Underhood heat issues

[LEB Ben]

Alright fellas...I've been battling heat issues in the Bronco for the last week or so...and replaced the thermostat last night. Since I bought the Bronco, underhood temps have always been astronomical, but coolant temp remained good and constant. Anyway, tstat failed last night, replaced it. Waterpump is only 2 months old...although, I've replaced 3 of them in the last year for various reasons (so probably a vendor issue). Head gaskets were replaced within the month...but I'll do a compression check just to make sure...and no coolant in the oil. Upper and lower hoses are less than 4 months old. I have a super cooler radiator that was pulled out of a JY 4 months ago, so I'm thinking this may be the wild card...seeing as all I did was run a garden hose through it. On top of that, the engine was stripped to a short block and just left underhood for about 2 months...so who knows what got in there. Currently, every single hose that has coolant running through it is extremely hot to the touch after running, so hot I can't keep my hand on it for more than a second or two. And it takes a good 4-5 hours for the engine bay to cool down enough so you don't get burned.


So before I throw new parts at it, I was thinking of just doing a full flush...at least a radiator flush. I can handle the radiator flush, but what's the procedure on an entire system flush?


Pull the tstat and let it free flow...I know that much. But what 'cleaner' do I use and how much? How long do I let it run for?


Any help would be much appreciated.

 

[73F100Shortbed]

Do you know what your actual coolant temp. is or going just by the hot and cold gauge? Is the coolant circulating? Are thhe hoses now hot after you did the t-stat or was it like that before? For the flush Prestone used to make a kit that you attached a garden hose to one of your heater hoses. I don't know if they still do.

 

[bucks77ford]

Are coolant temps at an idle still OK? If things are running cool enough internally than I'd say it's fine. I'd still do a nice flush though. I know my truck is amazingly hot under the hood and I can't touch the hoses for very long at all. I guess I just always thought that this is the way it is for underhood temps.

 

[LEB Ben]

Well I'm going off the dash gauge, a buddies electric gauge and a laser thermometer. Underhood has always been hot in the Bronco...hotter than anything I've ever had, but even this week is hotter than usual...and the outside temp is cooler than it's been in 2 months. The temp is remaining constant now in the 180ish range. But the rig is heating up super fast and I couldn't even touch the waterpump last night after it had been sitting for 3 hours last night...same with the heater core hoses and the rad hoses. That just doesn't seem right to me, even though temp is being maintained.

 

[Mil1ion]

You have to measure temps with a thermometer not a dash gauge.

Newly rebuilt engines run hotter than normal until about 5000 miles

If it is out of time that will cause it to run hot.

You could always try realigning the hood to make space in front of the cowl for heat to escape

 

[Mil1ion]

Increase the ratio of coolant to water to 80-20

 

[LEB Ben]

Are coolant temps at an idle still OK? If things are running cool enough internally than I'd say it's fine. I'd still do a nice flush though. I know my truck is amazingly hot under the hood and I can't touch the hoses for very long at all. I guess I just always thought that this is the way it is for underhood temps.

To me, it seems like it's heating up quicker while idling sometimes...doesn't seem to be consistent. Let it idle for 45 minutes in the driveway last night, it was just fine. Today I take it out for lunch and 20 mins of stop and go traffic had it heating up...but when I'd get some air moving it was fine and would drop back down.


So...another WP going bad? Or a fan clutch going bad?



Buck...what exactly do you suggest using to flush the system?

 

[73F100Shortbed]

Well if it is remaining at 180 it's not over heating so what's your problem? My truck runs at 200 all day long sometimes a bit higher. Did that with 2 different engines, different thermostats, and a different radiator. Since you have one of those laser thermometers check it like every hour and see if the temp. keeps coming down. Sounds like you are just looking for something to fix

 

[LEB Ben]

You have to measure temps with a thermoeter not a dash gauge.

Newly rebuilt engines run hotter than normal until about 5000 miles

If it is out of time that will cause it to run hot.

You could always try realigning the hood to make space in front of the cowl for heat to escape

Well I was using an actual gauge, a laser thermometer and seeing where my dash gauge was in line with it.


Bottom end is stock, but the top end is all new...and only has about 1500 on it.

I'll check timing and make sure it's not advanced too far.

Increase the ratio of coolant to water to 80-20

I just used pre-mixed 50/50.


dennis...you have any suggestions on a cleaner or process?

 

[73F100Shortbed]

It will heat up in stop and go traffic because of lack of airflow on the radiator. That is normal. When you did the thermostat did you bleed the air out of the system?

 

[LEB Ben]

Well if it is remaining at 180 it's not over heating so what's your problem? My truck runs at 200 all day long sometimes a bit higher. Did that with 2 different engines, different thermostats, and a different radiator. Since you have one of those laser thermometers check it like every hour and see if the temp. keeps coming down. Sounds like you are just looking for something to fix

Maybe...I just know how it usually runs, and it's not typical for this rig. But timing and running hotter during break in adds a little peace of mind.

 

[73F100Shortbed]

What did it used to run at if 180 appears high? Also take the laser thermometer and put it at different points of the radiator and see if the temp changes.

 

[LEB Ben]

What did it used to run at if 180 appears high?

No...the 180 is fine. But how quick it heats up from cold and how quick it heats up while idling...and the fact you could bake a turkey under the hood has me concerned. I wanna know why it's putting off so much heat and why it's heating up so fast. Low rpm issues are usually water pump and fan clutch related, right?

 

[73F100Shortbed]

Usually yes. But I don't know how come you would have some many waterpump issues in a short amount of time. How quick is quick in terms of it heating up?

 

[LEB Ben]

Usually yes. But I don't know how come you would have some many waterpump issues in a short amount of time. How quick is quick in terms of it heating up?

From 100% cold in the mornings, I can get to operating temp in about 2 miles. After idling for about 20 seconds in traffic, I the gauge starts creeping up. That being said, last night in the driveway, it idled for a good 30-45 mins with no issues.

 

[Mil1ion]

The ford gauges are prone to fluctuate on their own for no specific reason

This is why one uses a candy thremometer on an open cooling system ..occasionally revving the engine then let it idle for 30-40 minutes

Unless there coolant blowing out the cap, it is NOT overheating,regardless of what the gauge says

 

[Mil1ion]

Don't run anything less than a 180*F T-stat

The engine normally runs at 200-208*F

Do you have a fan clutch or viscious fan ?

 

[Mil1ion]

How many of the vanes on the rad are flattened out restricting air flow

If you lightly run your finger down the vanes do they bend over easy or do they scrape your skin

With the cap off at normal operating temp do you see coolant flow past the cap opening ?

 

[73F100Shortbed]

From 100% cold in the mornings, I can get to operating temp in about 2 miles. After idling for about 20 seconds in traffic, I the gauge starts creeping up. That being said, last night in the driveway, it idled for a good 30-45 mins with no issues.

Too me that sounds fairly normal. I drove my truck 2 blocks the other day and hit operating temp. after it idling for about 3 minutes. But it also was 100 degrees out.

 

[old blue]

i know this sounds crazy but my radiator was clogged i needed to drive my truck and had no money for a new radiator. but i had a bottle of c.l.r that stuff they advertise on tv as the super cleaner. i drained my radiator and put the bottle of c.l.r in with hot water and ran the truck for a bit. then drained the stuff into a jug and cycled the stuff through the radiator for about ten minutes and the really flushed the engine and everything with fresh water. the inside of the radiator looks brand new and no more overheating.