Update: Thermosyphon Cooling System Stop Leak

Wed Jun 27, 2012 4:06 pm

5 days since 2nd installation using 7 lb pressure cap. No leaks, no seeps, or coolant loss.

Changing from partial thumbs up to thumbs up on the following product. Worth a try. List price is $13.??.

Mendtite, cooling system sealer, heavy duty. Manufactured by Zecol Products Company, Medina, MN 55340. Available at Federated Auto Parts, and probably other locations.

Radiator stop leak for Cub thermosyphon system. Installed the above listed product in a Cub 154 Low-Boy with multiple minor and major radiator leaks. Radiator didn't leak until I removed it from tractor and flushed it and the engine block. Two radiator tube were open at the top, never soldered to radiator tank.

Filled radiator with tap water. Started engine, let warm up to temperature, topped off radiator, installed product. Replaced radiator cap with 7 lb cap. Let engine run for about 1 hour.

My first attempt with this product left a couple of small seeps after setting for 2 or 3 days. I didn't use a pressure radiator cap on my first attempt.

Re: Update: Thermosyphon Cooling System Stop Leak

Mon Jul 09, 2012 9:33 am

thiggy wrote:Does this sort of product tend to clog up the radiator passages and reduce it's effectiveness?
The statement on the side of the container says it will not plug up radiator passages.

It's been about 2 weeks since I installed the product and the fluid level in the radiator has not dropped. So the product is working.

I have ran the engine for several hours after installing the product and have not noticed any overheating.

Re: Update: Thermosyphon Cooling System Stop Leak

Mon Jul 09, 2012 1:11 pm

Thanks for posting. I have a small seep in one radiator and didn't know if any stop leak product would work in a non-pressurized system. Obviously the use of the 7 psi cap was needed to make it work. That is good to know. I might be exploring that soon.

Thanks again,

Rick