AC Delco Seal Tabs Anyone?

[Roger D.]

Folks:

I recently took out the radiator on my 72 small bock coupe and had it cleaned and repaired at a nearby radiator shop. After ony a few miles I've noticed a pinhole leak in the passenger side tank about 8 inches down from the top. I don't relish the thought of removing the radiator again. I've heard about a product called seal tabs made by AC Delco that may "cure" the pinhole leak. Has anyone ever used this product and what are the disadvantages if any?

Any input would be appreciated.

Regards,
Roger

[Terry M.]

Re: AC Delco Seal Tabs Anyone?

Folks:

I recently took out the radiator on my 72 small bock coupe and had it cleaned and repaired at a nearby radiator shop. After ony a few miles I've noticed a pinhole leak in the passenger side tank about 8 inches down from the top. I don't relish the thought of removing the radiator again. I've heard about a product called seal tabs made by AC Delco that may "cure" the pinhole leak. Has anyone ever used this product and what are the disadvantages if any?

Any input would be appreciated.

Regards,
Roger

GM put those pellets in ALL the 1995 (I suspect 1994 to 1996, but my research is with 1995) B-body (Caprice, ImpalaSS) coolant systems at the factory. During that time period I believe their use was far more wide spread in the GM car and truck production. In the B-body there is a coolant flow restrictor in the hose to the heater core that was prone to clogging from the material in those pellets. A good flush of the coolant system generally solved the resultant no-heat condition. The FSM for those cars stated that on changing the coolant another application of the pellets was to be made. Those of us with those cars learned quickly NOT to reapply the pellets.

I am confident the factory motivation for introducing them was to prevent minor coolant leaks from becoming a warranty issue. My take is they have a useful place, but yours is not one of them. If you have any kind of warranty for that radiator using the pellets may void it. As difficult as it is -- take the radiator out and have the shop fix it properly. You might even drive the car over to them to show them what you have before removing the radiator. Of course you must consider that if they did this poor job the first time, you may not want to give them a second bite of the apple.

BTW: As Dave has suggested there is nothing magic about those GM pellets. I believe there are several commercially available products that are the same (such as Barrs-Leaks) and likely one of those companies makes the product for GM.

[Joe L.]

Re: AC Delco Seal Tabs Anyone?

Folks:

I recently took out the radiator on my 72 small bock coupe and had it cleaned and repaired at a nearby radiator shop. After ony a few miles I've noticed a pinhole leak in the passenger side tank about 8 inches down from the top. I don't relish the thought of removing the radiator again. I've heard about a product called seal tabs made by AC Delco that may "cure" the pinhole leak. Has anyone ever used this product and what are the disadvantages if any?

Any input would be appreciated.

Regards,
Roger

Roger-----


GM has recommended the addition of these coolant supplement tabs for years. In many cases, they are part of the factory service manual coolant replacement procedure. The GM part number is 3634621 and this is an ancient part number. You can use them safely in your cooling system.

[Roger D.]

Re: AC Delco Seal Tabs Anyone?

The shop was recommended by a well respected classic car repair/restoration shop in my area. I immediately felt comfortable leaving it there when the owner exclaimed "There's someone bringing in a Corvette radiator" when I was still 30 feet away from him. The finished product looked great. When I noticed the leak the initial thought was to take it back in and see if he could solder over it in place and seal the hole. It looks like its in a difficult spot as far as access and visibility to do that.

Dave, have you noticed any obvious film buildup in the cooling system over time with the product? It won't eventually cause clogging or heat transfer issues will it?

One other thought, if the end result of the product is to seal small leaks, how about adding the seal tabs and running until the leak is sealed. Then replace the seal tab laden coolant with new? Perhaps the only way it will continue to seal is to continue running with the product in the system?

Regards,
Roger

[Terry M.]

Re: AC Delco Seal Tabs Anyone?

Roger,
The coolant flow restrictor I mentioned is a "feature" of the reverse flow coolant Gen II LT1. I have never encountered one on any other GM vehicle that did not have that engine. Of course I have not seen every engine GM has made, so my proclamation does have a disclaimer. Without that restrictor I don't think there is much to be concerned about in using those pellets. I have used them on other vehicles in the past (beater, hoopties, or daily drivers) with success.

I did have a minor coolant leak in my 1967 Chevelle with an L98. It has some out of the ordinary coolant hoses due to fitting that more modern engine into the more elderly chassis. There was some seepage from the lower radiator hose when I first picked up the car. I drove it several times and that leak has sealed itself. But that was a leak (actually what we used to call in the Air Force: "Minor Seepage") from the radiator hose connection to the radiator. Not at all what you have. Your situation as you describe it will not get better by itself.

I think Dave is offering some good advice -- my suggestion is to follow it.

[Jim T.]

Re: AC Delco Seal Tabs Anyone?

I have used the supplemet mentioned in my 1996 Corvette LT4 as per the owners manual when changing the coolant since it was new. I have had no problems with it. When I do a coolant change I remove the two knock sensors to get a good block drain in addition to draining the radiator.

[Dick W.]

Re: AC Delco Seal Tabs Anyone?

Your '72 left the factory with at least one tablet in them. It was standard production line policy

[John H.]

Re: AC Delco Seal Tabs Anyone?

Your '72 left the factory with at least one tablet in them. It was standard production line policy

Yup - Every assembly plant on the planet has dropped two Bar's Leaks pellets in the radiator at the coolant fill station for at least the last fifty years; they've always been the industry-proven cure for avoiding "minor seepage" warranty issues, and continue to be today.

[Richard M.]

Re: AC Delco Seal Tabs Anyone?

I know they used them at the Arlington Tx. assembly plant an employee I know that worked there said they referred to them
as "dog turds", I know they recommend not using them in the LT5, I have used them on different occasions and they work.

[Roger D.]

Re: AC Delco Seal Tabs Anyone?

Great stuff there. With a little more digging, I found a very interesting AC Delco Tech Connect pdf document from January 2005. Since the document was so large, I cut out and attached Page 2 which was which was dedicated to an article on the Seal Tabs. Of particular interest to me was the section named "Side Effects of Seal Tabs". Check it out and let me know what you think.

Regards,
Roger

[Terry M.]

Re: AC Delco Seal Tabs Anyone?

Great research Roger.

[Paul J.]

Re: AC Delco Seal Tabs Anyone?

Thanks for sharing that, Roger. That was interesting.