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302 eng. 87 year. My w pump was down with extreme leak and I replaced it at last weekend. When I make this procedure, I was disconnected 3 hoses from pump, some coolant drained, after replacing all hoses was returned to their ports: short 90 degree from thermostat to upper left, long from heater brunch to lower left and wide from lower main line core to lower right... After that I refill coolant to normal level. All works good - no leaks, no overheat, seems good - but... Today is cold, I use a heater - and strange thing - blower takes slightly warm air in cab, even at max power... Thermostat is ok, I see how it's work. When I start cold engine, temp gauge is rise up to "more than half-normal" in some minutes, than it drop to "less than half-normal" - it's thermostat is opening, then it slowly rised to half-normal temp... But when I drive - only warm air and at high speed eng. temp stay at "some less than half-normal" mark... It was not so before replacing - even at high speed in cold weather it was exactly on "half-normal" and hot air from cab heater...
What's wrong? Any suggestions? What's happens and where is joke?

P.S. Fan clutch and temp sender is ok - new and workable.
 

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Ford Hoarder
78 & 92
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How cold is cold there? Maybe block off section of radiator, as the coolant system is now working and before maybe its was only 80%... May also be that your heater core is plugged up.
Also do you happen to know what degree t-stat was installed?
 

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Bet you have air in cooling system. Start Bronco, open radiator and check level bet when the thermostat opens, the level of antifreeze in radiator drops. Keep adding antifreeze until full. Heater isn't working because no warm antifreeze moving through it.
 

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Discussion Starter #4
Cold - not so terrible - about 27 F...
Blocking radiator or heater core - not sure - it was normally before replacing and nothing to change or doing with this parts... Why was system working for 80% before? Old pump gave full coolant flow - it was just leak, was not stucked bearing or shaft. After removing it was rolling easy and quickly by hand.
T-stat is 86 degree (in Celsius ?) - standard t-stat. But it was not replaced too. I know, that can be 92-93 t-stats - it can be trouble solver but I want have reliable system at hot in summer - it can be extreme enough... And second - temp mode was absolutely excellent before with standard t-stat...
 

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Charlie don't surf..
'92 Ford Bronco XLT
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Bet you have air in cooling system. Start Bronco, open radiator and check level bet when the thermostat opens, the level of antifreeze in radiator drops. Keep adding antifreeze until full. Heater isn't working because no warm antifreeze moving through it.
x2
 

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I had bad cooling system problems for a while. After changing the radiator cap and adding some clamps where there were none I finally got it all to work, but it took me DAYS to get all the air out of the system. I drive it, let it cool, top it off, run it a bit, top it off, close up the radiator. Drive it some more, let it cool off, Top it off, run it a bit, top it off,........you get the idea. Keep doing that till it wont take any more coolant. Might take a while to get all the air out of it.
 

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Mine operates the same, been chasing it for a week now.

I can tell that the core is flowing right by the temp of hoses and the air box is not plugged up with dirt, pretty clean to be honest. My HVAC control cables are junk and I did find that the temp control flap inside the heat/ac box was stuck open, nothing blocking it, just wouldn't close with the control. I closed it by hand and that helped some, I think it will at least defrost the window now.

But my truck still runs in the second 1/4 of the temp gauge and never gets over half. I am certainly not getting the heat everyone claims these truck put into the cab. I replaced my stat, it was operating correctly before but seemed to hang open too long. The replacement stays in a tighter range but again, never gets over half.

I had to replace the top Rad hose, and have been checking the coolant level daily. It seems to have leveled out and I only lost coolant from the top side of the engine, plus that truck was parked on an incline with the rear lower than the front. I have put in maybe a gallon of coolant total the last two days and the overflow is staying full now.
 

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Nice to see you're not the only one with issues. I had the same cooling issues. Now she pegs to the full H when maintaining a cruising speed. I recently replaced water pump, t stat, and heater core. That didn't seem to fix it properly although a lot better after a 5 min heater core change. Then a leak from the t housing happened. Now thats fixed! Next will be the temp gauge sensor. At least she stopped blowing cool air at me when the heats on but still not at her best.
 

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Kitteh Commandaar!
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Bet you have air in cooling system. Start Bronco, open radiator and check level bet when the thermostat opens, the level of antifreeze in radiator drops. Keep adding antifreeze until full. Heater isn't working because no warm antifreeze moving through it.
I agree. Remove the radiator cap and start the truck. Let it run and warm up. Once warmed up, the level of coolent will drop as the thermostat opens. When that happens, fill with more coolent.
 

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I agree. Remove the radiator cap and start the truck. Let it run and warm up. Once warmed up, the level of coolent will drop as the thermostat opens. When that happens, fill with more coolent.
Yep. The neck is pretty much the highest point in the system, so it will purge itself of air naturally if you bring it up to temp with the cap off. Then just fill to capacity. Make sure you have the appropriate fill level in your overflow tank as well.

Just saw op is a coupla weeks old....hopefully he got it figured out.
 

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Discussion Starter #11
Yes, I was make it 3-4 times, cap-off, start, refill, drive some miles, refill. After period repeat. And it seems much better now! Thanks!
 

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The highest point in the system is the heater core nipples at the firewall. If you bleed air & fill coolant there, it should be full the first time. Leave the radiator cap off until coolant comes up in the neck, then cap it & continue filling the heater hose. When coolant spills out the heater nipple, connect the hose, and you're done.

86C = 187°F (190) which is the correct temperature thermostat.
http://www.visteon.com/utils/unitconverter/
 

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The highest point in the system is the heater core nipples at the firewall. If you bleed air & fill coolant there, it should be full the first time. Leave the radiator cap off until coolant comes up in the neck, then cap it & continue filling the heater hose. When coolant spills out the heater nipple, connect the hose, and you're done.

86C = 187°F (190) which is the correct temperature thermostat.
http://www.visteon.com/utils/unitconverter/


The only problem with that is the "bubble" is now in your heater core.
 

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a lot of times when I do a core or other work,i will remove the heater hose and fill system through the hose and core
when I get coolant out the fitting in the block when the hose is removed from, I quickly install hose and continue filling system up from rad

some vehicles air lock is a bitch to remove unless a specific procedure is followed to the letter
 

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The only problem with that is the "bubble" is now in your heater core.
Exactly what do you think that problem will be?

Bubbles go to the highest (local) point, which in this case is the same as the opening that's letting the air out as water/coolant goes in elsewhere. If you end up with a bubble, it will be so small that just starting the engine will push it out instantly. The WP impeller will break it up, and it will rapidly work its way to the top of the radiator, where the cap & overflow tank will remove it all in a few drive cycles.

So unless you're REALLY slow & sloppy reconnecting that hose, the bubble will be too small to affect anything. Probably smaller than the bubble the factory put in.
 
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