Community Forums

jmfixitman · 08-30-2022, 11:22 AM

Ok, I know this is a fiercely debated topic for diesel engines in general. But has anyone successfully used any stop leak products in their DP coolant system?

In my Ford F250 with the 6.4L Powerstroke I reluctantly used K-Stop when it was recommended by a radiator manufacturer for a small leak I was having, and also to my surprise it fixed an issue regarding a little oil in my coolant tank. And it has been running fine now for several years (Towing a fifth wheel, etc.) without any other possible related issues.

So now with a heavy-duty diesel engine/system in a Class A motorhome, has anyone used that product or another? I've heard Cummins has approved Zerex sealer for use in Cummins engines, but not sure if that's the case?

Domo · 08-30-2022, 12:39 PM

I'm glad you had luck?

Oil in coolant - eeek! - I hope you tested your oil in case your have coolant in the oil as well.

Quite frankly - with our MH we don't "patch" anything that can result in chassis/motor/tranny components failing. Just too expensive and we'd lose too many style points on the side of the highway waiting for the proverbial tow truck.

twinboat · 08-30-2022, 12:47 PM

In large diesels, oil in the coolant is typically a failing oil cooler. The oil is cooled with coolant.
Oil psi is 60 and coolant is 15 psi. A slight leak let's oil push out but not let coolant get into the oil.

The fix is a new cooler.

code2e · 08-30-2022, 12:54 PM

Hard to recommend any brand of stop leak. They work by literally plugging any hole small enough to catch stop leak material from passing.

Good example of small holes to be plugged is your heater core. Stop leak is known to plug the tubes thru your core, restricting or even stopping flow. You find out the following winter with less or no heat.

Maybe better to fix the leak.

1972VWbus · 03-20-2023, 01:26 AM

Going to depend on how big the crack/hole is. But the only one that works well consistently is...

https://irontite.com/p/8197-all-weat...al-pint/v/8197

The great thing about this stuff is you put it in and leave it in. It dissolves to a micro-emulsion that doesn’t clump or settle so there is nothing there to clog your system. Activation only happens when both heat and air, under mild pressure, is encountered by the solution.

Argosy · 03-20-2023, 05:59 AM

I'd be most worried about the coolant filter. I've never cut one open to see how fine the medium is but it seems like any stop leak would plug the filter, or drastically reduce flow, if it actually works.

98fleetwood · 03-20-2023, 06:52 AM

Quote:

Originally Posted by Argosy

I'd be most worried about the coolant filter. I've never cut one open to see how fine the medium is but it seems like any stop leak would plug the filter, or drastically reduce flow, if it actually works.

Been working on various vehicles for decades, I have never even heard of a "coolant filter" please tell me you are making this up??

wolfe10 · 03-20-2023, 06:55 AM

Quote:

Originally Posted by 98fleetwood

Been working on various vehicles for decades, I have never even heard of a "coolant filter" please tell me you are making this up??

Common on many larger diesel engines.

Just do a search for "diesel coolant filter".

98fleetwood · 03-20-2023, 07:16 AM

Quote:

Originally Posted by wolfe10

Common on many larger diesel engines.

Just do a search for "diesel coolant filter".

New to diesels. Couple years. They sure are complete different animals! I will keep learning....

dons2346 · 03-21-2023, 08:39 PM

Have a friend that had a pretty serious leak. He dumped a couple of teaspoons of black pepper into the cooling system. That was over a year ago and no leak to date

tuffr2 · 03-21-2023, 09:38 PM

I had good luck with both black pepper and stop leak products in gas car engines. But in a big diesel engine - that is above my pay grade.

Good luck getting that leak stopped.

rssnape · 03-22-2023, 06:27 AM

I would investigate if you can determine the location of the leak before I put stop leak in. If it’s an oil cooler or radiator I think I would repair replace those. Stop leak would be my last choice. It may or may not stop the leak, but yet could cause other problems that could add to the repair bill.

Kjlunda · 03-22-2023, 08:09 AM

Several years ago on my trip to Florida, I developed a leak in the radiator. I used the Zerox stop leak and when I got back up north to my home, I flushed the cooling system and replaced the radiator. That was i 2012 and the motor home is still on the road today. My opinion, if you use it, flush the cooling system and then locate the leak.

Jim_HiTek · 03-22-2023, 10:22 AM

I developed a heater core leak that I was able to bypass for 2-3 years but eventually, tired of replacing antifreeze after every trip of my DP.

So I bought a bottle of Bars Leak Stop Leak and poured that into the surge tank. Then I time controlled opening the heater control so the heater would be slowly warmed.

Surprisingly, the leak stopped. Even though the heater core is 34' away from the engine.

I am careful to slowly open the temp control valve so the core heats up (and expands) slowly. Not sure that's needed but so far so good. Added the stop leak in 4-'21 and have used the heater for hours over many days of travel since then (full timer-snow bird). This last trip I used it all day every day after leaving NE Oregon, stopped needing the dash heat in Beatty, NV.

So yes, it is working for me.