thermostat location and replacement?

Hi:
The pictures didn't come through. However, are you making sure the thermostat is seating before putting it together. There should be a slight recess that the t-stat sits into. Here are the diagrams to hep you see what I am talking about for both the 4 and 6 cylinder engines. Check out the diagrams (Below). Please let us know what happens.

here are the pictures

From the pictures, everything looks fine. Are you certain that the t-stat is seating in the recess of the housing? If that slips out, you will get a leak. Other than that, check to make sure everything is flat and true.

The first picture shows the thermostat placed on top of the housing gasket, and the second picture shows the thermostat placed under the housing gasket. Which is the correct one? The third picture shows the housing, but I don't see any places for the tabs of the thermostat to fit in to.

Check the housing and the engine block to see where the recess is located for the t-stat to fit into it. Install the t-stat into that recess, then the gasket goes on the opposite side.

ok, I'll do that. Now, the question about the gasket in the picture, which picture is correct, the first or the second one?

also, it is hard to see the last two pics. They are dark. It appears that there is old gasket material still on the housing. Make sure that is clean and dry when installing. (both the housing and the engine block should be clean and dry)

it is a brand new housing as well, so it is already clean. The area around the engine block is clean too, what a challenge that was!

I know that cleaning old gasket material is a pain!!! Have you been able to locate the recess I mentioned?

FOUND YOU A DIAGRAM IN "MITCHELL 1"

IS IT POSSIBLE THE HOUSING IS FLIMSY AND OVER-TIGHTENING IT MIGHT MAKE IT BOW OUT IN THE MIDDLE????

THE MEDIC

what is the normal thermostat reading on a 1994 ranger 4.0. Mine usually reads between the O and R in normal on the dash. Should it read cooler

O and R are in the normal range, do you have an issue with the cooling system?

the heat and a/c work fine, but the thermostat gauge use to always be below the O.

Thats still within normal operating tempature range.

Thanks alot, I guess no need to worry. You been a great help

Your welcome

Will not blow any heat need to replace thermostat

Is the coolant flowing in the cooling system? When you change the temperature and vent, do you hear the bleed/blend doors moving?

What engine do you have? The procedure is different for different sizes.

Yes the coolant is flowing in the system. Yes I do hear the doors moving. 2.3 4 cylinder 8 spark plugs.

See image. Drain cooling system. Valve is on the bottom of the radiator. Use a drain pan. Coolant in the gutter is a felony in most places. Remove housing. Clean block and housing, removing all traces of old gasket. Note orientation of old thermostat. Apply RTV blue to housing and block. Reassemble.

I replaced my thermostat installing the new one exactly like the old one. Later I read the air relief valve hole should be a 12 o'clock, mine is at 6 o'clock.

Is this worth the hassle to re-install?

What is the purpose of the air relief valve hole?

Thank you,

Only matters if the tstat mounts on the side of the block. The valve should face up to allow air to bleed out of the system. If your cooling system and heater work OK, dont bother with it. Older tstats never even had em...

Drained and flushed water through my radiator, also back flushed the heater core. Work done outdoor in mid twenty degree temperatures. Upon refilling the radiator and running, the engine warms up but the thermostat does not open. If I leave cap off it spits fluid out. If I keep cap on, no spill, but still thermostat does not open and engine temperature rises till I turn off so not to overheat. Will close hood afterward to warm engine compartment in case thermostat is froze, then try again with no success.

It is possible to get a new one that does not work or that is the wrong temperature.

How hot are you letting it get? That is a 192 degree unit, If you test it in hot coolant it should start to open at 192 and fully open by 212 degrees.

It is also possible that the water flush has frozen in a small spot and the pump cannot circulate the coolant past it. Not really likely unless you took a couple hours from flushing to filling.

What was the original reason for the flush? no heat or overheating?
If you fill the system and just start the engine, does the coolant start bubbling or running over? If it does and the issue was overheating you may have a bad head gasket. Especially if it goes from cold to hot in a very short time.

Install a brand new thermostat.

The cooling and heating systems were fine before starting radiator and heater core flush. Was only doing routine maintenance, it had been five years. Only used water to flush. Could their be an airlock/bubble in the system, if so what could I do ?

Also, I warm the engine until the heat gauge moves halfway from cold to hot.

Since there is no bleed valve, jack up the front end on the side where the radiator cap is until the radiator cap is higher than the rest of the cooling system which includes the heater core, then remove the cap, top off the coolant, start the engine and allow it to warm up for five minutes or so, Shut off the engine and then grab the top radiator hose with both hands push it down as far as you can then squeeze real hard with both hands and force any air out the filler neck. Top off the coolant, leave the cap off for now, start the engine and let it idle and make sure the thermostat opens and the system does not overheat before putting the cap back on and lowering down the vehicle.
You could also just pull that one front side up onto a curb also.
If this does not work, then install a new thermostat cause I learned long ago from an engine re-builder who told me once an engine overheats it ruins the thermostat. I suppose though to what degree it overheats just how much it ruins it though but it can be true.

Temperature gauge moving half way will not normally be overheating. That would be about a normal area for the thermostat to start opening. What you need to do would be to actually measure the temperature to see if it is okay or actually running hot.