PowerTech Isuzu Generator overheat

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PowerTech Isuzu Generator overheat

February 04, 2025, 02:14:36 pm

I have a 1999 U320, and the generator is overheating and shut down. I made sure (I think) that there is no air in lines. It starts and runs about 5 minutes, then shuts off due to overheating. In the first picture below, both hoses are warm/hot. On the second picture, the hose is not warm at all. Is there a simple fix for this, or am at at the point of taking it to a professional.

Most of my insulation is gone, so it is possible that the radiator is dirty, but I don't think I want to tackle removing the remote fan and radiator cover.

Re: PowerTech Isuzu Generator overheat

Reply #1 – February 04, 2025, 02:57:56 pm

I betcha the belt is bad. You can barely see it. Removal is the 4 bolts on top pulley. There is no tensioner on this unit. Happened a couple times to me.

Re: PowerTech Isuzu Generator overheat

Reply #2 – February 04, 2025, 03:02:09 pm

Kevin, My coach was only 20 coaches ahead of yours back on the assembly line, so I expect we have the exact same generator. Looking at your photos (thanks for including them) they are the same. In my experience there are three likely culprits, none of which are expensive or difficult to repair. I have had all three of these problems over the years.

Most recently the 25 year old water pump belt broke. Replacing it requires the removal of two or three bolts. In my case I was unable to remove the bolt in the back so I just removed the other two bolts and pushed the header tank over enough to allow me to replace the belt.

The first time my generator acted like yours it turned out to be the radiator fan circuit breaker. That breaker looks for all the world like a toggle switch. It had become weak over the years and would trip from the vibration of the engine. That was easy to replace and I later relocated it into the bay with the radiator fan.

The other problem I had was that the start capacitor for the radiator fan died. It was somewhat hidden inboard of the radiator. When I replaced it I relocated it to the near side of the radiator for easier access in the future.

Hope this helps.

Richard

Re: PowerTech Isuzu Generator overheat

Reply #3 – February 04, 2025, 03:24:27 pm

Ernie, You beat me to the send button. On my unit there are three bolts and no tensioner. It would have been easier to replace the belt if there had been a tensioner.

Re: PowerTech Isuzu Generator overheat

Reply #4 – February 04, 2025, 03:49:44 pm

Quote from: Jan & Richard – February 04, 2025, 03:02:09 pm

Kevin, My coach was only 20 coaches ahead of yours back on the assembly line, so I expect we have the exact same generator. Looking at your photos (thanks for including them) they are the same. In my experience there are three likely culprits, none of which are expensive or difficult to repair. I have had all three of these problems over the years.

Most recently the 25 year old water pump belt broke. Replacing it requires the removal of two or three bolts. In my case I was unable to remove the bolt in the back so I just removed the other two bolts and pushed the header tank over enough to allow me to replace the belt.

The first time my generator acted like yours it turned out to be the radiator fan circuit breaker. That breaker looks for all the world like a toggle switch. It had become weak over the years and would trip from the vibration of the engine. That was easy to replace and I later relocated it into the bay with the radiator fan.

The other problem I had was that the start capacitor for the radiator fan died. It was somewhat hidden inboard of the radiator. When I replaced it I relocated it to the near side of the radiator for easier access in the future.

Hope this helps.

Richard

Thanks richard. The remote fan runs fine - I had that fixed last year. Sounds the belt is my best place to look next.

Re: PowerTech Isuzu Generator overheat

Reply #5 – February 04, 2025, 03:51:56 pm

Quote from: erniee – February 04, 2025, 02:57:56 pm

I betcha the belt is bad. You can barely see it. Removal is the 4 bolts on top pulley. There is no tensioner on this unit. Happened a couple times to me.

Ernie : don't by any chance have a picture of the belt, bolts and/or location so I am looking in the right place?

Re: PowerTech Isuzu Generator overheat

Reply #6 – February 04, 2025, 04:35:03 pm

Quote from: kstine98 – February 04, 2025, 03:51:56 pm

Ernie : don't by any chance have a picture of the belt, bolts and/or location so I am looking in the right place?

Not Ernie, but if you look under generator you will see a bottom cover 2 9/16 bolts in the front 2 1/2" rolocks in the back remove that vibe and slide the generator out. There is an idler to tension the belt.

Re: PowerTech Isuzu Generator overheat

Reply #7 – February 04, 2025, 06:57:57 pm

Quote from: bbeane – February 04, 2025, 04:35:03 pm

Not Ernie, but if you look under generator you will see a bottom cover 2 9/16 bolts in the front 2 1/2" rolocks in the back remove that vibe and slide the generator out. There is an idler to tension the belt.

Are you referring to the sheet metal type piece under the generator? And then the belt is on the back of the generator?

Re: PowerTech Isuzu Generator overheat

Reply #8 – February 04, 2025, 07:21:49 pm

If the fan works, the radiator is full, and the belt is good, I would install a new thermostat.
If it overheats in 5 minutes I would suspect the thermostat first.

Re: PowerTech Isuzu Generator overheat

Reply #9 – February 04, 2025, 08:40:41 pm

Quote from: kstine98 – February 04, 2025, 06:57:57 pm

Are you referring to the sheet metal type piece under the generator? And then the belt is on the back of the generator?

the belt and water pump is on the front of the motor. It you slide the generator out, and pull the bottom, on mine its rubber on a metal frame it will allow you access to the belt adjustment and belt. Much easier than trying to access it from the front. Of course you will need to put the coach on safety stands before you go underneath.

Re: PowerTech Isuzu Generator overheat

Reply #10 – February 04, 2025, 09:57:27 pm

Kevin,

If you look between the 2 radiator hoses down in that black hole you should be able to see where the water pump belt should be running. That tank that has the radiator cap is just a volume tank and ends right where you can peer down through. If the belt is bad you can DIY just let us know and we can guide you through the process. Now did you open the petcock behind the top hose to bleed out any trapped air? If not start there before you start fixing things that are fine.

Mike

Re: PowerTech Isuzu Generator overheat

Reply #11 – February 10, 2025, 05:20:19 pm

Went back to the coach today and it looks like the water pump belt is the culperate. It is off. I removed the plate below the generator and took some pictures. It is definitely tight under there. A few questions for you pros:

1. I assume the best thing to do is replace the belt while I am in there (rather than just putting the old one back on)?

2. How do I access that area the put on the belt? Do I remove the "cover" (see pic above) that is over that pulley area, or do I just work around it the best I can?

3. Is there a 'trick' to replacing the belt and tightening it (i.e., what bolts do I remove)?

4. Is the bolt on pic below a tension adjuster?

ALL HELP IS GREATLY APPRECIATED!!

Re: PowerTech Isuzu Generator overheat

Reply #12 – February 10, 2025, 06:00:56 pm

That is the slide adjustment for fan belt. Maybe it came loose or maybe the pulley is bad.

Re: PowerTech Isuzu Generator overheat

Reply #13 – February 10, 2025, 06:40:44 pm

I would replace the belt while you are at it.

When I replaced mine, I did not change the idler pulley position. I just threaded the new belt over the water pump pulley and the tensioner pulley, then started the belt over the crankshaft pulley and with a socket wrench rotated the crankshaft while popping the belt into position.

Re: PowerTech Isuzu Generator overheat

Reply #14 – February 10, 2025, 06:57:36 pm

Before you start to wiggle in the new belt (yes it is a PITA but doable) take and see if the water pump spins smoothly along with the idler pulley. If either is rough replace while there. The idler is not difficult to get out but the water pump is hard to get to.

Mike

Re: PowerTech Isuzu Generator overheat

Reply #15 – February 10, 2025, 08:50:03 pm

Quote from: Pamela & Mike – February 10, 2025, 06:57:36 pm

Before you start to wiggle in the new belt (yes it is a PITA but doable) take and see if the water pump spins smoothly along with the idler pulley. If either is rough replace while there. The idler is not difficult to get out but the water pump is hard to get to.

Mike

Can someone take of picture of this and point out the water pump, idler pulley and crankshaft pulley?

Re: PowerTech Isuzu Generator overheat

Reply #16 – February 11, 2025, 12:41:53 pm

Kevin,

I am confined to the recliner due to Dr. orders so lets look at the pic you posted in reply 11. The pic with the red circles you can see 3 sheaves/ pulleys set in some what a triangle. The top one is the water pump driver. The lowest one is mounted on the end of the crankshaft. The one that is left (it appears closest to the camera) is your idler which is mounted on a bar and an adjustable slide. Hope this is some help to get you going.

Mike

Re: PowerTech Isuzu Generator overheat

Reply #17 – February 13, 2025, 08:04:50 am

Anyone have any idea where I can get a replacement belt? I have looked all over the internet and the soonest I can get one is 4 weeks. Or, is there a substitute for this part?

Isuzu IZ-8970687980 Cooling Fan Belt

Re: PowerTech Isuzu Generator overheat

Reply #18 – February 13, 2025, 08:24:59 am

Got one at Napa. Just bring the old one there

Re: PowerTech Isuzu Generator overheat

Reply #19 – February 13, 2025, 06:10:12 pm

I have seen NAPA walk around their inventory to match up belts. And when it comes to finding special shaped radiator hoses, I have seen NAPA find exact match in the middle of a new hose with the need to cut off an end. Always bring in the original part.

Re: PowerTech Isuzu Generator overheat

Reply #20 – February 13, 2025, 10:53:40 pm

Kevin, The one that I got a couple of months ago for my generator was NAPA 9335. The package also says XL on it. I took the old belt in to NAPA for a match-up, just as Erniee said.

Re: PowerTech Isuzu Generator overheat

Reply #21 – February 14, 2025, 12:52:10 am

Also, there is Napa Auto and Napa Truck stores. Find the ones that deal with not only cars but trucks also.

Re: PowerTech Isuzu Generator overheat

Reply #22 – February 14, 2025, 08:36:17 am

The original belt is one that is really skinny. Napa gave me a wider one and it works perfectly. No, I don't know the number.

Re: PowerTech Isuzu Generator overheat

Reply #23 – February 14, 2025, 09:10:08 am

The skinny one you removed may have been wide when it was new. My experience is that they wear out getting narrower and go deeper into the pully, then slip.

Re: PowerTech Isuzu Generator overheat

Reply #24 – February 14, 2025, 09:12:57 am

Quote from: erniee – February 14, 2025, 08:36:17 am

The original belt is one that is really skinny. Napa gave me a wider one and it works perfectly.

Same with me, the new belt is slightly wider than the original but seems more robust and works perfectly.

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