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Overheating and slight rumble when driving over 55mph

I just purchased a 1995 Ford E250 cargo van with 4.9L I6 and 3-speed auto. Everything seems to run fine and all fluid levels are up where they should be. No fluid is leaking. Tranny fluid is red, radiator fluid is green, oil is still somewhat clear. Prior to purchasing this vehicle a new temperature gauge was installed as the old one had stopped working. Fluid gauge indicates just below the 'high' level.

The fan on the radiator is running fine. The vehicle drives fine with no problems until I get on the highway and get it over 55 mph. At this speed a deep low rumbling sound is felt/heard and the temperature gauge steadily increases and approaches the red after about 10 minutes of driving around

60-65. Strangely the low rumbling sound stops if I exceed around 65mph.. I'm assuming this is where the tranny shifts into 3rd? Sometimes when accelerating rapidly I can actually see the temp gauge jumping up. After I get off the highway and drop down to usual street speed the temperature goes back into the normal middle level after a few minutes. I pop the hood and can feel the heat coming off the engine but It's not to the point that there is smoke or steam or anything like that but I haven't driven it all the way into the red! I'm no mechanic and only have a basic knowledge of repairs. I'd appreciate any help as to where I should start. My uninformed newbie guesses would lead me to look into a new radiator or something involving the transmission. I just ordered a printed Haynes repair manual and the Ford factory service manuals on CD hoping these may help. I bought this van with no warranty 'as is' so I'm stuck dealing with the problems myself and appreciate any pointers.

Thanks Jay

Reply to
Ford Warrior
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The rumbling and heating are likley unrelated (rumbling may be to to aerodynamics at certain speeds). Check thermostat and clutch fan operation is so equipped and make sure the a/c raditor cores are not plugged with bugs abd dirt. If that all checks out, you make have deposit buildup internally in radiator restricting cooling.

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Reply to
TheSnoMan

This engine is just-about bullet proof, but it shouldn't run near the H mark on the gauge. My 4.9 runs at 210° with the AC On and that shows 'just' past N on the factory gauge. I installed a real temp gauge long ago.

Anyway, I'd look at the water-pump and/or a loose/bad drive belt. Could be a faulty radiator cap. Possibly the previous owner didn't flush the system, so the radiator may be somewhat restricted. The symptoms don't read as a T-stat problem, unless some fool install one up-side down....which I've seen. T-stats either work or they don't, and there is no guessing about one not working....lol A new stat is cheap and easy enough to replace.....as is a new radiator cap. The cap regulates pressure within the cooling system. Correct pressure is everything to the cooling system.

You might try flushing the system with a chemical flush. Also, Prestone make a 'back-flush' kit. This kit enables the system to be 'back-flushed'.....which means the cooling system is flushed opposite the normal way coolant flows....a good procedure. The kit cost about $10 and is a simple installation.

Well, I hope something here helps....

Dave S(Texas)

Reply to
putt

Generally if it is plugged up that bad, no chemical flush over the counter will work and a trip to the radiator shop to have it rodded out is in order.

Reply to
TheSnoMan

An update is in order here... The lot/shop I bought the van from claimed they were "sure" it was a bad thermostat.. so they took some more of my $$ to replace the thermostat and now the problem seems even worse. Now it seems to run at normal speeds slightly hotter and STILL overheats on the highway at speeds over 55mph. I just went to autozone and purchased a new fan clutch but haven't installed it yet as I'm not even sure this is the proper next step. It seems to me the speeds at which I'm driving on the highway should be enough to cool the engine to some degree just as much as the fan clutch would be doing.. or am i thinking wrong here? I'm just thinking that if it were the fan clutch that were out of order then perhaps the overheating would be happening while idling. The shop claims the radiator is not clogged at all and is circulating and the water pump appears to be fine. Does anyone have any further input before I blow $40 by trying to install this new fan clutch which may or may not fix the problem?

Thank again for your help Jay

Reply to
Ford Warrior

On Sun, 25 Sep 2005 19:35:24 -0500, Ford Warrior rearranged some electrons to form:

I guess I would ask how the shop knows the radiator is OK... did they clean it?

You might also make sure they didn't install the new t-stat backwards.

I doubt it's the fan clutch, or you would be seeing a problem at idle too.

Are the belts OK? I suppose if the belt driving the water pump was slipping, it could cause this problem.

Reply to
David M

General rule of thumb is overheating on the highway, start with the radiator, overheats at idle, start at the fan clutch.

Reply to
ross via CarKB.com

Did you try any of the checks I suggested? Like the drive belt? A new Radiator cap? The KISS principle........

DS

Reply to
putt

Check your antifreeze concentration. If it's 100% antifreeze and zero percent water, this could be the problem.

Bill M

Reply to
Bill M

one more update.. I just noticed after getting off the highway today that there is a tiny spot on the radiator itself near the top that is now leaking a minute amount of fluid but only when driving at highway speeds. Should I just go ahead and buy a new radiator at this point? I'm thinking there may be a large portion of corroded/rusted walls in this radiator with potential for pressure & fluid loss. Prior to this leak developing on the radiator the mechanic still insisted the cause of my overheating on the highway must be the fan clutch as it doesn't seem to go any faster when gas is applied.

Reply to
Ford Warrior
<<snip>> Prior to this leak developing on the

The fan won't go faster when gas is applied unless the temp under the hood is high enough to engage it. That's the purpose of the clutch fan- no load on the engine unless high temperatures warrant it. From your latest update, I would say you're looking at a radiator replacement. Usually when you see a small leak from the inside out like that, the rest of the radiator is shot. Good luck!

SC Tom

Reply to
SC Tom

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