M818 PTO seals and boots replacment

[Brutacus]

I've decided to replace all the seals and boots on my M818's pto. The PTO boots have recently started leaking way more than usual. Since I don't know how much oil was in the transmission, or when it was last changed I've been wanting to change it out for some fresh. I'm putting in some Amsoil SEA 50W, which is good for the yellow metal. When I drained the oil out of the transmission, I noticed some shiny flakes in the oil. It looked like brass. Some of that is from the magnetic drain plug I wiped clean.


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As mentioned above, I don't know when the oil was last changed, or even what kind it is. I also have never serviced 5 ton transmission, so I didn't know what to expect. If this is excessive, or not, someone please let me know.

Now moving on to the second part, removing the PTO accessory drive, and replacing it with a standard plate. This part was the easiest. I took off the 6-bolt plate to inspect the inside and found more oil with yellow metal shavings in it. I suspected I would find something like this because the PTO is the lowest place where the transmission oil reaches, almost like a sump on the transmission.



The next part was a little aggravating. I've read on other post the retaining rings and seals are easy to get out. That might be for someone else, but not me. I must not have the right tools. Anyways, I had to use picks, a hardened nail punch, a mallet, and some hooks. I had to use the nail punch to poke some holes in the front of old seal so I could hook it and pull it out. Everything is pressed in, there are no lock rings or anything like that. I was able to get everything out, but when I went to put the new seals in, the new seals couldn't fit over the shaft. I don't want to tear them up, but wasn't sure these are the correct ones anyways. The original ones are metal frame, the replacements are all rubber. The metal frame ones are a National brand with part number 28 P 21. I took the originals up the parts store, and they can order some new metal frame ones for $4 each. I'm getting two when I get off from work tomorrow. I'll have more on this post when I get my new seals in. Sorry about the focus on some of the pictures, my camera doesn't like me.







The grade 8 bolts in the last photo is what I'm using to reattach my battery plate.

 

[US6x4]

This is good stuff! I need to do exactly this to mine as I my PTO leaves more drips on the ground than a college campus crying closet.

Are you using a gasket for the new cover or straight glue?

 

[Brutacus]

Yeah, mine recently starting dripping ALOT. I know these trucks are suppose to mark their territory, but their not suppose to drain themselves. I'm using a gasket with a very thin coating of silicone on both sides. I'll have some more info on the seals when I go pick them up after work. I'll have the correct part numbers too.

 

[gringeltaube]

.... but when I went to put the new seals in, the new seals couldn't fit over the shaft. I don't want to tear them up, but wasn't sure these are the correct ones anyways. The original ones are metal frame, the replacements are all rubber.......

For dimensions and seal part numbers (various brands), see this post...



(Usually I put double-lip seals wherever possible.)

 

[Brutacus]

I have gotten my new seals and boots installed. The parts store got me the National brand 471538 oil shaft seal. This is the correct seal. You can see the size difference in the rubber seals. The outside diameter is correct, but the inside diameter is too small.




Installing the seals over the shaft proved to be an easy task. I used 3/4" and 1/2" pipe with couplings with a mallet to seat the seals. The seal facing the front of the truck was a little difficult, but that is due to the lack of room to swing the mallet. The rear facing seal was very easy, plenty of room to work.



Now seating the boot retainer rings was a bit of challenge. At first I was trying to find a deep well socket that could fit over the boot, and be used to seat the retainer ring. That wasn't going to work. I ended up using a 1" open end wrench, a flat end punch, and 5 lbs. sledge hammer.



The wrench was slipped over the boot, and was used to provide a more even surface to press the retainer ring into place. It's not perfect, so the flat end punch is used to finish seating the ring.




I also replaced my 6 bolt cover gasket. I now only need to replace my main output shaft seal and gasket. I'll have to remover the woodruff key for this. Any ideas on how to get that out? Mine is looking chewed up, so I'm thinking of just getting a new key. The seal is not leaking now, but since I have the oil out of the transmission, and the seal is 30 years old I might as well do it since I'm down there anyways.

 

[77 AMG]

If that Woodruff is showing ANY wear/ abuse, REPLACE it. It can cause ALOT of problems when it decides to fail, usually, when you need it to hang on for just a little bit longer. Ask me how I know that...

 

[Brutacus]

How do you know, and what kind of damage did it cause?
Anyways, I've gotten the woodruff key out over the holiday. I ended up using a small air hammer. I did find a new key at the local hardware store for $1.78. I also replaced the gasket and seal for the output shaft. I got some pictures and details for my next post. I just got to get the pictures off my camera and up load them.

 

[Brutacus]

Here is my update.



I didn't get everything done that I wanted to do. I got rained out, and I didn't get to put the oil back in the transmission. I did remove the woodruff key, and replace the gasket and seal on the main out put shaft. I'll probably replace the oil today or tomorrow. With the PTO, I'm supposed to use 11 quarts of gear oil. I'm using Amsoil SAE 50w oil.

Before I got to the gaskets I had to remove the worn woodruff key. I ended up using a small air hammer with a flat chisel bit. The key flew out of there and went to the back of the truck. You can tell the difference between the two.



I found out the bolt closest to the transmission is the hardest to get out. My sockets and regular wrenches couldn't fit or get to it. I needed an angled 1/2" wrench. My sockets worked fine with the other 3 bolts. When I got the seal retainer off, I used a small chisel to scrape of the remains of the old gasket off the PTO housing. Removing the old seal out of the retainer was the hard part. It will come out, but it is stubborn. Installing the new seal was easy. After cleaning up the seal retainer, I used a 1" socket and a 2 lbs. sledge gently to set the new seal. I also rubbed a little bit of oil/grease mix on the seal lip to lubricate it when sliding it over the output shaft. Before installing the new seal, I used some emery clothe to clean up the output shaft to make sure there are no burrs that could damage the new seal. I went ahead and cleaned up the 4 bolts using my wire wheel on the bench grinder. I don't know if the bolt holes on the pto for the seal retainer are blind, or fully tapped, but I noticed what looked like old thread sealer on the bolts, so put some new thread sealer back on the bolts prior to install (teflon tape). I also put new grade 8 lock washer on them too. The old ones were flat and worn. The gasket got a thin coating of black silicone on both sides. After all that prep work, the install went smooth.

 

[US6x4]

Great detail in your write-up! This will be a big help to folks like myself.

Where did you end up sourcing the rubber boots or are they generic non-NSN type parts?

 

[gringeltaube]

....... I don't know if the bolt holes on the pto for the seal retainer are blind, or fully tapped. ....

Bolt holes all go through; fully tapped. So yes, sealing the bolt threads is important.

 

[Brutacus]

This is should be my finale update to this post, unless something starts leaking. Thankx to the nice weather, I filled the transmission with the new oil.

All I needed to do this job is a large crescent wrench, some teflon tape, a funnel with a flexible tube attached, and the oil.



Even with the good funnel, I still managed to spill some oil. Anyways, according to the tech manual the 5 ton spicer transmission with PTO takes 11 quarts of oil, and it does. Just as I got down to the 11th quart the oil started to drip out of the fill hole. With a quart left, the transmission full of fresh oil, and new gasket and seals on the pto, all I need to do is run it, and check for leaks.

 

[Brutacus]

I got the boots and seals from Big Mikes Motorpool. I thought it was strange for someone who deals in this stuff to have the wrong seals in stock. Now I just jump across the bridge to Memphis Equipment. I can get the parts at their counter sale.
All in all, this was an easy thing to due. My biggest problems where daylight, and the weather. i.e. Not having enough daylight in good weather. Hopefully when you, and others put new seals and gaskets on the PTO, everyone who reads this will have an idea what to expect. I didn't, and I still read all the post I could find on the subject. I also read the tech manuals too.

 

[Ajax MD]

Winter is tough, just not enough hours of daylight and the angle is low, shrouding everything in shadow. Work lights are a must.
Pretty much every job in the TM's say "discard lock washers" and direct you to obtain new ones. Better than having a critical bolt vibrate out.

 

[77 AMG]

To answer the Woodruff key question- My little Geo Tracker had a worn key in the crankshaft snout and it was letting the timing "walk". I found out the hard way that the key was side-shearing when the timing moved enough that the engine decided to stop running during a rather steep up hill trail. The key had actually "smeared" over some and let the crank balancer rotate out of place. Ever since then, every 30K miles a new key has been installed. I got lucky that the engine is a NON- interference type, meaning that the valves would not crash into the pistons, if the key had failed completely, and destroy the engine. On something like the PTO, might not be a catastrophic failure, but, a loaded winch kicking back does some UGLY things to stuff around it when the cable gets loose!

 

[US6x4]

I hear that shifting should be smoother and easier after replacing the heavy military GO stuff with the proper 50W oil.

 

[Ajax MD]

My little Geo Tracker...

No epic story ever started with "My little Geo Tracker..."




Just busting your chops.

 

[MyothersanM1]

I just recently replaced both front and back seals on my PTO's shift shaft. It was leaking like a sieve from the front seal. I decided to pull the PTO and do all the work on the bench top. It's "more better" than beating your head up underneath that beast. Removing and replacing the seals is much easier with the shift shaft out. Lucky I did pull the shaft as I found why the leak was so bad. There was bad pitting on the shaft right where it sits in the high neutral (locked) position. The pitting was 1) a pathway allowing copious amount of oil to sneak through to freedom and 2) prematurely wearing out the seal.

I hear that shifting should be smoother and easier after replacing the heavy military GO stuff with the proper 50W oil.

Yes, it is! Love the 50W!

 

[Brutacus]

I decided to pull the PTO and do all the work on the bench top. It's "more better" than beating your head up underneath that beast. Removing and replacing the seals is much easier with the shift shaft out.


I know what you mean, I almost started naming the bumps on my head. I thought about taking my PTO off, and that would have made things easier, but I don't know anything about shimming them properly.

 

[MyothersanM1]

I know what you mean, I almost started naming the bumps on my head. I thought about taking my PTO off, and that would have made things easier, but I don't know anything about shimming them properly.

This is the gasket I used. It set the right gear lash for me. Here are the specs...
https://www.parttarget.com/5330-01-396-0000_5330013960000_5330002343317.html/-B3E2D75C-4B27-4DFE-907D-540BAAF101E7


I did get a .010 and a .020 for safe measure, but did not need them.

 

[Brutacus]

After completing another project, I managed to get my truck back on the road. Driving around for about 30 miles or so, I noticed my pto has no leaks yet. So I'm pleased with my work. I will say this, the oil change hasn't seemed to improve the shifting of the transmission. When I drained the oil, I noticed a lot shavings in the oil. I'm now assuming this is connected, but I've been told driving more smooths things out. Time will tell.