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1998 F-150 4.6L Overheating Towing in Summer

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  #1  
Old 07-15-2017, 06:02 PM
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1998 F-150 4.6L Overheating Towing in Summer

Hello,

I have a 1998 F-150 XLT, 4.6L V8, automatic, and 170K miles. I've been towing a relatively light 2004 Tracker Pro Team 185 boat that weighs around 2,000 lbs (boat + trailer). I've been towing the boat using this truck for around 18 months now.

I made a run to the lake yesterday, which involves around 50 miles (one way) of most highway and some stop/go traffic. Some of the driving includes mountains and hills.

Last summer I noticed that the truck would get hot on the way home only when pulling off the highway near my house. When I got off the highway and came to a red light, coolant temperature would climb quickly. The temp has not redlined--I've been able to catch it control the engine temp by running the heater at full blast.

Yesterday, the truck started overheating through the mountains and periodically on the highway. Yesterday's temp was hot with the heat index around 100F. I had to turn the heat on for over half the drive. Not fun for creature comforts in that heat, but it's better than an overheated engine.

I bought this truck from my brother to tow my boat. When I bought it, the truck was a bit neglected but in overall good shape. I put a couple months into maintenance before I started towing. Some of that maintenance was flushing the cooling system and replacing the water pump, thermostat, and the radiator fan clutch (all around 18 months ago). Everything appears to be working fine when not towing; the temperature runs just below half of the way up the temperature gauge when not under load.

To summarize, the cooling system performance has gotten worse in the last 12 months. I'm inclined to replace the original/OEM radiator with what appears to be a more effective one (thinking of the SPECTRA CU2165).

What do you guys think? Replace the radiator? Flush the cooling system again first? Any thoughts are welcomed.

Thanks in advance,
Pete
 
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  #2  
Old 07-15-2017, 10:38 PM
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I think I'd replace the radiator with a larger unit, maybe one for the 7700 truck. Does your truck have a transmission oil cooler? If not put a big one on it.
 
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Old 07-15-2017, 11:01 PM
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I'd be tempted to not only get a bigger radiator, but maybe do an e-fan conversion.

The Spectra 2165 is a good choice.
 
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Old 07-16-2017, 02:14 AM
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Agree with Roadie and glc regarding the radiator. I'm sure with a truck that old, that some of the tubes in your radiator are clogged, or have accumulated a coating that reduces the heat transfer capability. I also like the idea of a transmission cooler if you don't have one.

I'm less sold on the idea of e-fans. I have them in my 2014 truck and think they are great, but things I've read about e-fan conversions make me think the process is not always a joyful success. The problems I recall center around the controller for the fans. This may have been overcome, naturally - do some research.

- Jack
 
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Old 07-16-2017, 10:05 AM
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And use distilled water in the 50/50 mix in the cooling system. Tap water sometimes has lots of calcium that plates out on the cooling system surfaces and reduces cooling efficiency.
 
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Old 07-22-2017, 10:45 AM
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Folks,

Thanks for the inputs. I went ahead and bought a new radiator with new upper/lower hoses. They should be here this coming week.

I will post a follow up once I have the new one in and tow the boat to the lake.

Thanks again,
Pete
 
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  #7  
Old 07-22-2017, 03:12 PM
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Originally Posted by nixdorf View Post
Folks,

Thanks for the inputs. I went ahead and bought a new radiator with new upper/lower hoses. They should be here this coming week.

I will post a follow up once I have the new one in and tow the boat to the lake.

Thanks again,
Pete
I forgot to mention I also ordered a Hayden 678 transmission cooler. I will install it with the new radiator.
 
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Old 07-23-2017, 08:27 PM
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My guess would be maybe a head gasket starting to go?? Might just be enough to allow some pressure into the system, but not show any obvious symptoms?

Towing a #2000 boat should not overheat that rig??

If you've already done all that fluid change and other work on the cooking system, it's got to be something else?

Or, just throw parts at it until it either fixes it or you just have a bunch of new parts that still does not address the issue..

Good luck!

Mitch
 
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  #9  
Old 07-28-2017, 01:40 AM
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Ok, so I've started the radiator swap out and transmission cooler install. I pulled the old radiator and hoses tonight and will install the new radiator, hoses, and cooler in the morning.

I'm glad I bought the new radiator. The OEM one (19 years old with 170K miles) definitely needed replacing. The radiator had scale built up on the fins and rows, with sludge in the passageways. Here's a pic of the lower radiator hose showing some of the sludge in the system.



Inside of lower radiator hose.

I do have a question for you fine folk: which transmission line to the radiator is in the inlet (from transmission) and which is the outlet (back to transmission)? I'd like to tap the auxiliary cooler into the return line to maximize cooling (ATF cools through radiator first then auxiliary cooler). I have googled a bit and haven't been able to find a definitive answer. I'm guessing the bottom is the outlet. Thoughts?
 
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  #10  
Old 07-28-2017, 06:01 PM
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It is done.

I installed the new radiator and transmission cooler, then flushed the system. The coolant system definitely had a good good bit of scale and rust built up. I took my time to flush the system. I added radiator flush and water and ran it to operating temp plus 15 minutes, hitting 2500 RPM for a bit every now and then to try to break loose what may have been in the block and heater core. I then opened/removed the radiator drain with a hose in the degas bottle and ran the engine at idle for about 45 minutes. I refilled with about 2.5 gal of concentrated antifreeze. With the water left in the block that should give me a little over 50/50.

The cooler did drive me nuts though. I bought the Hayden cooler and the Hayden adapter kit for Fords to connect into the radiator. No dice. The thread patterns were different between the adapter and both the old OEM and new radiators. I ended up installing the cooler by itself without the radiator connection. I'll research adapter kits and see if I can find one that actually works. I am not impressed with Hayden so far. That's the second product of theirs I bought that didn't work for me.

Anyway, I'm taking my son to the lake tomorrow with the boat. We will see how the new radiator and transmission cooler perform.

Thanks for all the help!
 
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  #11  
Old 07-28-2017, 06:06 PM
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Why didn't you flush the system before removing the old radiator?
 
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  #12  
Old 07-28-2017, 06:20 PM
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Originally Posted by Roadie View Post
Why didn't you flush the system before removing the old radiator?
I didn't realize how bad it was. After all, I flushed it just over a year ago and the degas bottle looked green, not brown.

In the end, I have a better performing radiator (two core vs. stock 1 core) plus the cooler. I'll take it.
 
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