Expert: Ernest (Ernie) Kenward - 9/1/2007

Question
Hi Ernie,
We have a 1995 Ford Econoline (Conversion) with a 351 engine.  In the spring, my husband was on a long trip with the van when it overheated and blew all the fluid out of the radiator.  

Since, we have had the following replaced:
Thermostat
Radiator
Clutch Fan
Temperature Gauge
Head Gaskets
Had Heads checked for Damage

The engine still runs HOT when traveling up hills, about 220 degrees. When I say it runs HOT I mean it gets to the 'L' almost to the white line on the gauge.  The engine runs about 190 degrees when traveling on flat road and when stopped at an idol.  The clutch fan is working as it will suck cardboard up against the radiator while the van is running at the 220 degree mark. It's almost as if the radiator has a hard time keeping up when the van is working hard. A reputable radiator shop has confirmed that this radiator should do the trick. We know that if we were to take this van on a long trip, it would eventually overheat again.  

This van has everyone scratching their heads. Any ideas?  Thanks!

Answer
You can add me to those scratching their heads!  I too have an Econoline (E250), one which I too converted to a Class-B motorhome in 1990.  Mine is a 351W as well, converted to four-barrel carburetion as a power-on-the-road and economy-around-town (relatively!) plus emissions upgrade in 1992.

My E250 still uses the OEM fan, albeit fitted with a fan clutch on 1994, not previously being equipped.  I fitted a new radiator in 1988 (upper tank seam opened suddenly) and a much better SPI radiator in 2001 when the 1988 radiator developed core leaks.

And, aside from the radiator replacements, I have had no issues whatsoever with the cooling system.  My calibrated  aftermarket temperature gauge rises to 190 degrees as the engine warms, then promptly drops to 180 as the thermostat (180 degree spec is what I always use) opens, and thereafter hovers in the range of 180 to 185.  On rare occasions of prolonged idle, when sitting in the annual AirCare (emissions-testing) lineup, it may begin a slow climb, but has not exceeded 190.

At present, I am adding an electric fan, in pusher configuration as a booster to the existing fan, along with a thermostat to turn this on should the water temperature exceed 195 degrees.  This is being done only as a proactive step, as I expect to begin hauling a small trailer in the next year or two.

Your 1995 Econoline differs from my 1978, but not that significantly in terms of the physical size of the engine and its cooling system.  These vehicles use sizable radiators, and the water pump capacity seems more than adequate, although I wonder whether there might be any benefit to a speed-up drive, or a thermostatically-activated electric booster that could handle the occasional but necessary prolonged idle, or being unavoidably stuck in grid lock (I do steer clear of the latter situation to prevent overheating ... MY overheating, not the van's!)

You have definitely serviced, in fact changed out, all the critical hardware.  I presume that you also reverse flushed the cooling system, notwithstanding the new radiator.  This is a bit of a reach in this case, but it might be possible that there was a legacy of over-abundance of debris and possibly radiator sealer in the system that has remained in there to block these nice new clean passages.

I presume too that the thermostat is the correctly specified one for your 1995 351.  The 180 degree stat certainly is a good choice for my older 351, although a higher temperature one may be specified for yours - note that I do not have shop information for any vehicles other than those in my own fleet (and I have always made it a point to get this for any vehicle I take on), so I cannot advise you there.  You "might" consider using a cooler stat, IF other avenues of exploration indicate no other problems, and PROVIDED that using a cooler stat does not have unintended consequences in other areas such as drivability or emissions.

My only final comment is that I have no doubt that the main reason for the absence of problems with my E250 is the fact that I do preventative maintenance on it on a frequent and scheduled basis.  This includes flushing the cooling system and replacing the antifreeze and rust inhibitor and water pump lube every two years (September), along with the thermostat, and any hoses that are in any condition other than pristine.  I like reliability.

Could there be any other issue with the engine, I wonder?  Is the oil used of the right spec?  Is the pressure adequate?  My calibrated gauge indicates a rise to 80 psig on starting, dropping to about 40 when warmed up, and going no lower than 25 at idle once well warmed; this is within the right range and healthy for my older 351.  In fact, should I crank the engine with the ignition off (which my controls allow me to do), I can get a pressure rise to 40 psig on the starting motor alone after 8 to 10 revolutions.  I do this as a matter of course, by the way, whenever I have left the vehicle parked for more than a couple of days.  Having oil already flooding the bearings before startup is probably one more reason the compression, power and general performance of my engine has remained healthy and predictable for the twenty-two years I have had it.  I recommend this.

If your oil pressure is low, verify your oil grade and check out your oil pump, if necessary.

Be sure that the ignition timing is correct too.  Excess initial advance can cause heating problems.

Do keep me posted, too.  Your findings may well help me, down the road.

Good luck and best wishes ... E G K