Truck running hot unless I run the heater fan on full

[sts95ranger]

I have been chasing a coolant leak for a while. About a year and a half ago my truck with just 100k on it started to run hot.. I took it to a local mechanic and he changed the water pump and the thermostat. It seemed to help, but the truck still smelled like coolant. The temp gauge also now sat on the lowest line on the gauge even when the truck was at full temp. I found out that the thermostat housing was bowed and would not seal. I changed that and it seemed to help a tiny bit, but it still seemed to run a little warm. Well a couple months ago the truck started to run warm again and I have to run the heater to keep it under control.. So I replaced the water pump again. The gasket on the water pump looked like he had just put it on over the rust and not even cleaned it. Then I had a leak with the lower radiator hose to water pump piece and had to replace that and the seal. Now the truck does not seem to be leaking any coolant. However the truck takes a while to warm up and when you drive it the temp still climbs up to about 1/4 of the gauge. When I turn the heater on it falls back to the lower line.. The top hose of the radiator gets hot. The radiator gets hot, but slowly, and the bottom hose seems to take a long time to get hot and never gets anywhere near as hot as the top hose.. I know it goes through the radiator, but its a pretty big difference.. So I have replaced the thermostat since it started doing this and it didn't help..

Any suggestions? replace the radiator? The coolant does seem to have some sort of metallic color to the very top of it when you uncap the radiator.. Someone told me that sometimes means there isn't much flow in the radiator..

 

[chrisab]

Let your truck idle for about a half hour. Then shut it off and feel the radiator to tell if there is any cold spots. Be careful parts will be hot. If thee are cold spots then you have a blockage in that part of the radiator. You could try to remove the rad. and run a hose through it but more than likely it is not going to work and it's time for a new one. My 97 has 221000 on it and I had to replace it last week. The On days 70 and up the gauge would climb and I would have to run the heater to cool it down. Mine had about 80% of the radiator cool to the touch. Replaced it and now it's fine.

 

[AlaskanRider]

However the truck takes a while to warm up and when you drive it the temp still climbs up to about 1/4 of the gauge. When I turn the heater on it falls back to the lower line.. The top hose of the radiator gets hot. The radiator gets hot, but slowly, and the bottom hose seems to take a long time to get hot and never gets anywhere near as hot as the top hose.. I know it goes through the radiator, but its a pretty big difference..

I don't think I understand your problem.

If your truck takes a long time to warm up, that means that it your cooling system is working. If the top hose is alot hotter than the bottom hose, that means the water is colder coming in than going out of your engine, which is what you want.

1/4 way up the gauge sounds like normal operating temperature to me. The heater core bypasses the thermostat, so when you turn it on, it brings the engine temp down BELOW operating temperature.

Sounds like your radiator is doing just what it should, so don't worry about it unless your gauge goes up into the red, or it starts boiling over.

 

[kimcrwbr1]

You can try backflushing your radiator since you have metallic flakes in it it sounds like it has been stuffed with stop leak stuff.pull both hoses off the radiator use the hose to blast it backwards then foward a couple times. Put a kink in the hose close to the radiator the longer the hose the better with the hose on high pressure with no nozzle on the end stick the end in the radiator with a rag to hold the pressure and release the kink in the hose. It is best to pull the radiator so the crap pours out of it. Two chemicals work good for radiators/heater cores to dissolve the crud regular bleach or easy off oven cleaner. use an old radiator cap empty the radiator and lay it flat so it holds fluid and fill it with either and let it soak overnite then flush it good both ways a couple times. If it developes a leak it was bad anyway. Oven cleaner is the best but you need to be careful with either where you rinse it. + 1 on the guage if it dont go over half your probably safe the cool coolant going into the engine is good putting a mechanical temp guage will tell you for sure.

 

[--weezl--]

1/4 way up sounds a little low, but not much... and slow to warm up is 100% a thermostat it's stuck open, or won't close fully... (could be a mechanical blockage, like a piece of rust or something)

top hose IS supposed to be hotter than the lower, that is normal and GOOD

 

[sts95ranger]

OK.. I know that when the gauge/sensor is working properly it should read in the middle. But here is another piece of info I guess I left out.. When the guy fixed my truck it ran at the lowest line on the gauge. It ran fine for a little bit but always smelled like coolant. Then after a couple days it slowly started to creep up the gauge. When it gets up to anymore than a 1/4 to 1/3 of the gauge the truck sometimes starts pinging a little bit and when you run the heater the air coming out is really hot.. Like the hottest air I have felt from a heater before. And when you are running the heater it drops the temp back to just above or right at the lowest line on the gauge... I think I might borrow a buddies laser temp gauge and measure the temp at the water pipe.. What should it be? It definitely seems like where the gauge should read is on the lower line. The truck seems to be very hot when you turn it off and open the hood after its at the 1/4 area for a while.. And when I say it takes a while to warm up I mean like 3-4 minutes of onroad driving. And I have replaced the thermostat and it still does the same thing..

If I can measure the temp on the water pipe, the block, the top hose, and the bottom hose, can anyone do the same and tell me what they get?

Thanks for your suggestions guys.

 

[kimcrwbr1]

I just did the water pump on my 2.8 and with the pump off I blasted the block good with high pressure water and alot or brown stuff came out. The upper radiator hose should be around the same temp as the thermostat rating when it is up to temp. If it was me I would flush the engine, radiator and heater core. Get a good t-stat (napa) and put it back together it sounds like the t-stat you have is bad even tho it is new. Put a new bypass hose in there also and make sure the nipples are clear but it is not uncommon for a net stat to be bad go get your money back and buy a good one the lower radiator hose being cool says there is a restriction in the flow of coolant.

 

[Earl43P]

It ought to be between 193-220 at the thermostat outlet.

190s - low 200s is what you will see, betcha. Drops as you rev the engine.

Gage temp senders are dirt cheap, unless yours is that expensive deal in the housing.
If it's getting hot enough to ping, that sender may be faulty and lying to you. Plus it's overheating. Look at the spark plugs. One might be burning coolant from a head gasket. It'll look cleaner than the others.

If they look all the same, it could be very well a blocked radiator. Run some Super Flush through it, according to the directions. You seem to have done everything else!

 

[sts95ranger]

So if it reads between 190 and 200 what would be the suggestion to check.. I drove it to work this morning.. still doesn't seem to be leaking anymore and the temp gauge took about 1 minute of idling and 2-3 minutes of driving to hit the first bar of the gauge. Then it went anywhere from the first line to a little less than 1/4 of the gauge.. So it doesn't seem to get as high up the gauge now, but it was also a cooler morning.. I didn't run the heat at all to see what it would do and it never got up to a full 1/4 of the gauge.. The temp definitely goes down after constant higher revs..

 

[Rogue_Wulff]

You never stated the year of the truck, but your username seems to indicate it is a 95. The guages in the later trucks are even flakier than the gen 1/2 trucks had, and they weren't very accurate.
Getting an accurate reading with an infared temp gun is really needed, to further assess the situation.

 

[--weezl--]

If your infrared reading shows 190-200, your truck is fine...

Ford has always had a reputation of having the hottest heaters...

My past few fords (with the exception of my mustang and my 150,) the heaters were so hot you can literally burn your hand on the vents... My dads 150 is the same...

 

[sts95ranger]

Yes my ranger is the 95 2.3 liter.. So today I drove it around and the needle stayed closer to the first line on the gauge until I had it in first holding it back going down a hill. Then it went to about 1/3 of the gauge.. I got to the shop and borrowed an infrared thermometer and checked the temps.. (gauge had fallen back to the first line or just a little above) 174-178 on the bottom of the thermostat housing, 154-160 on the top rubber radiator hose, 95-104 on the bottom radiator hose. It was dark and it was hard to see anything else like the radiator to get some readings on, but that is what I got... It seems to me the gauge is just crazy then... After all this I can still smell coolant a little when I stop and get out and the truck is running. I can't see any leaking or anywhere and its just faint.. How long would the truck smell like coolant if coolant had been building up with dirt all over the engine for a while? Or do I have a head gasket leak that is letting some out.. again just over 100k on this motor.. truck still runs good.

 

[alwaysFlOoReD]

Do you have to add coolant constantly? If so then you have a problem. Is your carpet wet under the dash - passenger side? Indicates a heater core leak. You can buy some additive that will glow under a black light, I've used that to track down oil leaks [ended up they were everywhere], and it should work with coolant. You can buy it at any good auto parts place. Use a black light to find the glowing and you have the leak.
Good luck,

Richard

 

[--weezl--]

Uv dyes are not interchangeable between oil and coolant! They make coolant ones, and oil ones... Get the right one!!

If you don't have to top up... Then you probably just need a shampoo...

Your temp sounds low to be honest... Sounds like a broken t-stat still

 

[sts95ranger]

I can't see anywhere from the top or the bottom of the engine where coolant is coming out of.. I don't see any signs of coolant at all. It just has a slight smell of coolant.. I don't have any wetness on the floorboards or anything either.. This engine was absolutely covered by coolant because it was getting in the fan and getting tossed all over the engine. I tried to clean everything up as good as I could when I did the water pump and such so I could see if it was leaking.. No signs of leak yet just the slight smell.

As of now I think the gauge is just crazy because it moves a lot.. for example it will drop from 1/4 of the gauge to the lower line in seconds.. that being said it seems that the gauge is somewhat right and the temp is actually low and that it may be because of the thermostat.. I wonder what temp thermostat I bought and put in when I did it.. I will have to look at advance auto and see what the options were... I have a new one to put in.. I just don't have time to do it right now..