Seeking tips on changing T-stat on 99 SOHC

[mikepier]

I am planning to change the T-Stat on my 99 XLT SOHC. It looks as if its straightfoward. I know I should drain some coolant below the T-stat, but any other tips or advice would be appreciated. Should I use Motorcraft T-stat,what gasket to use,etc. Thanks.

 

[williams.cory]

Are you going to be keeping this vehicle for a long time? If so, I would definetly get a Motorcraft brand. Get the job done once and dont worry about it for a long time. I've seen other brands have to be replaced quiet often, and after all the headache of warranty replacement or having to buy it again they could have just got a Motorcraft and be done with it.....

 

[Premier]

dont know how much different it is on the sohc, but here is a thread. http://www.explorerforum.com/forums/showthread.php?t=199949

i have changed them on other fords, and its the same basic concept/location

 

[CDW6212R]

The SOHC thermostat is high, about $20 or more. Buy a Failsafe thermostat, they do not fail closed if they ever fail. Any other thermostat will fail closed, thus the vehicle will be undrivable or blow up.

For the SOHC, do not remove any of the bolts or sensors at the thermostat except the three on the cover piece. The sensors will strip if you try to remove them, leave them alone.

Buy a new seal, do not reuse an old rubber seal. Two of the three bolts are very easy, and I think 10mm is the size. The trick to the third is a swivel socket or joint that flexes just enough. With the right socket tools it's about a 30 minute job. Take off the plastic cover piece under the radiator(four bolts). That makes draining the radiator much cleaner. Regards,

 

[mikepier]

The SOHC thermostat is high, about $20 or more. Buy a Failsafe thermostat, they do not fail closed if they ever fail. Any other thermostat will fail closed, thus the vehicle will be undrivable or blow up.

For the SOHC, do not remove any of the bolts or sensors at the thermostat except the three on the cover piece. The sensors will strip if you try to remove them, leave them alone.

Buy a new seal, do not reuse an old rubber seal. Two of the three bolts are very easy, and I think 10mm is the size. The trick to the third is a swivel socket or joint that flexes just enough. With the right socket tools it's about a 30 minute job. Take off the plastic cover piece under the radiator(four bolts). That makes draining the radiator much cleaner. Regards,

Thanks. Does the rubber seal need any gasket sealer, or is it good by itself?

 

[CDW6212R]

It's great, just set it on the thermostat. You could wipe it with a little moisture from the coolant, but no sealant is needed.

 

[96eb96]

The SOHC thermostat is high, about $20 or more. Buy a Failsafe thermostat, they do not fail closed if they ever fail. Any other thermostat will fail closed, thus the vehicle will be undrivable or blow up.

Regards,

Just FYI, this is partially true, they can stick closed. In an extreme overheat condition they move past a one way tang and stay permanently open. If they never get to that point they are just a regular stat.

http://www.motoradusa.com/products/failsafethermo/index.html

I read on other forums where people had issues with them failing closed. I only trust Motorcraft/OEM thermostats, not saying they are perfect but I think they have engine warranties in mind and would have the best quality control. Just my opinion...

 

[unclemeat]

Be gentle when tighting bolts. Use loc-tight not muscle. Make sure the weep hole is on the top.

 

[chapsdeva]

One tip...When draining your coolant, use an Allen wrench on the drain petcock instead of a socket, especially when tightening it. The drain petcock is made of plastic and the head will break very easily...I learned the hard way. You might as well replace your hoses as long as you are doing the thermostat..cheap insurance and it will make the job easier with the small ose out of the way. I didn't put any gasket sealer on my housing, but I did clean the housing surfaces well. Good luck.

 

[gijoecam]

Be gentle when tighting bolts. Use loc-tight not muscle. Make sure the weep hole is on the top.

One tip...When draining your coolant, use an Allen wrench on the drain petcock instead of a socket, especially when tightening it. The drain petcock is made of plastic and the head will break very easily...I learned the hard way. You might as well replace your hoses as long as you are doing the thermostat..cheap insurance and it will make the job easier with the small ose out of the way. I didn't put any gasket sealer on my housing, but I did clean the housing surfaces well. Good luck.

I think you are both confusing the engines.... his is the SOHC motor, not the OHV. There is no bleed hole in the thermostat for the SOHC, and even if there was, you would you put it at 12:00?? It lays flat in the housing on TOP of the motor.

And the housing is sealed with an O-ring. Nothing more. Do not use any sealants in addition to the o-ring. They'll only cause trouble.

-Joe

 

[TheJackal]

From what I hear the enclosure is plastic and could be damaged if you overtighten the bolts. Torque the bolts properly and don't crack anything.

You do need to drain the cooling system first. If you don't drain it first, you'll be draining it through the thermostat housing.

 

[gijoecam]

I didn't drain down the system when I changed mine a few years back.... It's not a big deal.... Just rinsed the engine generously with a garden hose and it was fine. I'm cheap.... I'd rather waste some cheap water than unnecessarily drain out some coolant I'm not going to put back into the system. It turned out my coolant was so concentrated that I topped off the system with water just to get it back in the normal concentration for cold weather. (Friggin' dealership had mixed it so rich, I think it was pure antifreeze, or close to it anyways!)

 

[CDW6212R]

Just FYI, this is partially true, they can stick closed. In an extreme overheat condition they move past a one way tang and stay permanently open. If they never get to that point they are just a regular stat.

http://www.motoradusa.com/products/failsafethermo/index.html

I read on other forums where people had issues with them failing closed. I only trust Motorcraft/OEM thermostats, not saying they are perfect but I think they have engine warranties in mind and would have the best quality control. Just my opinion...

Most thermostats, when they see very high temperatures, they snap closed. They fail closed, while Failsafe units are locked open when they see overheating.

I have my original Failsafe thermostat in my SOHC truck. After if failed open(270), I replaced it with another one two months later. That one went in January at 282 degrees. O'Reilly's no longer lists the part, didn't have it in stock, so I unlocked my first one and installed it. They are well made.

Thermostats are not magical parts, most issues people have with them can be traced to when they were new. Often the temperature rating will be incorrect, or the valve sticks or doesn't move smoothly. If you want to be thorough then pretest them.