Red1990VT

Curious if anyone else has experience with this.
Last Summer I replaced my Coolant Temp Sensor on my 1990 L98, and at that time completely flushed out and refilled the coolant. The FSM said to add two GM sealant pellets, which I did not have and simply shrugged off.
Subsequently the car would leak coolant across the garage floor. It wasn't a lot, and I just kept the reservoir topped off and ignored it.
As with most things ignored, it got a little worse over time.
While out and about yesterday I picked up a packet of 12378255 Sealant 8.800 (ACDELCO) at my local Chevy dealer, $4.41 after Maryland tax.
Since it was warm yesterday (rare for Maryland in January) I opened the petcock, drained fluid, removed the upper radiator hose at the radiator, dropped in the entire pack, put everything back together, topped off the coolant, drove for an hour or so, and so far so good. No evident leaking.
Anyone else have experience with this? The Parts guy at the dealer told me several GM cars will have leaks if these sealer pellets are not used...in my case he was certainly right about that.
Just curious if anyone else has experience using these pellets, and what if any the longer term effects (hopefully nothing but an absence of coolant leaks) may be.

c4cruiser

I had read a few years ago that GM had discontinued the use of those pellets at dealerships but I believe that it was for the 92-96 LTx engines. The L98 series may not have been included. Don't recall if this was a TSB or just a service procedure update.

IMHO, the pellets may do more harm than good especially in radiators that already have some buildup of corrosion that could block the coolant flow in the radiator tubes. It's possible that the compounds that are used in the pellets may also cause problems with various sensors that are screwed into the water jackets.

The best thing to do is to find the source of the leak and repair whatever is causing the leak.

A Peter C4

Where was coolant leaking from? block, radiator, hose?

VikingTrad3r

^^^

yeah it depends on where its coming from.

antfarmer2

They used to put them in every car at the factory.

billschroeder5842

Doing it the right way, is always the right way

Red1990VT

Thank all for your responses. I especially had not considered the possible effects on sensor inserted into the coolant...
But, hopefully GM considered that in recommending the use of these pellets.
Apparently even a factor fresh car built with new gaskets can leak coolant, hence the factory recommended use of these pellets.
The guy at the dealership told me that 2002 Grand Ams in particular have a known problem that these pellets solve.
My leak is apparently from somewhere around the back of the intake manifold, although it is not possible to pinpoint given all the structure and machinery blocking views. When I redid the fuel injectors last summer, I replaced all the intake gaskets EXCEPT the manifold to heads gaskets. The car was pulling excellent vaccuum, so I decided to leave well enough alone. Possibly that was a mistake.
I'm also aware there are head gasket problems with L98 engines, and it is possible the leak is where the head meets the block, although I have no other symptoms, like coolant in the exhaust (no indication of that on my 90).
So, hopefully GM accounted for any detrimental effects of the pellets materials on coolant immersed sensors (hopefully) and the leak is actually sealed. Time will tell on both.
I'd rather GM designed all the interfaces so that simply using compressible gaskets would be enough and sealant pellets would not be needed. But evidently for whatever reason GM has built millions of cars that leak if pellets aren't used.

As time goes by, I'll post updates if the car leaks, or behaves oddly in ways that might indicate sensors being adversely affected by the sealant pellets.

Thanks again to all who replied, these forums are a great help.

70ZZ3 96LT4

I have owned my 1996 for over 20 years since it was new and changed the anti-freeze every five years and added the supplement pellets like the owners manual says. No leaks yet.

VikingTrad3r

are they the AC Delco cooling system seal tabs? Part number 10–108? I see they say they are dexcool and yellow coolant compatible. The coolant in my 1987 is more of a green.

anybody use them in the L 98's with original spec coolant? I have no problem with this I think it's a smart idea

70ZZ3 96LT4

I used the AC Delco pellets for my 1996 coolant changes until I found the same pellets packaged by BARS LEAK in the parts store. The BARS LEAK pellets come in a blister pack and includes 6 pellets. They look the same as what is in the AC Delco package of pellets. I believe the pellets made by BARS LEAK are also sold in the AC Delco package.
My owners manual for my 1985 Corvette does not mention using the pellets and I do not use them. The same pellets are used in my 1996 Monte Carlo according to the owners manual.

Tom400CFI

X3. I've never used pellets in any cars....and "no leaks yet".

ctmccloskey

I have had this car for 19 years and it has never leaked any anti-freeze on the ground. I am still using the original green Ethylene Glycol and not DEXCOOL. I do change the anti-freeze regularly.

I saw the ad on Amazon for the "Genuine GM Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)".
It would appear that its only purpose is to stop leaks (and clog up heater cores).

Good Luck!

arbee

So how many heater cores do you think GM replaced on warranty for "clogging up" due to the pellets RECOMMENDED by GM on certain models of vehicles??? I would venture a guess - NONE!!! While a leak should be properly repaired as suggested, I have never seen any TRUE evidence from any reliable agency that would verify this will happen. And by "true evidence", I don't mean anecdotal "evidence" from people here that have a daughter who's boyfriend's step father's illegitimate son's best friend used the stop leak and all hell broke loose. Intelligent thinking would dictate that these companies would have gone out of business decades ago if these tales were true.

Joe C

can you find, and post, one documented instance of this happening? not saying it can't, but that heater core would have to be pretty clogged up to begin with, probably from lack of maintenance in the first place. i'd almost be willing to bet the clogged up heater core - clogged up by the pellets, is more urban legend than fact (just my 2-cents).

antfarmer2

You are indeed a moron they were put in all cars at the factory.

arbee

So what the hell is this post supposed to mean???

antfarmer2

Do you need someone to read for you?

Ok my bad just reread one to many beers hit th wrong thread

arbee

No, but I think you need someone to do it for you. Lay off the corn liquor or practice your comprehension. My post AGREES that there is nothing wrong with using the pellets.

antfarmer2

Mised this one.

arbee

So what's with the hostile posting and name calling for no reason?