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1986 7.3L - Heating problem..
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1986 7.3L - Heating problem..
Ill start off saying im new to these forums. Just got this truck a few days ago, it was not running, was a huge risk I took, and im glad I did, I got it running just today (air in fuel line).
Its running great except that its heating up pretty good. I think the cooling fans clutch is bad, since its not locked when hot (tho it does spin). Would a tach weild work as a quick fix on the fan or is that a really bad idea?
Its running great except that its heating up pretty good. I think the cooling fans clutch is bad, since its not locked when hot (tho it does spin). Would a tach weild work as a quick fix on the fan or is that a really bad idea?
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if its not spinning fast enough (not locked) then i would say just buy a new one, i dont think they are fixable. but if you get it to stay locked it will definatly work. mine is frozen and stuck, havnt replaced it yet prviouse owner used red lock tite so i'll probably have to replace the water pump, mine works this way well enough. still if its dead it should not get any worse if you make it spin till you get a good one on
Post Fiend
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From: Nutter Fort, WV
Tool,
Welcome to FTE and the IDI diesel forum.
First unless someone has swaped engines in your 86, it has a 6.9 engine.
Fan clutches are rather expensive new, if you have a local salvage yard you might check there first.
Welding it solid would make your MPG take a big hit if you drive it much.
Also I think all the parts are cast, so welding may not be to easy to get it to stick.
Learath,
A bit of heat and the red locktite will let it turn right off the water pump.
Remember the fan clutch has left hand threads.
I use red locktite on mine every time I install the fan.
I have had one spin off and go through the radiator, that was a 400 dollar repair that I never want to repeat.
Welcome to FTE and the IDI diesel forum.
First unless someone has swaped engines in your 86, it has a 6.9 engine.
Fan clutches are rather expensive new, if you have a local salvage yard you might check there first.
Welding it solid would make your MPG take a big hit if you drive it much.
Also I think all the parts are cast, so welding may not be to easy to get it to stick.
Learath,
A bit of heat and the red locktite will let it turn right off the water pump.
Remember the fan clutch has left hand threads.
I use red locktite on mine every time I install the fan.
I have had one spin off and go through the radiator, that was a 400 dollar repair that I never want to repeat.
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thanks for the advice on the red locktite actually why it was put on there the fan spun off and threw the radiator. some part of how it conected to the fan clutch. so mine is locked up tite but good to know i can get it off without pulling the pump. and hey more mpg good 
cause this is gonna be my daily driver for a bit.
cause this is gonna be my daily driver for a bit.
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Originally Posted by Dave Sponaugle
Tool,
Welcome to FTE and the IDI diesel forum.
First unless someone has swaped engines in your 86, it has a 6.9 engine.
Fan clutches are rather expensive new, if you have a local salvage yard you might check there first.
Welding it solid would make your MPG take a big hit if you drive it much.
Also I think all the parts are cast, so welding may not be to easy to get it to stick.
Learath,
A bit of heat and the red locktite will let it turn right off the water pump.
Remember the fan clutch has left hand threads.
I use red locktite on mine every time I install the fan.
I have had one spin off and go through the radiator, that was a 400 dollar repair that I never want to repeat.
Welcome to FTE and the IDI diesel forum.
First unless someone has swaped engines in your 86, it has a 6.9 engine.
Fan clutches are rather expensive new, if you have a local salvage yard you might check there first.
Welding it solid would make your MPG take a big hit if you drive it much.
Also I think all the parts are cast, so welding may not be to easy to get it to stick.
Learath,
A bit of heat and the red locktite will let it turn right off the water pump.
Remember the fan clutch has left hand threads.
I use red locktite on mine every time I install the fan.
I have had one spin off and go through the radiator, that was a 400 dollar repair that I never want to repeat.
Its a 7.3, says it on the side. I think its been swapped out, because like you said, only a 6.9 was in an 86, as I found out when I got belts. It could possably be the temp gague showing it running hot, on word NORMAL (N = cool side) it usually stays on the A and L.
I found a temp gague(that a friend used in a 72 scout, aftermarket) that goes up to about 300 degrees that im going to stick into the heater hose to see how hot the water gets (temp riging). Also, when hot, the top hose to the radiator is HOT and the bottom one is cool(warm), so it seems the thermistat may be good (hate to replace it, its in a horrable place to get to). The radiator may need to be flushed since its been sitting a long, long time.
Ive run into a starter problem with the truck too, I will make a new post about it once I get a wireing diagram drawn out. Sticking starter = bad.
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From: maricopa az
sounds like your rad may be clogged from what you said after it warms up use temp guage or run your hand across rad core the coolspots will be where its clogged at the hot places where the coolant flowing properly if more cool spots than hot spots might look into getting repaired or replaced
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..
Checked radiator, upper parts are very hot including top hose, lower hose is luke warm, parts of the lower radiator are cool to luke warm. Must be clogged up. Think I will first try to flush it really good to see if it will unclog before getting another radiator.
Another thing to note, fan sometimes spins very freely after driveing it a bit, as if the clutch isnt grabbing, and sometimes its taunt. It also passed the rolled up newspaper test, couldnt stop it, so im thinking maybe it does need to be replaced, its going out, but works half the time.
Another thing to note, fan sometimes spins very freely after driveing it a bit, as if the clutch isnt grabbing, and sometimes its taunt. It also passed the rolled up newspaper test, couldnt stop it, so im thinking maybe it does need to be replaced, its going out, but works half the time.
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From: NC
Originally Posted by TooL
. It could possably be the temp gague showing it running hot, on word NORMAL (N = cool side) it usually stays on the A and L. .
I am willing to bet that it has the wrong tstat installed, it is manatory to use an oem motorcraft or IH tstat. replacement is easer that it looks I would change it
When i got my truck it had the wrong tstat in it, it would run between RM on the factory gage with a temp of 220, with the oem tstat it runs at 195, 200 to 210 on these 100 deg days with the a/c blasting
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Would you recommend a certain gauge? Browsing thru the Advance Auto list of Gauges there is a huge variety and list of them. Ill also look into the thermstat, im not that afraid to change it, just that alternator/vacume bracket looks like a pain.
Also, tho my truck is a 86 model, it has a 7.3L Diesel in it. They started putting that engine in it around 88? It has a sticker on the engine that says its a 7.3. Im not sure how to tell the diffrence, if its a diffrent head cover with the wrong sticker on it. Most places ask what year your truck is and cant look up parts by engine alone heh, so I gotta identify what year motor this is.
Also, tho my truck is a 86 model, it has a 7.3L Diesel in it. They started putting that engine in it around 88? It has a sticker on the engine that says its a 7.3. Im not sure how to tell the diffrence, if its a diffrent head cover with the wrong sticker on it. Most places ask what year your truck is and cant look up parts by engine alone heh, so I gotta identify what year motor this is.
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From: Boston, Ma
welding genius
Anything stupid ever done to a poor diesel ...that would be me...welding not a good idea...specially on cast....I was able to find one (After attempted abuse) in a salvage yard after for $35.00. It's been on there for about three years now. Probably not your problem....just sharing.
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From: Nutter Fort, WV
Actually I looked at a spare I have in the garage.
The shaft is cast iron, the fan clutch housing is aluminum.
So that is not going to weld together anyway.
Since the clutch is locking and releasing, sounds like it is OK.
But I have seen a lot of the wrong thermostats installed in these diesels.
With a little finesse you can get the thermostat out and back in by removing the alternator only. When you work in there, watch you don't knock the wire connector off the temp switch for fast idle and timing advance right beside the thermostat housing. It is a real bear to get it plugged back in after the alternator is reinstalled.
When you remove it, if the outside of the thermostat is not about 1/2" tall with a rubber gasket on it it is the wrong thermostat.
The shaft is cast iron, the fan clutch housing is aluminum.
So that is not going to weld together anyway.
Since the clutch is locking and releasing, sounds like it is OK.
But I have seen a lot of the wrong thermostats installed in these diesels.
With a little finesse you can get the thermostat out and back in by removing the alternator only. When you work in there, watch you don't knock the wire connector off the temp switch for fast idle and timing advance right beside the thermostat housing. It is a real bear to get it plugged back in after the alternator is reinstalled.
When you remove it, if the outside of the thermostat is not about 1/2" tall with a rubber gasket on it it is the wrong thermostat.
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I also have an 86 with a 7.3 that I installed and it does the same thing. It seems to run back and forth between the A and the L of the word NORMAL on the temp gage. I know the stock gages are not reliable, but that is all I have right now. I installed a Motorcraft t-stat when I did the swap. I also flushed the radiator out. I'm not sure exactly how the fan clutch is supposed to operate. After running a while and then shutting down the fan spins freely with no resistance. But when it is cold it does have resistance. Is this correct? When I did the swap, the salvage yard engine I got had the fan on it. I spun both fans by hand and put the one that felt the best on (the one off of the 6.9). Maybe that was the wrong thing to do. Also, I noticed there is a difference in the fans between the 6.9 and 7.3. The fan blades on the 6.9 are evenly spaced. On the 7.3 the fan blades are evenly spaced but between one blade. I thought it might just be bent at first, but after looking at it, it is made that way. Could that cause a difference?