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65K views 52 replies 21 participants last post by  Submariner409 
#1 ·
:crying2: Okay .. I know I have posted before asking about safe temps for my 97 deville but I have to ask again. Yesterday I drove to my parents house for Easter .. left around 10am but it was already warm and humid and the A/C was on AUTO and 71 as usual. It was a little more than 80 degrees outside and very humid. I was moving along at around 75 or so and I decided to speed up ... I nailed it and was going about 97 when I noticed the coolant temp raise steadily from 206 up to 233 ... this happened in about 20 seconds time. I slowed down a lot and it went back down to around 217 and hung there most of the remaining trip. I drove about 60 miles one way to my parents. I didn't go over 75 or so after that happened and was scared it was developing a problem. There was quite a bit of stop and go traffic (which I drive in on a daily basis). I have driven 97 and much faster many times before and never saw the temp get close to that. Last evening when I left for the trip home it was about the same temperature outside and still humid. The temp ran around 217 again for a lot of the trip .. I was in stop and go again and it spiked up to 230 this time ... I was only going around 60mph this time. It then went back down to around 212 until I got home. Traffic wasn't as heavy this time and I was moving most of the time. The coolant level is normal and the oil is full. It was hot again this afternoon and I took my regular trip down I-4 in stop and go to and from work. It never went about 206 today. I do NOT understand this car. I know I seem to worry a lot about this but I am totally paranoid that it will run hot and I will blow a headgasket. Is this normal? What signs should I look for before stopping (other than the warning lights). I guess what I want to know is what is the highest temp I can drive at before I pull over and idle to cool down? Thanks again Everyone!! :banghead:
 
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#28 ·
94eldorado said:
By the way what are those pellets for after you flush the coolant system? What are they made of? Do you just disconnect the upper rad hose and toss them in?
True story. Back in 1958 during a mission, the first nuclear submarine ,USS Nautilus, suffered a small leak in its condenser system. This jeopardized the mission and could have damaged costly equipment so they sent the crew dressed in civilian clothes to purchase as much Stop-Leak as possible and dumped it in the system.

The problem was solved, and did not reocurr.
http://www.historylink.org/essays/output.cfm?file_id=3739


Due to casting porosities in aluminum, this same stop-leak supplement is a factory additive. Note that as Ranger mentioned, it is made out of ground ginger root and walnut shells. Don't get the ones that look like Rabbit pellets in oil or any of that other aluminim or whatever stuff. It won't work the same and could clog a passage.


You don't need to, or should, flush the cooling system as it introduces harsh chemicals and to get them out you need to use lots of tap water, thereby introducing minerals.

Simply drain and refill. Prior to refilling, you put the tabs in (4 I believe) or the tubes (2) that Ranger mentioned (both are made by the same company that saved the USS Nautilus from embarrassment and failure).

We like to use distilled water and coolant in a 50/50 concentration.

If your car came with green, stick to green. If it came with Orange, stick to Dex-Cool.

Once you put green in an system that was orange, you may as well keep using green because you get no added benefit from using orange thereafter (IIRC something regarding sylicates plating the internals?).
 
#31 ·
Ranger said:
To tell you the truth, I am not sure how to check the relays. Hopefully someone will chimne in on it. Even at 45 degrees, the A/C should come on when commanded for dehumidification. In defrost mode, it will come on at any temp.

The "pellets" or "sealant tabs" aka cooling system suppliment are ground ginger root. Get them at any GM dealer or look for Barsleaks product "HDC" (tabs) or "G12BP" (powdered). They go in the radiator hose (high flow area), not the surge tank (low flow).
You were right I put on defrost mode and the fans started. They seemed slow though. You can feel the flow but I'm use to allot more flow. Do the fans vary in speed depending on need? They seem so quiet is this normal?
 
#33 ·
Another question please.

What's the proper step-by-step procedure in coolant flush? What's a good radiator flush and anti-freeze and how many do I need to get 50/50 coolant. Besides the pellets do I put any other additives? How about water wetter type products? After flush do I need to bleed the system as is needed in some newer cars?
Anything I have to look out for or take certain precautions?

Thanks in advance
 
#35 ·
94eldorado said:
Another question please.

What's the proper step-by-step procedure in coolant flush? What's a good radiator flush and anti-freeze and how many do I need to get 50/50 coolant. Besides the pellets do I put any other additives? How about water wetter type products? After flush do I need to bleed the system as is needed in some newer cars?
Anything I have to look out for or take certain precautions?

Thanks in advance
There is a tiny drain on the bottom of the radiator, almost like a key. It is located at the bottom facing the engine, on the driver side.

It may be more difficult than to just undo the lower radiator hose and let it all come out.

No block drain on the N*.

I believe the system holds 12-14 qts (check your owners manual).


Flush is neither required nor recommended. Just drain, put in the Barsleak product in the hose (NEVER in the tank), and refill through the normal path.


Ir you have a 94 get a brand antifreeze, and gallons of distilled water (cheap at store). Pre mix it in the gallon containers and pour it in.

I think to burp it you run it to 2500 RPM with the reservoir open a few times. Then when it reaches op temp you turn it off. It is a self purging system. Keep the premix in the gallon container, and check level cold for a few days.


You won't get any benefit out of running water wetter. I thought I did for a while.. maybe 1 or 2 degrees... not really significant. The only way to get lower temp results with water wetter is to use plain water which will kill the headgaskets fast.
 
#37 ·
blunted said:
Call it a coincidence but after I used some water wetter my 94 Eldo starting running a little cooler.. didn't see 230 after that.
If you started using the AC more frequently the temperatures would remain closer to 200 degrees.

On the Water Wetter packaging it states it would not be as dramatic of an improvement on an ethylene glycol based system.

I may have noticed the slight decrease (or wanted to) in temperatures. But mine were never going as high as 230. A few months later my radiator cracked, and although it is likely very unrelated I have not gotten the courage to pour it in again.
 
#38 ·
In moderate weather the fans actually do not run very often. Just at longer idles and when the AC is on in warmer weather. The fans have different speeds so you are not going to just hear them unless they are on high...and high is usually reserved for the hottest conditions.

Let the car sit and idle for 10 minutes or so when it is hot and open the hood and watch the fans and see.
 
#39 ·
Ranger said:
The "pellets" or "sealant tabs" aka cooling system suppliment are ground ginger root. Get them at any GM dealer or look for Barsleaks product "HDC" (tabs) or "G12BP" (powdered). They go in the radiator hose (high flow area), not the surge tank (low flow).
Lower radiator hose, you dont want those things getting in the t-stat right off the bat!

Also dont crush them, put them in whole as they will disolve.
 
#40 ·
STS 310 said:
Lower radiator hose, you dont want those things getting in the t-stat right off the bat!

Also dont crush them, put them in whole as they will disolve.
When I did my '97 and again when I did my daughters '99 I stuck them in the upper and never had a problem. Gonna do mine in a month or so. Will have to see which is easier to get at.

P.S.
Love your avatar :thumbsup:
 
#41 ·
Ranger

Do you remember my post about adding the crushed tabs to the upper hose?

What a nightmare, fouled the T stat, clogged the rad and overheated the day after I had a Welsh plug replaced.

I still dont have the supplement, kind of scared now....

Yea, the avatar.

Shes something else!
 
#47 ·
mtflight said:
There is a tiny drain on the bottom of the radiator, almost like a key. It is located at the bottom facing the engine, on the driver side.

It may be more difficult than to just undo the lower radiator hose and let it all come out.

No block drain on the N*.

I believe the system holds 12-14 qts (check your owners manual).


Flush is neither required nor recommended. Just drain, put in the Barsleak product in the hose (NEVER in the tank), and refill through the normal path.


Ir you have a 94 get a brand antifreeze, and gallons of distilled water (cheap at store). Pre mix it in the gallon containers and pour it in.

I think to burp it you run it to 2500 RPM with the reservoir open a few times. Then when it reaches op temp you turn it off. It is a self purging system. Keep the premix in the gallon container, and check level cold for a few days.


You won't get any benefit out of running water wetter. I thought I did for a while.. maybe 1 or 2 degrees... not really significant. The only way to get lower temp results with water wetter is to use plain water which will kill the headgaskets fast.
Thank you mtflight.

Why is flushing not needed or recommended and why are the pellets needed. Also why will the headgaskets fail if maintainance is not done on a yearly basis? I've never heard of such a finicky and picky motor
 
#48 ·
94eldorado said:
Thank you mtflight.

Why is flushing not needed or recommended and why are the pellets needed. Also why will the headgaskets fail if maintainance is not done on a yearly basis? I've never heard of such a finicky and picky motor
Harsh flush chemicals introduced into cooling system, cannot be rinsed out without a lot of water. The water that you use would likely be from a hose (to rinse of the flush chemicals), hard to get all that out so in the end you end up contaminating it with minerals which will buildup on the inside.

The green coolant has anti-corrosive additives that wear out. I believe 2 years, not every year. The headgasket has metal that rusts, if the anticorrosive additives deplete.

Rust a headgasket, and you spring a leak!

Any engine is prone to corrosion if the coolant is left in there beyond its useful span. Difference is in order to replace a headgasket on the Caddy, you need to drop the cradle and timesert the headbolts. So... its good preventive maintenance to avoid that costly expense.
 
#49 ·
mtflight said:
Harsh flush chemicals introduced into cooling system, cannot be rinsed out without a lot of water. The water that you use would likely be from a hose (to rinse of the flush chemicals), hard to get all that out so in the end you end up contaminating it with minerals which will buildup on the inside.

The green coolant has anti-corrosive additives that wear out. I believe 2 years, not every year. The headgasket has metal that rusts, if the anticorrosive additives deplete.

Rust a headgasket, and you spring a leak!

Any engine is prone to corrosion if the coolant is left in there beyond its useful span. Difference is in order to replace a headgasket on the Caddy, you need to drop the cradle and timesert the headbolts. So... its good preventive maintenance to avoid that costly expense.
Well I did it but have some concerns. Emptied fluid through lower hose filled with distilled water then emptied again until I got clear water. Allot of distilled water. Mixed 50/50 plus 5 pellets (missed one) in separate containers. Only used one and ¾ gallons though. I'm afraid I have less than 50/50 mixture. What should I do? Should I put soom rust inhibiters?
 
#50 ·
94eldorado said:
Well I did it but have some concerns. Emptied fluid through lower hose filled with distilled water then emptied again until I got clear water. Allot of distilled water. Mixed 50/50 plus 5 pellets (missed one) in separate containers. Only used one and ¾ gallons though. I'm afraid I have less than 50/50 mixture. What should I do? Should I put soom rust inhibiters?
To avoid having the ratio off, it's best to pre-mix (no rinse is necessary). Next time all you should have to do is drain and refill.

I think you are better off than with old coolant anyway. Hopefully someone with more experience will chime in.
 
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