1990.7.3 Ford deasel cooling problem

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tramp bushler

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The other day my delivery truck started blowing cold air . Then I checked th radiator and it was 2 gallons low on coolant . I put water in the radiator as I didn't have any anti freeze w/me . The truck was doing good for about 8 miles one the way homew . Then it over heated . The heater only blew warm air for about 5 miles . There after itr blew cold air . It was 30. Below f . It over heated about 5 times on the way home . It has been cold here ever since . .I have had it plugged in ever since . I have started it and the temp guage stays bottomed out in th cold zone .

Could the over heating been caused by a faulty thermostate ..
 
Yes it could be cause by a bad thermostat. It could also be cause buy a plugged radiator,blown head gasket,or a collapsing hose some where. You really need to figure out where the coolant went. If I remember right some of the older Ford diesels would get a cavation problem in the back cylinder(s). The coolant would get old and eat though the cylinders leaving pin holes in the cylinders. They would burn coolant. The only fix was to sleeve the block. Hope you find out what it is.

Scott
 
Yes a faulty thermostat can cause overheating but the big question is where is that antifreeze going? Those motors of that vintage were know to develop pinholes in the cylinders (leaner liner cavitation erosion).
 
Thermostat is stuck shut.

As far as missing anti freeze! Head gasket? Check oil! Water pump leaking? Could be many things. Get under the hood and look for leaks.
 
A lot of fords thermostats have a catch built in to them that if they over heat the will stay open and never close. It sound to me that the leak is the first thing to look for and then the thermostat.
 
Well first of all, if you added two gallons of plain water to the cooling system in -30 degrees you've most likely plugged the cooling/heating system with ice somewhere. Chances are good that some (or all) of the veins in the radiator are plugged and maybe the heater hoses and/or heater core. A plugged radiator will cause over-heating in pretty short order, and driving down the road with air rushing through the radiator will freeze it pretty darn fast. Plugging it in won't heat the coolant enough to thaw-out a radiator. The temperature sensor sensor needs to be submersed in coolant for it to read properly, and it the system is plugged with ice it could very well be that the engine is now "air locked", causing the sensor to be dry. An "air lock" will also cause the heating system to go cold and/or dry.

I agree that you need to figure out where the two gallons of coolant went (might just be as simple as a loose clamp somewhere or a water pump seeping), but first you need to get it in somewhere warm and make sure it's completely thawed out, and coolant is flowing through the radiator. If it, as you say, over-heated some 5 or so times you should definitely replace the thermostat and probably the temperature sensor, they're most likely trashed.

Keep it plugged in, you don't want that water freezing in the engine block because that could make for even bigger problems.
 
The coolant would get old and eat though the cylinders leaving pin holes in the cylinders.
Scott[/QUOTE]

scott-----old coolant aint what caused it--and i dont want to type out the explanation
 
Dang. I just bought an 89 this week!

Dang.

just go get some strips--to check for the anti cav additive level--and get it up to par--you can get the additive at MOST Ford dealers,,and a lot of international shops--dont over add it either--too much,,is as bad as not enough--
 
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pm dhibbs75,, he is my neighbor and a master diesel mechanic. he can give you an answer
 
on your ford,,you have a oil cooler--on the left side of the block..there are o rings in that assm, to keep the oil from the water,,and vice versa..and yes--they get hard with age, and start cross leaking..normally--because oil pressure is higher than coolant pressure,youll get oil in the antifreeze,but you know how murphy is
!!!!! you can pull the rear "header" of this assm,,and the coolant tube, leave the front header on the block,,and pull the assm apart--then replace the o rings... and put back together...use vaseline on the orings to assm..and make sure there are no sharp edges ANYWHERE...leaving the front header on,,saves much frustration,,but watch when you put back together,,so no dirt hits the orings--or gets in the front header--
 
Yes it could be cause by a bad thermostat. It could also be cause buy a plugged radiator,blown head gasket,or a collapsing hose some where. You really need to figure out where the coolant went. If I remember right some of the older Ford diesels would get a cavation problem in the back cylinder(s). The coolant would get old and eat though the cylinders leaving pin holes in the cylinders. They would burn coolant. The only fix was to sleeve the block. Hope you find out what it is.

Scott

sometimes!!! but normally,when they got this far,,the wall was so thin in that spot--that it would break loose--and goodbye engine!! destroys them well!!!!!!
 
Like the others have said, you need to determine the source of the leak first. On the earlier 6.9's and 7.3's I have owned the fan was equipped with a clutch, if that no longer engages you can overheat, though I doubt it at the temperatures you indicate.

Most of my diesel overheating problems have been due to plugged radiators.
 
if the truck overheated you are in a high likely hood of doing a head job and replacing the gaskets. they dont like that at all, cavitation is a result of using coollent that does not have an additive.

basically what happens is without this additive every time the cylinder fires it flexes the cylinder wall a little. this happens so fast it pushes the coolent back creating a vacume. once the pressure stops the coolent slams back into the cyinder. this constant back and forth can wear through the cylinder bore from the backside eventually. additives give the coolent enough cushion to prevent this from happening. the older 6.9's were less prone to this than the later 7.3's since they were basically just a 6.9 bored out more.
 
Always use an additive in your coolant, I use Napa Kool. Use high grade anti-freeze as well.

IDI's are known for cavatation and blown head gaskets. So pay attention to those details no matter what the problem ends up being.
 
A lot of fords thermostats have a catch built in to them that if they over heat the will stay open and never close. It sound to me that the leak is the first thing to look for and then the thermostat.

thats a new one on me,,and ive been working on all makes for over 35 years--esp Fords

Yeah, that’s a new one on me also. I managed the service department of a Ford Dealership for 22-years, 1982-2004, and never saw any such thermostat. Actually we (the family) owned the dealership; I ran parts and service, my brother ran sales and F & I, and dad... well, he kept an eye on us. I’m not sure where such an idea gets started... but there ain’t no “catch” on a ford thermostat to hold it open, and never has been.
 
Yeah, that’s a new one on me also. I managed the service department of a Ford Dealership for 22-years, 1982-2004, and never saw any such thermostat. Actually we (the family) owned the dealership; I ran parts and service, my brother ran sales and F & I, and dad... well, he kept an eye on us. I’m not sure where such an idea gets started... but there ain’t no “catch” on a ford thermostat to hold it open, and never has been.

Ive seen it on three fords. The first pic on this thread shows one side is caught on the brass colored latch
Ford Escort Owners Association
Its the only pic i can find but it talks about it being ''fail safe''
 
I have never heard of some of these things. Are these strips for checking lubricant common?
 
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