92 civic vx overheating when cold outside (40°F) after 20 minutes driving at 75 mph
03-17-2007, 05:13 PM
#1
92 civic vx overheating when cold outside (40°F) after 20 minutes driving at 75 mph
<U>Update</U>: New radiator seems to have resolved the overheating issue. No change in temperature on the gauge going uphill at 75 MPH after 30 minutes at sustained speed. I hope that this cures all that was wrong. I will add to the thread if anything changes.
I have a 92 VX with 152K miles. On March 9, it nearly overheated on the highway - the gauge reached hot and I luckily saw it and got off the interstate. It was 50°F outside that day.
During the past week I replaced the thermostat with an OEM Honda part and replaced the timing belt and water pump with OEM Honda parts - needed to anyway since it was time. I pressure tested the radiator cap with a loaner tool from Autozone- no issues there.
All I can think of is there is some restriction somewhere in coolant flow when the engine is running at 2500 RPM under load at high speed Turning on the heater full blast did reduce the temperature to normal today but this technique was less effective when the outside temperature hit 50°F like it did on March 7 when it nearly overheated the first time. Turning on the heater did reduce the coolant temp but only to the 3/4 mark.
What's really odd is what happened today. As I said, the outside temperature peaked at 40°F today and it took 20 minutes for the temperature gauge to move over the halfway point. When I stopped to check the upper and lower radiator hoses both were warm / hot - the upper was hotter as expected. I touched the radiator about halfway down its surface and it was cold???? Shouldn't the radiator be at least a little warm to the touch if both hoses are hot/warm???
What I would like to know is: Can a clogged radiator restrict flow enough to result in the radiator surface to not heat up at highway speed or is it just that the radiator surface temp is always the same as the outside temp when moving fast? It's almost as if there is not enough coolant passing through the radiator per unit of time to warm the radiator fins. I wish I had a way to check the temperature of the radiator core while at speed. It could be that the radiator does cool off the reduced coolant flow quite well but there's just not enough of it to keep the rest of the coolant in the engine at the right temperature. Just thinking out loud here. I may have this all wrong.
This is my last best hope in solving this mystery since this car has never overheated before. The radiator may be original - I bought the car two years ago. I hope the head gasket isn't leaking. There is no evidence that it is. The coolant level does not decrease. No white smoke. No change in the color of the oil. No white goo anywhere.
I guess the next idea will be to go to a radiator shop that can test for evidence of combustion gas residue in the coolant overflow tank. I sure hope it's not there!!!!!!
Modified by jadziasman at 11:31 AM 3/24/2007
I have a 92 VX with 152K miles. On March 9, it nearly overheated on the highway - the gauge reached hot and I luckily saw it and got off the interstate. It was 50°F outside that day.
During the past week I replaced the thermostat with an OEM Honda part and replaced the timing belt and water pump with OEM Honda parts - needed to anyway since it was time. I pressure tested the radiator cap with a loaner tool from Autozone- no issues there.
All I can think of is there is some restriction somewhere in coolant flow when the engine is running at 2500 RPM under load at high speed Turning on the heater full blast did reduce the temperature to normal today but this technique was less effective when the outside temperature hit 50°F like it did on March 7 when it nearly overheated the first time. Turning on the heater did reduce the coolant temp but only to the 3/4 mark.
What's really odd is what happened today. As I said, the outside temperature peaked at 40°F today and it took 20 minutes for the temperature gauge to move over the halfway point. When I stopped to check the upper and lower radiator hoses both were warm / hot - the upper was hotter as expected. I touched the radiator about halfway down its surface and it was cold???? Shouldn't the radiator be at least a little warm to the touch if both hoses are hot/warm???
What I would like to know is: Can a clogged radiator restrict flow enough to result in the radiator surface to not heat up at highway speed or is it just that the radiator surface temp is always the same as the outside temp when moving fast? It's almost as if there is not enough coolant passing through the radiator per unit of time to warm the radiator fins. I wish I had a way to check the temperature of the radiator core while at speed. It could be that the radiator does cool off the reduced coolant flow quite well but there's just not enough of it to keep the rest of the coolant in the engine at the right temperature. Just thinking out loud here. I may have this all wrong.
This is my last best hope in solving this mystery since this car has never overheated before. The radiator may be original - I bought the car two years ago. I hope the head gasket isn't leaking. There is no evidence that it is. The coolant level does not decrease. No white smoke. No change in the color of the oil. No white goo anywhere.
I guess the next idea will be to go to a radiator shop that can test for evidence of combustion gas residue in the coolant overflow tank. I sure hope it's not there!!!!!!
Modified by jadziasman at 11:31 AM 3/24/2007
03-17-2007, 06:00 PM
#4
Re: (ARMED)
Wow, I didn't expect replies this fast. Thanks guys and kudos to the amazing honda-tech forum - don't fix a Honda without looking at the posts!
I would buy a radiator if I was sure it would do the trick. An OEM Honda radiator is $250.00. I wouldn't want to guess wrong on a $1000 car. I forgot to mention that I replaced the coolant and upper and lower radiator hoses in September 2006 and have had no trouble up till now.
Yes. The radiator cooling fan works. The radiator temp has to go up enough to turn the fan on which it did on March 9 when it got so hot - I watched it spin.
To be more clear. I replaced the parts myself. One reason I have this old Honda is it is a bit of a hobby car in addition to being my daily driver. If for some reason I really screw up a repair I'm only out a thousand dollars or so.
Anything else I can think of? I know all parts were installed right. I have a Helm manual which is pretty good of showing what to do. Not everything though, still need to use the gray matter!
I would buy a radiator if I was sure it would do the trick. An OEM Honda radiator is $250.00. I wouldn't want to guess wrong on a $1000 car. I forgot to mention that I replaced the coolant and upper and lower radiator hoses in September 2006 and have had no trouble up till now.
Yes. The radiator cooling fan works. The radiator temp has to go up enough to turn the fan on which it did on March 9 when it got so hot - I watched it spin.
To be more clear. I replaced the parts myself. One reason I have this old Honda is it is a bit of a hobby car in addition to being my daily driver. If for some reason I really screw up a repair I'm only out a thousand dollars or so.
Anything else I can think of? I know all parts were installed right. I have a Helm manual which is pretty good of showing what to do. Not everything though, still need to use the gray matter!
03-18-2007, 07:07 AM
#6
Re: (stripes777)
Thanks for the idea, stripes777 - but the Autozone near me in Michigan does not stock a dual core radiator for $99 - too bad!
Well, I decided to get a cheap ebay radiator ($42 shipped) just to test if it's the problem. The OEM Honda radiator I have on the car now has bent fins all over the lower 1/3 since there is no screen on the front bumper cover to prevent debris from hitting the radiator. So if you really come down to it, I probably needed to replace the current radiator before too long anyway. Old cars are like old houses -something is always needs repair.
Unlike other posters I will provide a final update to this strange overheating problem if and when I can figure this out.
Well, I decided to get a cheap ebay radiator ($42 shipped) just to test if it's the problem. The OEM Honda radiator I have on the car now has bent fins all over the lower 1/3 since there is no screen on the front bumper cover to prevent debris from hitting the radiator. So if you really come down to it, I probably needed to replace the current radiator before too long anyway. Old cars are like old houses -something is always needs repair.
Unlike other posters I will provide a final update to this strange overheating problem if and when I can figure this out.
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