Help me diagnose cooling system problem

[mcompton1973]

My moms 2008 Explorer XLT 4.0l with 135k miles

Symptoms:

Started out as an occasional rough idle...mainly at idle
A couple of times the engine temp has gone to hot...always at idle
some coolant loss

Steps I have taken so far and observations:

I am just starting to try and work out what is going on. Pulled codes...no CEL on...had a code for intermittent misfire. I am assuming this is a byproduct and not the root problem. I will check and deal with things like plugs, wires, coils once the cooling issue is resolved if it comes back.

No sign of water in the oil

with cold engine, there was no fluid in the overflow container...nor was there VISIBLE fluid in the radiator. I added plain water to both and started engine and let it warm up.

I tried to squeeze top and bottom radiator hoses as the engine got to temp. Neither gave me any indication water was moving through them. Neither felt hot to the touch at all.

There might have been a little leaking on the very top of the radiator under the overflow bottle...but not certain it was leaking, or just leftover from filling them. Went back a day later and does not appear to have been any water loss while siting. Did not start it again until I get some advice of where to go next.

Heater on high, air was not really warm, but if I gave the engine some gas it got HOT....let it go back to idle and it cooled off again.

There is something floating in, and on sides of the overflow bottle. Almost looks/feels like dirt. Has a coppery color in the tank, but I rubbed some between my fingers, feels like dirt...not really metallic.

After engine was warm...seemed like ho heat at radiator. I removed cap and water in there was not hot at all.

Preliminary thoughts:

Kind of thinking that it might be a stuck closed thermostat. This is not my area of expertise...but wouldn't that explain why it doesn't feel like water moving through hoses? If so...any thought what the dirt/shavings looking stuff might be? Would the same symptoms be a result of a clogged up radiator? Is that even a thing?

I hate to just throw parts at it without knowing what is the actual issue.

 

[07EddyB]

Honestly - at 135K I would start throwing parts at it. If the cooling system has never been flushed out then you are overdue. I have the V8 - but I hear that the thermostat housings crack often on the V6s. You are losing water somewhere. Pressure test the radiator - HF has a fairly cheap kit. Otherwise, start taking everything off that you can to get a good look at the radiator. Mine had a leak at the top - never put any water on the ground. Once I started pulling the fan shrouds to get a good look the problem was obvious.

 

[PotatoExplorer]

Yeah, I'd start with throwing in a new thermostat. They are pretty cheap to begin with, pretty easy to change (at least on the V8... not positive on the V6) and will help rule that part out of the equation. Then while you're in there tearing things apart, you can get a good look at the thermostat housing, hoses, and upper radiator as EddyB stated. Then you can purge the system afterwards to also help rule that out.

When my thermostat went out the upper hose got really hot, but the bottom one never got hot.

 

[mcompton1973]

What is the best way to flush the radiator on these? Only way I've done it before is one of those old "Flush-n-fill" kits that tap into a radiator hose

 

[Explorer75]

As said before, new thermostat and seal, check for leaks at broken hoses and/or thermostat housing. Check for a leaking water pump. Check radiator isn´t clogged. Refill with new coolant. One trick, when you verify/repair everything and comes the part to fill with new coolant, leave the thermostat open, start filling until coolant starts coming out the thermostat housing, assembly everything, then continue to fill. I do this to prevent air pockets. Another way would be to take out the coolant temp sensor and wait for the coolant to start coming out and get the sensor in.

 

[07EddyB]

When I did my V8 I planned to change the thermostat so I removed the old one and put the housing back on. I basically then drained the radiator, refilled with water, and ran it with the heat on for a few minutes, Then drained, refilled, repeated a few times to get the most concentrated part of the old coolant out without dumping it all over the driveway. Once the majority of the coolant was out, I took the cap off and ran it while I refilled the radiator with the drain open.

 

[tripplec]

Bump to the above but I would fork out for the FORD T-STAT !!!
I would not use an aftermarket despite any few $$$ saved. Its critical to work right so use the right part from square one. Compatible antifreeze to refill which depends whats already in there. If in real doubt I am told the Universal ones are safe as the OEM claims they are such as Prestone.

 

[mcompton1973]

I installed the Motorcraft T-stat. I am having a leak now where the housing covers the t-stat. I can not seem to get it tight enough to seal and I wonder if I am missing a gasket of some sort or something? This is not a crack or leak in the housing itself...its at the seam between the two pieces.

 

[swshawaii]

O-ring seal IS used for the upper housing. DON'T over tighten. Fel-Pro 35617 (W702837S300)

Torque spec is only 89 inch pounds, or 7-8 foot pounds for the six lower and upper housing bolts.

http://www.rockauto.com/en/moreinfo.php?pk=447251&cc=1441674

 

[Explorer75]

Just like swshawaii says, you need that seal, it sits on top of the thermostat. You put the thermostat, jiggle valve at 12 o´clock, put the seal on top of the thermostat, and put the top part of the housing.