I bought a 92 diesel breakaway that has to many problems. I have worked my tail on this one . The help with these post have saved me big time and I've got to say this is the best site on the web. I have a couple more issues. The first is at low speed I hear a knocking noise that I think maybe the differental. Kinda a knocking noise. This is a 4 speed Allison on a Spartan chassis. It almost like a drive shaft noise but the drive has no play I can find. Has anyone else had similar problem and found what the repair was ? My next question is this couch has a central air conditioner that is mounted in a compartment under the stove. It looks like a window unit manufactured by Duo Therm model 39015 601. I'm looking to replace this unit because it does not cool down the couch and never stops running. Does anyone have the same unit and where would be a good place to start looking ? I don't want to hire someone to do this because I'm almost sure it looks to be a different install that I have seen and would probaly cost an arm and leg to get done. This does not have a roof unit and I wish it did because this is what I see on all units.

quote:

Originally posted by bigcat:
at low speed I hear a knocking noise that I think maybe the differental. Kinda a knocking noise.... It almost like a drive shaft noise but the drive has no play I can find.

Did you check the driveshaft for being out of time. The driveshaft could have been installed wrong and what your hearing is the binding of the driveshaft.



This picture has an improperly installed driveshaft. Notice how the yoke is at two different angles from each other on the same shaft? The yokes need to be on the same plane like in the lower picture.



You would find them to be out of alignment at the carrier bearing or on a two piece driveshaft. Remember, look at one driveshaft at a time. Each driveshaft must be aligned to itself. The yokes on any one given driveshaft should be at the same plane.

The only time there 90 degrees off is if you have a very severe (monster 4x4 truck) working angle or if it's on a steering shaft u-joint.

Is the height control valve adjusted properly? Are your airbags inflating? Do you have a dump switch for the airbags?

quote:

Originally posted by bigcat:
My next question is this coach has a central air conditioner...

Sorry, someone else will have to help you on that one...

Duo-Therm is made by Dometic. If it were I, I'd remove the unit (which will involve a lot of grunting and cussing) and take it to a local A/C repair shop for testing. Compressors are pretty much generic, and yours may have failed, or the unit's low on refrigerant. If it's some other part, here's the place to find a Dometic service/parts dealer.

Thank you for responses. The yokes on the drive shaft are correct.

I have taken the advice on the second question and have removed the central air . In process of doing a complete overhaul. Already have located numerous repair needs. May just replace the unit because I have called around and found that Duo Therm makes a much better larger unit that is supposely a direct replacement for not much more than repairs might cost. They also sell the same unit in a heat pump.

Bill What is a height control Valve ? This couch has no air bags.

quote:

Originally posted by bigcat:
Bill What is a height control Valve ? This coach has no air bags.

A height control valve goes to the airbag that you don't have.

You stated you had a 92 Breakaway, Spartan chassis, 4 speed Allison and that you believe it to be in the driveline. How many miles are on your coach? Is this noise constant or does it come and go? Does the noise get softer after greasing the driveshaft slip spline and U-joints? How long is your coach? How many drive axles are on your coach? Have you heard this noise while standing outside and someone else moving it? How many driveshafts/carrier bearings do you have? Diesel pusher/puller?

I have heard driveline noises come from what "felt like" good u-joints only to have them really be bad. If you have two drive axles it might be in the interaxle-differential. If it has two drive-axles what does it sound like with them locked in?

The more information about your coach that you can give the better off I or someone else might be able to answer your questions. No detail is too small.

At this time I'll make a recommendation to all about having a good signature profile with coach info and a picture. You don't need to use it every time. It helps all to visualize your coach. It's sort of like a peek into your persona, just like a web handle is, I'd like to see what a bigcat would drive.

Bill thank you for replies
I have a 92 30' breakaway diesel pusher 5.9 cummins with 86000 miles. The drive shaft is a split drive shaft. I do not see any grease serts . I can not hear the noise outside the coach. I have tried listening with the bed door open but can't hear anything over the engine noise. I can hear and feel the knocking noise from the the area standing over the differential. Anyone that may have had a similiar problem please relate what was fix.

OH YA The noise is constant at low speed and goes away at around 30 MPH. It also goes away when applying brakes.

"The noise is constant at low speed and goes away at around 30 MPH. It also goes away when applying brakes."

I don't know if it is helpful, but that sounds very similar to the noise from a bad bearing in one of the U-joints on my former Isuzu P'up. We had the front wheels, bearings, and U-joints checked, and were told no problems, and there was no free play in the drive shaft when I checked it.
However, when I just went ahead and had all the U-joints replaced, one was found to have a frozen bearing in it which had caused the noise. Having all 3 sets of U-joints replaced was less expensive than what was spent on the dianostics that did not reveal the problem...

quote:

Originally posted by geoffrey:
...I just went ahead and had all the U-joints replaced, one was found to have a frozen bearing in it which had caused the noise. Having all 3 sets of U-joints replaced was less expensive than what was spent on the dianostics that did not reveal the problem...

I'll add that the cost of a road breakdown would be insane compared to new u-joints. I'm looking at an invoice right now from a trucking company who's driver stated that he heard the same noises you did for a little while before failure. The invoice cost him over $2,100

Of course you probably think I porked him - Far from it - It's easy to look at the total and think he got the shaft - He kept driving it to the point that there was a cascade event that tore things up...

What did he get for that amount?.. 6.75 hours of road side service. A new yoke for the back side of the front rear - A pinion nut - A driveshaft made up at a machine shop (slip yoke, stub shaft, end yoke assy) - broken down for 3 days because it happened after 11am on a Saturday - 2 new U-joints - He lost his load for the run because he had to sub it out - Repaired torn out airlines - Replace a beat up and leaking maxi brake chamber - And he lost over $2,100 - Ouch!

I worked on him Saturday and had his inter-axle locked in, temp repairs to the airlines to get him to a motel so he didn't have to pay for a tow - Went back again on Monday to finish up after the machine shop finished there thing.

It's easy, and wrong, to think that because it happened in NY, or for that matter the Northeast, it really cost him. I was informed by his company that they expected to pay more and was very happy with what was done. Photos were taken and all authorization was obtained before and during the repairs.

If it looks like a duck, walks like a duck and quacks like a duck - Call It fowl (pun) and replace it.

A good U-joint cost between 50-75 for most trucks. I'm sure you could find it for less and the amount of time to do it isn't that long. And, if it's not a U-joint then the peace of mind from changing it out should make you feel better after reading this!

At this point I agree the shaft is being removed and taking it to drive shaft shop to get it checked as soon as this is sent. Thank you all for the input.

Removed drive shaft and u joints good nut replaced anyways and nothing changed.

I wonder if you have a bad tooth in the differential or a bad pinion bearing...

Might be time to jack up both wheels and listen with a stethoscope.

Jack up both rear wheels and block the front wheels - try operating the coach to see what's happening.

You removed the U-joints and they were good - are you telling us that you re-installed the u-joints or did you replace them? What nut did you replace anyway? Did you ever find the grease fittings?

Bill N.Y.