Broken Hydraulic Pump Drive

Mike Canter · 08-06-2011, 06:53 PM

I would like to post this as a check item for big rig Monaco owners. On my MH I have a PTO that comes out of the curb side of my Allison 4000 that drives a hydraulic pump that runs the hydraulic radiator fan on my side mounted radiator. While my DW was at the wheel driving through Barstow, CA on I-40 the overtemp warning light came on so she pulled over right away. I shut the motor down and went back and checked the motor. No water dripping and the belt was still on. Started it up and found that noisey radiator fan was not running. Thought maybe the therm switch in the radiator went bad so I bypassed it with a hose coupler and it made no difference. I still had power steering so I figured the hydraulic pump was good. I traced the hydraulic lines that went to the fan motor and one went over the top of the transmission into a hydraulic pump. I found that pump had pulled back away from the red PTO drive and become uncoupled because three bolts that held a flange on the PTO had sheared off. This PTO goes into the side of the transmission and it is a Chelsea 267 10 bolt PTO. I found the pdf manual online and it mentioned this happening which kind of surprised me. I have no idea on how long the pump had been loose from the PTO. I do not know which model Monacos have this type of setup. I do know the Signature, Navigator, Executive and most likely the Dynasty have it. I would highly recommend that if you have one of those models that you get under the MH on the curb side of the transmission and grab hold of that pump and give it a good hard shake and see if it moves. I am sitting here waiting for a machine shop to open Monday to remove the broken bolts so I can put in new bolts with red Locktite. I will try and include a couple of pictures in a future post so you know what to look for. Like I said I still had power steering so I have two pumps which was a surprise to me.
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Mike & Nancy · 08-06-2011, 07:14 PM

Mike.....I am going to check my MH tomorrow morning to see if I have the PTO you are talking about. Ours is Dynasty with Cummins ISM and Allison 4000. Additionally, if you need any help I live about 70 miles south of Barstow.

Mike Canter · 08-06-2011, 07:37 PM

Mike, I sure appreciate the help offer. Sitting here in a WalMart. I drove it for a short distance at a time until the water temp got to 202 then shut it down and waited until it cooled down then drove it some more. As you probably know it is 104* here but 5% humidity, not bad if you stay out of the sun, lol. I have a machine shop picked out for Monday so I hope everything goes well. I tried to turn the broken bolts in the flange with a small cold chisel but it didn't work. Stopped because I didn't want to mess it up.

texnet · 08-06-2011, 07:42 PM

How about drilling the center and use an easy out to get them out?

Mike Canter · 08-06-2011, 08:04 PM

If I could get a straight shot at it then I would. Don't have a drill with me but I would buy one if I could get to it. I am going to remove the whole PTO from the side of the transmission. I think it is high enough that no fluid will come out of the transmission. I do have one gallon of Transynd with me. Since I don't have my drill or extractors with me it is easier to take it to a machine shop. I extract bolts all the time from racecars

texnet · 08-06-2011, 08:14 PM

Quote:

Originally Posted by Mike Canter

Since I don't have my drill or extractors with me it is easier to take it to a machine shop. I extract bolts all the time from racecars

I figured you did, but sometimes brain goes in lockdown

I carry a drill and all sorts of tools with me!

moisheh · 08-06-2011, 08:16 PM

Mike: Are you saying that the bolts backed out and then sheared? How did that happen? It sure cannot be they were loose from the factory as it has been 6 or 7 years since that pump was installed? Thank you for the warning. I will check mine tomorrow morning.

Barlow46 · 08-06-2011, 08:24 PM

Quote:

Originally Posted by Mike & Nancy

Mike.....I am going to check my MH tomorrow morning to see if I have the PTO you are talking about. Ours is Dynasty with Cummins ISM and Allison 4000. Additionally, if you need any help I live about 70 miles south of Barstow.

Mike, if you would, take a camera with you when you take a look at your rig and post what you see. The next time I go under, I am going to take pics of everything I can see so that I don't have to keep going to storage to take a look when something like this comes up. Thanks.

Mike Canter · 08-06-2011, 08:53 PM

Moisheh, yes the bolts came loose then sheared. The flange is not installed on the PTO when built and it is up to the installer to put it on in the position to match the device being driven. There was no evidence of Locktite on the bolts and the book says to torque to 20 ft lbs. Don't know how long they had been loose.

I have pictures but do not have the software on this laptop to shrink them down to put on the forum.

boaterok · 08-06-2011, 09:37 PM

The pic you sent me looked like they were at least 1/2 bolts (maybe just the picture) but I can't imagine just 20 ft/lbs.

Mike Canter · 08-06-2011, 09:48 PM

Roger those big bolts hold the pump onto the rotatable flange. What broke were the three 5/16 socket head bolts that hold that flange onto the PTO. You can't see them in the pictures because they went back up inside the flange. You can just see the bolt holes

moisheh · 08-07-2011, 06:19 AM

Lots of fun getting Allen headed bolts out. They are very hard as you already know. You can use tinypic.com if you dont have the software. That site gives you a choice of sizes or just shrinks it to a forum size.

Mike & Nancy · 08-07-2011, 07:02 AM

Mike......Went over and checked our MH (curbside) and I did not see the PTO.....pictures would be great. Also, offer still stands if you need something I can drive up.