.

Only one D318 Engine book that I know of. The form number 30027 on the book I bought from Cat in the 80's. It has extra parts about industrial, marine, scrapers, graders, and tractors. From members here there may be a special vernation used in a grader, that might not be covered in this book. But all you need for tractors is in the general book.

The biggest change in the U series tractors is the change to the master clutch running in oil. From my use of them you can slip the oil clutch a long time and never damage the friction surface. The ones I changed where about out of drive teeth where it drives from the fly wheel. The friction surface was the same thickness as the new one, no adjustment of the clutch was necessary.

The other change is they increased the high idle RPM from 1400 to 1600 if I am remembering correctly. Which was done at the same time as the change in clutches.

Thank you I have been scouring the old eBay getting more specific manuals instead of the 3T ones I have.