bronco overheating???

[77bronco77]

Hey there. So heres whats goin on. i just finished re building my tired 302. and i put new 62-67 closed chamber 289 heads, comp cams cam (step above rv cam), comp cams mag roller rocker arms, heads totally rebuit and port and polished "exhaust ****" removed in heads also. Brand new water pump. all new hoses, eddie performer manifold. Holly truck avenger 670 cfm carb, and a k&n air filter. few other things im forgeting too....but i was driving it to the gas station today and it started to get a lil hot so i babied it back towards my house. and i wasnt really hot roddin it or anything in the first place. so then it got a lil hotter and pretty soon it was at 190ish. then 200. then it hit 210 and i was almost home so i put it in nuetral and coasted it. but when i got there it was at 220ish and i killed it in the driveway and it just steamed out the hood and boiled out. so i popped the hood and let it cool. but why did it do this? it did this a while back too. but the thermostat somehow got installed backwards and that fixed it. im running 50/50 anti/water with water wetter additive in it. any help would be nice.

thanks

 

[Seabronc]

I was going to guess the T-stat was stuck or in backwards, but since you seem sure that isn't the case I think I would check the flow. How long have you run it since rebuild? Did you give it some test time in the driveway or just take off down the road? Squeeze the radiator hose after it warms up to make sure you have flow. Do you have a mechanical or electric fan? If electric, what is the CFM rating of it? *** big is the radiator?

Good luck,

>-

 

[Orangecrush]

I was going to guess the T-stat was stuck or in backwards, but since you seem sure that isn't the case I think I would check the flow. How long have you run it since rebuild? Did you give it some test time in the driveway or just take off down the road? Squeeze the radiator hose after it warms up to make sure you have flow. Do you have a mechanical or electric fan? If electric, what is the CFM rating of it? *** big is the radiator?
Good luck,

>-

* check is for air pockets. Burp them out if possible.

* make sure the lower hose isn't collapsing.

* check the spark timing to make sure it's not late. Late SPARK timing initiates the fuel burn process a little late in the cycle. The result can be fuel that isn't done burning by the end of the power stroke. The remainder keeps burning, but with no work to do (pushing the piston down), it transfers the energy to heat, which is absorbed into the water.

if none of these seem to work, I'd say either the water pump isn't pumping properly, for some reason, or the gauge may not be grounded properly and is giving a high reading. Since you were drving when it got got, I wouldn't worry about the fan too much. The fan is for 25 mph or less and is useless above 35.

 

[Seabronc]

* check is for air pockets. Burp them out if possible.
Since you were drving when it got got, I wouldn't worry about the fan too much. The fan is for 25 mph or less and is useless above 35.

I agree if the system is functioning at top efficiency, but anything less brings in the need for a fan, and the CFM definitely counts based on the engine environment and it's ability to move air and dissipate heat. The water pump is the least efficient at low RPMs which is when the egine needs the most help to keep cool. The outside air temperature becomes a key component in how soon a fan is needed. For example, this time of year, in the frigid North East, mine only comes on when I've been setting at a light for 4 to 5 minutes and goes off as soon as I start to move, it might never come on during a trip around town in January and February. However, that lag time creeps down as the out side temps increase until midsummer when surface temperatures are 130+ degrees F, then the fan comes on under 35. The CFM is also extremely important when off roading with low RPMs and hot outside air temperatures, where a 2500 - 3000 CFM fan will find it hard to impossible to prevent overheating. Another factor in the CFM requirement is the engine size and how well the rest of the cooling system is designed.

By the way, I missed the boiling over at 220. Check the radiator cap, it should not do that in a pressurized system. Granted, that is hot and the boiling point of pure water at sea level pressure, but your system is a mix and pressurized.

 

[Broncobill78]

Hey there. So heres whats goin on. i just finished re building my tired 302. and i put new 62-67 closed chamber 289 heads, comp cams cam (step above rv cam), comp cams mag roller rocker arms, heads totally rebuit and port and polished "exhaust ****" removed in heads also. Brand new water pump. all new hoses, eddie performer manifold. Holly truck avenger 670 cfm carb, and a k&n air filter. few other things im forgeting too....but i was driving it to the gas station today and it started to get a lil hot so i babied it back towards my house. and i wasnt really hot roddin it or anything in the first place. so then it got a lil hotter and pretty soon it was at 190ish. then 200. then it hit 210 and i was almost home so i put it in nuetral and coasted it. but when i got there it was at 220ish and i killed it in the driveway and it just steamed out the hood and boiled out. so i popped the hood and let it cool. but why did it do this? it did this a while back too. but the thermostat somehow got installed backwards and that fixed it. im running 50/50 anti/water with water wetter additive in it. any help would be nice.thanks

Ok, the previous posters pretty much covered the bases but I just had a quick question about your post. You mentioned that you *just* finished rebuilding the engine. How long has it been in and running ? Was this by chance a maiden voyage or has it been running & driving fine for a few days/weeks/month or so before doing this ? I ask because I had this EXACT same issue pop up with a buddy back in high school and have never forgotten the experience. We removed & tore down his 327 (this was a FireBird not a Bronco but hang with me, it's relevant) and dropped the block off at a local parts store that did machine work. We picked it up after with a .030 overbore and then re-assembled & reinstalled it. It overheated right from the first turn of the key and always ran hot even after we went to *triple* electric fans (2 pushers & 1 big puller), a huge 4-core aluminum radiator, swapped in a high-flow water pump and then swapped THAT for an ever higher rated electric and finally removed the freaking t-stat in desperation. After a month of running at 220+ regardless of what we did we finally pulled the engine back out, tore it back down *again* and brought the block to a race shop to be checked. Turned out he didn't have ANY two cylinders the same diameter and the 8 of them averaged in around .027 over. Not having any confidence in any of the *other* work that had been done we had the race shop clean the whole thing up & redo everything. We got it back, re-assembled it again and didn't have a single problem with it after that.

Didn't mean to turn this into such a longwinded post, I guess the short version would have been, "are you sure the rebuild is correct & the cylinders are't too tight ?"

 

[77bronco77]

the truck has been running good for 2 weeks or so. runnin around town it did good. i did the 25 mins break in for the cam and then the radiator cap popped after that, so i refilled it the next day. ran it a bit more in the drive way. took it around the block and parked it. i came back out after lunch inside and drove it 3.7 miles to walmart down the road. came back and i pulled in the driveway killed it and it got really hot and steamed again. so i finally found this leak at the timing cover gasket. so i took it all apart again and replaced the gasket using a genourus ammount of black gasket sealer which is gunna be a bi*ch to get off. but i am almost done gettin it back together. i need to put the bottom rad. hose on and put the belts and *manual* fan on. but this should fix my overheating issue. if it doesnt then i will cheak back in to this topic. but it if it works ill leave a reply and let ya know if it fixed it. Thanks for your help

P.S. turns out the t-stat WAS backwards....oops.

>-

 

[77bronco77]

hey i got it runnin good again. would you guys recomend putting in an electric fan? it seems to me like most of you have one. i read somewhere that it saves a bit of horsepower because you eliminate the manual fan.

thanks

Eric

 

[Seabronc]

hey i got it runnin good again. would you guys recomend putting in an electric fan? it seems to me like most of you have one. i read somewhere that it saves a bit of horsepower because you eliminate the manual fan.
thanks

Eric

Obviously I would since I have one. However, you need one that has a high CFM rating. I recommend you look around your local junk yard and put the one I have in. If you want a new one, you can get them from Ford. A lot of the ones sold on the market have too low of a CFM rating for a 5.8L engine and I have read numerous complaints by people who have installed them about poor cooling, especially if they are off roading on hot days. I run mine at high speed no matter what atmospheric conditions exist when it comes on.

Saving horsepower is a little inaccurate. What it does is take a little less HP to run the truck down the road which gives a small improvement on gas mileage since you aren't expending the energy slinging a fan around. The Hp you don't use on the fan is then available to the drive train when needed. If you were to run the electric fan full time, you wouldn't save anything since the load would only be shifted from a mechanical load to an electrical load on the alternator and the larger the load on the alternator the more resistance it has to being turned. The savings is in the fact that the fan hardly runs at all if set up correctly. Like I've said in previous posts on this subject, mine probably runs less than 1% of the time I have the engine running. In winter virtually never and in the Summer when surfaces are 130f + it comes on when running less than 35 MPH. If you were top compare the mileage with it running against the mileage without it running, I honestly would say less than 1%.

Also if you are an off roader, you need to be able to totally shut it off if going through water, and the ability to also over ride the control to force it on is nice. Also, if converting to a high power fan like the one I have, I strongly recommend upgrading to a 130+ Amp 3G alternator to handle the start current.

A couple of pictures of mine: Before, After, the control (old picture, relocated with massive modifications this past Summer),Current control location under the cover with a tie wrap on it, Inside control panel (meter not part of it, it monitors the voltage at the main distribution post on the under hood fuse box, the same point the alternator monitors) and indicator lets me know when 12V is applied to the fan ( A good trouble shooting aid if the fan fails to come on :-B ), A Schematic of the control I used, There are minor wiring modifications depending on how and what you want to control with it.

Food for thought :blink:

Good luck,

>-

 

[77bronco77]

Obviously I would since I have one. However, you need one that has a high CFM rating. I recommend you look around your local junk yard and put the one I have in. If you want a new one, you can get them from Ford. A lot of the ones sold on the market have too low of a CFM rating for a 5.8L engine and I have read numerous complaints by people who have installed them about poor cooling, especially if they are off roading on hot days. I run mine at high speed no matter what atmospheric conditions exist when it comes on.
Saving horsepower is a little inaccurate. What it does is take a little less HP to run the truck down the road which gives a small improvement on gas mileage since you aren't expending the energy slinging a fan around. The Hp you don't use on the fan is then available to the drive train when needed. If you were to run the electric fan full time, you wouldn't save anything since the load would only be shifted from a mechanical load to an electrical load on the alternator and the larger the load on the alternator the more resistance it has to being turned. The savings is in the fact that the fan hardly runs at all if set up correctly. Like I've said in previous posts on this subject, mine probably runs less than 1% of the time I have the engine running. In winter virtually never and in the Summer when surfaces are 130f + it comes on when running less than 35 MPH. If you were top compare the mileage with it running against the mileage without it running, I honestly would say less than 1%.

Also if you are an off roader, you need to be able to totally shut it off if going through water, and the ability to also over ride the control to force it on is nice. Also, if converting to a high power fan like the one I have, I strongly recommend upgrading to a 130+ Amp 3G alternator to handle the start current.

A couple of pictures of mine: Before, After, the control (old picture, relocated with massive modifications this past Summer),Current control location under the cover with a tie wrap on it, Inside control panel (meter not part of it, it monitors the voltage at the main distribution post on the under hood fuse box, the same point the alternator monitors) and indicator lets me know when 12V is applied to the fan ( A good trouble shooting aid if the fan fails to come on :-B ), A Schematic of the control I used, There are minor wiring modifications depending on how and what you want to control with it.

Food for thought :blink:

Good luck,

>-

so if i went to a junk yard and found a fan from a 5.0 later model bronco would it fit in my early bronco with little to no modification? and how can i tell if its a high CFM fan? i would like to go to a junkyard and look for one. do you think theres any advantages of running duel fans? or will the single one do just fine? so if i just used a high amp switch in line with the fan i would be able to turn it on and off as i please, but how would i get it to run on its own since the early broncos never came with an elecrtric fan?

thanks for your help i appriciate it.