Gary Hatt
September 25, 2022

Keeping your Generator Cool

When I had my MC-9, I was having a problem with my generator overheating. It would get so hot that it would shut down about 15-20 minutes after I started it on a hot summer day in southern California. I would have to run it with the luggage door open which allowed the excess heat to escape when parked. When driving down the road it would not overheat as long as I kept moving. But within about five minutes after I stopped the bus it would shut down every time. After it cooled down, I could reset the heat pop-out circuit breaker and it would restart again. However, as you can imagine, this is a bit inconvenient as well as very frustrating, and not good for the engine.

Generator without any insulation around the exhaust pipe.

Because my over-the-road air did not work all of the time, I relied on my generator while traveling on hot days to keep the inside of the bus comfortable. This also kept the batteries charged so I could have a cold beer when I arrived as my refrigerator would stay colder as well.

Penn and Tod cutting the ceramic material to fit.

I talked to Penn Lenson of Engine Heat Protection, a long-time advertiser with Bus Conversion Magazine about my overheating problem and he suggested that I use his “Wet Blanket” insulation to wrap the exhaust pipe that ran through the generator compartment in the luggage compartment of my bus. The walls of the compartment were insulated nicely which made the generator run quietly, but it also had a tendency to trap air inside the compartment as well. Penn came over one Saturday afternoon and brought some of his products to wrap my exhaust pipe throughout the compartment. 

Penn and his son Todd inspecting my work.

Penn said that by wrapping the exhaust pipe with his ceramic insulation, each layer of material would keep 50%-75% more heat inside the pipe thereby transferring it out of the insulated generator compartment, and out of the bus. 

Generator with the ceramic Wet Blanket wrap installed before it sets up.

We spent about an hour cutting the material and wrapping the pipe from the manifold all the way up to the edge of the muffler outside of the bus. I even wrapped the exhaust manifold itself as that is the hottest part of any engine.

This made a tremendous difference. The EHP insulation prevented the generator from overheating on the hottest days as it did before I wrapped it. I could then run my generator at rest areas and truck stops while I was taking a break or fueling up, whereas I could not do that before we installed the insulation.

Generator with the ceramic Wet Blanket wrap installed before it sets up.
After exhaust pipe was wrapped and before manifold is wrapped.

f you are having a similar problem with your generator or your engine, which may be right under your bed, you may want to try this too. This will keep your generator and/or engine cooler and also muffle the sound a bit more while you are sitting inside or even out of the bus as the Wet Blanket also acts as noise abatement material to make it more comfortable sitting in or around your bus. This is a DYI project and is very easy to do, and the cost of the Wet Blanket material was very nominal for the benefits achieved.

Bottom view after manifold is wrapped and strapped.
Wrapped exhaust pipe going through the floor.

If your compartment is not insulated as mine already was, you may want to consider using the Rollboard material that Engine Heat Protection offers to keep the heat and noise outside of your bus and away from the surrounding area. You will see the Engine Heat Protection ad inside this issue and you will see more information about this product at

Wrap under the bus up to the muffler.
Article written by Gary Hatt

Since July 2012, Gary Hatt has been the Publisher of Bus Conversion Magazine. Gary does most of his own work on his bus with the help of mechanic friends. He has owned tents, truck campers, travel trailers, and stick-n-staple motor-homes until he bought his first bus in 1997 which was a 1972 MCI MC-7 Combo. When he had a chance to buy a 1983 MCI MC-9 Log Cabin bus with larger windows he jumped at the chance. On Thanksgiving of 2014, Gary bought a 1967 Model 08 Eagle and has since been living and traveling full time in that.

You may reach Gary Hatt at

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