Do Stop Leaks Really Work?

Arsalan Service Manager District of Columbia Posted   Latest   Edited  

Hello DN.

My question is do stop leaks really work for power steering, A/C, Transmission ETC ETC.

I myself always tell peoples that its not a good idea to use these because it will eventually clogged up the system or lines especially for cooling system. How has all you your experience been? 

I see about 3-5 peoples showing up at my shop everyday to add those leaks in there vehicles.

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Robert Technical Support Specialist
New York
Robert
 

Yes they stop the leak then clog up every orifice in a system

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David Business Development Manager
Ohio
David
 

Hello Arsalan, I believe that the primary function of stop leak additive is to cause the o-rings to swell (since they usually shrink to due heat and age). I’ve seen power steering pump leaks resolved in the short term (a few months) but eventually the pump was replaced. Coolant leaks ended up having heater cores clogged due to the stop leak “crud”. I guess it is hit-or-miss depending on the…

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James Instructor
New Jersey
James
 

Dave is correct. The seals will keep swelling until they blow apart.

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Kevin Educator
California
Kevin
 

Seal swelling additives have been the dominant “Stop-Leak” for most of my career. But new technologies have evolved. All things considered, “Stop-Leak” should not be considered as a desirable or permanent fix. Subaru, GM and others have used stop-leak as a factory remedy for "known product concerns" (defects). Results have been questionable at best. The real fix is to eliminate the defect…

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Doug Owner/Technician
North Carolina
Doug
 

Yes and no. It's reasonable to expect science to formulate chemicals that recondition worn seals that have hardened over time and temperature changes. It has its limitations and we should never expect a proper result from using them. I often say we can go from a big puddle to a smaller one, or the transmission may actually shift and pull better during warmup, and some other make believe-isms…

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David Owner/Technician
Alberta
David
 

These additives will not cure a failed clutch pack or pressure hose joint. There is no such thing as “engine rebuild in a can” LOL. Surely we are all able to realize for most situations the various “snake oils” often do not live up to their billing. Having said that, there are some that really perform well without further deleterious effects. Not all of them work the same way or with the same…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Arsalan, You are asking a broad question without any one answer. They (stop leaks) are a temporary measure to delay actually fixing the problem(s). A “mechanic in a can” is cheap and quick. People often try the cheapest approach first. With today's economy, that is how many people are just getting by. I have used them at a customer's request before, but I will not go out of my way to push…

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Jesse Engineer
Missouri
Jesse
 

I would say there are too many variables to say 100% for sure one way or another. At best, they're a short term fix to maybe get you out of BFE, make it to payday, or until you can find a replacement vehicle. As long as you and the customer realize this and the customer understands they still need to keep an eye on things, that's all that can be accepted. Until a proper repair can be made or…

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Andrew Diagnostician
New York
Andrew
 

Only two things I've had good luck with are brake fluid for oil or power steering leaks from seals, and ac delco cooling system tablets for small, non head gasket cooling leaks. Ane even then no guarantees on how long they last. They have both surprised me though.

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Glenn Owner/Technician
Texas
Glenn
 

Old Farmer trick I was told about years ago: If a brass radiator cracked a cooling tube pour ground black pepper in it, fill it full of water and run it until the leak stops. I thought it was some kind of joke until I seen it work on an old Farmall H I have. It finished out the season, then I pulled the radiator and soldered the cracked tube.

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Obie Technician
Washington
Obie
 

“Road apples” that are thoroughly dry do the same thing. I hade a guy bring in a Ford pickup with a two inch hole in the radiator. He told me he was 30 miles up in the mountains and hit a limb. Pulled the limb, installed ground up “road apples” and added water til it quit leaking. I saw the swollen material hanging out of the tubes!

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Eric Owner/Technician
Michigan
Eric
 

3-5 a day?? Do you have a sign out offering free stop leak? I haven't had one of my customers in years even ask about it. Maybe a sign that proclaims, we don't believe in stop leak, stop asking about it.

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Alex Diagnostician
Australia
Alex
 

I've never had significant positive results using additives. I think there are 2 main variables, and then bunch of “sub” variables within those. - What is causing the leak in the first place - What type of product is used to try to fix the leak. Cause: If it's hardened or shrunken rubber seal, then yes it may work … to a point Lord Copperfield;-) … but how shrunken and how hardened, and…

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Raymond Mobile Technician
Michigan
Raymond
 

for me, I would never put anything in a/c for stop leak it will expand and clog condenser so I just don't do any kind of a/c stop leak , as for as cooing system I have had good results with K-seal depending on size of leak the particles r smaller that pepper and looks like gold flakes, so I never had a issue with heater core clogging, as far as lubricants tri seal, I believe its made in…

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