[Jeff]

Why are you questioning it Art? Unless something is wrong, or unless the system has been overfilled it is unlikely any cap will vent coolant.

I am sure our cooling systems are more than capable of handling higher pressures unless we have bad hoses or connections, in which case the cap isn’t the problem it is the defect.

[David]

On my November 2005 manufacture date Series 60, the Prevost parts manual states its pound rating is “14+”

I apparently have a leak SOMEWHERE that I have been unable to detect. I have done a used oil analysis and it is not in the engine, but I cannot locate a coolant leak.

I ordered and installed a replacement from Prevost and it is labeled 14 Pounds. I have inserted a piece of paper in the overflow tube that goes straight to the ground to see if coolant is leaking there.

In 8,000 miles in our first big trip, I never got a low coolant warning, yet once home added a gallon. And, now, we have travelled about 2,500 miles with no low coolant warning, yet the level is again below the coolant reservoir site glass.

Have searched high and low without success trying to find a leak. Any suggestions?

Going to refill reservoir today and will drive about 150 miles in the Colorado mountains Thursday so hope will then be able to see if the note card in the over flow tube is stained or pushed out. Thank you, Jeff

[Archived]

You could be burning it through the engine. If you have an EGR motor, it could be the EGR cooler leaking coolant into the exhaust and getting blown out. EGR Coolers are not terribly expensive. Do you have an aqua hot or equivalent? I had several connections for my radiant heating leaking. In 1995 someone thought it would be a good idea to use plastic “Y”‘s for all my house coolant connections, its been fun swapping for brass.

[Tim]

Our coaches have an almost unlimited potential to leak air and coolant. Both have multiple fittings, devices, hidden areas, and age related possible sources.

Both ultimately require getting under the coach, inside compartments, behind service panels and both are from front to rear and side to side.

Coolant leaks that are slow such as one so small it takes a month to drain a gallon drip by drip are often only found by luck because if a gallon of water is about 60,000 drops, a month has about 43,000 minutes so you are leaking at a rate of a little over a drip per minute. If the coolant and it piping or hoses is as hot as the engine it is likely to evaporate before it is even visible.

So to find that one gallon per month leak you need to pressurize the system for a while and then get your face in every nook and cranny until you see or smell the coolant and can identify it as the leak source.

This may be heresy, but if I did everything I could do to find a coolant leak of a gallon a month and failed I would go the store, buy some Barr’s stop leak, dump it in and see if that did it. I regret saying that but unless someone has a fool proof way to detect those annoying little leaks what else could anyone do?

[Pat & Jan]

I just remembered on my 2002 Country Coach I had a leak at the upper radiator hose, it was random. Check that connection at the hose to the radiator for any white residue, maybe its an easy fix!

---

2025 Marathon H3 / 4th Prevost
21 Ram 1500 EcoDiesel 4x4

[John]

Art,

Found this information in the Prevost parts manual for XL coaches,

E638 Up To J621, Cap, Filler 7 PSI.

J622 Up To X6383, Cap Pressure / Over 14 LBS.

X6384 Up To Y7045, Cap Pressure / Over 14 LBS.

Just passing along what I found.

[Archived]

Thanks guys, Everything is working great no leaks, We have been stuck at home have not used the bus since last October, did lots of maintenance and have a couple of small trips end of July and August. Drove bus 30 miles today just to get blood flowing, last month did same thing.

[Ron]

I wouldn’t have said this if it were not for Jon’s post above.

I’m a firm believer in Barrs Leaks. Every engine has many places that it can loose coolant and to let coolant get into places it shouldn’t be. Stop leak products are put in new vehicles even including new Cadillacs. Barrs Leaks is also an excellent lubricant for water pumps.

There’s an 8V92 running around right now out there that one of us was about to spend a little more than ten grand on due to some seepage around the cylinder liners until I had him restrained while I dosed it up with a little Barrs Leaks and now it’s running problem free and he’s still got his ten grand.

And just for the record, I’ve never used, or advocated the use of Motor Honey!

[Archived]

Our coach was 14 years old when we bought it and there were no maintenance records. Based on Jeff Rowe’s recommendation (and Jon’s “nod”) all the belts, hoses, and fluids were changed. Shortly after I noticed coolants under the engine on the concrete bus pad and I had to put coolant in once in a while.

After a few trips took it back to Jeff, mentioned the coolant on the concrete and needing to put coolant in from time to time. He wasn’t pleased. When we settled up he said they checked it over really well and put a nut driver on each clamp.

Still had the problem. At next trip to Jeff’s when I told him he ratcheted up his displeasure a couple of notches. Finally he came back and said they found a clamp that he thought was a reused one when they replaced the hoses that they were pretty sure was causing the leak. IIRC the leak was under the clamp and needed lots of pressure to present itself.

So … leaks can be very, very hard to find.

That pretty much solved the coolant leaking. Every once in a while I have to toss in a gallon of coolant, but since recoring the radiator this past spring it shouldn’t happen that much anymore.

[Jon … you don’t have to read the following.] I never thought about how many drops there were in a gallon, but wasn’t surprised Jon had a number. The National Bureau of Standards (Google) says there 75,708.24 drops of water in a gallon. Since engine coolant has a touch higher viscosity than water, I think Jon’s 60,000 is pretty accurate.