New member - first question. Might be very serious.

[tedhontz]

Hello guys. I bought a 2004 Grand Prix GT2. Series 3 motor 3800 non-supercharged. Today I was driving it and the check engine light came on. I noticed days before that the temperature gauge wasn't quite correct. Took the car to AutoZone to have it scanned and the check engine light told me to first add more coolant. If that doesn't work, replace thermostat. The tech noticed my reservoir bottle was very low and said I needed fluid. He said DEX-COOL ONLY. So, I bought a jug of 50/50 Dex-Cool and added it in, probably 2/3 of the bottle. But when putting the reservoir cap back on I noticed the anti-freeze on the underside of the cap was GREEN, not Dex-Cool. Is it okay to run it with mixed? Should I flush it and go back to green or should I flush it and go back to DEX-COOL. I have heard some pretty nasty things about DEX-COOL. Like, the stuff is acid and eats away at your parts. I've also heard it gels up like pudding. Can you run green only? Do I need to do a flush right away or am I okay with it the way it is?

[SubwayGuy]

Hello guys. I bought a 2004 Grand Prix GT2. Series 3 motor 3800 non-supercharged. Today I was driving it and the check engine light came on. I noticed days before that the temperature gauge wasn't quite correct. Took the car to AutoZone to have it scanned and the check engine light told me to first add more coolant. If that doesn't work, replace thermostat. The tech noticed my reservoir bottle was very low and said I needed fluid. He said DEX-COOL ONLY. So, I bought a jug of 50/50 Dex-Cool and added it in, probably 2/3 of the bottle. But when putting the reservoir cap back on I noticed the anti-freeze on the underside of the cap was GREEN, not Dex-Cool. Is it okay to run it with mixed? Should I flush it and go back to green or should I flush it and go back to DEX-COOL. I have heard some pretty nasty things about DEX-COOL. Like, the stuff is acid and eats away at your parts. I've also heard it gels up like pudding. Can you run green only? Do I need to do a flush right away or am I okay with it the way it is?

You are gonna want to flush that ASAP. Green and DEX-COOL do not mix and will gum up your cooling system. Newer versions of coolant have become more compatible with each other, but it's still not recommended to mix them, especially with DEX-COOL.

[Travisgt2]

FLUSH IT NOW NOW NOW! That is going to gum up and be a living nightmare! Just go fully green don't even try going back to Dex cool

[Travisgt2]

Welcome to the forum btw lol!

[tedhontz]

Thanks guys for your help. I already bought all new green anti-freeze and plan on draining it this week and I won't drive it until I drain it. I only drove less than 2 miles with the dex-cool mix added to it. I also bought a new thermostat and seal so I'll replace that at the same time. I heard from the AutoZone "expert" that there is a little brass screw that I use for bleeding the system. He said to open it until it starts to spray anti-freeze and then add more anti-freeze and bleed again until that screw it squirting out fluid. I don't even know what the screw looks like or where it even is! This should be a fun job because the guy said that Grand Prix 3800 engines are easy to drain but very difficult to bleed.

I just bought this car from my ex in-laws for my son. Yes I said ex in-laws. I get along with them great. I have full custody of my kids and my ex is now in jail. Since she is in jail she couldn't or can't pay her mom back for the car, so I bought it for my son. It seems to be very well taken care of especially on the outside. My ex only owned it for two weeks. The paint is so glossy and the chrome rims look like new. The rear spoiler is starting to fade though from sun damage so I'll have to fix that. The car does have 197,000 miles on it but it drives very nice. Engine seems to be perfect until the check engine light went on after having it a month with no problems but the check engine light said "thermostat fault" so that shouldn't be a big deal. It has all new brakes, new power steering pump, hood shocks, and both sides rear hubs. All of that was done by my ex father in-law before I bought it as part of the deal. I paid $2000. Hopefully I got a deal? Also, my ex father in-law mentioned that the new hood shocks were much bigger and that hood really flys up when you release it and is kind of hard to close. My problem is that I noticed it looks like the hood isn't closed on the passenger side of the car. Would too powerful of hood shocks cause this?

So, did I get a good deal? Are my hood shocks causing the hood to look like it's un-popped on the passenger side? And where is that bleeding screw at to bleed my coolant when I do the job? Any pics for doing the coolant drain and thermostat change would help me. I know how to change the thermostat but otherwise I'm lost on the coolant drain and bleed. I watched one video where it showed all the new coolant being poured into the reservoir and slowly added at intervals. But the "AutoZone expert" told me to add the coolant straight into the radiator. I was thinking if I added the coolant into the reservoir bottle would that save me from having to bleed the system? So those are all my problems. I will setup my profile and post pics soon! Thanks everyone for all your help!!

[Travisgt2]

On top the thermostat housing is the bleed screw just leave the radiator cap off with car running and blast heat on high that's the fastest way and keep the coolant over flow tank full. The longer the dex-cool and coolant sit together it congeals. If it doesn't look like or drive like a 197k mile car then I think got a good price

Sent from my SM-S820L using Tapatalk

[Scottydoggs]

turning the heat on does nothing at all. theres no shut off valve, it flows coolant through the core year round.

[Travisgt2]

Good to know I was always told that

Sent from my SM-S820L using Tapatalk

[SubwayGuy]

Don't bother with the radiator drain plug. It will likely crack and break on you. Pull the lower radiator hose. Scotty has an easy, simple radiator flush write-up (I hope he shares lol). About the hood shocks, try taking them off and see if the hood closes any better. If it does, go to a JY and snag some hood struts of bad car for cheap.

[Scottydoggs]

how to flush coolant.

remove the t stat, put the t stat housing back on, take the upper hose off the radiator, then push it down to the ground to a bucket or let it fly.

get your garden hose out, put it in the rad turn it on, then fire up the car, let it run till clear water pumps out the top hose.

then turn the hose off, run the car till no more water comes out the upper hose. then turn it off.

put your t stat back in, with new gasket, the upper hose back on.



now take 1 gallon of full strength green antifreeze, not the 50/50 crap. ( parts store cheap green is fine to use) dump the whole gallon in the radiator, fire up the car, fill the rad with hose water till its full. top as needed till its ready to be bled of air. it will burp and take coolant as the water in the block warms up the t stat opens up for a few seconds till cold coolant hits it and it shuts again.

now to bleed the air out, let it idle rad cap off till the fans turn on, (when the fans are on the temp is over 195 deg, the t stat is wide open) then open the bleeder screw on top the t stat housing a few turns till a steady stream of coolant comes out the hole, shut the screw, top off the rad. cap it.

done.

[tedhontz]

Thanks ScottyDoggs for the directions. I plan to start on it Tuesday morning. To answer others. Yes it idles and runs and shifts like a brand new car. It has the dual shotgun muffler so I was expecting the car to do loud but it is very quiet. Paint job is perfect except the spoiler. Otherwise the car is very glossy and the chrome rims are flawless. It did need some work but my ex father-in-law put the parts on and paid for them before I paid $2000 for the car. New power steering pump, new brakes all around, hood shocks, and new rear wheel hubs on both sides. Car has tinted windows but the back window has bubbles so I know a friend who owns a tint and detail business so I'll have him do it. I'll post soon hopefully with an update! Thanks guys!

[tedhontz]

Scotty, I tried your method twice and I'm not having any luck. When I put the hose in the radiator it pushed out all the liquid from the engine and pushed clear water into the radiator but when I put everything back together I try to dump a gallon of antifreeze in the radiator, it won't take it. It's full of clear water! I've even started the engine thinking it will empty the radiator into the engine and then I'll be able to dump the antifreeze in, but that won't work either. I've left the car parked until today when we finally have a good weather day and now I can't do this so the car is stuck in the driveway still. Please help!! Thank you!!

[SubwayGuy]

Maybe buy a cheap radiator pressure tester and pressure the system so all the water gets flushed out? Did you leave the thermostat out when you tried getting rid of the water? Because with the upper hose disconnected, the thermostat left out and water pump forcing all the water around should be enough to get the rest of the water out.

[ItHurtz]

pull the lower hose from the radiator, drain it, put hose back on. Pour the antifreeze in, then top off with water, start car bleed then done

[Scottydoggs]

Scotty, I tried your method twice and I'm not having any luck. When I put the hose in the radiator it pushed out all the liquid from the engine and pushed clear water into the radiator but when I put everything back together I try to dump a gallon of antifreeze in the radiator, it won't take it. It's full of clear water! I've even started the engine thinking it will empty the radiator into the engine and then I'll be able to dump the antifreeze in, but that won't work either. I've left the car parked until today when we finally have a good weather day and now I can't do this so the car is stuck in the driveway still. Please help!! Thank you!!

i turn the hose off, then run the car till noting comes out the upper hose. the rad should be rather dry, some water may flow back past the pump, but once you hook the hoses back up and fire it back up it should take the gallon of coolant.

or you can use a clear tubing and siphon the rad out. i just did this to do a lim job, took a gallon and a pint maybe out the rad to drain the engine's lim. put back the same coolant as its like 3,000 miles old.

[tedhontz]

I made sure the thermostat was out when I was flushing the system. I've opened up the bleeder screw and nothing but air and the system won't bleed and the radiator still has all the water in it. Plus when I start the car now, it dies on the first try. So, I'm going to attempt to drive it about 1 mile down the street to get a flush and fill done and I HOPE that's all I need done. I don't want to pull the bottom radiator hose and have it go everywhere, which is why I liked Scotty's method but it didn't work on my car and now it's all messed up. The mechanic up the street said he would install a new thermostat and do a flush and fill for $120 or if I bought my own thermostat and installed it, he would just do a flush and fill for $60. So, I'm hoping that my bill will only be $60. And, I'm hoping the car will make it one mile without overheating.

[Scottydoggs]

120? f that crap.

your doing something wrong, fire up the car dump the coolant in. take the t stat back out while you add coolant, that way theres nothing to stop the coolant from cycling round the system.

[ItHurtz]

You said the radiator was full of water, thus the pulling the lower hose solution.

[tedhontz]

You said the radiator was full of water, thus the pulling the lower hose solution.

I said in an earlier post that I have no way of getting under the car and don't want water and anti-freeze going all over the place and possibly getting into my eyes. Furthermore I don't have jack stands and my driveway is on an incline. So, I just decided to drop the $60 in it for a flush and fill. But as I said the nearest place to safely drive the car is a little shady in my opinion. They called me and said that there was a bunch of coolant and oil laying on the engine block (which the coolant sprayed all over into that area when I did the flush) and that they REFUSE to do a flush and fill until I have them replace the Lower Intake Gasket for $500. They said it was a 5 1/2 hour job. I said no and just picked the car up. Again, everything was fine until one day the check engine light came on and said I needed a thermostat and it was a little low on coolant in the reservoir bottle. When I went to do the flush and fill, the reservoir bottle didn't look like it had oil in it. The oil dip stick according to the shop owner looks "murky" but I think it looks like oil. So, now what do I do?

My brother's brother-in-law used to be a mechanic and he feels that I just have an air pocket and it'll take time to bleed. He said the 3800's are notorious for being hard to bleed. He said to open the bleeder screw and take the cap off the radiator and run the car even up to half way on the temp gauge until it starts to spray out of the bleeder screw. So, weather pending, I'm going to try that tomorrow and if not, then I'm going to try to bleed the system as soon as I can. But does anyone know how to tell if my car is indeed mixing coolant, oil, and water together? Do I really need a Lower Intake Gasket put on for the price of $500?

[Fivefingerdeathpunch]

This picture is of a supercharged motor but whatever I'm saying here is the same for both motors.

If you see oil pooling or coolant pooling on either the front of back side on the lower intake manifold, the gaskets are failing. You can see the oil pooled up in notch there and coolant in the other.

So if you said you spray coolant on the front side, look on the backside to double check the condition. If they have never been replaced and car has over 100k miles, you are just playing with fire. They will fail, it's not a matter of if but when.