Wednesday, September 28, 2022


Manage your temperatures for a long and happy RV life

By Greg Illes

When running an RV, most people think about temperature fairly minimally: How’s the engine? Usually, there’s (at least) an engine coolant temperature gauge on the dash, and all too often that one datum gets undivided attention.

Well, there are a lot of reasons to divide your attention to other matters of temperature. If you are doing any hot weather driving, hill climbing, towing or heavy-load transporting, there are many places in your RV that are going to heat up, perhaps excessively. Here are a few of the important ones.

Transmission — Some coaches have a gauge; most don’t. Sometimes you can get the info from an OBD (on-board diagnostics) port reader like a Scangauge. Transmission temperatures can be reduced by adding a large-capacity sump or additional cooling radiator. Synthetic automatic transmission fluid won’t reduce temperatures but it is more tolerant of higher temperatures. Knowing if/when your transmission got hot can also inform you to make earlier fluid changes.

Differential — Like the transmission, differentials can get hot under load. They also can benefit from synthetic lubes (but check manufacturers’ specifications). Some providers like B&M or PML offer enlarged differential covers, which hold more fluid and dissipate more heat. Gauges for differentials are rare; typically proactive action is an adequate mitigation for heat in this area.

Batteries — Normally only when charging, but sometimes in other odd cases (exhaust pipes too close, etc.), battery temperatures can become problematic. Some solar converters have a temperature option for this reason. Make sure your batteries have a supply of fresh air, and use or buy a monitoring system if you think they might be in jeopardy.

Tires — The only way you can tell tire temperature is by a pressure monitoring system with this option. Since a TPMS is highly recommended for safe RV tire oversight, make sure you get one with a temperature capability. Low pressure with high temperature is a sure warning for an incipient blowout. [Editor: Click here for more information on Tire Pressure Monitoring Systems.]

You can check for temperature issues with gauges or in some cases (transmission and differential) by checking fluid conditions. For all temperatures, different vehicle configurations have different limits, and space doesn’t allow us to try to catalog those here. You will need to do some homework to know your various temperature “OK” operating zones. Knowing whether you are in-bounds, and taking measures to stay there, will help your coach run long and trouble-free.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at



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2 years ago

Some good information.
I’ve pulled different types of trailers for most of my life. Its a good idea to get in the habit of watching your on board diagnostic readout.
Doing so may help you avoid costly repairs.

2 years ago

TPMS temperatures from the valve cap location are worthless.

2 years ago
Reply to  teubner

I agree.

Bill T.
2 years ago

Another important temp I worry about is the RV fridge when camping in the hot summer. I have a remote temperature sensor and display to monitor my fridge temp.

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