Big Secz 26 Report post Posted June 29, 2011 It seems to me my car is running hot. I had the motor rebuilt last summer and have only put 1,013 miles on it since it's rebuild. I drove it around for a little bit this morning and when I got home the temp was reading just above half so I let it idle. The pictures below show the temp at 5 mins, 10mins, and 15mins at idle. It seems to me it shouldn't be running that hot. Also I'm still running break-in oil in the motor (15/45) which I don't know if it could be factor. Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 29, 2011 The temp after 10 min of rest. I know it's normal for the temp to continue to creap up a little bit after the car has been turned off. Quote Share this post Link to post Share on other sites
LoneWolf2U 136 Report post Posted June 29, 2011 You need to verify the temps to the guages display. I place a thermometer in the rad neck and watch the temp and what the guage shows, It also allows me to conferm at what temp the stat starts to open and when it is fully open along with coolant flow. Only then can you say for sure it is running hot. Quote Share this post Link to post Share on other sites
MikeStang 247 Report post Posted June 29, 2011 You need to recheck that thermostat too, the one im working on reached the same place on the guage and i checked the thermostat and it was LOCKED open, so once its heated up to a point the thermostat locks and will not unlock, thus you have coolant flow all the time and this doesnt allow the water enough time to soak all the heat out and move on to the radiator for cooling.....you and i are having the exact same problem....im gonna try moving the fan closer to the radiator, its only 1/4 of the way in the shroud. Place a fan in front of the radiator and let it idle if it stays cool you have your answer....like everyone says in my post its not a coolant flow its and air flow problem. Mike Quote Share this post Link to post Share on other sites
danno 128 Report post Posted June 29, 2011 It almost makes you wonder if some part was installed wrong in the rebuild. One part might be blocking the flow of water, not allowing it to cool. But the thermostat is an easy thing to try. The shroud only makes a difference if you are going slow or stop and go driving. If you take it on the road at 60mph, would it heat up then? If it does not, then it is a radiator problem. Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 29, 2011 It almost makes you wonder if some part was installed wrong in the rebuild. One part might be blocking the flow of water, not allowing it to cool. But the thermostat is an easy thing to try. The shroud only makes a difference if you are going slow or stop and go driving. If you take it on the road at 60mph, would it heat up then? If it does not, then it is a radiator problem. The first time I noticed the problem was in stop and go traffic. Hit about five consecutive red lights in a short distance and I thought I was going to have to pull over because the temp gauge got up so high. Then the light turned green and once I started moving again the gauge dropped down pretty quickly. The radiator is only about two years old and it's a 3 core big-block style radiator. Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted June 29, 2011 The first time I noticed the problem was in stop and go traffic. Hit about five consecutive red lights in a short distance and I thought I was going to have to pull over because the temp gauge got up so high. Then the light turned green and once I started moving again the gauge dropped down pretty quickly. The radiator is only about two years old and it's a 3 core big-block style radiator. That tells me you have a cooling fan issue. At idle or low speeds your fan should be drawing air through the radiator to keep the engine cool. And that does not sound like it's happening. What fan setup do you have? Bruce Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 That tells me you have a cooling fan issue. At idle or low speeds your fan should be drawing air through the radiator to keep the engine cool. And that does not sound like it's happening. What fan setup do you have? Bruce I'm running the stock belt driven fan. Would a clutch fan be better? I have aluminum pullies so my belts are shorter than stock, but I don't think the length of the belt would have anything to do with, would it? Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted June 30, 2011 Unless you are running underdrive pullies then yes it could make a difference. If the water pump is turning to slow it will cause overheating issues at idle to low speeds. So you have a flex fan now? Bruce Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 Unless you are running underdrive pullies then yes it could make a difference. If the water pump is turning to slow it will cause overheating issues at idle to low speeds. So you have a flex fan now? Bruce Yes, that's what I'm running now. I would think smaller diameter pullies would equate to turning the pump faster? Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted June 30, 2011 Yes, if your pullies are smaller in diameter then the shaft they are driving will spin higher. So that's most likely not the problem. Who did your long block assembly? Also, you are running a thermostat right? The stat does more than allow the engine to reach operating temperature faster, it also slows down the flow of the coolant so it hangs around inside of the radiator longer and thus exchanges more heat. We need you to verify the water is actually getting hotter then it should. Like others have said check the temp with an appropriate thermometer at the rad cap opening or use a laser temp reader at the top hose. Bruce Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 The motor was rebuilt by a shop in Richmond, VA. I live 65 miles north of the shop, they came highly recommended by a friend of mine that restores cars and has had over a dozen motors rebuilt by them and has never had an issue. It looks like my next step is to try and get a reading on the temp and then check the thermostat. Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted June 30, 2011 Yeah, lets lock down for sure weather or not the engine really is running hot. That will go a long way to diagnosing your issue. The reason I asked about your builder is I was trying to see if maybe the head gaskets were flipped end for end. But now that I think about it you would be having a problem at any speed if that were the case. Bruce Quote Share this post Link to post Share on other sites
Pakrat 1,043 Report post Posted June 30, 2011 I'm running the stock belt driven fan. Would a clutch fan be better? Just to address this comment while we wait on your actual temp readings. I am a big believer in cluth fans in general but it would not aid in your current issue. The whole purpose of it is to free up horse power when the fan is not really needed like initial cold start up and highway speeds. At idle and in traffic is when it should be working just like any other fan. Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 I added a thermal gun to my collection of tools this morning. So here's what I did. From a cold start I let the car idle for an hour and took pictures of the gauge and temp readings every ten minutes. I took the temp readings from two different places; at the top hose and from the right side of the radiator which should be the hottest side. Here are the readings that I got: 10 min = 147/hose, 157/radiator 20 min = 157/hose, 179/radiator 30 min = 160/hose, 196/radiator 40 min = 164/hose, 183/radiator 50 min = 174/hose, 180/radiator 60 min = 179/hose, 192/radiator To me the temps don't seem bad at all. But after an hour you can see my gauge was creaping up toward the "H". Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 (edited) And the last pic after 60 mins. I also took a pic and temp readings after 20 minutes at rest. 20 min. rest = 190/hose, 210/radiator Edited June 30, 2011 by Big Secz Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted June 30, 2011 Well if you are running a 190 or 195 thermostat then that's just right. You can see your thermostat full on opening points at 30 and 60 minutes. So it looks like you may indeed have a guage/sending unit issue. Are all of your other guages working correctly? I'm with Pakrat on the fan. I to preffer a thermostatic operated fan but it's up to you. Bruce Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 I just ordered a new temp sending unit today. I'll start there and see what happens. Quote Share this post Link to post Share on other sites
Powershift 19 Report post Posted June 30, 2011 I didn't see it mentioned, but what degree T-stat are you running? Maybe try a 180 to lower the temps a bit, if that isn' what you are already using now. Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted June 30, 2011 I think they installed a 180 when they built the motor. Does anyone know anything about callibrating the temp gauge? Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted July 1, 2011 Well, if the sender AND gauge are working correctly and you need to make adjustments as to where needle reads on the gauge, you can try different resistors inline with the sending unit wire to change the readings. It will be a crap shoot and you most likely will have to try different resistor values to get the gauge to read where you think it should be reading. That's the only way to adjust a gauge that I know of. Given your instrument cluster voltage regulator is working AND your other gauges are where you think they should be that is. Bruce Quote Share this post Link to post Share on other sites
stangme428 33 Report post Posted July 1, 2011 (edited) purchase a potentiometer from radio shack and dial in the resistance, once you have the needle where you want it.. remove the pot, measure the resistance of the potentiometer and solder in a resistor with a similar value... just make sure you get a pot that will work in the range you need.. I'm not sure how close in resistance you are, or what values your dealing with from the sending unit or the gauge... edit --- the above will work.. but solve your problem first.. looks like your resistance is drifting when the sending unit or gauge gets hot.. the above will not fix this.. i would guess the sending unit is drifting due to the heat being at that area... but thats what makes troubleshooting fun..!! Edited July 1, 2011 by stangme428 Quote Share this post Link to post Share on other sites
Big Secz 26 Report post Posted July 7, 2011 I replaced the temp sending unit today. No change. In fact the gauge when up even faster. At 160 the gauge was in the upper 3/4 range just under the "H". I guess my only option is to install an aftermarket temp gauge somewhere in the car. Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted July 7, 2011 Bummer. I have been hearing of others having the same issue with sending units. Not fun. Bruce Quote Share this post Link to post Share on other sites
sportsroof69 13 Report post Posted July 7, 2011 Mine ran hot today too. It's 107* outside! Quote Share this post Link to post Share on other sites
