Overheating - HELP I'm baffled...!!!
Thread Starter
|
Freshman User
Joined: Apr 2004
Posts: 38
Likes: 0
Overheating - HELP I'm baffled...!!!
1984 F150 4.9L - 206K miles - manual trans - orig motor
Occationally my truck would overheat way up past the HOT then cool down again. Sometimes I may drive 50 miles and everthing is normal. Sometimes I may drive only 1 mile and it overheats!
Changed the thermostat - and drained the system - still erratic overheating
Changed the thermost again - backflushed the system - removed the old A/C condenser - still erratic overheating
Removed the theromstat - run cold for a while then suddenly overheated...!!!
Tested my collection of thermostats - all open in boiling water
New radiator - new coolant - still erratic overheating usually after idling for a while in traffic then pulling away - the gauge shows a rapid increase in temp. At speed, even under load, it never overheats.
I have 2 theories water pump or head gasket. Any others?
Paul
Occationally my truck would overheat way up past the HOT then cool down again. Sometimes I may drive 50 miles and everthing is normal. Sometimes I may drive only 1 mile and it overheats!
Changed the thermostat - and drained the system - still erratic overheating
Changed the thermost again - backflushed the system - removed the old A/C condenser - still erratic overheating
Removed the theromstat - run cold for a while then suddenly overheated...!!!
Tested my collection of thermostats - all open in boiling water
New radiator - new coolant - still erratic overheating usually after idling for a while in traffic then pulling away - the gauge shows a rapid increase in temp. At speed, even under load, it never overheats.
I have 2 theories water pump or head gasket. Any others?
Paul
Last edited by LimeyZ; Jul 16, 2005 at 06:17 AM. Reason: info
Logistics Pro
Joined: Apr 2005
Posts: 4,447
Likes: 0
From: Georgia
I have heard of timing being retarded causing overheating. I don't know if this is the case but grabbing a timing light and checking it wouldn't hurt. If the gauge is the only indication that it is overheating could be a faulty temperature sending unit.
Logistics Pro
Joined: Apr 2005
Posts: 4,447
Likes: 0
From: Georgia
If you have access to one of those nifty laser thermometers you could find out how hot your engine really is. I would not suggest going out and buying one unless you are gonna use it alot. They are sort of expensive.
Cross-Country
Joined: Jan 2003
Posts: 65
Likes: 2
From: Winthrop Harbor, IL
Paul,
Is the truck physically overheating and boiling over... or is this just the gauge going high? I'm wondering if it might just be a gauge / wiring issue? Hate to see anyone rip into a water pump / cylinder head project for what might be a grounded out wire or a bad sender. If it's not actually boiling over, pinging, etc I would look into some other way of reading the actual engine temp. Maybe an aftermarket gauge/sender or check replace the stock sender and inspect the wiring.
Is the truck physically overheating and boiling over... or is this just the gauge going high? I'm wondering if it might just be a gauge / wiring issue? Hate to see anyone rip into a water pump / cylinder head project for what might be a grounded out wire or a bad sender. If it's not actually boiling over, pinging, etc I would look into some other way of reading the actual engine temp. Maybe an aftermarket gauge/sender or check replace the stock sender and inspect the wiring.
Trending Topics
Cargo Master
Joined: Apr 2003
Posts: 2,408
Likes: 5
From: Parkesburg PA
Here's my 2 cents... Fan clutches go bad. The fan goes around, but doesn't pull the air that's needed to cool the engine. The problem shows up at slow speeds. I've replaced a few recently... Last two I did were in the 150 - 160k mile range.
I also wouldn't trust the stock gauge.
David
I also wouldn't trust the stock gauge.
David
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread Starter
|
Freshman User
Joined: Apr 2004
Posts: 38
Likes: 0
Dungeon Master, The fan clutch is NOT working properly. After driving around for a while I stopped and checked the fan clutch. If anything it felt looser than the cold state! I can almost hand spin the fan when it's hot. Not good I guess!
Adam79, The engine never boils over and there's no pinging (I've experienced these events in other vehicles...). There's some relationship between idling for a while then pulling away and the gauge going off the scale then returning to normal at speed.
One thing I'm testing right now is an increase in idle speed. It was idling at approx 500 rpm and I reset to 750 rpm. My thinking is that at VERY slow idle speed the water pump is hardly circulating the coolant (AND the fan clutch is not working!) which overheats in the head. As I drive away, more heat is added to the coolant before any cooling by the radiator and circulation takes place.
Adam79, The engine never boils over and there's no pinging (I've experienced these events in other vehicles...). There's some relationship between idling for a while then pulling away and the gauge going off the scale then returning to normal at speed.
One thing I'm testing right now is an increase in idle speed. It was idling at approx 500 rpm and I reset to 750 rpm. My thinking is that at VERY slow idle speed the water pump is hardly circulating the coolant (AND the fan clutch is not working!) which overheats in the head. As I drive away, more heat is added to the coolant before any cooling by the radiator and circulation takes place.
Elder User
Joined: Oct 2004
Posts: 984
Likes: 0
From: Winnipeg, Manitoba
Install a decent temp gauge. The stock gauges in these trucks are crap, and often misleading. I still have my stock gauge functional, but it will shot overheat, when the mechanical gauge i have is showing a nice even 180 degrees.
Thread Starter
|
Freshman User
Joined: Apr 2004
Posts: 38
Likes: 0
Fixed...!!!
Well, looks like the fan clutch is an important part of the cooling system 'cause since I locked it to the water pump pully there's been NO hint of overheating! Just bought a new fan clutch off eBay for $17.50 + $12.00 S&H to do a proper job.
Thanks everyone for your input - I was initially looking in the wrong direction and you straightened me out!
Paul
Thanks everyone for your input - I was initially looking in the wrong direction and you straightened me out!
Paul
Last edited by LimeyZ; Jul 17, 2005 at 03:49 PM. Reason: Bad grammer
Junior User
Joined: Feb 2005
Posts: 50
Likes: 0
From: Dallas, TX
Overheating Issue ...
Hey ... I've got a thermo clutch of my own to change ... '91 300 I6-runs warm in traffic w/ac on. Fan spins like a top. Found a nice new $30 Hayden clutch at O'Riley (In Dallas). They also have the tools. Other than making sure that I unscrew the fan in the right direction, is there any thing that can jump up and bite? I hate that stuff!. Question though, is there any way I can sub. a plain old solid mounted fan to the pully and never worry about fan clutches again?
Thanks,
Dusty(and hot/humid) in Dallas
Thanks,
Dusty(and hot/humid) in Dallas
Post Fiend
Joined: Jan 2004
Posts: 6,610
Likes: 2
From: Northwest, Arkansas
You can replace it with an aftermarket fan but then you would have all that drag on the engine all the time. Another option would be a electric fan. As for removing it, you have it about down, just turn it the correct direction. If you have a full fan shroud it might be easier to unbolt it also and pull them out together.