My truck usually runs at a normal temp, so the gauge says. But every once in awhile it will get a little warm and if I shut it off and start it back up, the gauge will read HOT. I opened the hood the last time it did this and it actually felt hotter than normal, but could this be the gauge or what else would cause this to happen? This started happening after I overheated my truck when the radiator got full of mud. Any help will be appreciated. Thanks

 

Not sure what bogging it up with mud would have to do with it, maybe just already running hotter than normal so you didn't notice it before but...

It is pretty much normal for the engine to heat up when shutting it off. The reason is simple, the water pump isn't running once you kill the motor so all the heat stays around the cyclinders. Once you start the truck back up, the gauge reads this higher temp but ti should go back down fairly quickly as the coolant starts circulating again.

As I said, I don't know what the mud would have to do with it unless you are just running a bit more hot than normal due to some clogged fins in the radiator not allowing good air flow.

Wait until the radiator is cool, then spray it well with a hose and clean out all the gunk stuck in it. After your done, CAREFULLY, CAREFULLY CAREFULLY straighten out the fins on it as I imagine that the mud hitting them bent a bunch over restricting air flow.

If it still runs hot, especially when pulling a load, climbing hills and trying to accelerate etc then I would start suspecting a warped head or bad head gasket leftover from when you overheated the first time. You can usually have a radiator shop do a sniff check at the radiator cap for this if you don't see other signs like coolant in the oil, oil in the coolant or blaoted radiator hoses when the motor is running. The sniffers are great at spotting small leaks you and I would never notice but the equipment is very expensive and needs constant calibration making it beyind the shade tree mechanic's ability to own one.

PS - All the shops around me always have done this check for free. I had a Triumph that rfefused to keep a head gasket seal for more than a year at a time so I would just have them sniff it then change it myself if it came up bad. ( and yes, had the head and block milled but it was just a poorly designed bolt pattern on the inline 6 they had)

Good Luck,

Lee

 

Is the Radiator full, Sometimes it may be low which could give you false gauge readings?? Or your thermostat could be sticking, working normally and then not opening all the way!!!

 

Boss-50 - How did you clean the mud out of the radiator? Maybe the fins are bent or still have crud trapped in them?

I'd agree with Lichterman about the temps being high after the engine is shut off. The heat from the engine has time to soak into the coolant, but should be only a temporary spike upon startup.

SOmething cheap to try if you feel like tweaking things is to change out the temperature sending unit. They are about $6, easy to get to, and do occasionally go bad.

 

I used a garden hose with a spray nozzle thing on it. I can see through most of the radiator so I thought it would be clean. The temps getting high after shut down seems logical, but why didn't it do that for the last 2 years I had the truck? It starts up fine, it usually has to crank a few seconds to start when the engine is hot so I'm guessing the temp is fine. I'll try not to worry about it.

 

Well, before you decide not to worry, make sure it isn't running hot all the time or when you are going slow/stopped. You say you can see through "MOST" of it. Why can't you see through the rest? It doesn't take much blockage to cut down the efficiency of the radiator. I would make sure the fins are ALL clean and straight. My truck is in great shape as far as cooling goes and still gets hot stuck in traffic with the A/C on.

Also, do you have a shroud on it like it is supposed to? I just thought of it but it might be geting hot just before you shut it down due to low speed and sitting. Without a shroud the air just goes around the radiator instead of through.

Have you checked the fan clutch? It should spin freely when the motor is cold and then be hard to turn when the motor is hot. If it spins all the time, the clutch is shot and the fan isn't pulling air after your engine is warmed up thus the only air you are getting is what is forced through as you drive forward.

Find a friend or freindly shop that will check your temp for free to see how hot it is at normal range and slightly warmer than normal like after sitting there at idle. It is hard to understand internet messages when it comes to broad terms like hot. Is hot 195 degrees? 210, more? I changed my gauge cluster and my readings on the stock gauges varied a lot between the 3 sets I tried. ( Stock, wrong year cluster, then the one I have now). One read low in teh "gap" between C and the N in Normal, one was warmer in the RM of NoRMmal and the one I used reads at the beginning of the line and N or Normal.) Stock gauges are better than idiot lights but they are far from perfect. Know your range so you know when you need to worry and what Hot really is so you know when to shut it down. Sooner or later you are going to get a leak, blow a hose or something where you are going to get close to over heating and it is better to shut it down and let it cool than to be facing a head job because it got too hot and warped.

I wouldn't be worried about it being warmer than normal after it sits a couple minutes not running but still think you might be running hotter all the time which is why you didn't see it until the Mud incident. I have to straighten my fins all the time. Bugs, mud, rocks will fold them over in a heart beat.

Not sure what mix on your fluid is either but too much coolant actually runs hotter than water. I see you are in Wisconsin so probably already cooling off and you want max winter protection now but in the summer, the cooling is better with a 50/50 mix than a 25% water to 75% coolant mix. I see people do this backwards all the time.


Good Luck,

Lee

 

My radiator has probably mostly antifreeze in it now. I put 50/50 in it when I changed the fluid but I had to keep adding so I just used strait antifreeze. I'll have to check the bent and/or any other clogged fins. I had a screen over it to catch the bugs but that got full of mud so I took it out. My friends uncle has a repair shop, I'll just stop by there after school one day and have him check the actual temp. Thanks!