Generator overheating blues

[mchero]

Even if you could play contortionist and get that temp sensor installed w/o dropping the genset what happens if your back to step 1?
Perhaps you need to really get a close look at the water pump, belt hoses and such. Maybe the impeller on the water pump disintegrated or the fan belt is glazed and slipping.

[Dan4Governor]

Well guys, I figured out how to get the sensor out. Drilled a small hole in the shroud next to it so that I could get the proper angle for a drill bit. I stuff some paper towers down the thermostat housing below the temp sensor to catch debris, then drilled out the broken piece. Cleaned out the sensor hole with a bottle brush, pulled out the paper towels (now soaked in water from sitting in the thermostat housing) which grabbed all the little metal shavings on its way out. Installed the new temp sensor, and went to fire it up. Of course now it decides to not crank at all. The fuel pump works (clicks as it primes the line), but no turn over.
So I check the battery connections, the negative terminal is a little dirty, so I loosen to it to clean it and SNAP! No more negative terminal 🤦*♂️ How can one person have so much bad luck with a generator???? Luckily, a new neighbor pulled in and was willing to help and between the two of us we came up with a ghetto temporary fix. Then the generator fired right up and ran fine with both AC’s cranked for 30 or 40 minutes. That’s all the time I had left to test if before I had to start packing things up to move out. Maybe it’s fixed? Maybe not. I’ll report back after I’ve had a chance to test it some more.

[edge68474]

WOW!!! I feel for you my friend. Well, maybe now somehow it is fixed. Best of luck. What a process, huh. I will still be watching. Thank you for updating us.

[SacRV]

Maybe try putting a 8" fan in the generator bay.

[edge68474]

Originally Posted by SacRV

Maybe try putting a 8" fan in the generator bay.

I am thinking of that also.

[mchero]

I still find it hard to believe an Onan shop tells you they don't know what's wrong with it.

[jerichorick]

Originally Posted by Dan4Governor

Okay so I’ve read a million threads here on what to fix on my Onan QD 8000 generator and can’t figure out what to do next. Here are the symptoms:

Generator overheats and shuts off (giving the 33 overheating error code) consistently after 30-40 minutes under moderate load (running one AC) if the outside temps are above 85 degrees. If cooler than 85 outside it will run one AC just fine indefinitely, but will overheat if I run both AC’s regardless of outside temps.

Here’s what I’ve done (following advise on this forum in other threads)

Changed oil and new oil filter
Flushed and changed coolant
New thermostat
New radiator camp
New air filter
New fuel filter
Generator is not on a slide so I just had Cummins diagnose and do new water pump and belt

They told me it was fixed and they load tested it (not good enough apparently) because nothing is any different. Exact same issues. Not even a little better (Cummins charged me $1,400!).

I’m at my wits end. I see people running their generators and ACs all day long in the campsites I’m visiting without issues so I know mine should be working better than this. Even the Cummins onan website says this model should run two AC’s and more without issue.

I don’t think it’s the temp sensor (although I have one on hand just in case) because normally it won’t run more than a minute if the sensor is bad, and since it runs longer, then shuts off when overheating that tells me the sensor is doing its job. Temp gun verifies 220 degrees at the water pump and thermostat housing, so it is definitely overheating.

Anything else I can do????
Thanks so much for your wisdom!

I'd go back to the shop and tell them to fix it. No more money. Don't be a victim to the big guys.

[mchero]

I'm with Rick.
We don't know what's wrong....CYA! Just doesn't work for me.

[Bobby F]

I think they did know what was wrong, but the factory-approved fix was very costly and he was looking for alternatives.

[triplewide]

Originally Posted by Dan4Governor

Well guys, I figured out how to get the sensor out. Drilled a small hole in the shroud next to it so that I could get the proper angle for a drill bit. I stuff some paper towers down the thermostat housing below the temp sensor to catch debris, then drilled out the broken piece. Cleaned out the sensor hole with a bottle brush, pulled out the paper towels (now soaked in water from sitting in the thermostat housing) which grabbed all the little metal shavings on its way out. Installed the new temp sensor, and went to fire it up. Of course now it decides to not crank at all. The fuel pump works (clicks as it primes the line), but no turn over.
So I check the battery connections, the negative terminal is a little dirty, so I loosen to it to clean it and SNAP! No more negative terminal 🤦*♂️ How can one person have so much bad luck with a generator???? Luckily, a new neighbor pulled in and was willing to help and between the two of us we came up with a ghetto temporary fix. Then the generator fired right up and ran fine with both AC’s cranked for 30 or 40 minutes. That’s all the time I had left to test if before I had to start packing things up to move out. Maybe it’s fixed? Maybe not. I’ll report back after I’ve had a chance to test it some more.

I wonder if the terminal was the problem all along?

[edge68474]

Did this problem ever get resolved??

[Dan4Governor]

Hey guys, I know some of you have been asking for an update, but it’s taken until now for the weather to be warm enough to really put it through the ringer. The good news is that everything appears to be working as it should. The last couple weeks it’s been in the 90’s with high humidity here in Oklahoma where I’m working on remodeling the interior of my motorhome, so I’ve been running AC’s a lot. I only have a 20 amp outlet to connect my RV to for this remodel, so to run both AC’s I need to use the generator or I’ll trip the circuit. I’ve been running the generator to run both AC’s the majority of the day as well as higher amperage power tools. The EMS is telling me I’m drawing upwards of 40ish amps consistently, and the genset doesn’t seem to mind at all. Hasn’t overheated since my fight with the temp sensor/negative battery cable.

So I’m gonna call it fixed, praise the Lord!
Thanks for all the help and friendly motivation. My guess is that the cause of the overheating was the corrosion in the radiator and coolant passages which had eaten away at the temp sensor as well, but the corrosion was also what was holding the temp sensor together, so when I replaced the radiator, and flushed the corrosion out with the Restore plus, the temp sensor finally bit the dust completely and needed replaced as well. I think the negative battery cable was just bad luck/me not being gentle with the generator after so much frustration. Note to self, take it REALLY EASY when removing/reconnecting those battery cables. That brass is very soft.

[RayAZ]

I myself is going through this same scenario , overheating code 33 . I too have also changed out the temp sensor , coolant , thermostat and still get a code 33 my only worry some is that this relay clicks and clicks right after the generator shuts down. Something also clicks in the back compartment where all the inverter components are ( breakers I'm assuming) . An i posted another thread on here when i first purchased the coach and quite a few people say stay away form cummins repair shops . So with that been said should i too just purchase a new radiator do all the flushes stated before or could my problem be something else? thanks in advance

[shootist]

I admit to not reasing the whole thread. Did you check or change the fan belt in the rear?