Classic British Bike Magazine



K-Seal coolant leak repair

Wonder fix or snake oil? We try a bottle and see.


Would you use this product or anything similar on your motorcycle or car? If you have, we'd like to hear if it worked, and if it didn't.



The Problem


A friend's old 4x4 was overheating and pressurising the radiator until it blew the seal. Sounded like the head gasket had blown, and further inspection supported that diagnosis. There was no tell-tale white smoke from the exhaust, mind. And there was no emulsified oil as far as we could tell either. But there were highly visible bubbles appearing in the overflow tank, and the temperature gauge was unable to decide where it wanted to be (which suggested air/combustion gases in the system). So the head gasket was shot at the very least, and that might be due to a warped head or a cracked head, or both.


The vehicle was old and hardly worth repairing. A remanufactured service exchange cylinder head was quoted at a not unrealistic £360 plus VAT, and then there were new stretch bolts to buy, plus a gasket set, and then a new cam belt for good measure. To add to the financial woes, it was odds on that other things would break during the strip down; things such as studs, bolts and seals. So except for emergency short hop beer runs and the like, the vehicle had been pretty much abandoned.


We'd heard of K-Seal and similar "gasket sealing" products, and we wondered if now might not be a bad time to test the product—not least with regard to motorcycles, plenty of which are on the market with similar cylinder head problems. Except that we suddenly couldn't find anyone who (a) had a coolant leak that needed a quick fix, and (b) was willing to have a bottle of "snake oil" poured into the radiator where it might (quote/unquote) "gum up the effing works". So we looked to the old 4x4 that could now be abused without penalty.



The Solution


We use the term "solution" ironically, but K-Seal is literally a solution. A bottle of gloop. However, in the event it solved nothing. Here's how you use it...


First you shake it like Elvis for a minimum of 30 seconds (we shook ours for a full minute), then you unscrew the lid, then you peel back the tab and peer down the hole. It looks like dirty goats milk. Presumably, the dirty bits are the ceramic particles we've heard about that have been engineered to fill any voids/cracks in the cylinder head and block the coolant escape route or combustion gas path. K-Seal reckons that this juice will work on engine blocks and anything else where the coolant has access. So does that include the radiator core or heater matrix?


Apparently so. The formula, we're told, keeps circulating until it finds a "low pressure area". Then it goes to work and micro-fibres lock together into a solid clump of ceramic material, and copper particles help ensure adequate heat exchange, and then all your problems are solved.


Except that it didn't solve our problem, and we didn't really expect it to. However, we was hoping that it would at least improve matters, perhaps by slowing down the cylinder gas flow into the radiator thereby extending the range before overheating. This point could be important if, for instance, you've blown the radiator some miles from home and need a quick fix.


Remember, a blown radiator doesn't necessarily mean that it's totally unusable. In many instances, once you release the pressure and put the water back, the radiator is still serviceable, albeit on a temporary basis. Our 4x4 test rig, for example, simply needed a little persuasion with a small hammer to close the gap at the top of the radiator from where the coolant was escaping. So any bodge repair at the roadside could make the difference between getting yourself home, and being got home by a third party (which in turn could mean a long wait as your recovery outfit politely notifies you by text message that you're not one of the 93 percent of members who were recovered within 50 minutes, or whatever).




The K-Seal instructions are simple. After shaking the mixture, you simply pour it all into the radiator. It can go in the overflow tank, where applicable. But the radiator is preferable. The bottle we used contained 8oz/236ml of "sealant", and that's suppose to treat up to 12 cylinders. Our vehicle had four cylinders.


Once you pour in the mix, you fire up the engine and run it up to temperature. That's important because, we're told, the heat bonds the ceramic particles, etc. So we ran the motor as instructed, watched and waited for the next ten minutes as the temperature gauge climbed and the cooling fans kicked in and out, then the needle dropped, then it rose, and then stayed fairly high. Then we went for a drive.


Within four miles the needle was way up part the three-quarter mark, so we headed back to base just as the needle went into the red zone. By the time we parked up, the radiator top seal had blown again and the coolant was squirting out and running down the core. We probably lost a cupful or two.


After some thought, we checked to see if we'd done anything wrong (except, arguably, apart from using the product in the first place—and many would counsel strongly against such usage), but we could see that anything was amiss. It's supposed to be a simple application. In fact, so simple that idiots can do it [take a hint—Ed].


So the 4x4 it right where it was when we started, technically speaking—except perhaps that there is now a mess of ceramic particles floating around and possibly gumming up the radiator and heater matrix. But seeing as the vehicle was headed to the knacker's yard, it's not really a great loss. It had a good life. And incidentally, note that K-Seal is not designed to work where oil is present. So if your coolant is contaminant with engine oil, forget it. You need a mechanic.







Firstly, the K-Seal distributor in the UK (at Kalimex Ltd) was as good as his word. He promised to send us the product for evaluation and explained that he didn't mind what we wrote, as long as we were fair minded and presented the results honestly.


Secondly, although the product does claim to "Work in minutes", in the smaller print we're also advised that K-Seal seals "most leaks in the cooling system and has a high success rate." And note that if you add it to the expansion tank, you're advised to remove some radiator coolant first and/or mix the K-seal with some water to ensure if enters the system—which is what we did.


Next, we used the aforementioned term "snake oil" advisedly. Originally, snake oil was a component of traditional Chinese medicine and was used as an ointment for minor aches and sprains (and yes, it is derived from snakes). Later, particularly in 19th America where travelling fraudsters were flogging any old mix of oils, herbs, spices, tonics, chemicals and whatnot as a universal panacea, the term took on a new meaning and fell into disrepute.


The thing is, these kinds of products do occasionally produce results; or, at least, they appear to. The world of medicine is replete with similar stories of patients taking non-prescription bottles of snake oil and quickly finding that their disease is cured or goes into remission. However, it's difficult (if not impossible) to prove that one thing really led to another. Why not? Because diseases occasionally do spontaneously clear up, and you can attribute that to the bottle of snake oil you just poured down the hatch, or the state of the weather, or the joke you just heard down at the pub, or the machinations of the psychic surgeon next door.


The same thing occasionally happens with automotive wonder cures, usually as the result of a misdiagnosis. So we asked around to see if anyone had EVER seen results with K-Seal or any of the other miracle liquid engineering fixes on the market, and the best we could find was one or two people whose "mate" had fixed his car with it, or who claimed that some bloke down the street said it worked. And when we asked if anyone had seen long term improvements or a permanent repair, the answer was "no". The best we heard was that one guy fixed his BMW long enough to flog it.


So it's all just a con? We don't know, and we certainly wouldn't go that far (not until we've spoken to our lawyers). But if we broke down in the middle of the Sahara on a liquid cooled bike or car and found the head gasket blown or the head cracked, we'd probably buy the first bottle of K-Seal (or snake oil) offered by the next passing Arab.


But anywhere nearer home, we'd bite the bullet and talk to a mechanic, or we'd fix it ourselves the old fashioned way, or we'd scrap the vehicle and stick out a thumb.


In short, this is a desperation product. Might work. Might not. But we certainly didn't see the slightest sign that it worked for us. Having said that, we once pumped a can of tyre inflation goo into the inner tube of a classic car we owned. That was supposed to last a few dozen or maybe a hundred miles until we changed the wheel. However, three or four thousand miles later the tyre was still inflated. Not wise of us, perhaps. But it worked. And we've also used radiator sealant in an emergency, and that worked too.


Pity, however, K-Seal didn't.



UPDATE: The importer of this product promptly emailed us to complain that we hadn't conducted the test appropriately, and also suggested that we hadn't used the right product. We phoned and discussed this at length, and we reiterated exactly how the test was done—and that was 100 percent in line with the manufacturer's instructions. The product claims to "WORK IN MINUTES". Well, we ran the engine for a full 30 minutes on tickover (with the expansion tank cap removed) before taking the vehicle out on the open road and significantly pressurising the system (with the expansion tank cap replaced).


It failed that test.


We were then asked if the vehicle heater was switched on? We explained that it was. Well had we poured the product directly into the radiator? We said no; we used the expansion tank and flushed it into the system as required.


Finally we reiterated that the product claims to provide "HEAD GASKET REPAIR" as printed on the bottle. Well, that was what we were trying to repair. A head gasket. The importer then said that they have a dedicated product (with a money back guarantee) that was more geared to head gasket issues. But we explained that we didn't have that product to hand. We tested what we were sent (after clearly explaining that a head gasket failure was the problem).


We then asked the importer if he wanted us to test this alternate product.


Our offer was declined.










Think you know better? Good, drop us a line at Sump and we'll include your thoughts/experience.



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