Overheating six
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
At 45-55 MPH, you might as well take the fan completely off because it's strictly along for the ride at that point. The fan is ONLY useful for providing airflow at low speeds.
How does the oil look? Does it have any coolant in it? If no, it's probably not the headgasket.
If there are no obvious leaks then I'd guess your radiator is clogged.
How does the oil look? Does it have any coolant in it? If no, it's probably not the headgasket.
If there are no obvious leaks then I'd guess your radiator is clogged.
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
Oil doesn't appear to have coolant in it. Level isn't going up. No milkshake look. The Windstar needed head gaskets, so I know what the milkshake looks like.
Haven't done the fan clutch. The truck is my 3rd vehicle, so it is not a pressing need at this point.
Haven't done the fan clutch. The truck is my 3rd vehicle, so it is not a pressing need at this point.
Posting Guru
Joined: Nov 2004
Posts: 1,137
Likes: 2
From: Asheville, NC
As for the water gurgling in the heater core,
Just keep driving it. The air will work its way out of the core over time.
Did all this when I bought my truck earlier this year. Thermostat was stuck open. Flushed it all out while I had it apart. Glad it was just old anti-freeze, and no rust in there.
My heater gurgled on start-up for about a week. I drive it everyday.
Just keep driving it. The air will work its way out of the core over time.
Did all this when I bought my truck earlier this year. Thermostat was stuck open. Flushed it all out while I had it apart. Glad it was just old anti-freeze, and no rust in there.
My heater gurgled on start-up for about a week. I drive it everyday.
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
Drove my Aerostar. When warm, the fan was blowing nicely, much more than the faint breeze from the truck. Fan clutch on truck might be a culprit.
Are the rads (Spectra) and/or fan clutches available from Autozone any good? Got a coupon for 15% off if they are.
Are the rads (Spectra) and/or fan clutches available from Autozone any good? Got a coupon for 15% off if they are.
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
From discussions on the straight six forum here and elsewhere, the water pump impeller isn't directional. Stamped water beater is the consensus.
On trucks with AC, the belt runs around the pump the other way from trucks not equipped. The part listings online don't seem to have a AC/non-AC difference.
The new pump has better flow through the heater hoses, and the heat works well now.
On trucks with AC, the belt runs around the pump the other way from trucks not equipped. The part listings online don't seem to have a AC/non-AC difference.
The new pump has better flow through the heater hoses, and the heat works well now.
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
Is the lower hose supposed to have a spring or similar in it?
I went out today and squeezed the lower hose, not much resistance.
I've heard of this happening, the hose contracts and cuts off flow without something in it. Would make sense, works fine until it gets hot, then the hose would contract and cut down-off flow.
I went out today and squeezed the lower hose, not much resistance.
I've heard of this happening, the hose contracts and cuts off flow without something in it. Would make sense, works fine until it gets hot, then the hose would contract and cut down-off flow.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,652
Likes: 79
From: Mooresville, NC
1994 F150 4.9L E4OD.
New hoses-belt-water pump-thermostat (looks like NAPA)-thermostat housing-rad cap (16 lb)-flushed. About 50 degrees F outside temperature, so it is nowhere near hot out. Old water pump leaked, less than premium flow (feeling the heater hoses, no heat), but the truck didn't overheat with old water pump-thermostat-hoses-cap.
After driving around for about 30 minutes, temp gauge goes up and stays up. Coolant boiling out of overflow tank. One time the 13 lb rad cap shot off, lost most of the coolant a mile from home. I figured when I lost heat in the cab I might have an issue.
Second NAPA thermostat, 16 lb rad cap, first drive over 30 minutes, still boiling over, erupting from overflow. Let it cool down 10 hrs (work), added good half gallon coolant, drove 30 minutes, temp gauge way up.
Shut it down, boiling into overflow, but didn't spew out.
Probable thermostat, or other things to check? The gauge goes to "O" or "M" during the first few minutes like it should, fluctuates a bit in the normal range, then after 30 minutes or so, goes up and stays up. The top rad hose doesn't feel like there is much flow when the gauge is high. The coolant boiling out of the overflow tank is brownish. Previously quite a bit of stop-leak dumped in to cooling system, might still be some in the system to get boiled out. No bubbles in the filler neck when engine is running cold. Doesn't appear to be water/coolant in oil. Next thing to acquire is one of those funnels that attaches to rad neck, to bleed air out.
My feeling is the thermostat is still sticking closed after a while. Any other suggestions?
New hoses-belt-water pump-thermostat (looks like NAPA)-thermostat housing-rad cap (16 lb)-flushed. About 50 degrees F outside temperature, so it is nowhere near hot out. Old water pump leaked, less than premium flow (feeling the heater hoses, no heat), but the truck didn't overheat with old water pump-thermostat-hoses-cap.
After driving around for about 30 minutes, temp gauge goes up and stays up. Coolant boiling out of overflow tank. One time the 13 lb rad cap shot off, lost most of the coolant a mile from home. I figured when I lost heat in the cab I might have an issue.
Second NAPA thermostat, 16 lb rad cap, first drive over 30 minutes, still boiling over, erupting from overflow. Let it cool down 10 hrs (work), added good half gallon coolant, drove 30 minutes, temp gauge way up.
Shut it down, boiling into overflow, but didn't spew out.
Probable thermostat, or other things to check? The gauge goes to "O" or "M" during the first few minutes like it should, fluctuates a bit in the normal range, then after 30 minutes or so, goes up and stays up. The top rad hose doesn't feel like there is much flow when the gauge is high. The coolant boiling out of the overflow tank is brownish. Previously quite a bit of stop-leak dumped in to cooling system, might still be some in the system to get boiled out. No bubbles in the filler neck when engine is running cold. Doesn't appear to be water/coolant in oil. Next thing to acquire is one of those funnels that attaches to rad neck, to bleed air out.
My feeling is the thermostat is still sticking closed after a while. Any other suggestions?
The simple fact the truck didn't overheat prior to the water pump/thermostat/hoses/cap is very telling and should lead you away from a blown head gasket theory (brown coolant color is more likely from rust / corrosion, not necessarily a head gasket) and back to what was performed on the vehicle --- I'd start with a power flush (I do reverse flushes often on vehicles and getting bi-directional movement inside the engine is a plus to dislodge rust, blockages, other things floating around) -- some shops have the right equipment and most shade tree types can't achieve the same level of flush with conventional approaches)---Stop Leak in and of itself can cause many of the problems you're experiencing --- time to purge that junk from your engine (water jackets, core, etc)................then revisit the thermostat, water pump, etc..............I use a laser IR sensor to locate hot spots in engines and more often than not I can pinpoint where a water jacket is clogged or other problem present..........I started troubleshooting race engines with an IR camera decades ago and these simple tools will surprise you......
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
I bypassed the heater core last time I drove the truck. With the 16 lb rad cap, it can boil over in about 10-15 minutes of driving, 45 mph country roads, about 70 degrees ambient temp.
With the cap in the first notch, it gets hot, but didn't boil over, and the fan clutch actually seemed to work for once, had breeze by the engine.
I'm thinking radiator is Junk at this point. Fan clutch should be easier to replace with the rad out of the way. Can also see if condenser is allowing airflow or not.
Truck has what looks like single-core radiator. Would the double-core radiator listed for the 300 fit?
With the cap in the first notch, it gets hot, but didn't boil over, and the fan clutch actually seemed to work for once, had breeze by the engine.
I'm thinking radiator is Junk at this point. Fan clutch should be easier to replace with the rad out of the way. Can also see if condenser is allowing airflow or not.
Truck has what looks like single-core radiator. Would the double-core radiator listed for the 300 fit?
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Senior User
Joined: Sep 2008
Posts: 287
Likes: 1
From: SE WI
Replaced the radiator Sunday. No more overheating, at least on my test drive of about an hour.
Got the single-core, as it didn't look like the 2-core and my shroud would co-exist happily. The 2-core looks like it would have been awful close to the fan.
Now to fix the brake line that failed during the test drive...
Got the single-core, as it didn't look like the 2-core and my shroud would co-exist happily. The 2-core looks like it would have been awful close to the fan.
Now to fix the brake line that failed during the test drive...
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