Water leak and I'm probably screwed

[Texas97x]

Bought a 2001 XLS a few weeks ago with the SOHC 4.0 and it had a small water leak around the thermostat housing. I fixed it with a new gasket and then yesterday dropped in a new MAF sensor to get it running. Any way today I ran it down to the car wash and then stopped to get gas. All around about a 7-8 mile round trip. On the way home noticed temp guage was running on the high side so I checked the water in radiator and it was low. Put in some water and the did someother stuff under hood and in about 20 minutes was about to put radiator cap back on and it was low again. WTF? Put more water in and noticed could see it drop almost immediately. No leak around thermostat housing nor the heater/ radiator hoses. Look underneath and water is rapidly dripping around the starter somewhere above it. Now I am almost 100% sure it is going to be a freeze plug but is there anything else it could be? And if it is a freeze plug I am sure that no amount of stop leak is going to work, right?

 

[lobo411]

I'm not familiar with the SOHC, but...lower intake manifold gasket?

 

[koda2000]

The plastic thermostat housings on your engine are notorious for leaking/cracking. When they do the antifreeze can run down the block valley and can drip from the rear of the engine.

If that's the source of your leak, metal versions of the 4.0L SOHC housing are available or you can purchase another plastic replacement.

 

[koda2000]

I'm not familiar with the SOHC, but...lower intake manifold gasket?

No, Not on the SOHC.

 

[imp]

Bought a 2001 XLS a few weeks ago with the SOHC 4.0 and it had a small water leak around the thermostat housing. I fixed it with a new gasket and then yesterday dropped in a new MAF sensor to get it running. Any way today I ran it down to the car wash and then stopped to get gas. All around about a 7-8 mile round trip. On the way home noticed temp guage was running on the high side so I checked the water in radiator and it was low. Put in some water and the did someother stuff under hood and in about 20 minutes was about to put radiator cap back on and it was low again. WTF? Put more water in and noticed could see it drop almost immediately. No leak around thermostat housing nor the heater/ radiator hoses. Look underneath and water is rapidly dripping around the starter somewhere above it. Now I am almost 100% sure it is going to be a freeze plug but is there anything else it could be? And if it is a freeze plug I am sure that no amount of stop leak is going to work, right?

@Texas97x
Here's the part we're talking about. Before I knew about this probability, I was certain the water pump was leaking, throwing coolant around, so replaced it. Still a puddle under truck. Then i learned of the T-stat housing:

Above, the entire housing, upside down. Below, the plastic parts disassembled. Many thought this was a one-piece part; not so, the factory seals the two flat surfaces together with a special gasket and glue. That's what failed on mine, and DAMNED if you could see exactly where the leak was occurring while still assembled on the engine.

You can see what's left of the gasket material on the top piece above. The coolant was settling in the valley between the heads; when enough gathered, it leaked forwards during breaking, backwards during acceleration, so leakage was seen under the bell housing as well as the front of the engine. This whole situation was thoroughly thrashed out awhile back, complete with discussion of the two metal replacements available. I went for the plastic at O'Reilly Auto Parts, about $40. Been well over a year now, coolant level constant in catch tank, always at the low mark, cold. imp

 

[Texas97x]

The thermostat housing was leaking at the top and that I have fixed. I really don't think it is leaking along the seam of the lower housing but I suppose it is possible and I just can't see it. Time to break out the small mirror and light to go searching. Indiana Jones and the Invisible Leak. LOL

 

[sehaare]

any chance you had a bubble in it when you originally filled it?

 

[donalds]

Get a cast one
4.0 SOHC Metal Thermostat Housing Comparison

 

[Texas97x]

Well it looks like it is leaking on the back side of the top piece of the housing. Now since it is just a beater I have to figure out do I try to seal it or just break down and buy a new housing.

 

[koda2000]

Well it looks like it is leaking on the back side of the top piece of the housing. Now since it is just a beater I have to figure out do I try to seal it or just break down and buy a new housing.

I can't speak for the quality, but there are complete new housings available on eBay (with temp sensor and sender) for $18. The upper end runs around $160 for a one piece metal housing. Pick your price point.

 

[donalds]

I got the two piece metal housing
Works good no leaks so far
It's a cheaper $80 option ebay

I wasn't gonna pay $160 I'm to cheep

 

[shucker1]

What's wrong with cheap? For some things....

More $$$ for beer...

 

[imp]

What's wrong with cheap? For some things....

More $$$ for beer...

@shucker1

Yeah! As a well-invested "lush"...........imp