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๐ Seal leaks fast, keep your engine unstoppable!
K-Seal ST5516 is a 16 oz heavy-duty coolant leak repair solution designed for rapid, one-step sealing of leaks in radiators, head gaskets, freeze plugs, blocks, heater matrices, and water pumps. Compatible with all antifreeze types and requiring no flushing, itโs engineered for large engines in commercial and agricultural vehicles, delivering trusted, industrial-strength performance.








| ASIN | B002BJEG3U |
| Best Sellers Rank | #9,998 in Automotive ( See Top 100 in Automotive ) #47 in Antifreezes & Coolants |
| Brand | K-Seal |
| Customer Reviews | 4.4 4.4 out of 5 stars (1,683) |
| Date First Available | May 29, 2009 |
| Item Weight | 1.17 pounds |
| Item model number | ST5516HD |
| Manufacturer | Solv-Tec |
| Manufacturer Part Number | ST5516 |
| Model | ST5516HD |
| Product Dimensions | 5.9 x 4.1 x 1.9 inches |
M**O
K Seal did fix intake manifold gasket leak.
So I have a 2005 Chrysler Pacifica, with about 206,000 miles. For the last 2 years I've been fighting this leak through the intake manifold gasket, where I would have to put in about of quart of coolant every 3 days. I've been working on cars all my life so I know how hard it is to change a head gasket or even a intake manifold gasket. Throughout the two years I've been using J-B weld aluminum extreme heat which were only suppressed the leak for about 2 months at a time. After doing a little bit of research I came across this product. Started watching videos and reading testimonials. I was like what the heck let me try it. The leak would occur usually about three to five minutes after I start my car. I added a little bit more coolant, and started my car. I followed the instructions shaking the bottle for 30 seconds vigorously and proceeded to pour the whole bottle into the reservoir tank. My car was really low on coolant so when I added the k seal it went directly from the reservoir into the block. I added a little more coolant to top the reservoir tank off and and place the cap back on the reservoir. At this point my car had already been running for about 5 minutes and what do you know not a trace of coolant was leaking. Like I said before this been happening for 2 years so I know that the coolant should have been leaking by now. So I let the car run for 30 minutes. I turned on the heat full blast just so it wouldn't get clogged into the coils of the heater core. Usually about 30 minutes of running my car the coolant would have been pouring out of the gasket in between the intake manifold and the head. There was no leak at all. After close inspection the area was bone dry. I have never witnessed a product that can fit fix a gasket leak like this one. It literally save me about $1,500 in costly repairs, actually would have been less because I would have been fixing it myself ,but still save me about 5 to 8 hours of labor. So my review for this product is definitely 5 stars and it definitely worked in my situation. I will update this in about 30 days. See the video for yourself. UPDATE: As of today, (May 19th). the leak is still sealed. It's been about 45 days and the seal is still going strong!
W**E
Works really well on minor leaks
This stuff really works. Had a minor leak in the radiator. Follow the directions as they were written on container leaked up within a couple of days.. very easy to use
M**S
This stuff save me about $20K! It works!
I waited 5 days to write this review on my birthday. Mainly because I am so impressed with this product and I didn't know that it would hold. I'm not getting paid for this review and I rarely write reviews. A little history. I own a 2007 Mercedes E-63. This car is a beast and is a joy to drive. The dealership diagnosed a blown head gasket on the car. The report shows coolant mixed with the engine oil. My oil almost looked like a mocha espresso. A very bad sign. The car was immediately overheating. I was adding antifreeze every day. The dealership estimated repairs to start at $15K but could easily rise to $25K. Once the top of the motor is opened up I'm sure they would recommend new cams (4), new cam adjusters and of course new seals. A new crate engine for this car from Mercedes-Benz costs $57,000.00. After carefully reading the directions I added coolant with the bottle of K-seal after shaking it for 1 minute. Then I drove the car normally for 20-25 minutes. The car came up to temperature and stayed there. It didn't overheat! After feeling terribly about having to sell the car as a mechanic's special or donating the car I can instead enjoy driving the car daily. I did end up changing the oil 3 times before it didn't appear to have any more coolant in it. Thanks K-seal!
L**S
extracted a head bolt with odd rusty pitting on its starting thread- showing the possibility of a bad spot in the block
I saw coolant leaking out the exhaust ,could not find (any or) two adjoining cylinders with problems on a compression test. Changed head gaskets anyway, a head bolt came up with odd rusty pitting on its starting thread- showing the possibility of a bad spot in the block.Needed to use the vehicle and could not guarantee that it needed a full motor rebuild over this. Went on with the gasket change(no obvious problems on the old stock gaskets),the heads were decked,installed,everything went good,and now the leak was milder but still there. Compression test results still looked the same,so I tried K seal. I had tried the copper fleck stuff before on other vehicles not much luck. K seal did the job and no more leak out the exhaust.
I**N
It'll work on anything but bullet holes I think.
I just concluded a 7,000 mile drive from Georgia to Oklahoma, then to Cali and from there, Washington state and then back to Georgia in my 2002 Chevy Tahoe while hauling a 21' toy hauler heavy laden with toys. My Tahoe has an aftermarket radiator that produced a pinhole leak during travel. I couldn't directly locate the leak nor was I able to just replace the radiator as I was traveling. So I considered using a radiator stop leak but hesitant to do so as I didn't want to plug up my cooling system at all. I found this product and due to the reviews, decided to try it. It worked almost immediately after running the engine for a while to circulate the solution. And it still has not shown signs of leaking and no affect of the cooling capabilities either. I highly recommend this product!
T**D
It does help.
I canโt say it worked 100%. I was not able to have the product work completely into the system to have it work fully. But it did slow down the leak to where I was only putting 1 gallon of coolant instead of 2 gallons of coolant a day into my truck. I end up getting repairs done sooner than I wanted. One of the seals had a crack in it. Thatโs why it was leaking coolant into my oil. But the stuff gets all through your system, and I had to flush everything out. It did end up in my oil pan. It did not seem to cause any harm to the system at all. It was easy to pour into the reservoir tank. When you look into the reservoir tank, you can see the small particles of copper. It did not seem to cause my heat level to rise either.
C**L
Not worth the money
I used the whole bottle for a small Toyota engine , did not work at all , problem still exist
J**E
Quali
Good product
A**R
Rad stop leak
So far so good. Seems to work well. Put on 5500 kms and no signs of coolant leak.
A**N
Very effective with intake gasket coolant leak
I had an unsatisfactory result with one of my cars I earlier reviewed. However, I had a visible gakset leak between the plastic intake manifold and cylinder head in 2007 Town Car, and was about to remove it for servicing until I thought, let me give K-Seal another shot since I had a small quantity left. The result was magic! The leak is gone, and been running dry and clean for a month now.
A**R
It really worked and saved a lot of money
There was a crack in head gasket of my car and coolant was leaking from there. Results in engine overheating. I added Kseal HD in in coolant and I had driven 5000 KM after that and crack is healed hence no overheating. Authorised service centre had asked to change the head gasket , that could have costed me around Rs. 75000. Local mechanic suggested to weld the crack. That too have costed around Rs. 20000. But Kseal costed me only Rs. 3500. And it really worked for me.
A**O
Gran sellador
Funciona y es fรกcil de usar
M**N
No use for coolant pump mild leaks
It s not sealing coolant pump mild leaks.. I can only seal radiator leaks, not in other places- saying by my own experience.. if coolant pump leaks, u better repair it instead of wasting on it..
Trustpilot
5 days ago
1 month ago