Tips/Tricks for Thermostat Replcement

[harriw]

Hey guys and gals,

'94 4.0 w/ AC. I'm replacing my thermostat (lukewarm heater, engine never comes up to temp). Drained the radiator, pulled out the air intake (replacing air filter and cleaning MAF while they're out).

Using all sorts of socket extensions, u-joints, etc., I managed to get all 3 T-stat housing bolts out, but it's awfully cramped in there, and I'm not confident I'll be able to maneuver an RTV'd gasket back in there and get all 3 bolts re-tightened (all beore the RTV hardens up).

Any tips on how to maneuver and/or free up space around there? Looks like my biggest culprits are:

1.) The (metal) AC line - don't think I can do anything about that.

2.) The alternator isn't a big problem, but the bracket that holds it and the serp. belt idle roll is really in the way. I can take off the belt and alternator easily enough, but can I remove that bracket that holds the alternator, idle roll, and belt tensioner? I see 3 good-sized bolts right on the front - any others holding it on? I guess I'm concerned whether alignment of that bracket is crucial for proper serp. belt steering, or if I can pull it off and put it back on without issue.

So what say you? Can I remove them, or do I have to work around it somehow? Any other tips or tricks to free up some room or make the job a bit easier?

Thanks a lot!

-Bill

 

[harriw]

Oh, one other thing - when I drained the radiator, I only got about a gallon and a half of fluid out of it - should be about 3.5 gallons all together in the cooling system for the 4.0, right?. Is there really that much of it that sits in the engine and reserve tank? Or am I missing some? Radiator was full right up to the neck before I started draining it...

Thanks.

-Bill

 

[AKBroncoII]

3.5 gallons is a lot. I doubt it takes that much. If I had to guess just in your radiator, maybe 1 to 1.5 gallons. That would be if complete full depending on manual tranny or auto.

 

[harriw]

Ok, that sounds better. Haynes manual said the coolant system capacity was almost 3.5 gallons, and I got a bit concerned when only 1.5 gallons came out of the radiator.

Anyone have any tips for gaining access to the thermostat?

Thanks!

-Bill

 

[woodyedmiston]

Take the belt off. Unbolt the AC and pick it off the mount, rotating the entire pump so the the pulley then faces toward the back of the engine. Use wire/bungee cord to hold it out of your way. The hoses will flex. Unplug the alternator and take it off if you want. Just unscrew the idle roller out of it's mount and that might buy you some room. As far as alignment of the bracket is concerned you won't have a problem. But . . .

If it makes any difference, it's a PITA but you can replace a thermostat with out all of that. Do it frequently between all the Ford products I have.

 

[harriw]

Awesome - that's just the stuff I need. I might have a go at it as-is, but I got the "minute gasket" stuff from permatex, and I'm afraid it'll set up before I can get the housing fished in there, get all three bolts started, screwed in, and torqued down. I'm also a little concerned about getting accurate bolt torque (w/ torque wrench) while using a universal joint to get to the bolts. How crucial are the torque specs here? I'm guessing not very, as I've seen a few different specs. As long as they're snug it's OK, right - gasket material does the rest?

Thanks a ton.

-Bill

 

[jasonl]

Don't all the 4.0 Rangers use the rubber O-ring that goes around the T-stat??

 

[Stranger ranger]

its not that big of a deal, i didn't even use rtv, the gasket that came with it was adhesive on one side and i had all the time in the world to play with it. You don't need to remove any of those things, if i can do it so can you, i've got huge sausage fingers that requires a size 17 ring, so if i can do it, so can you. PS, use a wrench

 

[harriw]

I got a gasket to go on the T-stat (yes, 4.0), but still need to make an RTV gasket on the housing-to-block mating surface, right? Or does the gasket seal both sides of the coolant passage? I was under the impression that the t-stat gasket sealed the t-stat against the block, but coolant was free to flow around the housing on the other side (when the t-stat is open, that is), thus the need for an RTV DIY gasket on the housing-to-block mating surface.

Maybe I'll just give it a shot. Worst case I clean off the RTV and start over.

Thanks guys.

-Bill

 

[jasonl]

I just read the instructions on autozone in their repair guides. Place the air bleeder at the 12:00 postion and it does say to use a sealant on the mating surfaces, but I have done several without sealant, just the O-ring. I recently replaced mine in my truck and it didn't have any sealant from the factory and it doesn't leak. I will from now on put a small amount of gasket/sealant on it just to be safe.

 

[Sasquatch_Ryda]

I've never used anything but the rubber seal that goes around the t stat itself, never any sealant.

 

[97ranger4x4]

If I remember correctly, the Coolant capacity is just around 2 gallons.

Also I used RTV the last time I replaced a T-stat. Doesnt leak a drip.

 

[ranger dude]

you should not need to use any rtv the gasket you should use is a oring that has a groove on the inside to place the thermostat once the oring is placed around the outside of the thermostat push into intake with bleeder up 12 oclock position it should stay there oring will hold it in place tighten just snug the oring is a very good seal to get extra room you can remove the serp belt tensioner there are 2 bolts that hold it on they should be 15mm head I have had problems with the oring thickness where the oring once installed on the stat will not push into manifold fel-pro gaskets all ways seems to work just fine

 

[harriw]

Hey guys,

Thanks for all the tips - I got the job finished tonight. Managed to leave the serp. belt on and leave the AC, alternator, and belt tensioners alone. Wasn't so bad once you see how it all goes together, and realize the RTV is really only a "just in case."

Fired it up and no leaks so far. Heater seems to come up hotter, faster, but the temp gauge is still pretty low. Might need a new sending unit.

Looks like there are 2 sending units on the block just above the thermostat housing. I suspect one is for the gauge, one for the computer. Anyone have any idea which is which?

Thanks again guys!

-Bill

 

[AllanD]

I put the '94 Alt bracket and tensioner on my '93 engine because it's easier togdisassemble the front of the engine..

I long ago decided that "Working around" things didn't save an time over uwing a direct brutal approach to getting things off.

Basically if I'm doing anything to the front of a 4.0 the belt, alternator
and alternator bracket are going to wind up on the tailgate before I
seriously attempt do do anything else.

T-stat? Oh yeah, that stuff is comming off.

I have universal sockets and all the rest but I like a direct approach to hit it with my 3/8drive air ratchet comming off and my 1/4 drive going back on.

And that allows for the fact that my T-stat bolt holes were helicoiled while
the engine was still on the engine stand.

No, no sealant on the T-stat gasket.

If you feel you must put anything on there use some silicone GREASE.

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