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ceephis · 04-25-2025, 05:39 PM

Hello all you RV gurus

My RV has a tendency to run a little warm when there's very little air traveling past the radiator.

In other words idling and doing reasonable amounts of inclines. It's never gotten into the red but it does creep up fairly well.

That being said I'm looking to flush the radiator and replace the thermostat.

I've tried to find a amount of radiator fluid that's in the vehicle based on the p30 manual but I have yet to find a true amount listed. Does anybody know how many quarts or gallons the system usually takes?

And what would the recommendation for draining and cleaning it out be?

I know that they have radiator cleaning fluid that you run through a radiator with just water to dissolve the rust and other sediments in there. Is this a good idea? Also what is the best recommended radiator fluid for a 94 Damon intruder 454 Chevy engine.

Thank you all for your wisdom and insight

SafariBen · 04-25-2025, 08:16 PM

Getting hotter idling points more toward a fan issue than an internal radiator issue. Blowing the outside of the radiator out, then rinsing, washing, and rinsing again, is common practice with diesel pushers that suck more crap through the radiator, but might help yours also.

To recommend a flush type, you'd need to know what's in there that you want to flush. If you can see the ends of the tubes from the radiator cap, that's a good enough snapshot of what's in there. Basically you have either mineral deposits from hard water, or oily gunk deposits. Mineral needs an acid to dissolve, and oily gunk needs an alkaline cleaner. Fleetgaurd restore is both types, restore is one, restore plus is the other. If you don't know what's in there, drain, fill it with rainwater, run it an hour or so, drain it hot into a white bucket. Let it settle and check for sediment. If there isn't any, refill with new coolant. Can't go wrong with an OAT like Peak final charge etc. but any number of automotive coolants would be fine.

Dutch Star Don · 04-25-2025, 08:29 PM

If that is the original radiator and has never been cleaned by a radiator shop, I would pull it, have it rodded out and checked for leaks. Again, if it's original, half of its capacity could be reduced by corrosion.

As noted above, the fan could also be the issue. It should have a fan clutch that when it engages should sound like an airplane talking off. If not, it may need replacement.

ceephis · 04-26-2025, 01:33 AM

Thank you so much this is exactly the information I was looking for and I will look into those certain products and see what I'm dealing with.

I did notice that evaporust came out with a radiator cleaner that could be left in for a long period of time. That kind of appealed to me as well as we will be going on a trip this summer, and I'm concerned about following the directions on these products precisely and if they have a time period where they could cause damage to the engine. I just didn't want anything that I use to cause leaks or problems in either the radiator or the engine itself.

The good news is I do have the fan airplane noise so at least at some point in the process the fan clutch is kicking in. Whether that's doing it at 100% capacity or at the right temperature I don't know but I do hear the fan clicking on.
Thanks again for this amazing insight and information it's very helpful.

ceephis · 04-26-2025, 01:34 AM

My guess is it's the original radiator. I don't know that pulling it is in our ability right now we just lost our house and will probably be living in the RV and that's not because we have a bunch of money lol.

So hopefully anything I decide to do will be safe for what I do have in place, and as inexpensive as possible.

The good news is I do have the fan airplane noise so at least at some point in the process the fan clutch is kicking in. Whether that's doing it at 100% capacity or at the right temperature I don't know but I do hear the fan clicking on.
Thanks again for this amazing insight and information it's very helpful.

ceephis · 04-26-2025, 01:47 AM

I assume this is the stuff you're talking about when referring to the peak antifreeze.

I don't necessarily see anything with Chevy listed here. And I wanted to make sure. I know very little about cooling systems

https://a.co/d/0WpHXZI

SafariBen · 04-26-2025, 06:36 AM

Yes, that's the stuff, not needed for your gas engine, but will work well. Not that bad at $11-12/gallon, distilled water is under $1.50 at walmart, no need to ship that. As long as you stay above -20F you can go 33% antifreeze and 66% water, but we're talking pretty cheap here, and if you need to top up, it's easy to add distilled water and not bother to carry antifreeze, if you already have 50/50. There are premium automotive antifreezes around $12/gal on sale for concentrate.

If the fan comes on "airplane mode", then let it idle and watch the temp before the fan comes on loud, that is NORMAL engine temp. The dash gauge may be off, you can get a non contact thermometer to check the engine temp directly to confirm the gauge accuracy.

If this was a 70's RV I'd suspect mineral deposits, it was typical to add lots of water in those days. By the 90's, things had improved and adding hard water to concentrate was still common, but constantly adding water is what really makes the deposits. It's not how long the water is in the system that makes the deposits, the water drops the mineral in seconds at engine temp, water only contains so much mineral, but if you keep adding hard water, you'll plug the tubes. Nothing you've said suggests an internally plugged radiator.