Scotty Posted May 8, 2005 Report Share Posted May 8, 2005 I have been noticing something interesting about my coolant temperature. Driving at highway speed (55 to 65) my normal operating temp is about 203 degrees with the tranny in OD and my RPM at about 2100. If I put the tranny in D, my RPM increases to about 2400 to 2500 at the same speed and my coolant temperature drops to about 196 within 2 minutes. Put it back in OD and it goes back up to 203 degrees. I am pretty sure this is related to the increased RPM that circulates the water pump faster, BUT could this be an indication that my water pump belt is slipping or my tensioner is not providing proper tension.. If I "can" run cooler if the water pump turns faster, could I change the size of the pulleys on the water pump to cause it to turn faster? Try this experiment for me if you would and report your findings, Thanks, Mike Link to comment Share on other sites More sharing options...
Ranger Posted May 8, 2005 Report Share Posted May 8, 2005 Funny you should mention it Mike. A couple of nights ago on my way home from work I gave it the obligitory WOT and was watching the temp guage. I was at normal operating temp, 212. After the WOT in 2nd up to 70, and let it back down to 60, then dropped it in "OD" and looked at the temp. It was at 196. I noticed your RPM's seem high though. I turn 1950 @ 70 MPH in OD. Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 I wonder if we have the same gear ratio? I will look closer tomorrow, I am pretty sure I am at 2100 at 55...in OD Link to comment Share on other sites More sharing options...
adallak Posted May 8, 2005 Report Share Posted May 8, 2005 I think not only the water pump but also all other pumps (oil, transmission) run faster contributing to cooling. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Ranger Posted May 8, 2005 Report Share Posted May 8, 2005 I wonder if we have the same gear ratio? I will look closer tomorrow, I am pretty sure I am at 2100 at 55...in OD I'm pretty sure we do. Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 HMMMM, I just did a little research and found out that we both have a 3.11:1 axle ratio... Why pretell would we not have the same RPM at 60 MPH? Link to comment Share on other sites More sharing options...
Ranger Posted May 8, 2005 Report Share Posted May 8, 2005 BTSOM. I just checked it to be sure on the way home from work. At 60 MPH I am turning 1650 RPM, 1950 RPM @ 70 MPH. We are talking about "D" (overdrive) aren't we? Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 Yes overdrive.. I will check tomorrow, maybe I am mistaken, Thanks Link to comment Share on other sites More sharing options...
Poobah Posted May 8, 2005 Report Share Posted May 8, 2005 Scotty, Have you looked in your trunk lately? Maybe it's full of old National Geographics! Happiness is owning a Cadillac with no codes. Link to comment Share on other sites More sharing options...
JimD Posted May 8, 2005 Report Share Posted May 8, 2005 HMMMM, I just did a little research and found out that we both have a 3.11:1 axle ratio... Why pretell would we not have the same RPM at 60 MPH? Tire OD? Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 Scotty, Have you looked in your trunk lately? Maybe it's full of old National Geographics! OUCH! Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 HMMMM, I just did a little research and found out that we both have a 3.11:1 axle ratio... Why pretell would we not have the same RPM at 60 MPH? Tire OD? 225-60 16 here.... Ranger? Link to comment Share on other sites More sharing options...
JasonA Posted May 8, 2005 Report Share Posted May 8, 2005 Scotty, with a 3.11 ratio and 225/60/16 tires, you should not even be close to 2000 rpm at 55 mph. For me (3.11 and 225/60/16), 2000 rpm in overdrive is about 75-80 mph. 55 is about 1650 (as stated above). Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Scotty Posted May 8, 2005 Author Report Share Posted May 8, 2005 Scotty, with a 3.11 ratio and 225/60/16 tires, you should not even be close to 2000 rpm at 55 mph. For me (3.11 and 225/60/16), 2000 rpm in overdrive is about 75-80 mph. 55 is about 1650 (as stated above). Jason, I will check and pay close attention today, Thanks Link to comment Share on other sites More sharing options...
Ranger Posted May 8, 2005 Report Share Posted May 8, 2005 HMMMM, I just did a little research and found out that we both have a 3.11:1 axle ratio... Why pretell would we not have the same RPM at 60 MPH? Tire OD? 225-60 16 here.... Ranger? I am at work now and carpooled in today so can't check but 225-60-16 sound right. I replaced them last summer with what ever it came from the factory with. Link to comment Share on other sites More sharing options...
JasonA Posted May 8, 2005 Report Share Posted May 8, 2005 Back to the original question, I've noticed too that in light throttle conditions (half cruising, half coasting) that if you force the engine to a higher gear, the engine tends to run cooler. Coasting down a hill will make this dramatic. I'm sure it has to do with more coolant circulating, and the engine forced to an abornally high speed for the conditions...meaning LOTS of coolant circulating and virtually no load on the engine. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Scotty Posted May 9, 2005 Author Report Share Posted May 9, 2005 I noticed today that at 55 I was doing 1575 RPM once the OD kicked in, so I am in line with you guys, wheew, I was worried, Thanks Thanks Jason, I think the higher RPMs causes the cooling system to run more efficiently, now, how do you think I can turn the water pump faster, larger CAM pulley? Link to comment Share on other sites More sharing options...
adallak Posted May 9, 2005 Report Share Posted May 9, 2005 now, how do you think I can turn the water pump faster, larger CAM pulley? Mike, you want to improve something designed by GM engineers? You think you know better? I cannot believe you said it! The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
JimD Posted May 9, 2005 Report Share Posted May 9, 2005 .... Thanks Jason, I think the higher RPMs causes the cooling system to run more efficiently, now, how do you think I can turn the water pump faster, larger CAM pulley? Be careful, Mike. We all know what Guru. is going to say about you redesigning the (fill-in-the-blank) powertrain system! Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
KHE Posted May 9, 2005 Report Share Posted May 9, 2005 I think the higher RPMs causes the cooling system to run more efficiently, now, how do you think I can turn the water pump faster, larger CAM pulley? Higher RPMs will circulate more coolant through the system and that would account for the lower coolant temp. Why would you want to mess with the cooling system??? Get your air conditioning fixed and you'll notice the coolant temp. wil be lower as one of the cooling fans will be on (which will lower the coolant temp.) whenever the A/C is running. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Scotty Posted May 9, 2005 Author Report Share Posted May 9, 2005 I think the higher RPMs causes the cooling system to run more efficiently, now, how do you think I can turn the water pump faster, larger CAM pulley? Higher RPMs will circulate more coolant through the system and that would account for the lower coolant temp. Why would you want to mess with the cooling system??? Get your air conditioning fixed and you'll notice the coolant temp. wil be lower as one of the cooling fans will be on (which will lower the coolant temp.) whenever the A/C is running. I know, I am ordering the condenser this week, so that project has been delayed a bit. I was just thinking that if I could speed up the water pump she would run cooler, looks like the idea would work.. Link to comment Share on other sites More sharing options...
JasonA Posted May 9, 2005 Report Share Posted May 9, 2005 I know, I am ordering the condenser this week, so that project has been delayed a bit. I was just thinking that if I could speed up the water pump she would run cooler, looks like the idea would work.. You could theoretically do a lot of things to try to make it run cooler. I don't see what you stand to gain though. 203*F while cruising is a-okay. Add 20* to that, and you're still well within the normal operating temperature. But you know that already! Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Scotty Posted May 9, 2005 Author Report Share Posted May 9, 2005 I know, I am ordering the condenser this week, so that project has been delayed a bit. I was just thinking that if I could speed up the water pump she would run cooler, looks like the idea would work.. You could theoretically do a lot of things to try to make it run cooler. I don't see what you stand to gain though. 203*F while cruising is a-okay. Add 20* to that, and you're still well within the normal operating temperature. But you know that already! I agree 203 is nice while I am doing highway speeds, but if I can improve the bumper to bumper cooling efficiency by simulating a higher RPM with a larger pulley, I would consider doing do. Its the bumper to bumper temps that concern me, and I know that Guru will laugh at this suggestion, but my summer temp theme is always in the back of my head... Link to comment Share on other sites More sharing options...
Scotty Posted May 9, 2005 Author Report Share Posted May 9, 2005 now, how do you think I can turn the water pump faster, larger CAM pulley? Mike, you want to improve something designed by GM engineers? You think you know better? I cannot believe you said it! Actually, I had discovered that the higher the RPM, the cooler my coolant temp, by dropping it into D from OD.... So I figured, hey if that works at 55-65, it must work in traffic! Turn the water pump faster and cool my engine in traffic better. Anyone that lives or has visited Long Island knows the traffic I deal with on a regular basis, and I have never been happy above 222 degrees.. Add to that the fact that I regularly drive to Brooklyn, Da Bronx and Manhattan which means bumpa 2 bumpa, and you know why I am looking for a tweak.... Of course Guru set me straight with the fact that it would cavitate, but hey can't fault me for thinking.. Link to comment Share on other sites More sharing options...
Scotty Posted May 9, 2005 Author Report Share Posted May 9, 2005 .... Thanks Jason, I think the higher RPMs causes the cooling system to run more efficiently, now, how do you think I can turn the water pump faster, larger CAM pulley? Be careful, Mike. We all know what Guru. is going to say about you redesigning the (fill-in-the-blank) powertrain system! I like to consider it tweaking not necessarily redesigning! Anyway, Guru popped my balloon with the cavitation potential... Hey, I thought I saw an opportunity to knock a few degrees off my bumper to bumper summer drives... Link to comment Share on other sites More sharing options...
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