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Discussion Starter #1 (Edited)
My apologies if this has already been discussed but being that this is my first doing my own maintenance this might be a hands-on type of thing. I plan to go to Autozone tomorrow and doing this in their parking lot with their tool borrow program

1987 Fleetwood D'Elegance
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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So you're going to drain over a gallon of coolant onto their parking lot! ? With the car cold, engine off, remove the radiator cap slowly by pushing down on it as you turn it. Then, get under the front bumper, locate the drain petcock and with a pair of pliers, unscrew it. Have a drain pan under it that holds at least 2 gallons. Once its just dripping close the petcock and add new coolant. Then start the car and have a gallon of water at the ready. Leave the rad. cap off till the car comes up to temperature, then you'll see the coolant level drop. Add the water till its full again. To the very top of the radiator. Then quickly reinstall the new cap you bought when you bought the coolant. I don't recommend any "tabs" be added. They were recommended when the car was still under warranty to stop any chance of porosity leaks in the aluminum block. If its not leaking now, it never will! I can't figure what "tool" you'll need to rent?
 

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Discussion Starter #5
So you're going to drain over a gallon of coolant onto their parking lot! ? With the car cold, engine off, remove the radiator cap slowly by pushing down on it as you turn it. Then, get under the front bumper, locate the drain petcock and with a pair of pliers, unscrew it. Have a drain pan under it that holds at least 2 gallons. Once its just dripping close the petcock and add new coolant. Then start the car and have a gallon of water at the ready. Leave the rad. cap off till the car comes up to temperature, then you'll see the coolant level drop. Add the water till its full again. To the very top of the radiator. Then quickly reinstall the new cap you bought when you bought the coolant. I don't recommend any "tabs" be added. They were recommended when the car was still under warranty to stop any chance of porosity leaks in the aluminum block. If its not leaking now, it never will! I can't figure what "tool" you'll need to rent?
I don't have pliers . . so tabs aren't advised now? I have a feeling with a 109,000 miles on it since 1987 . . I just did 15,000 miles in the last 5 months so I need to get it prepared for more useage and I'm started to grow really fond of the car. I've already had dreams about it . . and I've never had dreams about any of my former cars
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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The pellets are a type of stop leak. Adding stop leak every 2 years will eventually plug up the system, heater core, radiator. It doesn't all come out if you're doing the 2 year coolant change. Remain "fuzzy" till you have to replace a restricted heater core!
 

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1985 Sedan DeVille
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I noticed the other day, there's a sticker on the radiator support of my 85 saying to add 1 pellet with every coolant change.

I agree its unnecessary and probably harmful after 30 years
 

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We need to understand why pellets were recommended back in the day. After production started in 82 on the cast aluminum HT 4100 block, a few reports of casting porosity were reported in the field. The original bulletin said to peen around the hole and add an external sealant. Then someone found out about the stop leak at GM. A courtesy recall was issued soon after to bring your car in for a free oil change and new coolant plus the sealant. We did that and affixed a decal to the radiator support recommending bi annual coolant changes and add the pellets. This was not to prevent head gasket or any gasket leak. They were added to "patch" porosity casting leaks thru the warranty period. Period! I still recommend at a minimum, bi annual coolant drains and refills. Coolant like any chemical has a shelf life for its additives. Once those wear out corrosion can eat away the intake gaskets on this engine. Once eaten away, coolant passes into the lifter valley wiping off the oil on the camshaft. Flat cams, corroded main bearings result. Another issue at that time was dissimilar metals mating, cast iron heads to an aluminum block. Technology at that time found it hard to fit hardened valve seats in aluminum heads so cast iron was chosen as a cheaper alternative.
 

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Discussion Starter #10
I checked the coolant and it seems to be fine, a nice orange-ish color . . I added a stop leak powder just to make myself feel better . . hopefully that was the right thing to do.

Now what will I need to conduct my first oil change
 

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1985 Seville
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If that's true why does it specifically state to use them every coolant change in the service manual? Also do not drain that on the ground it could get into the water supply table or someones dog or cat could drink it.
We need to understand why pellets were recommended back in the day. After production started in 82 on the cast aluminum HT 4100 block, a few reports of casting porosity were reported in the field. The original bulletin said to peen around the hole and add an external sealant. Then someone found out about the stop leak at GM. A courtesy recall was issued soon after to bring your car in for a free oil change and new coolant plus the sealant. We did that and affixed a decal to the radiator support recommending bi annual coolant changes and add the pellets. This was not to prevent head gasket or any gasket leak. They were added to "patch" porosity casting leaks thru the warranty period. Period! I still recommend at a minimum, bi annual coolant drains and refills. Coolant like any chemical has a shelf life for its additives. Once those wear out corrosion can eat away the intake gaskets on this engine. Once eaten away, coolant passes into the lifter valley wiping off the oil on the camshaft. Flat cams, corroded main bearings result. Another issue at that time was dissimilar metals mating, cast iron heads to an aluminum block. Technology at that time found it hard to fit hardened valve seats in aluminum heads so cast iron was chosen as a cheaper alternative.
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Was it just a master plan to sell heater core's, radiator's, and coolant tabs and decrease reliability and increase service calls?

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It makes me feel warm and fuzzy to and my 30 year old engine isnt showing signs of oil contamination.
^
If you have the tabs I would use them.

See no harm there really and dropping in a set crushed GM tabs when changing Allante's coolant gives me a warm fuzzy feeling :)

-J


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People can run down the 4.1 but any engine that can stay together for 30 years there's something right about it that's pretty epic in my opinion.

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But my 1939 ford 9n still runs like a top that's truly amazing that tank will never die.
 

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The pellets are a type of stop leak. Adding stop leak every 2 years will eventually plug up the system, heater core, radiator. It doesn't all come out if you're doing the 2 year coolant change. Remain "fuzzy" till you have to replace a restricted heater core!
It is true that factory service manual procedures may not be applicable on 27 years old vehicle. So, I think you have a valid point

However, I think I'd rather risk, say clogged radiator than engine
damage.

So, this summers brake fluid, coolant and oil change will see me crushing tablets again ;)

-J



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1985 Seville
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You can lead a horse to water.......
Im not saying you dont know what your talking about you know darn near everything about these old cars and the 4.1. I just don't believe the tabs last forever nothing does..

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Yeah your right they could care less about are 30 year old vehicles i mean besides casting porosity there's other things to consider like small intake leaks and cylinder liner leaks.
It is true that factory service manual procedures may not be applicable on 27 years old vehicle. So, I think you have a valid point

However, I think I'd rather risk, say clogged radiator than engine
damage.

So, this summers brake fluid, coolant and oil change will see me crushing tablets again ;)

-J



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1985 Seville
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I value your opinion on the subject your the grand master of vintage cadillac knowledge on here. Your like Mr. Miyagi and i'm just young grasshopper that being said ill still probably drop a tab next year.
You can lead a horse to water.......
 

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My only input on the coolant tab usage comes from my dis assembly of an Alante 4.1 used as a base for the rebuild of an engine for my 85 Deville. After removing the heads and drying out the block i noticed the 2 rear cylinders water jacket area where clogged with tab residue around half of the diameter of the sleeve and about 3/4 of the way up the bore. I did not notice any cylinder damage or warpage from this. In fact the bores checked within spec for a new engine with the cross hatch still showing. These engines have an incredibly long lasting cylinder sleeve. I can only imagine what the rest of the cooling system must have looked like. (clogged heater and rad)
I do not use the tabs myself but would not discourage others from doing what they feel is correct.
 
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