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I have a 2000 gmc Sonoma 4wd 4.3l v6 and it only overheats when Im stopped for period of time like at a busy drive through with the ac on, anybody know what this could be? I was thinking water pump maybe?
 

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I had the same issue with both of my 03 Sonoma with 4.3 and my 04 Blazer. The solution I found that works best I upgraded to the three row aluminum radiator and went from a 195 thermostat to a 180 after that I had no more heating issues. The aluminum radiators are decent price on eBay and they do work I have them in all my vehicles. I just had one recently fail and that was after five and a half years of use. Also check your clutch fan it may be on its way out.
 

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I had the same issue with both of my 03 Sonoma with 4.3 and my 04 Blazer. The solution I found that works best I upgraded to the three row aluminum radiator and went from a 195 thermostat to a 180 after that I had no more heating issues. The aluminum radiators are decent price on eBay and they do work I have them in all my vehicles. I just had one recently fell and that was after five and a half years of use. Also check your clutch fan it may be on its way out.
Well dang I just put a brand new radiator in it haha I should probably start with the clutch fan since I have a brand new, just never put it on by any chance could it be the water pump?
 

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Well dang I just put a brand new radiator in it haha I should probably start with the clutch fan since I have a brand new, just never put it on by any chance could it be the water pump?
It could be but I would check the clutch fan first. Wait till your truck is nice and hot and see how stiff the resistance is if it's really loose it's toast. If not it could be the water pump not that hard to change and not that expensive to buy now and they all come with a lifetime warranty.
 

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It could be but I would check the clutch fan first. Wait till your truck is nice and hot and see how stiff the resistance is if it's really loose it's toast. If not it could be the water pump not that hard to change and not that expensive to buy now and they all come with a lifetime warranty.
Ok sweet, I’ll start with the fan clutch, then go to the water pump and then if those don’t work I’ll order the 3 row core radiator, is this the one you’re talking about?
351635
 

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Yes that looks like it I just put one in my blazer today here's a picture. For the oil cooler fittings the little nipple on the back side of the fitting will need to be cut off for it to fit in the aluminum radiator. Are you usually use the large step bit and drill into it until that nipples gone and it's flat. And you will go from a gallon and a half of antifreeze to about 2 and 3/4 gallons of antifreeze with the aluminum radiator.

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Sorry didn’t mean to reply with nothing haha, so I have to drill the fitting itself or the radiator? And does it come with fittings?
 

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Sorry didn’t mean to reply with nothing haha, so I have to drill the fitting itself or the radiator? And does it come with fittings?
Yes in to the back side of the oil cooler fitting. For the antifreeze I usually buy the full strength then cut it in half with a gallon of distilled water. It is cheaper to buy the full strength then dilute it with distilled water then you get 2 gallons for a for less than what you would pay for one 50/50 mix of antifreeze.
 

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Yes in to the back side of the oil cooler fitting. For the antifreeze I usually buy the full strength then cut it in half with a gallon of distilled water. It is cheaper to buy the full strength then dilute it with distilled water then you get 2 gallons for a for less than what you would pay for one 50/50 mix of antifreeze.
Ah ok I gotcha, that’ll be what I’ll have to do if it comes to it, don’t really want to have to drill it, I appreciate all the help man!
 

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Alright cool, thank you, just to be clear, I need to drill the fitting itself or the hole in the radiator where the fitting threads into?
No the oil cooler fitting that screws into the radiator that you push lock the cooler lines into. It looks like this.

Remove the back side off of this where the black o-ring is . Make it completely flat.
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No the oil cooler fitting that screws into the radiator that you push lock the cooler lines into. It looks like this.

Remove the back side off of this where the black o-ring is . Make it completely flat.
View attachment 351640
Alright sweet thank you, do I need to do that with all 4 or just the 2 to the engine oil cooler lines? I changed the radiator today and saw that the transmission cooler lines didn’t have that nipple and the i ring was inside so I’m guessing just the engine oil cooler lines?
 

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Alright sweet thank you, do I need to do that with all 4 or just the 2 to the engine oil cooler lines? I changed the radiator today and saw that the transmission cooler lines didn’t have that nipple and the i ring was inside so I’m guessing just the engine oil cooler lines?
Just the oil cooler fittings. The trans cooler fittings go right in without issue make sure to be real generous with the Teflon tape to make sure you have no leaks. Lately I've been using fast tape it works a lot better than Teflon tape.
1/2 in. x 260 in. PTFE Thread Seal Tape - - Amazon.com
Oatey Fastape 1/2 in. x 260 in. Thread Sealing PTFE Plumber's Tape-306212 - The Home Depot
 

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Just the oil cooler fittings. The trans cooler fittings go right in without issue make sure to be real generous with the Teflon tape to make sure you have no leaks. Lately I've been using fast tape it works a lot better than Teflon tape.
1/2 in. x 260 in. PTFE Thread Seal Tape - - Amazon.com
Oatey Fastape 1/2 in. x 260 in. Thread Sealing PTFE Plumber's Tape-306212 - The Home Depot
Great thank you, so use a big enough drill bit that won’t go in but will drill off the nipple just far enough until the threads start, then wrap it in fast tape very well to basically replace the o ring and tighten down like I usually would? I’m guessing you’ve had no leaks with drilling it off and adding the tape?
 

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Great thank you, so use a big enough drill bit that won’t go in but will drill off the nipple just far enough until the threads start, then wrap it in fast tape very well to basically replace the o ring and tighten down like I usually would? I’m guessing you’ve had no leaks with drilling it off and adding the tape?
I used the bit in the middle in the picture below. I drilled down until the nipple that held the black o-ring on the bottom of the fitting was gone no further than that.


 

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Be fore you go buying a rad, is your shroud complete and installed? Including the little side pieces at the side of the radiator covering the gap to the rad support. You want as much air as possible to go thru, not around, the radiator and fan.
A stock 4.3 should be able to sit quite a while in hot weather w/o overheating with all the stock components working. 1000's of them do every day in CA, FL, and AZ w/o problems.
 

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Be fore you go buying a rad, is your shroud complete and installed? Including the little side pieces at the side of the radiator covering the gap to the rad support. You want as much air as possible to go thru, not around, the radiator and fan.
A stock 4.3 should be able to sit quite a while in hot weather w/o overheating with all the stock components working. 1000's of them do every day in CA, FL, and AZ w/o problems.
But that's not what the cool kids want.
 
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