'86 300-6cyl heating problem
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Posting Guru
Joined: Oct 2000
Posts: 1,355
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From: Western NC
'86 300-6cyl heating problem
The heater in my '86 F-150 will not get hot. I have had the same problem for a while. Last summer, I replaced the thermostat, the hoses, the heater core, and put in fresh coolant. Last winter, I could tell an improvement, but it still wasn't as hot as it used to be. Now that it is getting cold weather again, I have noticed it seems to be even worse than it was before. It will get warm if I'm out on the highway, running 2500+ rpm. Before, the water temp gauge would sit on the lower end of the "normal" range. Now, it will not even get up to the lower end of the range. What else could be causing this problem? I need some heat before the really-cold weather sets in.........
Fleet Mechanic
Joined: Aug 2000
Posts: 1,504
Likes: 1
From: Texas
'86 300-6cyl heating problem
Might check your box under your hood. My dad's 82 had problems with the A/C not cooling right. He found out one day that there was a hole big enough to fit a regulation baseball through melted in the box outside, right next to the exhaust manifold. And everything on his truck was factory.
Might be something to check.
Hope you find it before it gets too cold. I know what it's like to go through winter with no heater in a vehicle. And summer in SE Texas with no A/C in the summer.
1988 F-150 Custom to XLT Lariat conversion, 5.0 EFI (formerly 300 I6), 5-speed M5OD, 3.08 rear gears (will be upgraded to 3.55's), Summit headers, Flowmaster muffler W/ dual 3.5" tips 24" long.
Pioneer CD, AC, Tilt, Cruise, Mobile Radio, Lightbar (Force 4 LP6000), Federal Signal PA300 Siren W/100W Siren Speaker. Caution Customizing in progress, Watch for flying tools & Parts!
Might be something to check.
Hope you find it before it gets too cold. I know what it's like to go through winter with no heater in a vehicle. And summer in SE Texas with no A/C in the summer.
1988 F-150 Custom to XLT Lariat conversion, 5.0 EFI (formerly 300 I6), 5-speed M5OD, 3.08 rear gears (will be upgraded to 3.55's), Summit headers, Flowmaster muffler W/ dual 3.5" tips 24" long.
Pioneer CD, AC, Tilt, Cruise, Mobile Radio, Lightbar (Force 4 LP6000), Federal Signal PA300 Siren W/100W Siren Speaker. Caution Customizing in progress, Watch for flying tools & Parts!
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Posting Guru
Joined: Oct 2000
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From: Western NC
'86 300-6cyl heating problem
OK, it's supposed to be 15 degrees here in the morning. I have been trying to figure out what I can do to fix this problem. I blocked off the radiator with cardboard, up until the thing ran hot, and still no heat!!!!! Well, I can feel a little warmth, but not nearly enough. I wonder if the water pump is circulating water through the heater core. I am out of ideas and would be so glad to find the remedy for this trouble.
Posting Guru
Joined: Apr 2000
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From: NorCal
'86 300-6cyl heating problem
Try running water through the heater hoses. That'll tell ya if theres blockage in the lines.
The hose that feeds the heater core comes from the thermostat housing (water outlet) and the return hose goes right to the water pump. Have you checked the feeder line on the thermostat housing for blockage? Just a thought.
The hose that feeds the heater core comes from the thermostat housing (water outlet) and the return hose goes right to the water pump. Have you checked the feeder line on the thermostat housing for blockage? Just a thought.
Senior User
Joined: Jan 2000
Posts: 242
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From: St. Paul, MN
'86 300-6cyl heating problem
Couple things to look at-
fan clutch- if the fan clutch is seized, your fan will be turning all the time instead of being slack when the engine is cold.
heater temp selector- your temp selector adjustment may be out of whack not allowing full heat into the cab. You should feel the lever bounce a little bit at each end of it's range (hot to cold). If it doesn't bounce on the hot end but bounces more on the cold end, you're not getting the heat you should be getting. Pull the glove box off and adjust the range by pulling the cable from it's retaining clip and shift the sleeve of the cable left or right to get the range centered then push the cable back into it's clip. The cable clip is right on top of the heater core cover.
Dustin Siebert
mrlaserboy(No Email Addresses In Posts!)
Registry: http://www.superford.org/cgi-bin/sf.cgi?uid=default&vr2=1&ID=201
Home Page: http://www.fortunecity.com/silverstone/gear/40
'88 Bronco XLT 302EFI/AOD/BW1356/44IFS with 8 lugs(open)/10.25 FF(Lockright locker)/4.56/6" Superlift complete/35's-street/38.5's-trails
2 BIG BRONCOS 4X4 CLUB - GREAT LAKES CHAPTER
fan clutch- if the fan clutch is seized, your fan will be turning all the time instead of being slack when the engine is cold.
heater temp selector- your temp selector adjustment may be out of whack not allowing full heat into the cab. You should feel the lever bounce a little bit at each end of it's range (hot to cold). If it doesn't bounce on the hot end but bounces more on the cold end, you're not getting the heat you should be getting. Pull the glove box off and adjust the range by pulling the cable from it's retaining clip and shift the sleeve of the cable left or right to get the range centered then push the cable back into it's clip. The cable clip is right on top of the heater core cover.
Dustin Siebert
mrlaserboy(No Email Addresses In Posts!)
Registry: http://www.superford.org/cgi-bin/sf.cgi?uid=default&vr2=1&ID=201
Home Page: http://www.fortunecity.com/silverstone/gear/40
'88 Bronco XLT 302EFI/AOD/BW1356/44IFS with 8 lugs(open)/10.25 FF(Lockright locker)/4.56/6" Superlift complete/35's-street/38.5's-trails
2 BIG BRONCOS 4X4 CLUB - GREAT LAKES CHAPTER
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Posting Guru
Joined: Oct 2000
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From: Western NC
'86 300-6cyl heating problem
OK, CGL and Laserboy.........I'm gonna check out all that stuff. I'll let you know how it comes out. I appreciate you all trying to help a fellow-Ford-driver out. It's mighty hard to drive when shivering out of control.........
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Tuned
Joined: Nov 2000
Posts: 426
Likes: 1
From: houston, texas (now Berli
'86 300-6cyl heating problem
I would go with laserboy: check the wires from your levers to the flaps in the air tubing. One of them was ripped of in my 1988 truck so it would heat all the time (and that was in Houston 100° weather - not nice!). Had to take the whole temp selector box out and fix the wire to the lever.
Good luck!
Good luck!
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'86 300-6cyl heating problem
simple my friend. buy a radiator flush kit i use prestone. install the tee and put some radiator flush liguid. follow the directions and back flush the system. your heater core may be clogged you will find out then. good luck i flush my system once a year
Fleet Mechanic
Joined: Aug 2000
Posts: 1,504
Likes: 1
From: Texas
'86 300-6cyl heating problem
I have heard some of the radiator flush kits can damage heater cores. Several people in my local car club have told me of this from first hand experience, because it happened to their own cars. I guess you just have to be careful with whatever you aer going to buy.
"You can always tell a Chevy owner, You just can't tell them very much."
"You can always tell a Chevy owner, You just can't tell them very much."
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