1976 Ford F-250 460 with about 256K on it. New radiator just installed as well as new thermostat, and temp gauge of the mechanical type. Water pump has about 21 K on it now and all belts and hoses are in good condition and have no appearance of leaking. No oil in coolant and no coolant in oil. Situation: at 35-45 mph normal range of temp on gauge is about 210( thermostat is new and at 195 degrees F). At and above 50, the temp gauge CLIMBS to 250-270 and the gauge is only good for 280 degrees. This situation has plagued me for some time now and am beginning to think that the water jacket itself is at fault OR the water pump is on it's last legs. Solutions and recommendations are GREATLY appreciated. And there is no weepng from hole on water pump....some slight noise but thats been goign on for a while now.

Please assist!..

Thanks!

 

How big is your radiator? Is it a 4 core? What kind of fan? Clutch fan? Is the clutch any good?

 

Normal fan type.....belt driven.....Radiator is the large foour core" super cooler".....forgot those little details.......and the transmission cooler that came with the truck has been re-mounted so as to avoid 80% of the blockage that I was expirencing.

It was right up against the radiator but as now been moved forward ( seperated by about 4-5 inches) and slightly down......the brackets even have been drilled out with the appearance of "swiss cheese" so that it gets air all around it and on to the radiator.

 

It is possible that you need a new fan. You can do it inexpensively by getting a flex fan at an auto parts store. No clutches invloved. What I am thinking is that your stock fan clutch has gone bad and not moving enough air. It spins, sure, but does it have the CFM? Can you spin it easily with the motor off?

 

Do you have your fan shroud on? I know if you don't the fan doesn't work properly?

Just an idea

 

Shroud is also in place......full shorud.....came with truck.....overflow tank also in place....

All the basics are where they belong except that it over heats accoring to the temp gauge,,.....and that is becomign more of a worry if, in the even I have to do any long disantce traveling. Compression check hasn't revelaed anything out of the norm. I have however read where a leak detector chemical is availabel to determine if any exhaust gases are entering the coolant. Know anything about this?

 

i had similar overheating in a cleveland 351. Turned out to be the type of thermostat. The cleveland has a bypass hole built into the bottom of the housing (part of the block). The thermostat is a special type that when it opens it blocks off this hole.

If it doesn't (ie wrong type of thermostat) then coolant is recirculated through the hot engine when the thermostat is open, so it gets even hotter, instead of through the radiator

I'm not familiar with the 460 at all but might be worth looking where the coolant goes when the thermostat is open and closed.

Open, it should go through the radiator and closed it should have some sort of bypass path so it stays in the engine and doesnt go through the radiator. (or only a small ammount goes to the radiator)

 

Well...that would be worht the thought and thanks for the reply. However, As I was looking thru the Haynes manual that covers this engine and series and all that I noted that the type of fan that they had picutred is slightly different from mine. they showed a 7 blade fan and I have a 5 balde fan.
I also noted that I don't really " see" any flwo at all , per se and it appears as thou there might not be any flow at all because at idle it registers about 200-210 and at 35-40 it went to 250 degrees in quite a urry. Now this brought on a few alarm bells inside me head as I was first thinking and was trying to run it down in a flow chart type of trouble shooting : A) No flow thru pump WOULD cause it to climb in temp due to the heating up of the coolant and at idle it would have just enuff air flow thru it to drop the temp some, and B) at normal city speed ( or interstate) while it would have airflow thru it, the heat put out by the engine to the coolant wouldn't have time enuff to cool and C) based on the premise that maybe, if the thermostat AND pump were both failing or have failed altogether, it would cause a very high rate of temp climb and just no real time to hold the hot coolant to allow it to cool. Parts man at work suggested that I A) replace the pump and inspect the back side of it for the type/style of impellar( some have the altenator type "fan" as an impeller and others have the true impeller style) and drop the temp of the thermostat from the normal and now present 190-195 to 180 which woudl allow it to open faster and thus cool sooner. I'm in agreement with that as well as the addition/replacement of the 7 blade fan instead of the 5 blade fan. any thoughts or comments on any of this?....

 

Good thoughts. Replace the fan and pump. You can get a 160 thermostat, but it won't solve your overheating problem, just mask it for about 2 minutes. I honestly think the whole problem is your fan...

 

I'm suspicious that the problem is in the remounting of the transmission cooler. They design the setup so that the air can rush quickly through the fins of both coolers. By moving the first cooler away and drilling holes, I think you have created turbulence and uneven air flow and effectively slowed the air down through the radiator even though it looks more open. But without looking at it first hand a person can't be sure. It just sounds like slower air from your statement about air going all around it. Might not be right, I've been wrong before.

 

Well...in this particualr case you are not wrong but your not right either...the trans.cooler is an add on that was ther long before I bought it and NOT a stock item.....i.e. condensor from and A/C unit that was piped into the trans and bottom of radiaotr......) And it has been done more than a few times. The saet up for the brackets NOW allows for more air THRU the trnas.cooler and the reason for the holes on the "shop" made brackets is to allow the air to go THRU them instead of aroudn them This overheating problem has existed for about the last 18K miles some 3K shy of having replaced the very first water pump which , after having removed the fan belt for replacement we noted the "movement" of the fan/water pump hub, indicating, bad bearings and about to go. Now ,......initally after having driven this rig to and from Gillette WY / Spokane WA, it only began doing this "wild swing" in terms of temps within the last 18K miles. My thoughts are two fold; First when I started her up yesterday my curiousity got the better of me and popped cap off of radiator...noted that I saw no " real flow",i.e. I did not detect any measureable movement of coolant flowing at all and temp was at or near opening of thermostat....say 190-200 range. Secondly, a seven blade fan with a more aggresive pitch > might< be part of hte solution...maybe......as it has a 5 balde on it now........the addition of a electric pusher fan has occured to me but I some how doubt that the benifit would be measureable. Bear in mind that this "wild swing" thing in temps has to be resolved BEFORE I begin towing a 5th wheel. Thsu the many questions and seriouls scratching of head. I may also point out that the trans cooler was >right< up against the front of radioatr and I saw a potential problem there thus the reason and why I moved it out in front of the radiaotr by a good 5 inches.....and the cores and vanes on that are open and cleaned.....A/C combs work wonders. \
I'm only left with one or perhaps two other possibles here; The engine block/water jacket has serious scale build up and to flush it with a new radiator on it now defeats this and or two, the water pump only works when it wants to...i.e. the impellar is slippin on the shaft intermittently. As to how to detect that without having to yank the entire contraption is a bit beyond me, but if it must be, then it must be.......not alot else to do this weekend sides throw money away.

Anywhose......don't take any of this offensivly....I'm just seriously frustrated and I hear so many conflicting stories from parts folks that I now know a few more things about this thing then they do. I have also been told that possibly by rasiing the back end of the hood something like half inch or so, where it isn't so cloesd up, it may allow more cooler air to enter and hot air to exit..........

HELP!!!

 

Are you hoses in good to excellent condition?
I worked at a shop where a customer came in and had a probelm with a HO 302 overheating . The customer changed the t-stat waterpump , even the engine , all this for a 10 dollar lower radiator hose that was collapsing when the engines rpms came up !
Check out your hoeses - I would think that since the radiator was replaced that all of the hoses were too?
Also is the t-stat installed upside down?
What is the condition of the coolent and what is the the mixture .. 50/50 is the best too much anti-freeze and it will not cool properly .
5 blade or 7 blade fan? - a fan is a fan and your truck should not over heat -even with a 4 blade fan -( not when driven normal anyway)

 

All the hoses have wire re-inforced in them and are also fairly recnt.... Thermostsat is upside right...and the water pump is also showing flow...good flow as far as I can tell...

However....and heres an obvious question....Whats the liklihood of the engine water jacket being partially clogged/occulded to some degree? Reason why I pose this is it doesn't ake to long for it to reach 210 upon start up. Also......and I'm about to do this.....what would a good thorough backflush reveal?....i.e. what would it do for me considering that the radiator is new ???...so is the heater core I may add...

This is beginning to look and have the feel of a complete tear down aqnd rebuild of the engien it self to hot tank it and hopefully rid myself of this "small"( sic) problem.

Any one have any thought to this?

Also....What commerically available solution is ther over the counter at parts stores to back flsuh the water jacket with?...i.e some sort of acid solution maybe??

Thanks in advance.

 

And another question......one that may be stupid in appearance but...
what woudl happen if I introduced a 160 degree theromstat instead of the 195 that is presently there...
Also....when the cap is or would be off and a person is peering in thru the filler neck on the radiator...what would constitute "good flow"?.... I'm of the opinion that after having read thru my maint. log that I have been keeping since day one on this rig that the thermostat gauge has been playing up ever sincve I changed out the water pump. Knowing the cycle of the coolant cycle and not seeing any good results, I'm of the opinion that something here isn't right. Flushed out the system last night at work and got nearly nothing to speak about on a reverse backflush.

If anyone has ANY ideas....I'd sure like to know about it....and soon. Towing a 5th wheel could be a bit of a bugger when the cooling system isn't up to snuff.

Thanks.

 

All you're going to do by putting in a 165* t-stat is put one in that opens up quicker. Once it reaches that temp, it will still overheat if something else is wrong.

As for what constitutes good flow, that's really just an opinion from looking in the filler neck.

Ok, maybe this was discussed earlier and I don't remember, but what about the fan clutch?