Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

These coolant sealing tablets fix a variety of leaks. My water pump weepage seguayed into a leak. I had to fill my reservoir on a daily basis! As the Water pump replacement entails the removal of the timing belt, I decided to try these tablets. Simply crush them and deposit into coolant tank or radiator if you have a non pressurized reservoir. Worked like a charm. 3 months later, and no more leak. Always carry these in my vehicles. Give them to friends and loved ones.

Been using these for years on all of my cars. Older cars tend to weep coolant, and these tablets are a good solution, especially after a coolant flush. I start with one tablet and work my way up to no more than three to solve any weeping at the freeze plugs, hose flanges, or water pump. On discount, these tablets are a good buy. Some say they are the same as the "Bars" products, but I have a lifetime boycott on "Bars" products for ruining a heater core and a radiator in the past. Neither of which have happened with the AC Delco tablets. Maintain your cooling systems and these will work fine.

A few years ago, a mechanic friend told me that GM itself uses these to seal up pesky leaks in the engines’ coolant system. So, i bought some to use in my 2014 Buick Encore which has been plagued by small leaks from coolant lines going to the turbo. The instructions say to use a certain number of tablets to a certain amount of coolant. I used 3. Two weeks and about 300 miles later, I'm no longer losing coolant. Im convinced that its no longer leaking.

Good product, works well!

Note: I received AC Delco tablets which is fine because they are all really re-branded Bar's tablets.Make sure you are using 1-1.5 g per liter of final coolant mix. If your coolant is aging anyway you should probably just drain the old stuff while the engine is cold (most GM cars have a petcock either on the passenger side or driver side). On my husband's 3.5L Pontiac G6 2008 it is on the driver side. On my 2008 Saturn Vue 2.4L XE it is on the passenger side. After letting the coolant drain completely (note you are not draining the engine block by this method), close the petcock. Fill the coolant system with distilled (not tap) from the coolant reservoir (or radiator cap if your vehicle has one). The minerals in tap water can corrode aluminum radiators.Next, once the system is full to the cold fill line there will be lots of air in the system. Turn on the engine with the heat on (turn to the hottest setting but do not turn the fan on). Keep the coolant cap on so air can purge from the system. Some vehicles have a bleeder screw but my two did not. Once the engine gets to temperature by running at 2000 RPM in short cycles the cooling fans will start. Make sure you are not overheating your engine as this is a possibility if your water level is low and air is still in the system so take it slow. If your engine temperature is starting to overheat turn off the engine and wait a bit. After the fans start running and the level is topped off of water let the engine run for 5-10 more minutes. This means that the engine block is circulating. Since water has a lower boiling point than a coolant mix you might boil over the top of the reservoir so be careful.Let the engine cool after turning off the engine. After that drain the coolant system with the petcock into a large drain pan. You may want to repeat this one more time with more distilled water if you really want to get out most of the old coolant. You are going to need 4-5 gallons of distilled water (roughly 80 cents a gallon from your local walmart or supermarket). Once the water is done draining close the petcock. Start refilling with full 100% coolant for most and 50% coolant to finish it off. Ideally you should crush the coolant tablets in a separate container then mix it with coolant you are adding into a radiator hose. The risk with using the tablets in the reservoir is that they can plug the reservoir or upper hoses. In my GM cars I used Prestone extended life (dexcool compatible orange stuff). They also make hydrometers (Prestone, Peak make one) to ensure you have the correct ratio of coolant to water (should be about 50/50 but 60/40 may be good as well if you are in areas that it gets very cold). Too little coolant is not good either as you may be more prone to corrosion. There are also coolant testing strips that are alternatives). Repeat the engine idling with the cap off until you get all the air into the system. Dexcool will destroy the engine with gunk if there is air in the system, the heat will not work, and you want to avoid that. Always keep the coolant reservoir to the max level. Ensure full burping of the system.Note: most manufacturers including GM do not advise these tabs for normal maintenance. You shouldn't really add this to your car unless it was recommended by the manufacturer or you have a problem. There were older GM vehicles (Northstar engines) that you needed these tablets but now the problem is no longer present in newer cars. The G6 I have isn't leaking anymore (so far) so it looks like the stuff is working.

Great price for these, which are often only available at a dealer. A must-have for some cars - my '99 Silverado with the aluminum 5.3 came with these in the factory fill due to the way the engine was cast, and it keeps the engine from losing coolant. Still great at 260,000 miles. (I had done a drain and fill when I changed the hoses and didn't;t use them ... lost a little coolant over time; these stopped the loss in its tracks).

Easy to install. Temp fix.

Backstory: 2008 Saturn Aura. Coolant leak last October... I was finding large puddles in the driveway by passenger front tire area. Dealer said waterpump. Had it done. Fast foward to this month. Same puddles appearing, same area. Could smell coolant burning after a drive. NO white smoke from exhaust. Took it back to the dealer, now they say headgasket..see attached. I call bs. On a whim, I bought these tabs.. seriously for less than $10, why not? I did have a bad experience with a sealant in my Durango though- it gummed up my radiator to the point it had to be replaced... that was a heavy, heavy liquid though. So I got these tabs, read the reviews, crushed three of them up and pre-mixed it with coolant (DEX) and added it to the overflow. I then drove the car for a solid hour with the heat on as high as I could stand. After a day or two..still a puddle the next morning, but MUCH smaller. Ok, I'm encouraged now...new car search suspended... I crushed/premixed/added the last two tabs to the overflow. It has now been a full week...no more burning coolant smell and no more puddles. I'm happy. This is my first Amazon review, but I had to share this.