Yet another c5 overheating problem...HELP!
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From: Westlake Village CA
Le Mans Master
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From: OK
Just how easy is it to take the radiator out? It looks like a pain in the ***. I'm assuming it slides out the top? Is it bolted to the fan shrouds anywhere?
My drain valve on the radiator is busted. It doesn't leak, but I cant' open it now. When I did a flush a couple years ago, there wasn't any sludge or particles present.
My drain valve on the radiator is busted. It doesn't leak, but I cant' open it now. When I did a flush a couple years ago, there wasn't any sludge or particles present.
Le Mans Master
Joined: Feb 2012
Posts: 6,644
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From: OK
It is a bit of a PIA. You need to get under the car to be able to disconnect all the electrical cables for the fans and pop the wires free of their hold downs on the fan housing/shroud. Disconnect the hoses from the radiator while you are there and since you cannot drain the radiator through the drain **** expect a bigger mess than ususal.... Then you need to pull the fans and radiator out the top ( have to remove the cover over the radiator but that is only 4 bolts.) The fans are held to the radiator by the shroud clipping into tabs on the radiator. Easiest to have two people lift the fans and radiator out to avoid damage to the fender paint but can be done by just one person. Protect the top of the fenders.....
Pro
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Took thermostat out with old pump still in place - no flow.
Replaced water pump with new pump, re filled with coolant - no flow.
It has to be an air pocket and the pump is not picking up the coolant. I'm just going to have to fight it until it finally takes the coolant and purges the air out. I love this car, but it can be a BIG pain in the *** sometimes.
Replaced water pump with new pump, re filled with coolant - no flow.
It has to be an air pocket and the pump is not picking up the coolant. I'm just going to have to fight it until it finally takes the coolant and purges the air out. I love this car, but it can be a BIG pain in the *** sometimes.
Burning Brakes
Joined: Dec 2011
Posts: 858
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From: Medford, Oregon
JThiesen, any updates on determining what was wrong with your cooling system issue yet !! 
As to the the prior post by CritiicalmassGT, it would be worth removing your stat again and do a power flush (garden hose full blast) . You might as well do your heater hoses as well as your block and see what that produces. Jus Say'n !!
Last edited by 2FAS4UU; Apr 23, 2015 at 05:34 PM.
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From: Westlake Village CA
JThiesen, any updates on determining what was wrong with your cooling system issue yet !! As to the the prior post by CritiicalmassGT, it would be worth removing your stat again and do a power flush (garden hose full blast) . You might as well do your heater hoses as well as your block and see what that produces. Jus Say'n !!I went ahead and ordered an aluminum 2-core radiator because, if I'm going to go to the trouble of tearing it all apart, I'm just going to get a new one to rule out a radiator problem. Plus, the fins are jammed with crap just like everyone says. Getting a 2-core is only going to help it run cooler overall.
I brushed the A/C condenser and then gently banged on the top to dislodge stuff. I could not believe how much junk came out of it!! It wouldn't stop! Tons and tons of tiny rocks, dirt, leaf particles, etc. My A/C should blow colder after this now too!
Radiator comes in some time next week. After I put it all together, I'll give an update. I pray that this solves the problem. If it doesn't, I don't know what else to do. If the block didn't flow very well, I could understand that I have a blockage, but that doesn't appear to be the case. No sludge or debris came out of the radiator or block at all, and the purge tank doesn't any have sludge on the bottom either.
Gonna put a new upper and lower hose on it, just because. She's got 101,000 miles on her now and it couldn't hurt.
Crossing my fingers this does it!
Safety Car
Joined: Dec 2009
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From: Birmingham Al
Here's my dilemma.
One year ago at about 85K miles, my 2000 started to overheat. It came on suddenly. One day it was running fine, next day the temps skyrocketed into the red, even while driving on the freeway. I replaced the thermostat but likely did not purge (burp) the system properly and was still having the same exact issue. So, I replaced the water pump with a Bosch pump. I refilled and burped the system as instructed and bam, no more overheating issues. The car ran perfect as before. When the temp would hit 230, the fans would hit high and drop in back down to 220. While driving, it rarely would go over 200. I realize that if I had burped the system when I replaced the thermostat, it would have likely been fine and not needed the water pump. Lesson learned. The water pump was not leaking or making noise. When I took it off, it spun just fine and the impeller didn't appear to be clogged. I replaced it anyway.
Now, again, at 101K miles, the car is all of a sudden overheating. Only this time, it will stay cool while driving, but then overheat in traffic. Once the temp hits 220, it skyrockets up past 240 and both fans turn on high but the temp will continue to slowly creep up to the red. I took the radiator cover off and there was a good amount of debris. I bought a long BBQ grill brush that would fit down in between the condenser and the radiator and brushed all that crap out of there and off the front of the condenser. I still had the same problem. Then I replaced the thermostat and burped the system. I still have the same problem.
If it's debris still stuck in the radiator fins, wouldn't I see temps gradually increasing over time instead of all of a sudden? Also, the water pump is only a year old. Now, this doesn't mean it can't fail, but I'm thinking that the radiator is possibly clogged inside and/or the fins are probably still full of junk that the brush didn't get out. Both hoses are hot with the one near the thermostat being hotter as it should. The fact that it runs at normal temps while driving leads me to believe it's not the pump.
I don't want to spend money I don't have to. From what I've described, what do you think it is? Radiator problem or the water pump again? Is there any way to clean out the radiator without pulling it? The fans appear to be turning on at the correct temps. I did the water pump myself and it was a bitch to get the gaskets lined up and a couple of the bolts back in, but an hour or so and many curse words, I got it all together. I used the opportunity to replace all of the idler pulleys as they were easily accessible with the water pump off.
Your input and experience is appreciated. She'll have to sit in the driveway until I can figure it out.
One year ago at about 85K miles, my 2000 started to overheat. It came on suddenly. One day it was running fine, next day the temps skyrocketed into the red, even while driving on the freeway. I replaced the thermostat but likely did not purge (burp) the system properly and was still having the same exact issue. So, I replaced the water pump with a Bosch pump. I refilled and burped the system as instructed and bam, no more overheating issues. The car ran perfect as before. When the temp would hit 230, the fans would hit high and drop in back down to 220. While driving, it rarely would go over 200. I realize that if I had burped the system when I replaced the thermostat, it would have likely been fine and not needed the water pump. Lesson learned. The water pump was not leaking or making noise. When I took it off, it spun just fine and the impeller didn't appear to be clogged. I replaced it anyway.
Now, again, at 101K miles, the car is all of a sudden overheating. Only this time, it will stay cool while driving, but then overheat in traffic. Once the temp hits 220, it skyrockets up past 240 and both fans turn on high but the temp will continue to slowly creep up to the red. I took the radiator cover off and there was a good amount of debris. I bought a long BBQ grill brush that would fit down in between the condenser and the radiator and brushed all that crap out of there and off the front of the condenser. I still had the same problem. Then I replaced the thermostat and burped the system. I still have the same problem.
If it's debris still stuck in the radiator fins, wouldn't I see temps gradually increasing over time instead of all of a sudden? Also, the water pump is only a year old. Now, this doesn't mean it can't fail, but I'm thinking that the radiator is possibly clogged inside and/or the fins are probably still full of junk that the brush didn't get out. Both hoses are hot with the one near the thermostat being hotter as it should. The fact that it runs at normal temps while driving leads me to believe it's not the pump.
I don't want to spend money I don't have to. From what I've described, what do you think it is? Radiator problem or the water pump again? Is there any way to clean out the radiator without pulling it? The fans appear to be turning on at the correct temps. I did the water pump myself and it was a bitch to get the gaskets lined up and a couple of the bolts back in, but an hour or so and many curse words, I got it all together. I used the opportunity to replace all of the idler pulleys as they were easily accessible with the water pump off.
Your input and experience is appreciated. She'll have to sit in the driveway until I can figure it out.
Burning Brakes
Joined: Dec 2011
Posts: 858
Likes: 75
From: Medford, Oregon
I pulled the radiator today. I flushed both the radiator and the engine without the thermostat on with a garden hose, full blast. Both cleared and flowed just fine. I noticed that the engine flowed more than the radiator, though. The block could have taken more water pressure and been just fine so I don't think it's the block or heads.
I went ahead and ordered an aluminum 2-core radiator because, if I'm going to go to the trouble of tearing it all apart, I'm just going to get a new one to rule out a radiator problem. Plus, the fins are jammed with crap just like everyone says. Getting a 2-core is only going to help it run cooler overall.
I brushed the A/C condenser and then gently banged on the top to dislodge stuff. I could not believe how much junk came out of it!! It wouldn't stop! Tons and tons of tiny rocks, dirt, leaf particles, etc. My A/C should blow colder after this now too!
Radiator comes in some time next week. After I put it all together, I'll give an update. I pray that this solves the problem. If it doesn't, I don't know what else to do. If the block didn't flow very well, I could understand that I have a blockage, but that doesn't appear to be the case. No sludge or debris came out of the radiator or block at all, and the purge tank doesn't any have sludge on the bottom either.
Gonna put a new upper and lower hose on it, just because. She's got 101,000 miles on her now and it couldn't hurt.
Crossing my fingers this does it!
I went ahead and ordered an aluminum 2-core radiator because, if I'm going to go to the trouble of tearing it all apart, I'm just going to get a new one to rule out a radiator problem. Plus, the fins are jammed with crap just like everyone says. Getting a 2-core is only going to help it run cooler overall.
I brushed the A/C condenser and then gently banged on the top to dislodge stuff. I could not believe how much junk came out of it!! It wouldn't stop! Tons and tons of tiny rocks, dirt, leaf particles, etc. My A/C should blow colder after this now too!
Radiator comes in some time next week. After I put it all together, I'll give an update. I pray that this solves the problem. If it doesn't, I don't know what else to do. If the block didn't flow very well, I could understand that I have a blockage, but that doesn't appear to be the case. No sludge or debris came out of the radiator or block at all, and the purge tank doesn't any have sludge on the bottom either.
Gonna put a new upper and lower hose on it, just because. She's got 101,000 miles on her now and it couldn't hurt.
Crossing my fingers this does it!
Hey brother, I hope you get this resolved with the purchase of the new radiator. I was chuckling when you explained what you were finding upon trying to clean the cores, you now have first hand experience and can validate what all of us have tried to explain to others. Anyway, good luck with the new install and keep us posted on the results !! The weird thing about cleaning the cores was that I got three times the amount of crap from the radiator core than the A/C core, go figure, it might be from the hot and cold cycling and baking the _hit in between the vanes. 
By the way, good call on getting new hoses !!
Last edited by 2FAS4UU; Apr 24, 2015 at 01:34 PM.
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Safety Car
Joined: Dec 2009
Posts: 4,360
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From: Birmingham Al
Use the same stuff you would use in a Coffee pot inside the thing ,my wife uses Vinegar and hot water so stop up the bottom hole pour it in let it soak sit for awhile and flush it or CLR type stuff I bet it's got build up in side also.. The flews inside the radiators are VERY VERY small it does not take much to slow the flow down and bam over heat.. Been working with old Corvettes 30+ years the cooling is all wrong in the first place on the deal so if you got 10-20 % stopped up well you got Prop. more so on a reg car.. Just saying been there do that and spent big money tiring to fix everything but the radiator and learned one big lesion have to make sure it all cleaned out them spend big money on the rest WHY that may not fix it but the first place to start.. JUST AN FYI
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
I pulled the radiator today. I flushed both the radiator and the engine without the thermostat on with a garden hose, full blast. Both cleared and flowed just fine. I noticed that the engine flowed more than the radiator, though. The block could have taken more water pressure and been just fine so I don't think it's the block or heads.
I went ahead and ordered an aluminum 2-core radiator because, if I'm going to go to the trouble of tearing it all apart, I'm just going to get a new one to rule out a radiator problem. Plus, the fins are jammed with crap just like everyone says. Getting a 2-core is only going to help it run cooler overall.
I brushed the A/C condenser and then gently banged on the top to dislodge stuff. I could not believe how much junk came out of it!! It wouldn't stop! Tons and tons of tiny rocks, dirt, leaf particles, etc. My A/C should blow colder after this now too!
Radiator comes in some time next week. After I put it all together, I'll give an update. I pray that this solves the problem. If it doesn't, I don't know what else to do. If the block didn't flow very well, I could understand that I have a blockage, but that doesn't appear to be the case. No sludge or debris came out of the radiator or block at all, and the purge tank doesn't any have sludge on the bottom either.
Gonna put a new upper and lower hose on it, just because. She's got 101,000 miles on her now and it couldn't hurt.
Crossing my fingers this does it!
I went ahead and ordered an aluminum 2-core radiator because, if I'm going to go to the trouble of tearing it all apart, I'm just going to get a new one to rule out a radiator problem. Plus, the fins are jammed with crap just like everyone says. Getting a 2-core is only going to help it run cooler overall.
I brushed the A/C condenser and then gently banged on the top to dislodge stuff. I could not believe how much junk came out of it!! It wouldn't stop! Tons and tons of tiny rocks, dirt, leaf particles, etc. My A/C should blow colder after this now too!
Radiator comes in some time next week. After I put it all together, I'll give an update. I pray that this solves the problem. If it doesn't, I don't know what else to do. If the block didn't flow very well, I could understand that I have a blockage, but that doesn't appear to be the case. No sludge or debris came out of the radiator or block at all, and the purge tank doesn't any have sludge on the bottom either.
Gonna put a new upper and lower hose on it, just because. She's got 101,000 miles on her now and it couldn't hurt.
Crossing my fingers this does it!
Sounds like a good plan, be looking forward to seeing how your running around 198 degrees.... and able to go where ever, when ever you want!
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From: Westlake Village CA
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From: Westlake Village CA
It may be that I have a Stant Thermostat. I'm pretty sure that's what Pep Boys sold me. I've heard a lot about these "fail safe" thermostats not letting the car burp properly and to cut the two clips that keep the thermostat open in this scenario. I'll look into at that as well.
Radiator should be here in a couple days, then it all goes back together and I cross my fingers.
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From: Westlake Village CA
Question for you guys. I get the idea of what the surge tank cap does and why it has a pressure relief, but if it fails, what kind of symptoms would this cause. Just wondering. I'm more talking about the pressure valve failing then the cap leaking which would be an obvious easy fix. However if it's leaking, it could be sucking in air and causing air in the system, no?
Damn these cars are finicky as hell! But, worth it.
Damn these cars are finicky as hell! But, worth it.
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From: Westlake Village CA
The pressure cap on the cooling system acts as a 2 way valve. As the coolant gets hot ( above 212 degrees F) it expands. The valve on the cap should close to allow pressure to build on the system. Each pound of pressure raises the boiling point of the coolant by about 3 degrees F. The pressure is limited to the rating of the cap, usually 15 to 18 pounds. Above that the coolant would flow out from the tank around the cap. In a correctly operating cooling system the pressure should reach the max (usually LESS than the cap rating) shortly after the engine is shut off due to the heat sink effect that occurs from a hot engine without coolant flow.
For the cost of a new cap, given your new parts and as yet unknown heating cause, I would but one and install it when the new parts are installed. Probably about $15.
As the coolant cools below 212 degrees F the valve opens and allows atmospheric pressure back into the system on top of the coolant.
If the cap fails to hold pressure the coolant may flow out around the cap and this should be obvious if it happens.
If the valve fails to open on the cooling then there will be a suction formed inside the cooling system. This causes the air that was on top of the coolant to be sucked into the system and it often causes one of the radiator hoses to get sucked closed (ie the walls of the hose squeeze together and may actually touch.
Once the air that was supposed to be ontop of the coolant is sucked into the system the car will usually overheat very quickly when the engine is started cold. The air cannot adequately extract heat from the engine so rapid heating occurs and hence the engine temp rises very quickly.
For the cost of a new cap, given your new parts and as yet unknown heating cause, I would but one and install it when the new parts are installed. Probably about $15.
As the coolant cools below 212 degrees F the valve opens and allows atmospheric pressure back into the system on top of the coolant.
If the cap fails to hold pressure the coolant may flow out around the cap and this should be obvious if it happens.
If the valve fails to open on the cooling then there will be a suction formed inside the cooling system. This causes the air that was on top of the coolant to be sucked into the system and it often causes one of the radiator hoses to get sucked closed (ie the walls of the hose squeeze together and may actually touch.
Once the air that was supposed to be ontop of the coolant is sucked into the system the car will usually overheat very quickly when the engine is started cold. The air cannot adequately extract heat from the engine so rapid heating occurs and hence the engine temp rises very quickly.
Also, does anyone have pics of a Stant thermostat with the "fail safe" clips that cause problems burping the system? I fully inspected mine and I can't see any. The thermostat doesn't say Stant on it anywhere either. The box went in the trash and I can't remember what brand it was.
Thanks!
Le Mans Master
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From: OK
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From: Westlake Village CA
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From: Westlake Village CA
She's alive.....ALIVE!!!!
Radiator came today. I had bought it on eBay, looked good and the business had great feedback ratings. When it arrived, it was exactly as pictured, good welds, solid, no epoxy, etc.
It fit pretty well, I had to coax it here and there and bend the aluminum tabs that holds the fans a little to get them to seat properly. All in all, going in wasn't too bad. I reconnected everything and began filling it with coolant. It took 2 gallons right off without even starting it. Once the surge tank was full, I said a prayer and then started the car. It slowly crept up to 180F and once there, the surge tank was drained. I began pouring in another gallon and it took all of it. The capacity is 12.6 quarts or 3.15 gallons. The 2 row radiator should have taken a little more coolant, but there was still some water in the block and heads from when I had purged out the system.
It's about 82F here today in So Cal where I'm at. The car sat and idled for 20 minutes at 180F without climbing with the hood open. It's never done that, that's a new (and 2 core at that) radiator for you. Once I closed the hood, the temp slowly rose to 220F and held for another 15 minutes, the fan didn't even come on. I turned on the max A/C and the temp shot up to 225 right away, but then quickly went down to about 210F and held. With it on normal A/C, it sits just under 220F idling in 82F weather.
I road tested it and it never went over 200F.
All in all a success. About 5-6 hours labor doing it myself and a lot of cussing at times. :P Now to check the transmission and see if it needs a top off from filling the new radiator with fluid.
So far, very satisfied and certainly relieved.
I likely didn't need a pump or thermostat, but I have the peace of mind that the entire cooling system, minus a few of the small hoses, is brand new.
I am going to install a screen under the car. The amount of crap that came out of the A/C condenser was unbelievable and I know I didn't even get all of it out. Going to go with a finer screen if I can other than what I've seen pre made. That will only keep leaves and twigs out for the most part. It would be nice to keep out the smaller debris as well, but I don't want to interrupt flow of air in any way.
Do you guys think that screen, like on a screen door, would be ok to use or would it block too much airflow?
Thanks again for all your help and advice everyone!
It fit pretty well, I had to coax it here and there and bend the aluminum tabs that holds the fans a little to get them to seat properly. All in all, going in wasn't too bad. I reconnected everything and began filling it with coolant. It took 2 gallons right off without even starting it. Once the surge tank was full, I said a prayer and then started the car. It slowly crept up to 180F and once there, the surge tank was drained. I began pouring in another gallon and it took all of it. The capacity is 12.6 quarts or 3.15 gallons. The 2 row radiator should have taken a little more coolant, but there was still some water in the block and heads from when I had purged out the system.
It's about 82F here today in So Cal where I'm at. The car sat and idled for 20 minutes at 180F without climbing with the hood open. It's never done that, that's a new (and 2 core at that) radiator for you. Once I closed the hood, the temp slowly rose to 220F and held for another 15 minutes, the fan didn't even come on. I turned on the max A/C and the temp shot up to 225 right away, but then quickly went down to about 210F and held. With it on normal A/C, it sits just under 220F idling in 82F weather.
I road tested it and it never went over 200F.
All in all a success. About 5-6 hours labor doing it myself and a lot of cussing at times. :P Now to check the transmission and see if it needs a top off from filling the new radiator with fluid.
So far, very satisfied and certainly relieved.
I likely didn't need a pump or thermostat, but I have the peace of mind that the entire cooling system, minus a few of the small hoses, is brand new.
I am going to install a screen under the car. The amount of crap that came out of the A/C condenser was unbelievable and I know I didn't even get all of it out. Going to go with a finer screen if I can other than what I've seen pre made. That will only keep leaves and twigs out for the most part. It would be nice to keep out the smaller debris as well, but I don't want to interrupt flow of air in any way.
Do you guys think that screen, like on a screen door, would be ok to use or would it block too much airflow?
Thanks again for all your help and advice everyone!