I’ve got an engine that looses about 4 oz of coolant each time we use it. We know because we check the coolant recovery container and it fills some when the engine is at operating temp. After it cools down cold the recovery container is 4oz short. No coolant is leaking out side and there is no evidence looking at the spark plugs. The system has a 13# cap and when use a 7# it’s a little less. We are guessing a head gasket weep when the cooling system is at running temp and pressure. I’ve read about K-seal and what the instructions say. It says you can drain it out after you use it by running it until hot and the engine has block drains. It’s always had antifreeze with distilled water. What do you think and what are guys experience with it. The engine is all case iron and an overhead valve with 15K miles.
As a hail mary, sure. On something I want to keep in good shape? Tear it down and replace the head gaskets.
That's all fine & dandy I guess , but I've never felt the need to tear something down , especially if you don't know precisely what it is you're supposed to fix AND your pretty sure a can of stop leak will keep things working swimmingly! Some are just hung up on this " do it right" bs , "right ", in my mind is proper operation with reasonable safety & longevity . OK ..bring it on ....
I've always considered it a roadside emergency get me home. I have seen vehicles with blocked up heater cores with that stuff so I would only use it in a desperate situation, otherwise you be changing more than just a headgasket.
I've never used it but If I had known about it I would have tried a bottle in the 2K Cad DTS I had that I figured had a cracked head.
I’ve never heard of it before. Way back I’d use silver seal? Then couldn’t find it, then use Bars Leak when needed. Neither plugged heater cores or radiators, both stopped coolant loss.
GM put bars leak tablets in new vehicles coming down the assy line , their explanation was they viewed it as a preventative nto ward of excessive warranty claims . I've used I for 50 years & never plugged up either a heater core or a radiator . Friend that ran a radiator repair shop swore by the stuff . There are chemical compounds that cure when they come in contact with air , those were developed by NASA to prevent leaks in the shuttle program , variations of those air activated epoxies are what is in modern radiator & a/c systems . There's a walk in cooler in one of our local stores that my HVAC friend put nearly 4# of stop leak in 15 years ago , the unit was so old it was deemed not worth repairing " the right way" ..it's still running..
Fair enough, I could be getting confused with an alternative more snake oil type product. I still feel if it was a vehicle I really cared about then I would try to fix the problem properly.
And there lies the conundrum , define "fixed" according to whom ? If the cooling system is functioning properly , it doesn't need further fixing . We used to get a chuckle out of people who bought a used car that had stop leak in it & drove around carefree for years never knowing they had stop leak in their cooling system.
If I strongly suspect my head gasket is compromised then it would be in my short to medium term plans to get it changed, whether the K-Seal had stopped the leak or not. That's just me though, I can totally understand the thinking of 'If it ain't leaking , It ain't broke' J
That's what diagnosis is for. You can pressure up the cooling system and see where it's going. Of course I wouldn't jump to replacing something that doesn't seem to need replacing, but if you can diagnose it and that's most likely, you're doing your future self a favor. Where I am my cars sit all winter, so there's time to repair those nagging issues. I don't think doing things right is BS. If you do, that's your choice. I've learned that not fixing things the right way just costs more time and money later.
Thanks so far. There are no heater hoses but if there were I’d remove them and make a loop. The GM tablets were for head bolts on SBC’s for sure because we’ve used it many times and I didn’t think of using it. I did finally search here and K-Seal was mentioned stopping a leak they could see on a flathead.
I've used k seal on many engines and it works awesome. A few Radiators also, that needed to be rebuilt for $800. The $15 sealer has fixed it for years. Just follow the instructions and you should be good.
It sure seems that more and more I'm seeing coolant leaks that are occurring during the time between the motor being cool and warm. There is no leak when the motor is cold, and there is no leak when the motor is operating temp, and there are no signs of any external leak. I have one going on in my truck. About mid way between cold and operating temp (warming up, or cooling off), I can smell an antifreeze leak, but that only lasts about 30 -45 seconds and the small is gone. I can't see it, there are no trails indicating a leak, and it doesn't show up in a pressure test. Its not just me, I have had a couple other guys look for the coolant leak as well. About once a month I have to add 3-4 ounces of coolant to the overflow tank, so I know I'm loosing some coolant someplace. The motor has about 65,000 miles on it, and everything was updated or replaced in the cooling system in 2022. This truck has 5 lbs of stuff crammed into a 2 lbs box, I'm not going to tear it apart looking for something with out any idea where to start. That may create more problems then I currently have. I'm going to add a tube of the silver aluminum seal stuff that comes in a tube and see if that solves the problem.
I've seen the silver powder, the brown tablets and the green liquid. I've never used them on my own stuff. I'd either be in the 'still works, keep going' camp or the 'diagnose and repair' camp. They do offer those fluorescent dyes that would aid in finding the issue. Not sure they would hold up during combustion to show on the plugs (tailpipes?), but I'm sure there are testimonials about that. Seems to be about 10 bucks for the fluid and 20 for the glasses and light. I would try to find before deciding on ignoring or fixing.
I have been looking at K-Seal recently for a little tractor I have. It has a small coolant leak into the oil pan after it has been used. The coolant stays separated and doesn't mix with the oil in less it gets run for several hours continuously. I replaced the head gasket but that didn't solve the problem. Figured its a crack or porosity issue so I used the Irontite product (sodium silicate) and that didn't solve it either. Now I am thinking it may be the cylinder liner (diesel engine) seals that could be leaking. K-Seal is my next product to try. Parts are not readily available, the cost and time to tear it down are not really worth it.
Maybe my explanation is off. I think what ever is leaking is only under the highest pressure. After shutting down the engine hot there is usually 8 oz of coolant added to the overflow tank. When it cools down to cold (the next morning) it’s 2-3 oz less than the morning before so that’s how much is lost. There is no evidence it’s left in the engine by checking plugs or not miss firing on cold startup. My fear is waiting too long and having a cut in the cast iron. I bought a bottle and will follow the instructions tomorrow. My plan is to add it to the system, start and run it with radiator covered and get it hot so the pressure will force the sealant in to the leak, turn it off, and drain everything after the temp gets down around 100 then refill with a 50-50 mix I’ll do with distilled water. Hoping for the best!
I know shops that use K-seal on modern daily-driven cars with great results. I used it once on a severely wounded 370,000 mile Ford V6. Took two bottles, but it quit using water.
@jimmy six sounds like a plan, but you might want to go thru more than one heat cycle before drain and refill.
I had a very similar issue on a 351W and used K-Seal and it cured the problem. The engine wouldn't run hot, but it did consume some coolant that I couldn't track down. After replacing a water pump, thermostat, hoses, and flushing the cooling system out I added the K-Seal and I left the stuff in there for about a week and drove it 60 miles everyday that week before I drained the system and put coolant back in. It was fine for another few years or so until I pulled the engine out for big upgrades.
I got mine from the Subaru dealership parts counter. I used it on a $1500 beater and it worked as advertised. Was about 5 bux there instead of 10-18 at Wallymart because subarus have had a million head gasket problems back in the day. It's a quality product. But I'd rather sleuth it out for any engine I built and deem HAMB worthy. -rick
I might try sodium silicate (aka "water glass") if I knew I had an external coolant leak only. I would avoid it if coolant is getting into the oil. Back in the "Cash for Clunkers" days, car dealers were required to add sodium silicate to the oil of the trade-in clunkers and run the engine to seize them up. This was in an attempt to prevent the engines from being resold and put back into service. Not that every dealership necessarily always followed the rules.
I agree. When I used it I drained the oil and water out after the treatment and it didn't run long enough for it to mix with the oil. One of the reasons I am planning on trying the K-Seal is because it doesn't contain sodium silicate like a lot of them do.
I have used this a number of times, and it worked great, however I had one instance on an o/t diesel and it seemed to work for about a month and them started to blow white smoke. I needed the vehicle for the next couple of days and could only get Rislone Block Weld so used that. It worked great for the next 18 months till I pulled the engine down. Basically the head gasket had rotted. Since then I have used the Rislone 4 or 5 times, always with success. I repair radiators and with these two products I have not seen any blockage from the product, I have seen congealed blockage from other products. I usually bring the vehicle up to operating temp, pour the product in with vehicle running and leave in the vehicle for 4 or 5 heat heat/cold cycles, then drain and fill with 50/50 antifreeze and rain water. It should be a band aid, however I have one customer who has over 30k miles in 5 odd years still going strong.
Reporting back. I added the 8 oz of KSeal and ran the engine thru 3 hot/cold cycles, then completely drained the entire system. Refilled with about a 40/60 mix of coolant and distilled water. I ran the engine from hot to cold twice after watching the level of the overflow and it was much improved but slightly lower each time. I decided to add 4oz of K Seal and leave it in. So far so good, the level in the overflow is exactly at the same point when cold; Yesterday and this morning. As a note when hot the overflow gains right at 8 oz.
An " up to operating temp" would mean a minimum of 15 miles @ highway speeds . The product can't work if it's not in the block .
I was always above operating temp using the vehicle during the first sessions with 1/2 the radiator covered with a cardboard panel. I continued to check with a thermo gun and was 15-20* above the thermostat. Yesterday to this morning’s check was30 mile drive… it looks like I’ve been successful but I will continue to monitor the overflow tank….thanks
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