Lower Thermostat Housing Help

[Pheadrus]

I have a 99 4.0 sohc 2 door sport with only 140,000km's(87,000 miles) on it but it's getting rusty and I've been waiting for the timing chain guides to become an issue so I'm not sure if I want to put more than a few hundred into fixing it. I can do the labour.

The last couple of days my temp gauge was reading slightly higher but I mean less than a 1/16th on the gauge so I wasn't too concerned. Yesterday I drove to town which is about a 30 minute drive and again it seemed a little higher than usual once warmed up.

We live in northern Canada so when I went to drive home hours later, I let it warm up for about 5 minutes and it was still reading in the cold. After driving for about 5 minutes, the temp gauge started rising from about the normal middle position to about a 1/4 inch from the red zone on the gauge. We turned around and head back to my parents place. The gauge stayed at that position until we almost got back to there house and then it dropped back down to about the middle, which was slightly higher than it would normally sit. I let it idle at my parents for about 5 minutes and it stayed in the middle. So we decided to drive home so my wife could drive her car to work today. The whole way home it stayed in the same position jumping up for a second one time about half an inch on the gauge. When we got home, I checked the reservoir and it was basically empty. It was very cold last night so I left it until today to explore further.

Their was some coolant in the snow under where the front of the motor is and the rad was down about 2 inches from the top. The oil while black, shows no signs of antifreeze at all. I moved on to the thermostat housing as the likely culprit and sure enough it has coolant leaking.

I have a few questions. How likely is it that there was further damge done to the engine(head gaskets) by driving it home? The red "check gauges" warning light never came on and it never pegged the temp gauge(highest it got was about 1/4 inch from red zone) if it can be trusted for accuracy.

I've searched for an OEM Motorcraft housing but the only ones I find are in the $400 to $500US range. What aftermarket brand would be considered the best alternative and can it be trusted? If I do the job, I'll do everything related. Hoses, water pump, bypass hose, switch, sensor, etc.
Thanks.

 

[swshawaii]

4.0 SOHC Metal Thermostat Housing Comparison

 

[Pheadrus]

Thanks so much! I couldn't find the Simmons one on Ebay but I did find the Austekk for $66.90. So I guess I'll get it and stick a Motorcraft Thermostat in it unless there is a better option for the thermostat.

Can the fan switch and temp sensor that come with the housing be used or should I go Motorcraft for them as well?

If I keep the reservoir and rad full, can I drive it until the parts come in and it warms up to do the work?

97-01 Explorer Mountaineer 4.0L SOHC Aluminum Metal Thermostat Housing Kit | eBay

 

[koda2000]

When the engine is cool/cold remove the radiator cap can see if it is low on coolant (it probably will be). It should be filled to the top. That's likely what's causing your temp needle to fluctuate. From what you've said, it doesn't sound like you've done any damage yet, but you have a coolant leak somewhere. Could be the t-stat housing, could be a small hole in a hose, could be the heater control valve leaking, could be your radiator. Fill the radiator and add coolant to the expansion tank to about where the seam in the tank is and monitor it daily to determine how quickly you're loosing coolant. That may give you some idea of where the leak is.

The temp gauge needle should be in approx the center of the gauge at normal operating temp. It operates w/in a range which it considers "normal" (maybe 167-210 degrees F). Less than 167 the needle will read colder, above 210 it will go to HOT very quickly and the "Check Gages" light will come on. Never keep driving if the gauge goes to HOT or you will do major damage to the engine.

The SOHC V6 often leaks coolant due to a cracked plastic t-stat housing, but there are many other places to check before you start throwing parts at it. A cooling system pressure tester is helpful in finding the source of a leak. These can be borrowed from most auto parts stores.

 

[Pheadrus]

Thanks for the info guys. I can see coolant around the T-stat housing so I assume that's the problem. As I stated, the level in the rad is about 2 inches from the top. I'm dealing with -20 Celcius temps so I'd like to wait for it to warm up before I tackle it in my driveway if possible. Anything specific for getting air out of the system or just fill and run with rad cap off?

 

[XLTrunner]

It helps to elevate the front end while letting the engine warm up with the radiator cap off. Never have had a problem with trapped air when doing this in my driveway.

 

[Pheadrus]

Are the screw in temp sensor and fan switch that comes with the Austekk housing a good quality or should I replace them along with the T-stat?

 

[Paul Fithian]

SimmonsAutosportz

 

[Pheadrus]

Great. I just ordered the Austekk one. Are you saying it's junk?? What about the sensor/switch??

 

[Pheadrus]

I watched the video and reread the thread about the two units. I've been busy with a leaking roof and should have researched more.

What I'm gathering is that if I RTV the two halves and the steel hose barb, I should hopefully be ok. I'm on permanent disability so my 99 gets limited use in general. Maybe one trip a week so I'm hoping the Austekk will last. How bad are the Chinese temp sensor and fan switch?

I also messaged the Ebay seller(bfoot58) and told him I need the outlet nozzle for a 99 so hopefully I get the right one.

Do I have to modify anything to make the Austekk fit? Is it easier to install the housing without the sensor/switch and then install them after?

 

[swshawaii]

@donalds

4.0 SOHC Metal Thermostat Housing Comparison

 

[Pheadrus]

I read that thread earlier after I ordered the Austekk this morning so I'm going to have to use it unless members here have used it and don't recommend it.

The plastic Dorman from NAPA was going to cost me $50 more than the Austekk so I figure it has to be better than the NAPA plastic option unless the temp sensor and fan switch are junk. If the temp/switch parts are junk, please let me know and I guess I'll have to order the Simmons unit.

If I use the Austekk, I'm going to apply Ultra Copper RTV on the two halves and the hose barb to hopefully avoid leaks. I really need to know how reliable the Chinese temp sensor and fan switch are and any tips or tricks on installing the Austekk.
Thanks.

 

[koda2000]

Great. I just ordered the Austekk one. Are you saying it's junk?? What about the sensor/switch??

The Austekk is better than a plastic housing (even Motorcraft). The only possible issues with the Austekk vs the Simmons housing is the screw in steel pipe, that may leak in the future and corrode do to electrolysis that occurs when you mix dissimilar metals, like steel and aluminum. Also the Austekk housing is a 2 piece design, so it might leak from the top gasket. Other's here have installed the Austekk w/out problems to-date, but personally I'd buy the Simmons housing. JMO.

 

[Pheadrus]

Thanks Koda. In hindsight, I would have gotten the Simmons unit. I couldn't find it on Ebay and needed to get a part ordered so I went with the Austekk. How bad a re the temp sensor and fan switch? Is it something I have to be worried about? Should I order some spares to have on hand?
As I said before, I'm going to follow the advice in previous threads. Ultra Copper RTV between the two halves, remove the screw in pipe and RTV it. Motorcraft RT1160 T-stat, Motorcraft upper rad hose, RS76 rad cap, etc.

 

[Paul Fithian]

The Austekk is better than a plastic housing (even Motorcraft). .

Totally agree.

 

[koda2000]

I have no opinion on the sensors. One is for the PCM and the other is for the temp gauge. What fan switch?

The sensors are easy to replace, so even it they have a problem it's not a big deal. You might as well use them.

 

[donalds]

If I use the Austekk, I'm going to apply Ultra Copper RTV on the two halves and the hose barb to hopefully avoid leaks. I really need to know how reliable the Chinese temp sensor and fan switch are and any tips or tricks on installing the Austekk.

I have been us the austekk. For a while no problems at all just use a little rtv common sense
follow the directions in the thread posted above and you will be fine
Just my .2