waldron4739

Hi guys, I have a temp issue I'm trying to figure out. The truck in my signature is the one i'm working on, It has about 235k on it. I don't pull much with this truck, Just the 3 horse slant trailer around town a bit and the occasional small boat, but over the last several months the truck seems to have developed a overheating issue, All my instincts tell me that my problem is airflow and the culprit is the electric fans, even cruising on the hwy at speed if I catch any sort of grade it heats up. I have heard lots of great things about the fans, but now I'm regretting them. It takes a few stop and cool off sessions to make a steep grade currently, the truck tries to climb in excess 220 regularly on a grade or when pulling. I ordered a fleece coolant bypass kit that should arrive today and ill get it put in tonight to see how it helps if at all. I have checked my thermostat and flushed my cooling system/ installed fresh 50/50, I have checked for head gasket issues and don't seem to have any problem there, the truck runs outstanding except it heats up too **** often. Any feedback/ideas are greatly appreciated.

CRF450R RIDER

Check to make sure that air flow is not restricted from a dirty ac condenser or a dirty radiator. I would put a new thermostat in and maybe your water pump is has gone bad. Do you hear the fan kick on when you hit those high temps?

johnh

99.9% of water pump failures are seal and or bearings, and those failures will most likley not cause the over heating issues waldron4739 has.....

Dynocon

Same issue, different thread. Stock fan was replaced last fall with computer failure. Work is a 30 minute drive which really only gets the truck up to operating temperatures with 70 degrees outside. If I drives more than that it goes up to 220 or so, especially in stop and go. Replaced the thermostat last week, nothing different. I assumed it was the fan since it seemed to be good at cruising speeds. Took to a shop today and the fan clutch seems to be engaging fine. Drove back to work and it with 30 minutes each way it was back up to 220, second zero on 200? Replaced the water pump 3 years ago due to a leak so I got an new on (lifetime warranty), put it on tonight and drove it for a while trying to see what happens. I did heat up a little, just on the high edge off 200, may be a needle with higher. Going to drive it and see what happens.

Dynocon

Forgot to mention, pump looked fine, did not leak, but did dump out a little old oil shen turned upside down.

.boB

The fans are only in play at speeds below about 45 or so. At higher speeds, there should be more air flow than the fans provide. If you're heating up at highway speeds, the fans are not the problem.

Make sure you do have good air flow. There's a lot of stuff stacked up there, and crud can get between them and block flow. Use something like a See Snake to look in all the cracks and crevices for debris or damaged fins.

Water pumps can fail without leaking. It's not common, but it does happen. Let the truck warm up with the radiator cap off. Look to be sure that water is flowing along at a good rate.

While you're at it, put a cooking thermometer in the coolant. Make sure the temp on the dash gauge matches the temp on the thermometer.

Put the cap back on, drive the truck around to get it up to at least 200*. With the truck in park, watch the lower radiator hose while some one runs the rpm's up to 1500-2000'ish. If the lower radiator hose collapses, that's a problem.

Borrow a coolant test kit from Autozone (or wherever) go through the whole test procedure and check for things like leaks and blown head gaskets.

If an injector is failing, one or more of the cylinders will run lean under a load. A lean condition will also cause it to overheat.

Dynocon

.boB thanks for your help.

I was able to put in another cup of coolant, still a little low from the water pump change.
Took the water hose and cleaned out the radiators, got a little grime out but not much.
Hooked up the boat (18 1/2' ~3,000#) and took it a drive.
While driving the gauge went from 180-210, maybe 2 needles above 200?.
Running 65-70 was 200 or less.
Poking thru side streets went up to 210 or so but came back down, fast if moving, very slow if poking.
Air conditioner on the entire time.
Got it back home and it was about 200, loosened the cap and coolant wanted to come out.
Let it cool down a little still 190-200, cap off and the coolant wanted to slow boil out, not sure if that is normal or not. Will let it set, cool off and try again. (Obstruction????)

Here is my conclusion - new water pumped help a little, it will cool down, before once it got to 215 or so it did not want to come down

Cleaning the rad helped a little.

Replacement fan that was put on last fall is not as strong as the OEM fan. I could hear the other one but not this one. Garage/Computer said it is locking up.

I think it will be fine, does everyone agree?

Dynocon

Truck cooled down to 160 or so, opened the cap, let it run for 15 minutes or so, temp gauge reading 190 or so. Coolant looked like it was moving slowly towards the cap side then down?
Tried 2 different kitchen thermometers both read just under 140 deg F. Does this sound right?

.boB

I think the stock thermostat is either 180* or 203*. At 190* it might be just starting to open, or could be completely open, depending on what you installed. Did you notice during installation?

If the thermostat is just starting to open, then water movement would be pretty sluggish at idle. But with the two thermometers reading 140*, the thermostat should still be closed.

It sounds like you have a bad gauge or sender.

Dynocon

The new thermostat is 190. Inside gauge was at normal just below 200, ran at 1200 rpm for 5 minutes after it stopped rising to make sure it would not go any higher.
Going to boil thermometer just check.
What should the temperature difference be between the top and bottom hose?

.boB

Temp difference will vary quite a lot according to conditions. There's no way to predict what it should be.

If the cooking thermometers are accurate, then the problems is your gauge or sender. The dash is telling you the water temp is 200, but the thermometers are telling you it's 140*, there's your answer.

Dynocon

Just checked the thermometer, both are accurate.
Would you just buy a new sender, or can you check it?

Dynocon

Latest update.
Drove to town 1/2 hour each way and bought an infrared thermo gun.
Truck ran fine temps were below 200 (180 to one needle width over 200).
Temp here is 80 degrees, sunny.

Got home, truck still running, air on in park and took the following readings.
Metal plate at sensor 190
Top of goose neck above thermostat 210
Gauge reading below 200 so guessing 190.

Shut if off for 20 minutes or so and went back out.
engine off gauge shows about 170
180 at sensor plate
pulled cap liquid at 120, gun and thermometer, surface cooled quickly.

Started it up with cap off and let it run for almost 30 minutes. Coolant was down about 1" from boil over, after running for a few minutes is started coming up very slowly, after 5 minutes or so it was barley dripping over the top, put a pan under to catch it and let it run. Now with the coolant at the top is danced around but could not tell that is was moving.

Here are the reading with cap off still running and dripping out.
Bottom hose 120
Top hose 180 close to goose neck, 165 on drivers side by rad.
Sensor plate 197
Goose neck 200
Coolant at cap 120
Top AL plate on radiator 150 on drivers side 85 on passengers side by cap.

Hopefully these measurements will help someone else. I am going to run it and see what happens. I will keep the infrared in the truck and if it goes up to the 220 range I will pull over and check it to make sure it is.

Also wiggled the wires to the sensor and nothing. Maybe the water pump and cleaning the rad helped.

Dynocon

Pulling the boat today fine on the interstate but was pulling back roads and thought it was going to overheat, it was at the top of the range almost in the red, luckily got to a down hill section and the temp cam down. Could it be anything but the fan? Stopped by the garage a month ago and the hooked the computer to it and said it was engaging properly.

Dynocon

Took it back to the garage and was able to catch the fan not locking up as it should. Fan clutch was put on just over a year ago when the computer went out. They were willing to pro-rate for 280, just went to autozone and bought a new one for 200 with a lifetime warranty. Took about 45 minutes to change. Borrowed the tools, both sets, one for the nut and one from the second case that was bigger than the but able to catch the nuts on the pulley to hold it. Took both nuts off of the top of the shroud and was able to squeeze the clutch in and out.
I have read that the nut was reverse thread but mine was standard.