1985 Itasca w/ 454.....left the outer belt on the highway.....

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Jack D

Jack D

Well-known member
Joined
Aug 27, 2010
Posts
231
Location
Elmira, Oregon
......somewhere. This belt drives the alternator, AIR pump, fan/water pump from the cranckshaft. NAPA sold me a 25-7450 belt and it is way too short. Searching the Internet, I find that number (NAPA 25-7450) and Gates 7450, Dayco 15495 and a couple of others that are all supposed to be the same size and also supposed to fit this application. Apparently, this is bad information.

Can someone tell me what the number of the replacement belt would be? There are three belts on my MH. Inner-most (closest to engine)belt drives from crank to PS pump. Middle track drives from crank to PS pump, AC unit, water pump/fan. And the outer belt (the one I need) drives from the crank to water pump/fan clutch, alternator, and AIR pump. Without the old belt, I'm at a loss as to which belt to order.

Thanks

Jack
 
Take a piece of fishing line and start at one of the pulleys and wrap it around each location until you get back. Measure the fishing line and you will have the length of belt you need. 

Now, would be a good time to replace them all. Might want to look at the hoses too. much easier to replace them in the drive way instead of the side of the road.
 
And once you have the length, any decent auto parts store can find a belt that fits.

I suspect the belt numbers you are being given are for a 454 in a pick-up truck or car. The Chevrolet motorhome chassis uses different alternator, a/c compressor, etc. and needs an entirely different belt. Few, if any, auto parts stores have the the P32 or P37 motorhome chassis in their computer database, but if they will call the belt manufacturer customer service hotline with your chassis VIN, they can probably get the right answer.
 
Thanks for the suggestions. I was able to find a different number for the belt in the Internet and it turned out to be the right one. The NAPA store was able to confirm the number in their books and then I found the old belt laying on the frame as I was installing the new one. The nuimbers matched. Got it on, tensioned by the seat of my pants, tested and everything works. I didn't change all the belts, although that's a good idea. They were checked by a mechanic last Summer and they were all good. And I looked them over real good today. Why this particular belt gave out after a clean bill of health is a mystery. Fortunately, it is an easy one to change, so I'll buy an extra and keep it on hand....just in case. Hoses look new.  BTW my chassis is a P30 with a 454.
 
I had a 454 in an 84 Allegro. I never had problems finding parts. I would go to a Napa auto parts store and tell them I had a 1984 P30 with a 454 and I need a...
 
Check the new belts tension after a 100-200 miles, they stretch when new. If the old belt you found on the chassis wasn't broken it probably flipped off from being loose. Check tension on the inner belts, if an inner one flips off it'll take the outers with it. You have to tell the parts guy it's a p30 motor home, class a, cab forward, and for some parts they need the gvw.

Bill.
 
"P30" is often (inaccurately) used to represent all the various P3x models of chassis.  To be accurate, look at digits 5-7 of the chassis VIN. They should read "P3x", where x can be from 0-9. For a Class A motorhome, it should be either P32 or P37 and never actually P30 (the P30 designation is a panel delivery van).  Check your VIN so that you know what to ask for at the parts store. Just saying "P30" may not always get you the right stuff.

To the best of my knowledge, the parts differences between a P32 and a P37 are slight, but the other P3x models can be quite different in some areas.

There are also Class C's with the 454. These can be built on the G chassis or other variants of the P chassis. Again, the VIN will get you to the right designation.
 
Gary RV Roamer said:
"P30" is often (inaccurately) used to represent all the various P3x models of chassis.  To be accurate, look at digits 5-7 of the chassis VIN. They should read "P3x", where x can be from 0-9. For a Class A motorhome, it should be either P32 or P37 and never actually P30 (the P30 designation is a panel delivery van).  Check your VIN so that you know what to ask for at the parts store. Just saying "P30" may not always get you the right stuff.

To the best of my knowledge, the parts differences between a P32 and a P37 are slight, but the other P3x models can be quite different in some areas.

There are also Class C's with the 454. These can be built on the G chassis or other variants of the P chassis. Again, the VIN will get you to the right designation.
Click to expand...

That proves you're never too old to learn. I just learned. Thanks, Gary. It's always been a "P30" to me. Now I'll have to find out exactly what it is and use the correct chassis term. I found this on the Internet this AM and it is very good at explaining things in terms that even I can understand. It has nothing to do with my broken belt, but explains the motorhome "P" chassis and possible handling problems. I see it is a draft copy and wonder if it has been changed much from it's final version. At any rate, I found it interesting and informative.
http://www.offroadtoybox.com/RV/P-Chassis-AlignmentProcess.pdf

Staff edit: Fix broken URL
 
Finally had a chance to test my belt repair on the road. For the first 1/2 mile, or so, all was well. Then I began to hear a rumbling sound from the engine area......followed by a squealing like a loose fan belt. We were on our way to a dump station some 15 miles from home, so we continued on....dumped the holdng tanks and filled with fuel. On the way home, the squealing got worse, but would squeal and then stop depending on what the fan clutch was doing. If the fan clutch was locked up, the squealing would stop, then the fan would kick out and the squealing would start again. Everthing pointed to the fan clutch bearings and when we got home, I checked the clutch by trying to turn the blades by hand (engine off) and it was locked up.

Today, my job is to replace the fan clutch. Water pump seems to be OK. A job I'm not looking forward to. I can only see the fan through a small hole through all the hoses and other objects and my hands won't have much room to work either. It will be mostly a "feel" job...lying on top of the air cleaner.....unless I remove a bunch of other stuff. But it has to be done and paying someone else to do a job I can do myself is objectionable.
 
It is a bad job but making it easier, I remove the air cleaner and rod in the carb or throttle body. Place a folded up blanket on top of the engine and lay on top of it. Just be carful you don't bend the throttle cable bracket, very easily done, I know. When I did the one on my Itasca I removed the fan blade from the clutch first and then the clutch from the water pump. I couldn't get it out altogether.

That's probably going to take care of the noise problem also. ;D ;D
 
92GA said:
It is a bad job but making it easier, I remove the air cleaner and rod in the carb or throttle body. Place a folded up blanket on top of the engine and lay on top of it. Just be carful you don't bend the throttle cable bracket, very easily done, I know. When I did the one on my Itasca I removed the fan blade from the clutch first and then the clutch from the water pump. I couldn't get it out altogether.

That's probably going to take care of the noise problem also. ;D ;D
Click to expand...

You're exactly right. I couldn't get the fan/clutch out either...even after cutting two heater hoses to get them out of the way. I was able to loosen the fan from the clutch with an impact wrench and long extension with swivel socket. Then removed the clutch leaving the fan inside the shroud. I'll reverse the process to get it back in, except the impact wrench will not be used to tighten anything. That wouldn't be good in aluminum. I'm halfway there. Lunch time.

Looking at the old clutch in the open, the bearings are not loose, but there is a rough spot as I turn it by hand. I can feel a grinding in spots as I turn it. Also there are definate signs of fluid leakage around the shaft. I'm hopeful the problem will be solved...including the noise.
 
Make sure to get an oem quality clutch, there are some cheap china ones on the market, and some of them don't last very long. I can't remember if I got mine at NAPA or O'Reillys.
 
92GA said:
Make sure to get an oem quality clutch, there are some cheap china ones on the market, and some of them don't last very long. I can't remember if I got mine at NAPA or O'Reillys.
Click to expand...

Got it at NAPA. Cost enough, so should be OK. I Saw some on the Internet for about half what I paid for it. Suspect they were sub-par.
 
Finished! It was a tight working space, but it's all back together and tested with fast idle. No "strange" noises but ran it with the bonnet off to look for leaks and to see if the fan kicks in as planned  (it did). When it cools, I'll check the bolts and hose clamps again then cover it up for a short road test. So far, so good.
 
dont wait too long on checking those fan bolts...I learned the hard way by having a fan blade go thru the hood of a 3/4 ton M37 overseas...scared the hell outta me.
 
Took it out for a 400 (round trip) weekend camping trip last week. One thing puzzles me. The fan clutch engaged every few minutes, ran a few minutes then disengaged. The first 200 miles the outside temp was quite cool (70's) and the trip back was quite hot(90's). But the outside temperature didn't seem to make any difference in the clutch operation. It was on....then off.....then on....then off every few minutes. I checked the coolant and it was full. The engine never overheated...the fan was doing its job. It just seemed to me that it was working too hard at doing its job. At highway speeds I believe there should be enough air passing through the radiator to keep the fan from engaging, especially if it's cool outside. Is this not right? The radiator seems clean outside and we weren't running the dash ac (it doesn't work). I don't remember it working like this before I replaced the fan clutch.....but then it had a bad bearing and was leaking fluid, so wasn't right.
 
Mine works off of engine rpm too. I can be running down the road 60 mph and make a turn on to another highway, the clutch will engage on mine for a bit, then go back off. Below about 30 mph and it seems to run all the time, but rpm on the engine is low and I don't really notice it much. The clutch on my old Itasca roared more than this coach but I think this one has more insulation, and the doghouse fits better. 
 
I just drove it into town to empty the holding tanks (about 20 mi each way) and when up to highway speed, the clutch never engaged at all. Around town it was on and off...just as I would expect. Everything seems normal now. Maybe the last trip, the wind was blowing from the wrong direction (it was quite windy). Perhaps it was pushing me????

Alternator and belt is squealing now, but it stops after a warm-up period. Dang! Looks like I had two problems...both driven by the same belt. My luck...the air pump will be bad, too. NAPA list 3 or 4 different alternators, so I'll take this one out so I get the right one.
 
Jack, check to make sure you can find the air pump. The one on my 80 Itasca locked up, and I burned the belt before I could get it pulled over. Couldn't find one around here, so I removed it and used pipe plugs in the exhaust.
 
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