[zuren]

Fluid for metal PK tranny and rear diff.​

What do you put in your PK transmission and rear diff.?

80w90 gear lube	0	0.00%
80w90 gear lube + "STP"	4	66.67%
Other (please specify in a post below)	2	33.33%

 

[zuren]

Before the weather gets too nasty I'm trying to replace all of the fluids on my 1618. I just completed the engine oil last night (10w30 Mobil 1).

Now I'm looking to the transmissions and the rear differential. I've read suggestions of straight 80w90 as well as "STP + 80w90, mixed 50/50". What is the STP product that I've seen mentioned and does this really make a difference? I put a poll at the top to make it a bit easier to see what everyone does.

In it's 37 years of life, I don't know if the hydraulic fluid on the tractor has ever been flushed. Is this something that I should consider doing as well? If so, what is the recommended product I should use?

Based on reading other posts, this will be my approach:

1. Drain fluids

2. Flush gears with brake cleaner or diesel

3. Replace fluids with the following volumes:

Tranny capacity - 1/2 pint each
Differential - 1 pint
Final drives - 1.5 pints each

Please let me know if I'm off base anywhere.

Thanks!

 

[Kyocum]

I myself would fill to correct level with whatever the owners manual specs out. I don't believe in custom oil mixtures per say. Not knowing whats in the additive packages in the different products they can actually work against one another.

 

[boyscout862]

I would be very hessitant to use any flush. It just seems to find places to stay in and then mix with the new oil. When in doubt, I do a normal change and then run it and inspect the oil. If it gets dirty looking or milky(water), I just change it again. That has worked for engines, transmissions, and differentials for me. Good Luck, Rick

 

[glgrumpy]

On trans, some use the mix you state. That is only to thicken it up and not have it grind as easy because the gears stop rolling quicker when clutch is pushed in. I have used that, and just the 80w-90 also and not much diff to me. One thing on the original trans is the front and rear bearings and seals. Stock trans has no seals and uses "oil-slingers" to keep oil from coming out past the shafts at both ends. Some still works it's way out, but not bad. Many times the slingers wear out over the years and leaks get worse. When most rebuild a trans, they now put in sealed bearings, or at least leave the outer seal on them to keep lube inside better. If no new bearings, it is best to keep the oil amount to 8oz. If you fill trans to run out the side level plug, it is really too full and the oils leak out bearings as noted. Any oil in the trans that leaks out, goes down the drive tube and into the rear, and then out to brake shaft seals or gear cases. They say it over-fills the cases. I never thought much of issue unless you KEEP adding oil to trans as it goes down. IN the differential and bull cases, just use 80w-90 gear oil. Only way to empty the rear is to remove the cover on back. You get good look at the gears then also if you wish. You'll have to make a gasket for it, or some use Silicone, which I'm not a fan of. Use the cover for pattern to make the outside shape and get holes correct. Inside edges of gasket don't matter much and can hang into case a little, but must be cut out so ring gear isn't chewing it up. Level for it is up to the hole with rubber plug in back, once it is together again. Bull gear cases have drain plugs most times and up higher in back is a level plug to have oil run out of to see if full. At top or high is third plug that has a small hole in it, and a breather mesh in it. Make sure that one is used up there only, or it will leak out the oil over time. I've never flushed the rear or gear cases. IN most instances it is fine as long as you have SOME kind of lube in them, not a real technical issue which one. ON trans, I have flushed out those at times, as they may have water in them or sludge. Water gets in thru the shifter shaft hole, you should have the rubber "witches hat" seal over that area. With top of trans off, IF you have that far apart, you can see all the gears and condition of trans. IF not all apart, just put some flushing agent in trans and roll wheels around a bit to make it roll and drain for long time to get that out and then re-fill as noted above. Let it drain awhile, it should get most of the cleaner out and not thin the oil any.

 

[MNGB]

Hi when I put my 76 1614 back into service I flushed the trannys with diesel fuel and as GL posted jacked up one rear wheel and turned it over a bit to sling the diesel around then drained and left it open to let it all drain out then serviced mine with a 50/50 mix of 80/90 WT and STP, I think that the STP helps with the shifting like GL said it may cause the gears to slow to a stop quicker(?) and the shift seems to be smoother but I maybe hoping that's it. And yes water likes to get in thur the shift so be sure to have a good witches hat grommet installed and like like to pack a good sticky grease around the sifter plenty of it then slid the grommet down and Zip Tye the top of the grommet as I've noticed they like to work up when using the tractor.

OH by the way on my 76 there is a differential drain plug its a 1/8" pipe with an Allen head located at about the 7 o'clock position, never looked on the 84 as someone previously had backed it the diff cover and bent it so it leaked I pulled it off pounded it straight, and used Yamabond (good stuff GL) and it doesn't leak now.

 

[zuren]

Thanks for the feedback. I spent some time with the tractor tonight starting by draining and refilling each tranny. The lube that came out was very brown. I did elect to flush with some brake cleaner but then propped a heat gun to blow into the holes to evaporate the cleaner. I also drained the left-side final drive (bull gears) and it looked like Hersey's chocolate syrup with roughly the same consistency. I'm not a lube specialist but I'm guessing it was time to get some new lube on these gears. I inherited this tractor from my dad and I have no idea when any of this service was ever done.

I looked at my rear differential and I do not see a drain plug. This means I will need to remove the cover and will probably destroy the gasket. Is there a replacement gasket available or do I need to get a sheet of the "make your own gasket" material? I'm not a fan of the liquid "form-a-gasket" products so I'm willing to cut my own.

Should I also be looking to swap out the hydraulic fluid? I'm sure it is the factory fill from 1979.

Thanks!

 

[Glenn Ayers]

Go to your local parts store (NAPA) & ask for a small roll of cork/rubber gasket material .... about 1/8" thick. Make sure it's large enough to fit your rear cover. I just made one for one of my PK's.

I used gasket shellac to glue the new gasket to the cover & laid it on the bench with some weight on it for a couple days to dry. I also drilled / tapped a hole for a 1/8" pipe plug in the bottom of the diff .... for future drain / flush operations. I'm kinda anal like that.

 

[zuren]

Go to your local parts store (NAPA) & ask for a small roll of cork/rubber gasket material .... about 1/8" thick. Make sure it's large enough to fit your rear cover. I just made one for one of my PK's.

I used gasket shellac to glue the new gasket to the cover & laid it on the bench with some weight on it for a couple days to dry. I also drilled / tapped a hole for a 1/8" pipe plug in the bottom of the diff .... for future drain / flush operations. I'm kinda anal like that.

Did you consider drilling and tapping the cover or is there not enough material to do that effectively? I like the idea but I'm not confident in my drilling/tapping skills to go after the case itself. If I were to mess up on the cover, at least I could find a replacement and be back to square one.

 

[Glenn Ayers]

No .... I wouldn't consider drilling & tapping the cover.

 

[MNGB]

Likewise I say don't, not near enough material to tap for a plug, and that reminds me while under my 84 PK trying to figure out the 3 pt operation I looked and the differential does not have a drain plug there is a flat spot that could be drilled and tap though.

 

[a.graham52]

When I drained and filled my rear diff, I used a vacuum pump with in line catch bottle to suck out old fluid. Then filled with new. Let's be realistic, if I get 95% of the old fluid out, it's still 100% better the before.

 

[Rocketcity]

A.graham52b did you drain yours via the plug or did you take off the cover of the differential?

 

[a.graham52]

Just through the plug. Vacuum pump, catch can and rubber hose. It took some time to get the oil out as its real thick but I didn't have a new diff cover gasket or rtv to replace if I was to remove the cover.

 

[2broke2ride]

Go to your local parts store (NAPA) & ask for a small roll of cork/rubber gasket material .... about 1/8" thick. Make sure it's large enough to fit your rear cover. I just made one for one of my PK's.

I used gasket shellac to glue the new gasket to the cover & laid it on the bench with some weight on it for a couple days to dry. I also drilled / tapped a hole for a 1/8" pipe plug in the bottom of the diff .... for future drain / flush operations. I'm kinda anal like that.

I used black RTV silicone just like we do on light trucks in the shop. Two years and no leaks.
As far as the transmissions go, both my trannys are running on straight STP after the tear down and bearing change last year. All good so far.