No. It looked new. I went out and bought a new used one. And it has now stopped overheating. But now there was a engine light... It said somthing about camshaft crank sensor... So I am changing the crank sensor tomorrow because it was running rough as hell.

 

The rad looked new.. I bought a new used one. put the Tstat back in everything seems good. Except now my crank sensor went

 

I have now got it running GREAT. Must have been he rad.

 

*My dad drives this truck, not me so I not sure of how hot it was actually getting*.

1995 Ram 1500 3.9 V6 2wd


Somewhat similar problem but...

Truck blew the small heater(from heater core) hose right where it enters the top of the engine block and right next to the large upper rad. hose enters the block.
This was a little split in the hose where the hose clamp was.
I figured the coolant temp sensor got soaked with the hot coolant as it 2 inches away and shorted out.
I disconnected the hose, cut about 2 inches (with the split part) and re-attached those hose. Ran fine (i thought) no leaks for several months.
The temp was still jumping straight to max though...just with turning the key to the on position, it would do this.
That was in Nov. '11
Now in April '12 it failed CA smog ( too high NOX emissions I think)

So I start at the EGR, which turns out to be melted and totally non-functional. (the black plastic part)
I replace that, the bad coolant temp sensor, which fell apart during removal, both heater hoses (top engine block to heater core, heater core to pipe coming off of the water pump) did the spark plugs as well.

Re-assembled, filled the system and started it up.
The temp was now reading 0 or cold and steadily climbed up as it should.
Then it kept climbing all the way to just shy of red line (260 degrees)

Took the 180 T-stat out dropped it into 190+ water.
It hardly opened so I replaced that and started the truck again the next day.

Same story with the temp slowly rising then getting just shy of red line.

After a 25+ minute drive, the upper rad. hose was hot, the lower was cold.
Both heater core hoses are hot and got hot within minutes of starting.


The fan turns and the belt is not slipping pulley.
Seems the engine hits a max temp just under red then stops rising.

So I experiment.
1st I removed the upper rad. hoe while keeping the system as full of coolant as possible.
Started the engine and nothing came out of the hose (no pressure or movement)
So I reconnected the upper and removed the lower rad hose.
I pulled it upward facing the sky, filled it with water to top it off and started the truck again.
Nothing... absolutely no movement or gargling sounds at all, as if the was no pump at all.

I then removed both the upper and lower rad. hoses and pointed them up to retain water and filled
them to the brim (rad cap on by the way)
Same thing. No movement of water at either end of the rad. hoses.

It's as if the water pump is not moving at all.
I then removed the heater hose coming out the top of the block and pointed that hose to the side, started the truck and there was some movement of water.. not consistent though. Like turning on a garden hose..
spurting and air coming out.

I believe I removed the rad. as a potential culprit when I took both hoses off it and still had no water movement?
I know I installed the new T-stat correctly and fully believe it to be functional.

Surely a functional water pump would have had some water spraying or even gurgling out a rad. hose?

After it's little 25+ minute drive, the upper was hot along with that (the right) side of the radiator.
The left side and it's lower hose were not even warm.
I just don't think it's the radiator... as it seems there is no circulation of water going on?


*edit* I replaced the water pump 4 or 5 years ago and the system is otherwise not losing coolant*

Truck runs fine actually. It runs hot obviously. Any ideas?

Thanks in advance.
I know this was a long post of someone else's problem LOL

 

There's only a few things to go wrong with the cooling system; bad water pump, t-stat doesn't open, fan/clutch doesn't engage, blocked radiator and/or broken fins, rad cap won't hold pressure, collapsed lower hose, a coolant leak, or air in the system. (I think that's about it?)

Cold spots in radiator usually signifies clogging, no? You can have it flow tested at a shop or look up the ways to 'test' it at home.

If it ain't clogged...
Make sure the fan clutch is spinning fast (and clutch engages) when it hits operating temp. Also make sure the fan doesn't wiggle back and forth.
Are the radiator fins badly bent/broken?
Make sure there's no air in the system.
Pressure test cap/buy a new one.
Verify the lower rad hose doesn't collapse.

 

1500, the only problem with your step by step test was that with the thermostat installed (and closed), you won't get any water movement in/out of the engine, with the exception of the heater hoses.

another version of that test is to remove a heater hose, and leave the bottom radiator hose connected, (and with engine cool) remove the radiator cap and stick the water hose in it. this keeps the system primed and you can test the water flow to and from the heater core.

another test that i like to do is completely remove the t-stat and run it. its a best case scenario to help identify what all might be wrong.

after all that screwing around, its usually just a matter of flushing the crap out of block (drain plugs in block behind engine mounts), replace the t-stat with a good quality Stant and not a Fail-Safe, and then if necessary, replace the radiator.

 

Thanks for replying Matt.

The upper and lower rad. hoses were replaced when I did the water pump 4,5,6 years ago. They don't collapse and appear to be in very good shape.
The clutch fan engages fine and the fan blades will take a finger off tempt it.
So fast in fact, the fan blades are a blur.

The radiator does not have any obvious dings, dents, folded fins.

There is no water movement to the radiator in the first place.
I wonder if I have some major pockets of air in the system and the T-stat is setting in one of those air pockets?

I might try to fill the system by removing the upper rad hose, holding it upward and filling to the brim?

Thanks again Matt

 

Yeah DH,

I was afraid of having to remove that shiny new, nicely installed t-stat

I thought of connecting the heater out connection from top of block back to the water pump connection thereby bypassing the heater core... just to see it that creates any movement of water.

 

you can remove the t-stat fairly easily by leaving the upper hose attached to the tstat housing and using it as a handle. just remove the 2 bolts from the housing.

if you bypass the heater core you won't see the water movement. just remove them one at a time and let it dump.

 

Not sure but I assume the flow of water is: up out the top of the block, to upper rad. hose, out bottom other side rad. hose to water pump?

I took the upper rad. hose off and ran the engine with the system otherwise full... nothing came out that hose (headed to the radiator) and the t-stat was surely open as the engine was near max temp.

Confusing