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96 SLS Coolant change


vdwarren

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Changing coolant, proceeding with GM specs etc. ( Have FSM, but can't locate.) I am looking for the block drain plugs that the manual refers to, but with no locations.

Have any of you drained the block, and if so, where and how many plugs?

Thanks Vern

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Not necessary, just pull off the lower hose. The guru used to say, DRAIN and REFILL is all that is necessary.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks for the comeback. The guru no doubt is correct, I could not find any sign of a plug or drain. The manual kind of throws you in to some confussion.

After reading all the posts on head gasket and pulled head bolts, I wanted to make sure that this part of the maintenance was done. The Cad has 111,000 miles, I purchased at 46,000, so doubt that the coolant replace had ever been done. The fluid looked pretty good, I removed the surge tank and washed it out, had some debrea, and grey mater. I thought this mater may have been from the original pellets for leak seals.

Going back with Prestone Dex Cool and the pellet treatment.

Can't thank our group enough for the tech. help and confirming what is correct.

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Thanks for the comeback. The guru no doubt is correct, I could not find any sign of a plug or drain. The manual kind of throws you in to some confussion.

After reading all the posts on head gasket and pulled head bolts, I wanted to make sure that this part of the maintenance was done. The Cad has 111,000 miles, I purchased at 46,000, so doubt that the coolant replace had ever been done. The fluid looked pretty good, I removed the surge tank and washed it out, had some debrea, and grey mater. I thought this mater may have been from the original pellets for leak seals.

Going back with Prestone Dex Cool and the pellet treatment.

Can't thank our group enough for the tech. help and confirming what is correct.

Hey good luck, I have a 96 with 105,000 on it and I have changed it three times due to mechanical work that entailed draining the cooling system. Change it more often if you have not changed it since 46,000 miles. While the coolant is reportedly good for 100K, you went 65,000 miles which is fine, I am just a belt and suspenders guy with an older engine. I am sure you have had some mechanical work done also that caused the cooling system to be drained.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Never push the coolant specs.

The Northstar has no freeze plugs. The FSM has a lot of boilerplate that is in every FSM, and the freeze plugs are an example of some of the things that slip through that are generic enough but don't apply to the Northstar.

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Just a little Northstar trivia - 93's (and probably 94's also) do have coolant drain plugs in the block. They were eliminated in later years.

Thanks jack that explains the drain plug reference!

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The fluid looked pretty good

Never go by looks. Unlike a cast iron engine, aluminum will not rust (it will corrode) so the color will LOOK like new even 20 years later.

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I ran my 98 Seville for 100,000 miles and proceeded to lunch the engine. When I rebuild it I found that the cylender that lunched had a ton of sludge built up in the water jacket around the cylinder. If your not keeping up on coolant changes, power flush the crap out of it, especially if it has dex-Clog in it. You'll be amazed on how much crud comes out. I just did my wifes 99 Deville with only 40K miles on it and it was nasty. Flush, Flush, Flush!!

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I ran my 98 Seville for 100,000 miles and proceeded to lunch the engine. When I rebuild it I found that the cylender that lunched had a ton of sludge built up in the water jacket around the cylinder. If your not keeping up on coolant changes, power flush the crap out of it, especially if it has dex-Clog in it. You'll be amazed on how much crud comes out. I just did my wifes 99 Deville with only 40K miles on it and it was nasty. Flush, Flush, Flush!!

Keep in mind that there is NOTHING wrong with DEXCOOL if you 1) DON'T USE IT IN A CAST IRON ENGINE and LET IT GO LOW as it allows RUST to form in a cast iron engine, as it was NOT designed for a cast iron engine, and 2) change it at the recommended intervals. WE DO BELIEVE IN DEXCOOL HERE, the URBAN MYTHS YOU HEAR are FALSE.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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And just to add a little to BBF's impecably correct post, NEVER FLUSH A NORTHSTAR. You need to keep the "residual" in order to maintain the 50/50 mixture.

Never underestimate the amount of a persons greed.

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I bought my 01 STS with 101,000 on it and the owner thought he was doing me a favor before he sold it and had the trans fluid flushed and changed :angry: .

I know you dont want to flush these coolant systems, but too late.

Im pretty sure it was done at a jiffy lube type place and not the dealer, but I am not sure.(not that it matters)

I have to do a front motor mount once it warms up anyway, which means I will pull the radiator.

He did not replace the radiator when it was done, but I plan to since I have to pull it anyway, and I do not trust the plastic ends after 7 years, and I am not going back and doing this later.

My question is, is there anything I should do when I replace the radiator to help remedy the system being flushed?

Also, does anyone know if a 99 STS radiator is the same as the 01 STS radiator?

I happen to have a brand new one for a 99 STS in the garage (thought it was leaking at the radiator ends, turned out to be a rotted alternator coolant line).

I totaled the 99 a few years back (young punk turned left in front of me when I was doing 60 :angry::wipetears ) and it would be nice to use the radiator since it was by no means cheap and I have no other use for it.

Just thought I would ask since I was reading the previous posts about coolant changes and this came to mind.

Thanks for the help,

Jonah

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Cooling system flush is the least of your worries. I'd be much more concerned about a trans flush, especially from Jiffy Lube. The dealer is much more likely to do it correctly.

Regarding the cooling system, it depends on how they flushed it. If they used water, then you will likely not have a 50/50 mix unless they used a refractometer to test and adjust it (not likely). That would be your biggest concern. You might want to buy one to check and adjust it. Otherwise, it will slowly get closer to 50/50 with each coolant change.

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Not a problem STS, had no idea that this subject would spark the interrest and the comments are very informative.

In my case, on the coolant change, I pulled the lower radiator hose, and removed and cleaned the resevior.

As Ranger stated the fluid would not look bad, in this case it was not bad but a little cloudy, also had a grayish residue that settled to the bottom of the drain pans.

One note that I would like some comments on is, " on the refill and that is after running and topping off, I was only able to use not quite 2 gallons of Dex Cool 50/50. The FSM states a 12 quart capacity. So if that is the case I left a gallon of old fluid in the system.

I am sure that everyone in this group feels the same, lucky day that I stumbled on to it.

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As long as transmission fluid changes was mentioned.

After I purchased this car, the dealer in Las Vegas said that all the fluids where checked etc.

I probably put on around 10,000, and checked the fluid, it was dark and smelled burn't, at that time I had no place to do any servicing myself, took it to dealer in Sacramento, and ordered a service, in cluding transmission fluid change. Picked up the car and the service guy said the fluid is fine and the change point was a 100,000.

I could not go along with this thinking, when I had the opportunity I pulled about 2 1/2 quarts at a time with a suction gun with the engine running, and replaced it with new, would let run and shift through the gears and repeat, went though about a case of fluid, this cleared up the fluid to a point, put on anouther 10,000, and repeated the same, the fluid really improved, but still had an oder, I put a quite a few miles on, and again repeated. The trans had always shifted well. At about 108,000 the fluid was clean, but a slight oder, I added the Lucas Trans Additive, and could feel an improvement in the shifting, as I stated it shifted ok anyway. The fluid at this point looks and the smell is very slight.

I have confidence now in getting many miles from the transmission.

I wanted to add this experience, I am sure there will be comments both ways.

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