Not reaching Operating Temp

[02x72]

My '90 is running around 130 degrees at full temp, which has been confirmed by two aftermarket gauges. Ive changed the t-stat with a new motocraft unit that I confirmed was working before it went in. Cooling system is building pressure and will hold it fine once the engine is turned off. What could be causing this? It started a few months ago after I put in a new IP, but was running fine when that went it and after for a few weeks. Its even got electric fans that I usually leave off and still doesn't help.

 

[whiteboyslo]

Dumb question, but where is your temp sensor located? And could it be possible the sensor has gone bad and the truck is actually OK?

Mike

 

[chris142]

Is there a possibility that coolant is somehow bypassing the thermostat? If you have a properly working thermostat that's all it could be

 

[02x72]

Its located in the head. I switched it with the gauge I have in the other truck, same gauges, same senders and its the same readings. Its not getting to temp, I can tell when I feel the coolant after the trucks been running. I'm pretty stumped on this one.

 

[sle2115]

Wonder if it could be a circulation issue...impeller gone on water pump or something. That's strange! If it's only 130 there, it has to be hotter than hell somewhere I would think. Access to a point and shoot temp gun? check lower block, radiator, etc

 

[icanfixall]

I'm thinking your getting a bad reading somehow. Where did you buy the Motorcraft thermostst. What makes you feel its an actual motorcraft part. Sadly we can't see what you installed now but there are some chinese aftermarket stats that really look the same as the factory ones. We had a member here that was having cooling issues and removed the statt. The top webs were mostly all broken off and it was barely holding together.

 

[rattleonby]

Best way I always used to get accurate coolant temp readings is an infared thermometer preferably with a laser pointer. At my top tank i usually get a reading of 190-196F at idle pending on t-stat just opened or not. The bottom hose i get about 150-160F. At the bottom part of the rad on the actual fin and core part i get usually between 85-100 F. These specs of coarse will differ from truck to truck as much as 20 degress sometimes depending on what type of radiator, condition of radiator and cooling system, what the weather is when your testing it and etc. An infared thermometer is usually bout 60-80 bucks at sears or home depot or lowes. A good investment for your trucks and 'round the house i think.

 

[02x72]

The reading is accurate. I switched both gauges and sending units between trucks and confirmed it. The thermostat was from the local ford dealer, and like I said was tested before it was put in and opened up at the correct temp. Hell, I even tested the old one which was a motocraft unit I put in last october and it tested fine. After a 15 mile highway run today in 80 degree weather, I popped the hood when I got home and opened the cap. There was pressure, but the coolant wasnt nearly hot enough, it actually felt like 130 degree water, and yes I did stick my finger in it. The radiator wasnt all that warm either, I could rest my hand on the top and it was just warm to the touch. My other truck, when at full temp, you cant do that so there is a definite difference. If it were a circulation issue, wouldnt that cause it to overheat? On another note, I did a full flush of the system when I replaced the t-stat, and water came out just fine of the petcock on the radiator, as well as the drain plugs on the block.
Its strange to me that the truck was running at a normal temp, then would run around 160 consistently for a few months, and now is cooler than that. I suppose I could try and find a laser thermometer in time just to see whats the hot spots on the motor, but nothing seems to be unreasonably hot on the block.

 

[bbjordan]

You mentioned it started after you installed a new IP. What did you set the timing to?

 

[sle2115]

If it is a circulation issue, it could well be getting hot somewhere...that was why I also suggested the point and shoot thermometer. I guess I missed the new IP install though, so you might want to look in that direction. If it isn't timed correctly or delivering fuel correctly (burning fuel is what makes heat) then that might be the direction to look.

I haven't seen you mention how the truck runs though, so that is my next question. Does it seem to be running good, power consistent with past performance?

 

[chris142]

The thermostat controls the minimum temperature. if its running too cold either the thermostat is opening too soon or coolant it is bypassing it somehow. that's all it can be

 

[02x72]

The truck runs great since the IP install. Timing was set to spec with a rotunda meter. I forget if the luminosity method is 8.5 or 4 degrees right but I looked it up then. Hopefully in the next few weeks Im going to buy a snap on adapter to use my timing light and ill obviously check it again. Power is noticeably up and mileage was about the same. Its gone down considerably since the cooling issue, but thats going to happen. I guess I'm gonna have to source a heat laser deal and check it out.

 

[Hyde]

Thats where mine usually runs, 130 or less, in the 90+ weather we have had here its made it to 160-180 a few times. Only time I have ever seen 200+ was towing heavy. Ive never even checked the t-stat though.