Getting ready to do an efan install this week on my 2002 GMC 4.3, but need to install a lower temp thermostat first. I was gonna do a coolant flush and refill, but I don't know if I should refill with Dexcool or the green stuff.

The only repairs I have had to do have been related to Dexcool eating my gaskets (intake manifold gaskets and heater core leaking).

Any help would be appreciated.
-Brad

You can switch to the green stuff, but I stayed with the Dexcool and change it more often than 5 years or 50,000 miles. I now change mine every 3 years, with a flush.

Just had mine flushed and refilled with the red Dexcool red bug juice. I stretched the mileage out to 69K miles and 6 years. OEM stuff seemed to work well and never had to add any coolant during that time. Had it done at the dealer.

Any coolant with Propylene glycol such as AMSOIL or Sierra is good.

Yeah, I was gonna do Dexcool, but I have had to replace the gaskets.

Also, what are you doing with the old coolant? I live in the country and can pour it out, but we have alot of wildlife around. I know autoparts stores don't know what to do and won't take it.

I take mine to the dealership for the flush and the coolant change. :)

I take mine to the dealership for the flush and the coolant change. :)
Thats what I was afraid of...:(:D

I suspect your local County management has a "tox away" or other hazardous material disposal day. In IN, most all counties have a free disposal day and they take coolant.

Don't dump it out; those of us that live on a well don't need any more crap in the ground than is already there ...

Yeah, I have a well also. I think I am just gonna dump it far away...:D

Yeah, I have a well also. I think I am just gonna dump it far away...:D
When I wasn't lazy/couldn't afford going to the dealer, I bought a 55 gallon drum, I think it cost 20 bucks, I just poured my oil and coolant in that. May be an alternative. When it's full of "Motor Oil" take it to the local Jiffy Lube or whatever, and have them take care of it.

Getting ready to do an efan install this week on my 2002 GMC 4.3, but need to install a lower temp thermostat first. I was gonna do a coolant flush and refill, but I don't know if I should refill with Dexcool or the green stuff.

The only repairs I have had to do have been related to Dexcool eating my gaskets (intake manifold gaskets and heater core leaking).

Any help would be appreciated.
-Brad

I'm so tired of seeing this. Dex-cool doesn't eat anything. Yes it will plug up things when there is air in the system because of a leak.

The problem is the gaskets are plastic. I've seen the gaskets leak out green or red coolant.

I'm so tired of seeing this. Dex-cool doesn't eat anything. Yes it will plug up things when there is air in the system because of a leak.

The problem is the gaskets are plastic. I've seen the gaskets leak out green or red coolant.
:agreed:

I'm so tired of seeing this. Dex-cool doesn't eat anything. Yes it will plug up things when there is air in the system because of a leak.

The problem is the gaskets are plastic. I've seen the gaskets leak out green or red coolant.
Yeah, but why was there lawsuits about it and why have I had only coolant problems with this truck? The LS series trucks don't have coolant routed the same through the engine so they don't have the problem.

I have yet to have a problem with dex cool. This includes my 96 my 03, my dad's 03, and both of my sister's cars. I believe an 01 and 03. Just have to keep up with maint.
For a place to dump your coolant/oil/anything else you have look here.
http://www.mobiloil.com/USA-English/MotorOil/Car_Care/Used_Oil_Recycling.aspx
If you click on the www.EARTH911.org link it will show you recycling centers in your area that will take care of alot of stuff.

Yeah, but why was there lawsuits about it and why have I had only coolant problems with this truck? The LS series trucks don't have coolant routed the same through the engine so they don't have the problem.

Are you saying that the way the coolant is routed directly affects how corrosive the coolant is? Gen III's don't have the same problems because they don't have coolant routed through the intake. :confused:

Are you saying that the way the coolant is routed directly affects how corrosive the coolant is? Gen III's don't have the same problems because they don't have coolant routed through the intake. :confused:
Thats what I meant. In the older engines coolant was routed through the intake. Hence Dexcool problems.

I had my Coolant flushed at 97,000 and had the problems at 120,000. About a year and a half later.

Thats what I meant. In the older engines coolant was routed through the intake. Hence Dexcool problems.

I had my Coolant flushed at 97,000 and had the problems at 120,000. About a year and a half later.
Brad92,
Can you explain what you are talking about in more detail? I am not following your posts. I believe the first year....don't hold me to this...of the reverse flow 5.7L LT1 engine was '92 in the Corvette which came with the green stuff.

I have a '96 Caprice with the 5.7L LT1 engine, which I think was the first year of the Dex Cool coolant. I didn't really have any problems realted to the coolant....still don't.

The biggest rumor was that people were mixing the two types of coolants which causes a chemical reaction that results in sludge building up in the cooling system. I think some of the issue comes from folks thinking because Dex is an Organic Acid, it is eating the gaskets. GM stated that the real culprit was running a long time with low coolant levels resulting in cap failure and parts being exposed to air causing iron particles to contaminate the system.

My fix is to change the Dex coolant and the cap every 2-3 years or 30,000 miles to avoid any issues with the cooling.

My 97 Suburban with the 5.7 and my 02 4.3 (basically the same engine) have had problems due to the gaskets. We also had an 89 Chevy 5.7 with the green coolant. On the 89, we didn't really take care of it like we should have and it had no problems with the green coolant. On our other vehicles, we have taken good care of the coolant, yet have had issues with the gaskets which I have been told, was due to Dexcool and the design of the engines having the coolant run through the intake.

I am not necessarily saying Dexcool is all bad, but I believe its not good for certain engines like our 350 and 4.3. The diesel has been fine with it and I wouldn't change Dexcool in that.

Not very technical, but thats my understanding of it.

My 97 Suburban with the 5.7 and my 02 4.3 (basically the same engine) have had problems due to the gaskets. We also had an 89 Chevy 5.7 with the green coolant. On the 89, we didn't really take care of it like we should have and it had no problems with the green coolant. On our other vehicles, we have taken good care of the coolant, yet have had issues with the gaskets which I have been told, was due to Dexcool and the design of the engines having the coolant run through the intake.

I am not necessarily saying Dexcool is all bad, but I believe its not good for certain engines like our 350 and 4.3. The diesel has been fine with it and I wouldn't change Dexcool in that.

Not very technical, but thats my understanding of it.
Oh I see. Well, it's definitely tough to argue with actual experience and the fact that the 4.3 is not known for it's robustness...is that a word?....can't really comment on your 5.7 problem.

On the reverse flow thing, originally the coolant flowed from the radiator into the block and then to the heads and intake (old style). Then in '92 the LT1 reverse flow showed up which rerouted the coolant from the radiator to the heads first, then to the intake and block. This alternate flow pattern supposedly provided better cooling and allowed GM to run higher compression ratios even with the iron head motors...like my 96 Caprice.

I guess the Dex Cool issue will continue. I am no longer afraid of the Dex as long as I change it more often with the cap. Thanks for the clarification.

Oh I see. Well, it's definitely tough to argue with actual experience and the fact that the 4.3 is not known for it's robustness...is that a word?....can't really comment on your 5.7 problem.

On the reverse flow thing, originally the coolant flowed from the radiator into the block and then to the heads and intake (old style). Then in '92 the LT1 reverse flow showed up which rerouted the coolant from the radiator to the heads first, then to the intake and block. This alternate flow pattern supposedly provided better cooling and allowed GM to run higher compression ratios even with the iron head motors...like my 96 Caprice.

I guess the Dex Cool issue will continue. I am no longer afraid of the Dex as long as I change it more often with the cap. Thanks for the clarification.


I'd say you over-maintaining your coolant. Just make sure the level is correct periodically to ensure you have no leaks.

Oh I see. Well, it's definitely tough to argue with actual experience and the fact that the 4.3 is not known for it's robustness...is that a word?....can't really comment on your 5.7 problem.

On the reverse flow thing, originally the coolant flowed from the radiator into the block and then to the heads and intake (old style). Then in '92 the LT1 reverse flow showed up which rerouted the coolant from the radiator to the heads first, then to the intake and block. This alternate flow pattern supposedly provided better cooling and allowed GM to run higher compression ratios even with the iron head motors...like my 96 Caprice.

I guess the Dex Cool issue will continue. I am no longer afraid of the Dex as long as I change it more often with the cap. Thanks for the clarification.
Really, other than the intake manifold gaskets and the heater core, it has been the most reliable vehicle we have ever owned. It has never stranded us and it has been abused and worked (although maintained). Like I said, I don't think it is just Dexcool, but it is the coolant in conjunction with the engine design.

Did you use distilled water the 1st round? I've noticed in the past that the Dex ran issue free when mixed with distilled water. But if it doesn't give you that warm fuzzy feeling the green should be fine.

I always buy premixed 50/50 or use distilled water.

I'd say you over-maintaining your coolant. Just make sure the level is correct periodically to ensure you have no leaks.
You are probably right and now that I have replaced the water pump and I don't have to worry about loosing coolant, I may back off on the 2 years replacement and flush.

Really, other than the intake manifold gaskets and the heater core, it has been the most reliable vehicle we have ever owned. It has never stranded us and it has been abused and worked (although maintained). Like I said, I don't think it is just Dexcool, but it is the coolant in conjunction with the engine design.
Is the 4.3 motor the one that came in the S10 Blazers? My nephew had one of these and we replaced the head gaskets and manifold gaskets in that thing twice until it ate the bearings. We replaced the engine with a low mileage donor and 6 months later replaced the head gaskets and manifold gaskets. He traded it before the bearings gave up. Same deal with his friend's S10, but I wasn't involved in that gasket change. This is the reason I have an aversion to that engine. Swapping one of those babies is just plain hell!

You are probably right and now that I have replaced the water pump and I don't have to worry about loosing coolant, I may back off on the 2 years replacement and flush.


Is the 4.3 motor the one that came in the S10 Blazers? My nephew had one of these and we replaced the head gaskets and manifold gaskets in that thing twice until it ate the bearings. We replaced the engine with a low mileage donor and 6 months later replaced the head gaskets and manifold gaskets. He traded it before the bearings gave up. Same deal with his friend's S10, but I wasn't involved in that gasket change. This is the reason I have an aversion to that engine. Swapping one of those babies is just plain hell!
Thats interesting. Yes, the 4.3 is the same one as in the S10. It is basically a 350 (5.7) but with 2 cylinders cut off. My cousin has a 4.3 also, but in a Ext cab Silverado that has been used as a work truck and beat up and is still going strong also. I don't think gaskets have been replaced on that truck. Just alternator, cats, and a/c. Everyone I have talked to has had bulletproof reliability with the 4.3s.

My 02 GMC has done everything our Dmax has done (except hauling 12 8x8 fence posts in the bed) including pulling our 8,000 lb travel trailer in a pinch without trailer brakes. She ain't fast, but she gets the job done. :D

Thats interesting. Yes, the 4.3 is the same one as in the S10. It is basically a 350 (5.7) but with 2 cylinders cut off. My cousin has a 4.3 also, but in a Ext cab Silverado that has been used as a work truck and beat up and is still going strong also. I don't think gaskets have been replaced on that truck. Just alternator, cats, and a/c. Everyone I have talked to has had bulletproof reliability with the 4.3s.

My 02 GMC has done everything our Dmax has done (except hauling 12 8x8 fence posts in the bed) including pulling our 8,000 lb travel trailer in a pinch without trailer brakes. She ain't fast, but she gets the job done. :D
It's hard to pass judgement on probably a million engines based on the experience of two junkers, but I guess that's how we all do it.

I have always wanted to do a jeep project and engine consideration has always been the sticking point. I would really like to do a 4cyl. diesel swap but a nice little V6 is also appealing. The rub was which one of the V6s to use. I quickly disreagarded the 4.3 because of my experience. Maybe I can rethink this judgement. :D

I am doing a Jeep restoration with a 1947 Willy's Jeep CJ2a. I would love to swap a 4.3 in it. Wouldn't hesitate to do it. Although I would put a 5.3 in my truck and swap my 4.3 in the Jeep. More power for my truck and the Jeep. I am doing an Efan install this weekend.

I don't recommend running green antifreeze with the Duramax. We tried it back in the '04 timeframe in a hard working Duramax engine because of commonality with other diesel maintenance fluids and it didn't work out so well... Stick to Dexcool.

I am doing a Jeep restoration with a 1947 Willy's Jeep CJ2a. I would love to swap a 4.3 in it. Wouldn't hesitate to do it. Although I would put a 5.3 in my truck and swap my 4.3 in the Jeep. More power for my truck and the Jeep. I am doing an Efan install this weekend.
Cool! Jeeps are hard to come by here WV, and I haven't built my pole barn yet. It'll be a year or two before I can think about this, but I ain't givin' up!
I don't recommend running green antifreeze with the Duramax. We tried it back in the '04 timeframe in a hard working Duramax engine because of commonality with other diesel maintenance fluids and it didn't work out so well... Stick to Dexcool.
What kind of issues did you have with the green stuff? Over heating?

Any coolant with Propylene glycol such as AMSOIL or Sierra is good.

Absolutely, as long as it meets the ASTM D4985-98 spec for diesel service. I use Amsoil propylene glycol which is good for 250,000 miles or 7 years in a light duty truck (with testing) and is not toxic. That other ethylene glycol stuff is poisonous and considered hazardous waste. I had the system flushed and refilled by a radiator shop for $150, well worth the cost because I didn't have to dispose of the used toxic stuff.