Grand Prix GTP cooling issue

SyntheticShield · May 21, 2006

Alrighty guys and gals, I am in need of some help.

I have a 2001 Pont. Grand Prix GTP. I have posted a couple oil analysis for it on here but dont have the links right now.

At any rate, I have a cooling issue. As of late, particularly with it warming up I have noticed that the coolant temps. gradually and somewhat slowly rise on me as I am driving. I have a drilled 180* T-stat in it. A few months ago I had a 180* Motor-Rad thermostat in it, designed to lock open in the event of an over temp situation. Well it locked open on me though my temps never went above 190 or so.

I thought it was just an isolated event and perhaps the t-stat was just defective. As a pre-caution though I went ahead and replaced the t-stat and the coolant sensor.

All was fine, but I noticed that my temp. reading was just a line or two above the 180 mark now where as before it was a tick below it. However it remained stead and even in city driving it would never go near 210. I thought that the higer indication was the result of the new coolant sensor and left it at that.

As it warmed up I noticed that even at highway speeds (70 - 80 mph) the temps would slowly rise up and as I got in the city it would progress up to 210 and sometimes a little beyond though it never overheated. The fans were coming on and the thermostat was working as it should.

After my last oil analysis, though no coolant was detected, the high sodium levels had me concerned. So I started looking for trouble. I found that the thermostat gasket was leaking a little but the bigger issue was that the throttel body gasket leaking and had escaped my attention. I replaced that, the PCV, the radiator cap and then the t-stat and the gasket.

The coolant was looking a little off in color so I made plans to flush it. Well this weekend I went out to flush it and pulled the drain plug and got nothing. No coolant was draining out though I could clearly see that the radiator was full. I also know that coolant was flowing because I could open up the bleeder valve and coolant would flow out nicely.

I shoved a coat hanger up the drain port and shockingly enough I was getting some sediment out of there. Almost like beach sand which I learned is a result of Dex-Cool.

I couldnt get the system drained so I took it to a shop and had them flush the system. I can pull the drain plug now and the coolant flows out some now, but by no means as it should. So Im pretty convinced that there is some build up in the radiator, but am at a loss as to how to successfully get it all out of there.

The guy that did my flush said he checked flow through the radiator and the engine and all was good, but he too on the test drive, noticed the engine was not cooling off as it should. Its not overheating yet, but it isnt as hot here yet either as it is going to get.

So I need some suggestions on how to get this crap outta the radiator. Im kind of ticked and even more set against Dex-Cool more than ever. The shop put in green coolant. So any ideas you guys have would be appreciated. If I have to buy a radiator then Im going to get an oversized one, but I want to make that the absolutely last resort if possible.

The person that did the flush at the shop told me to bring the car by when I could and he would take a look at it with an infrared gun to see if he could detect any sediment build up from temp. readings. I hope to be able to do this tomorrow.

Thanks in advance for your help and input.

Buford T. Justice · May 21, 2006

I don't think Dex-Cool is the culprit here. GM goes over board with those **** sealer tablets they put in the cooling system.

I like to use Prestone's Dex-Cool in systems needing them. If you are dead set against it, you might get some G-05 coolant. It's a proven performer.

Then you might try this is you are comfortable doing it...

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=37;t=000597

The above should get that junk out of the radiator if you are patient.

Best of luck to you.

The Critic · May 21, 2006

I think SS's problem was caused by his leaking throttle body gaskets. The leak in the system may have caused the cooling system pressure to drop below 15PSI, and there may've been problems with correct coolant recovery/vaccum.

The leak may've also introduced unwanted air into the system, which DexCool is notorious for being sensitive to.

Buford's suggestion is definitely the way to go...if that does not work, then replacing the radiator is next on the list.

SyntheticShield · May 21, 2006

Buford T. Justice I appreciate the link to the directions. It seems long and tedious, but I definately want to get this crud out. When I first bought the car I flushed the system then, though not with the attention you described and the radiator was pristine inside, coolant flowed out of the drain valve like a river, all was good.

I do agree with The Critic that the leaking throttle body gasket was the the issue here. Now that I think about it, I wonder if it were not the source of the original T-stat failing. If that seal suddenly broke, I would think there would be a spike in coolant temps. But because it was so cold at the time the air temps helped keep coolant temps down.

I hear it a lot, that if you keep air out of the system then Dex-Cool works good. Well that is fine, but how long would a normal person not using oil analysis had gone before realizing there was an issue? Too late perhaps? If not for the oil analysis I would have never checked for air leaks because of the high silicon or coolant leaks because of the sodium levels. If a coolant is THAT sensative to air, then I dont want it in the car, no offense to anyone and please, please dont take it that way, I have just read too many reports of issues with Dex-Cool so I'll definately go with something else.

I did buy a Prestone backflush kit but when I couldnt get the coolant to flow out of the drain valve I knew what was up. Now that the shop has flushed it I atleast have coolant flow from the drain valve. This morning, on the trip to work, I did notice that temps had stabilized some as well. I could see the gauge creep up and then come back down as the T-stat opens up. It seems to be regulating more than it has recently, but only the drive home this afternoon, when its in the 90's or so will really tell. Lately, when it gets up to a certain temp, it wouldnt come back down. It was atleast doing that this morning.

Anyway, I'll print out those instructions Buford and I appreciate the help. Is this process going to be good for breaking up/disolving that sediment?

SyntheticShield · May 21, 2006

Oh, one other thing, your directions seem to not be using the bleed process when running the motor, rather you are opening the bleeder valve as you fill it with coolant and let that push out the air, is this correct?

If so, that is great because this is the part of the flush process I hated most, trying to bleed all the air out of the system.

You say to quickly get back to the bleeder valve which led me to believe that coolant should flow out pretty quickly. The last time I did a flush it seemed like it was a good 5 minutes or longer of the motor running before coolant was coming out.

ATS-V · May 21, 2006

You must of had air in the system for a long time for the Dexcool to clog up like that. Dexcool and air do not mix but this doesn't happen overnight either.

I also use Dexcool in my GTP and check the coolant in between oil changes when the car might need the oil topped off.

SyntheticShield · May 21, 2006

Yes, I had flushed the system last year with 50/50 Prestone, but I dont think I did a good enough job at getting all the old Dex-Cool out, in fact if you were to press me on it I would say I know I didnt. At the time, the reason for flushing was simply because I had the infamous coolant elbow leak and had to replace it.

I did drain, flush, refill with distilled water, run motor, drain and then put in the prestone 50/50 but I dont think it was enough and whatever was left in there I suspect was a contributing factor if not cause of the sediment build up. When I pulled off the fouled throttle body gasket, some of it had gelled up around the gasket where the coolant goes through the throttle body. The gasket was clearly breached as there was coolant traces under the throttle body which I had not noticed nor bother to check for until the oil analysis indicated some troubles.

My main concern right now is just getting the sediment out of the system. Im half tempted to put a coolant filter on it and try and get some of it that way until I can get the flushing done. However I'd be afraid that sucker would plug up before I even made it to work.

m2200b · May 22, 2006

If the temps are in range you're repeated flushing with time in between should do enough cleanup.

If the temps not in range how come your radiator guy did not boil and rod this radiator or sell you a new one? You should have a nice aluminum radiator as the ones on 3.8 are pretty good radiators. I've seen 10 year dexcool only ones that still look brand new when they do get changed and don't have an air leak.

SyntheticShield · May 22, 2006

m2200b, you will get no arguement out of me that there are numerous people out there that have great success with Dex-Cool. The problem, for me at least, lies with the sensativity of Dex-Cool to air intrusion. That in and of itself is not bad, but when it goes undetected such as in my case for a longer period of time, then that becomes and issue and too much of a risk for me. I 'feel' that at least with green coolant or non Dex-Cool coolant I would have at worst just had the elevated numbers on the oil analysis. It is solely my fault for not ensuring I had all the Dex-Cool out, so I lay the blame where it is deserved and that is with myself and my flushing practice. I knew of the stories and had read trouble after trouble with Dex-Cool but never dreamed it could do this.

Now, consider just how few people use oil analysis and how much longer this could have gone on if not for the reports I had. I could possibly be wrong and unduly pointing a finger at Dex-Cool, but to me a coolant that sensative to air is not the one I want in my vehicle, especially my baby that I dearly enjoy having.

All that said, I had decided that if the radiator could not be cleared then I was going to get an oversized radiator from ZZP and be done with it. If it can be salvaged and the sediment cleared then I would rather go that route, for now anyway, I still want a bigger radiator though eventually.

I did not know about boiling and rodding a radiator or I would have asked about it. This wasnt a shop dedicated to radiators so I dont even know that they would be able to do such a thing. Its a very reputable place, albeit a little pricey, but they are well established and have an excellent reputation.

I perhaps should have inquired further about what could have been done but as I mentioned, I didnt know about those proceedures. In all the cars I have owned this is the very first cooling issue I have ever had short of the stuck thermostat or cracked hose.

The temps for now and have been in range, but above where they normally of. Prior to this starting I dont recall the temp. gauge ever touching 210, rather it was more on the 180 mark than anything and in the really cold days it may be just a tick under that. Even now, its never overheated, but has definately seen time above the 210 mark.

Buford T. Justice · May 22, 2006

quote:

Originally posted by SyntheticShield:
Anyway, I'll print out those instructions Buford and I appreciate the help. Is this process going to be good for breaking up/disolving that sediment?

It is the only way most folks who work on their own cars can do it without buying expensive equipment.

Buford T. Justice · May 22, 2006

quote:

Originally posted by SyntheticShield:
Oh, one other thing, your directions seem to not be using the bleed process when running the motor, rather you are opening the bleeder valve as you fill it with coolant and let that push out the air, is this correct?

If so, that is great because this is the part of the flush process I hated most, trying to bleed all the air out of the system.

You say to quickly get back to the bleeder valve which led me to believe that coolant should flow out pretty quickly. The last time I did a flush it seemed like it was a good 5 minutes or longer of the motor running before coolant was coming out.

I use to own a 1995 Pontiac Grand Prix GTP. As I recall, it had 2 air bleeder valves on it. One was by the thermostat and the other was by the water pump on the bypass line (heater core outlet hose). After filling with water or coolant, the one on the water pump would start spewing out liquid almost immediately after turning the engine on. The other one would take about a few minutes.

Anyway, it shouldn't take a long time for liquid to come out of them. If you wait too long and liquid stops coming out of them, you are sucking air into the cooling system.

SyntheticShield · May 22, 2006

Hmmm, I wasnt aware of the one on the pump, only the one on the thermostat housing.

Well I hope to try and get this done this coming weekend. I wish I could get to it sooner but the time just isnt there.

If I knew how to get the radiator out (never pulled one out before) I would probably just do that and power wash that thing or something. Oh well, lesson learned.

ron350 · May 22, 2006

Buford i bet your 95 GP had a 3100 motor in it. I think those have two air bleed points.

[ May 22, 2006, 06:10 PM: Message edited by: ron350 ]

SyntheticShield · May 22, 2006

Yeah, I believe it was over an extended time because both of my oil analysis showed elevated levels of silicon and sodium and the tests covered about 15k miles.

Ray H · May 22, 2006

quote:

Originally posted by SyntheticShield:
...If not for the oil analysis I would have never checked for air leaks because of the high silicon or coolant leaks because of the sodium levels...

If you're thinking the OEM DEX-COOL(tm) caused the elevated silicon and sodium levels, think again. OEM DEX-COOL(tm) contains neither, relying only on the hydrated potassium salt of 2-EH with no silicate content whatsoever for its protection against corrosion. If you'd added conventional antifreeze for top-up, though, then all bets were off regarding chemistry and the OEM DEX-COOL(tm)'s long-term corrosion protection. The supercharger, acting as a power-suck for low level dirt if there's even the slightest compromise in the cone filter's integrity, would readily account for the elevated silicon level in the oil, too.

SyntheticShield's UOA

[ May 22, 2006, 01:15 PM: Message edited by: Ray H ]

Buford T. Justice · May 22, 2006

It was the 3.4L if memory serves.

Grand Prix GTP cooling issue

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