Overheating with A/C on...
06-28-02, 11:54 PM
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Overheating with A/C on...
There was a post recently where several shared overheating, or running warmer than usual, with the A/C on at speed. I had a similar situation which I've "slightly" resolved.
A bit of background on my setup...I run a Fluidyne radiator, AST removed (for 30K miles now!), about a 60/40 mix of brand new, just flushed the system, coolant to water ratio with two bottles of Redline water wetter added. On the highway, above 70mph, the temps would rise to about 98 degrees C and stay put. Any traffic would cause it to go up to 100 unless I shut the A/C off.
Recently I did two things which made an improvement. The first was to replace the radiator cap (.9 bar) with a 1.3 bar cap which lowered my temps about 5-8 degrees C. The second was the addition of an aftermarket front end with a wider radiator opening. The combination of the two produced 93 degrees at the highest, usually 85-87 in city driving.
Additionally, I'm replacing a worn water pump belt. I'm running the GReddy airpump elimination kit so I've had to wait a bit to get the right belt delivered. Some have also theorized that the GReddy kit may not help as it slows the water pump down. I don't have an answer to that one yet.
The last modification I am making is to seal off the sides of the radiator. There's enough space in there to let air out the sides.
What concerns me is that my problem seemed to come on without anything changing. It happened some time after replacing the stock radiator, but not immediately. Either I had/have air in the system (the flush should have gotten it out, no?) or I initially didn't run enough coolant (10% at first with Royal Purple, Purple Ice) and may have damaged the waterpump bearings. While the pump is not leaking, it has a veeeeeery slight amount of play in the shaft. Perhaps .5mm at most. I thought perhaps the a/c belt was too tight as well, but that doesn't seem to be an issue. Perhaps the a/c unit itself, when engaged, is dragging excessively? With the belt off (engine off naturally), it turns quite freely, but the clutch is not engaged. If anyone else has ideas/concepts they'd like to share, I'd appreciate it!. Oh, stop and go city traffic doesn't seem to bother it as much, even with the a/c on. In the good ol days, I could turn the a/c on and my temps would actually drop due to both fans coming on. I've checked the fans, and both go on high speed with the a/c on. Additionally, I have the Datalogit for the PFC and have lowered the "on" temps for the three fan settings.
One waaaay out there theory I have, one that sort of sychs with the increase in water temps, is the addition of a vented hood. It seems to work very well at lower speeds, but could it be possible that the addition of these vents may disrupt the airflow in the engine compartment? I've run two vented hoods (mazdaspeed, and now Knightsports). The first time I noticed such a problem was on my trip up to MADS last fall. I installed the hood THAT morning, before leaving on the trip. After leaving from Nick Riefner's house, we ran into traffic on I-4 in Orlando (imagine that). My temps eventually got up to 103 degrees before I bit the bullet, shut of the a/c and opened the windows. Not a fun thing to do in August in Florida, LOL. If I can bring myself to do it, I may throw on the stock hood to test the theory.
A bit of background on my setup...I run a Fluidyne radiator, AST removed (for 30K miles now!), about a 60/40 mix of brand new, just flushed the system, coolant to water ratio with two bottles of Redline water wetter added. On the highway, above 70mph, the temps would rise to about 98 degrees C and stay put. Any traffic would cause it to go up to 100 unless I shut the A/C off.
Recently I did two things which made an improvement. The first was to replace the radiator cap (.9 bar) with a 1.3 bar cap which lowered my temps about 5-8 degrees C. The second was the addition of an aftermarket front end with a wider radiator opening. The combination of the two produced 93 degrees at the highest, usually 85-87 in city driving.
Additionally, I'm replacing a worn water pump belt. I'm running the GReddy airpump elimination kit so I've had to wait a bit to get the right belt delivered. Some have also theorized that the GReddy kit may not help as it slows the water pump down. I don't have an answer to that one yet.
The last modification I am making is to seal off the sides of the radiator. There's enough space in there to let air out the sides.
What concerns me is that my problem seemed to come on without anything changing. It happened some time after replacing the stock radiator, but not immediately. Either I had/have air in the system (the flush should have gotten it out, no?) or I initially didn't run enough coolant (10% at first with Royal Purple, Purple Ice) and may have damaged the waterpump bearings. While the pump is not leaking, it has a veeeeeery slight amount of play in the shaft. Perhaps .5mm at most. I thought perhaps the a/c belt was too tight as well, but that doesn't seem to be an issue. Perhaps the a/c unit itself, when engaged, is dragging excessively? With the belt off (engine off naturally), it turns quite freely, but the clutch is not engaged. If anyone else has ideas/concepts they'd like to share, I'd appreciate it!. Oh, stop and go city traffic doesn't seem to bother it as much, even with the a/c on. In the good ol days, I could turn the a/c on and my temps would actually drop due to both fans coming on. I've checked the fans, and both go on high speed with the a/c on. Additionally, I have the Datalogit for the PFC and have lowered the "on" temps for the three fan settings.
One waaaay out there theory I have, one that sort of sychs with the increase in water temps, is the addition of a vented hood. It seems to work very well at lower speeds, but could it be possible that the addition of these vents may disrupt the airflow in the engine compartment? I've run two vented hoods (mazdaspeed, and now Knightsports). The first time I noticed such a problem was on my trip up to MADS last fall. I installed the hood THAT morning, before leaving on the trip. After leaving from Nick Riefner's house, we ran into traffic on I-4 in Orlando (imagine that). My temps eventually got up to 103 degrees before I bit the bullet, shut of the a/c and opened the windows. Not a fun thing to do in August in Florida, LOL. If I can bring myself to do it, I may throw on the stock hood to test the theory.
06-29-02, 01:04 AM
#2
Have you checked your thermostat? I'd say that could be your problem. I've seen lots of FDs with thermostats that only partially open. You'll never see any movement of the stock guage but the temps will rise.
Otherwise 100C (212F) isn't really that high in FD land. The high speed fans don't come on until 221F with the a/c off.
Jeff
Otherwise 100C (212F) isn't really that high in FD land. The high speed fans don't come on until 221F with the a/c off.
Jeff
06-29-02, 08:50 AM
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I run the PowerFC with the addition of the Datalogit system which allows you to edit all fields of the Apexi software. I was AMAZED that the fans didn't come on (both on high) until 212F! You're right, 100C is not that hot, but considerably warmer than I had been running. The stock gauge does not budge (as you know) but I do monitor with the FC Commander which DOES change :-)
Maybe I'll just replace the thermostat as well. Just seemed to happen all at once though. Will take your advice however and replace that as it's such a small, inexpensive part. Trying to do things one at a time as well to determine what the cause is so I can tell others.
Michel
Maybe I'll just replace the thermostat as well. Just seemed to happen all at once though. Will take your advice however and replace that as it's such a small, inexpensive part. Trying to do things one at a time as well to determine what the cause is so I can tell others.
Michel
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