Sprag valve leaking air?

[kstate90]

I was working on one of our 5ton 6x6 firetrucks today and noticed that it had a substantial air leak under the cab by the gearshift. The truck is M818 tractor that we converted to a firetruck. I assume the air valve that shifts the sprag from forward to reverse is leaking. Are they rebuildable or is a replace the entire thing. Anyone have pictures of what it looks like under there and an idea of what all I should have on hand to fix it? We can't have the truck down to long so I want to get all the parts I might need lined up and do it. March is burn season here and we need the truck. Truck is at a satellite station and not my station. I stopped in to install a battery maintainer because they were complaining of the batteries being dead. If I hadn't stopped they wouldn't have noticed. The guy who was there helping thought that was normal for the air to be rushing out when they shut the truck off. I noticed that they had unhooked their air buzzer or it had came unhooked. I think I know why now. I will fix that when I fix the sprag. Thanks for the help.

 

[Westech]

Do you have the TM's? they can be Googled and downloaded from a couple of different places. The valves can be rebuilt in under 30 min no problem.

 

[area52]

here ya go:

http://www.steelsoldiers.com/5-ton-up/18459-frustrating-809-series-sprag.html

 

[pctrans]

So where do get the rebuild kits from?

 

[patracy]

So where do get the rebuild kits from?

You don't, or at least I haven't found anywhere to get kits from. (I've tried all the common ones) I just made my own kit. To the OP, if you like, I can make you the gaskets and get you seals.

 

[pctrans]

The gaskets and o-rings aren't the problem. Those rubber seats that the piston hits, are the ones I find hard to fix.

 

[patracy]

I had the same problem with one of mine. I took a knife to it and removed the rubber from it. Flipped it over, then used a patch of innertube glued to the plate.

 

[kstate90]

Thanks for the replies. I am going to call down to the KS forest Service tommorrow and see what they have for parts and go from there. Thanks for the link to Chris's pictures. That gives me an idea what to look for.

 

[Floridianson]

I had the same problem with one of mine. I took a knife to it and removed the rubber from it. Flipped it over, then used a patch of innertube glued to the plate.

I did about the same but just used 80 grit sand paper on the rubber then did like u rubber glue and the tire patch. Had trouble trying to pull it off so I installed and it's been working fine. I had posted on another thread about removing the battery cover and useing a extension and a 7/16 sockett tighten up the whole popit valve even if you don't have any problems yet. I have done most of my trucks and all bolt were loose. If they get to lose that can blow out the gasket.
I bet it's not the popets but the air cylinder on the transfer that need to be rebuilt. Memphis has the transfer cyl kits. Gaskets for the popet you can make and you can in some way repair the disc rubber on popet.

 

[Autocar]

This happened to me on both an M813 and an M818. Memphis no longer has the valve rebuild kits(as of 6 months ago). Sam Winers has complete NOS valves at a reasonable price-I think it was about $120 and they work great.

 

[patracy]

This happened to me on both an M813 and an M818. Memphis no longer has the valve rebuild kits(as of 6 months ago). Sam Winers has complete NOS valves at a reasonable price-I think it was about $120 and they work great.

$120 isn't a bad price for an entire assembly. But it can be rebuilt for much less. I can get the seals for $10 and make the gaskets.

 

[kstate90]

I got a complete valve from Memphis. When I called them I talked to the shop foreman. Seemed to be a very helpful guy. I told him what it was doing and he suggested that it was probably the air shift cylinder on the transfer case. He said that most likely the seal on it has a cut in it and is letting air return to the valve which is venting out of the valve. I guess I will see. Memphis does have parts for the valve. They are not complete sets but they do have the disks with the rubber on it and the other parts, but no springs. We went with a complete valve because we need this truck back in service ASAP. Hope to tear into it tommorrow morning. Hopefully it is something simple. Thanks for all the replies and help.

 

[kstate90]

Sprag Valve and Brake update

I went and worked on the two five tons today. The one with the sprag issue turned out to be the air cylinder needed rebuilt. I took it apart and the rubber seals were hard and the piston fell out on the floor. I installed the new seal cups and the snap rings. I ended up with two O rings left over. The one that was in it did not have any O rings that resembled the ones in the kit. I ended up using the old copper washers as the new ones were just a little smaller diameter and would not hold air.

After I got the first one fixed I drove to the other station and looked at the other 5ton with the brake issue. I started it up and pumped the pedal a few times and was able to lock the brakes up just sitting in the station. I could hear the airpak venting each time I pushed on the pedal. I think the master cylinder is the issue by the way that the pedal acted. It acts like it is not releasing back. We will take it into the mechanic on Monday and have them tear into it. For liability reasons I would just as soon have them work on it. Thanks for the replies on the issues I had.

 

[73m819]

You should add this to your other threads that you started when these problems first were posted so the fix will go with those threads

 

[kstate90]

I went and worked on the two five tons today. The one with the sprag issue turned out to be the air cylinder needed rebuilt. I took it apart and the rubber seals were hard and the piston fell out on the floor. I installed the new seal cups and the snap rings. I ended up with two O rings left over. The one that was in it did not have any O rings that resembled the ones in the kit. I ended up using the old copper washers as the new ones were just a little smaller diameter and would not hold air. Total cost was under $50.00. I get to send the air valve back. Thanks for all the help.

 

[pctrans]

I rebuilt mine today too. Gonna have to raise **** with Memphis Equipment. Those copper washers are definitely too small. I cleaned mine up, flipped them over, and put it back together. Worked fine after that.

 

[doghead]

I merged the two threads, from now on, please just continue the same thread and update as needed.

 

[kstate90]

Did you have the O rings too? I couldn't find any place to use them. Did you?

Sorry about the posting error. The other forum I am used to posting on the threads disappear down the page so you have to post updates under a new thread.

 

[pctrans]

My kit only came with spring clips, 2 rubber seals and the wrong copper washers.

 

[kstate90]

My kit had the 2 seals for the piston, a seal for the shaft going into the transfer case, 2 snap rings for the springs, 2 O rings that I could not figure out where they sent, and the two copper washers that were the wrong size.