I have an 89 2WD Ranger with a 2.9L engine and automatic tranny. At highway speed, I noticed the temp. was much warmer than normal, luckily I was only a few block from home. When I looked under the hood, the overflow tank was overflowing with antifreeze. After letting it cool down, all of the antifreeze was sucked back into the radiator. I suspect the water pump may have failed. With the engine cold, if I remove the upper radiator hose, there is no flow until the engine starts warming up and the thermostat opens. When this happens, antifreeze comes pouring out of the upper radiator opening (which would explain why the overflow tank is getting filled). The radiator seems to have adequate flow, and the thermostat was changed last year. Does this seem like a water pump issue? The vehicle has 178,000 miles, but I've only owned it less than 2 years, so I'm not sure if the pump has ever been changed.

 

Suggest checking thermostat first, make sure it's opening/closing.
Coolant levels have you changed it/added to it lately? Be sure it's checked COLD, and only filled to min level in overflow tank.

Are you losing coolant anywhere?

 

You say you have flow with the top hose pulled once the engine heats up, correct?
It sounds to me like you have flow (pump is pumping) and your thermostat is opening...
I'm chasing down a similar issue now and it looks to me like I'm going to need to have my radiator looked at.
https://www.ford-trucks.com/forums/s...d.php?t=240616

 

I can't say that I have the same set-up on my Ranger, but this is just a suggestion. Have you checked the oil lately? Years ago when was having trouble with my Trans Am it would do almost the exact same thing. We replaced alot of stuff on that frickin engine, but I think the biggest problem was a leak in the head gasket next to one of the water jackets. It was throwing compression into the cooling system and the temp would go up while it pushed coolant out of the resivior. You may or may not see oil in the coolant, or coolant in the oil. The pump is a possiblity, but I am a bit old school. It used to be if a pump was going bad you would see some discharge from the weap hole on the pump. I couldn't tell you if your pump has this without going to the manual and checking.

And Welcome to FTE!

 

I'll take my thermostat out today and check it/replace it. I've never had a history of replacing any antifreeze, and I haven't had to add any lately. I check the level often when it's cold and it's always right on the money.

Let me clarify 'flow with the upper hose off'. The flow comes from the radiator side, not the engine side. As I under stand it, the upper hose delivers antifreeze from the block to the radiator, then the pump sucks the antifreeze from the lower radiator hose and supplies to the engine. With the upper radiator hose off, with the engine coming up to temperature, I have a decent flow of fluid coming right ouf of the upper radiator inlet (with the hose removed right at the radiator). I initially thought this water coming out of the upper radiator inlet was due to thermal expansion, but now I'm not sure due to the quantity and relatively large flow rate. Also, would thermal expansion be large enough to push roughly 1 gallon of antifreeze out the overflow?

So if my pump is still pumping, and the thermostat is faulty, is the pump somehow pressurizing the system, for example pressuring the inlet side of the pump, which would backfill the radiator through the lower hose and cause an overfill condition? If this is the case, why doesn't this happen all the time when the engine is cold? Note that this flow at the upper radiator inlet only happens when it gets into the normal operating temperature.

Thanks for the inputs guys.

 

Check the psi capacity on the radiator cap. If it's not holding pressure, it will let out the coolant as you described. Any store should be able to test it for you.

 

When the truck is warm put your hand on the radiator, if you find a cool spot then you have a blockage. Usually this is on the bottom. We found that an after market radiator is around 125. That's in the Dallas TX area.

 

It's funny you mention oil, because earlier in the day my check oil light came on. I checked the oil and it was right at the add line. My plan was to go home and add a quart or so of oil, then on the way home is when I had the coolant problems. I can see where this could have irritated the head gasket issue, but i've read in these forums that head gaskets are usually not a problem on the 2.9's, unless the engine has been drastically overheated as some point in time.

 

I have the 2.3L in the Ranger, and the Trans Am has the 400ci so like I said.... It may or may not help you, but it would go a long way toward explaining some of your problems.

 

this happened with my s10 last summer - the cap wouldn't hold the pressure, dumping coolant out of the overflow. when it cooled, it would suck the coolant back into the radiator leaving the coolant overflow empty. replaced the cap, everything is now normal.

 

Just checked my thermostat. The thermostat has 92 degrees marked on it, which I'm assuming is Celsius. I plunked it in some warm water, slowly brought the temp on on the stove-top. The water reached 208 degrees F (via. my digital thermometer), and the thermostat didn't appear to open, it looks the same as when I dropped it in the water. 92 degrees C is about 197 degrees F, so it should have opened, but it didn't. I'll keep you posted.

 

If the thermostat doesn't work, I'll look at the radiator cap, thank you!

 

Replaced thermostat, everything back to normal. Thanks for everyone's help!

 

Replaced thermostat, everything back to normal. Thanks for everyone's help!GREAT!!