Coolant Leak Screw-up '04 4.0L

[imp]

OK, I admit it. Replaced water pump after now and then puddle of coolant under engine. Only occasionally, added water once in a month's time, down ~ a quart. Could not detect any wetness above pump, looking at possibility of cracked thermostat housing (plastic, I've heard they crack). Pump replace went OK, typical. Drove 100 miles, no puddle. This morning, my wife stops the action, she sees the new puddle as I'm ready to pull out of the shop. Look under hood; same as before, see no hint of leakage, the pump pulley obscures completely any view of the pump bleed hole. But, I swear it's GOTTA be the new pump leaking.

Much, much closer look, engine running & hot, pressure up, see no leakage. But, climbed up on step-ladder, hanging over engine room, I see coolant in the valley, congregated around what looks like a freeze plug in the lower manifold, which is new territory for me. I like FEs the best. Then, I see it: wet along seam on thermostat housing, not outlet neck, but below it. Here's the part in question:

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This thing is a marvel of design confusion, plastic, bolts onto lower intake water outlet, sends first hot water out top pipe to heater, bottom fatter pipe to bypass thermostat when it's still closed, top, obviously the outlet to the radiator. But, it turns out to be a 3-piece part: remove outlet neck, there remains a 1/4-inch thick top piece, not normally removable, and that's where my leak originated. I decided to rip it open. Factory "glued" the top in place with some sort of hardening gasket. It was difficult to clean off, and I thought about putting it back with RTV Silicone, but went to O'Reilly's first. They had the whole damned thing new on the shelf! So, I guess they crack, fail, etc., often enough.

So, given the unknowns, made in China, plastic similar, old part said "Ford", new says nothing, if the material is good enough, Cyclolac plastic, maybe,

Seals onto intake manifold using a square-cross section O-ring, like a wide rubber band. P-P idea. The new housing has it's top gasket already sealed in place, thermostat top outlet neck seals with a big O-ring, and the Engine Coolant Temp. Sensor presses into the top using an O-ring to seal it, no threads. Metal clip keeps it from popping out.

Has anyone else ripped one of these abortions apart, studied that factory-installed glue gasket? Vehicle made it to 160K, can't complain really, but metal pleases me more than plastc. They saved maybe half a pound with this thing. I could find no view of the damned thing separated into it's three parts. If you ask, I'll take pics of mine tomorrow. imp

 

[Tech By Trade]

Lol, I'm on my third. 4th if you count the one that was stripped out of the box from rock auto. Luckily the second gen sport trac you don't have to pull anything else off to get at them. its a 20 minute job to replace. They are about 40 bucks for a dorman one. For that price I don't mind changing it every 4 years or so. A fellow on here is selling a custom made aluminum (i believe) one for a few hundred.

 

[swshawaii]

metal thermostat housing soon available for v6 2005+ engine | Ford Explorer and Ford Ranger Forums - Serious Explorations

***02-10 Ford Explorer 4.0 V6 Metal Thermostat Housing Made in the USA*** | eBay

 

[Tech By Trade]

Yep, that's the one. Looks like someone ripped it off and is selling the same one for the Mazda, and less money. Probably the same Chinese guys that did the cast for the original. Now if only someone would come up with a metal framed and backed cassette for these things.
01-11 Explorer, Mountaineer, B4000 4.0L Aluminum/Metal Thermostat Housing Kit | eBay

 

[swshawaii]

TBT, I submitted a "New Product Idea" to Dorman a few weeks ago with this link. Not holding my breath.

4.0L SOHC ALL Metal Timing Chain Guides Possible? | Ford Explorer and Ford Ranger Forums - Serious Explorations

 

[imp]

Yep, that's the one. Looks like someone ripped it off and is selling the same one for the Mazda, and less money. Probably the same Chinese guys that did the cast for the original. Now if only someone would come up with a metal framed and backed cassette for these things.
01-11 Explorer, Mountaineer, B4000 4.0L Aluminum/Metal Thermostat Housing Kit | eBay

I can't really speak de-rog about my '04 much, got it w/92K on it in Mar., 2010, has 160K now; all the things which should have failed by now, have not. Eng. nice & quiet, idles so smoothly, ya can't hardly feel it in the vehicle; now and then I think it's stalled, check tach. Transmission still works fine. No leaks, no gear howl. Here's what-all I've done to/for it in those 7 years:
When I first got it: starter drive made lots of noise, bought new starter, same noise.
Replaced alternator w/new, general principles.
@105K, TCC solenoid crumbled it's bushing, replaced solenoid module. Made up the dipstick tube at that time.
Fuel Pressure & Temperature Sensor, 110K, failed again in a year, replaced again, replaced spark plugs about same time, still have original wires.
Throttle Body replaced @140K.
ABS Module replaced @140K w/used unit.
This week, water pump and thermostat housing. Installed the new t-stat I bought in 2010, had on shelf since.

Is that a lot of stuff for 160K? Nothing really major, like chain guides! imp

 

[Drewmcg]

I've replaced this thermostat housing on two Explorer 4.0's--a '97 (2nd gen) and my '02 (3rd gen). Of course, they are a two-piece design (Imps must have broken to get three pieces).

On each of my repairs, the hardest challenge was getting those three lower bolts out w/o breaking them. I had good luck with a Four Season replacement the first time. You can replace just the bottom half if you want (available separately, or used to be)--the top piece is pretty indestructible so far as I can tell. Personally, I would not trust Dorman for this part. On my '02 I went with Motorcraft for peace of mind.

Be sure to anti-seize the bolts (especially the lower). I replaced smaller-diameter hoses that attach to this thing at the same time since they are much easier to do with it out and, once installed, you don't want to mess with the thing (at least the lower half of it, bolted to the engine) after install if you can help it.

 

[imp]

@Drewmcg "Of course, they are a two-piece design (Imps must have broken to get three pieces)."

They have a top cover plate gasketed to the base which mounts to the lower intake manifold. The top cover is not intended to be removable. The factory assembles it using some type of sealant/gasket material which sets up very hard. I separated mine because that's where the leak was, not cracked, but seeping out and winding up in the "valley" behind it, and running down the front, over the pump pulley, dried alkali all over (used tap water while losing coolant.) Here's how it looks assembled, and with the top cover plate removed:

Below, the underside of the top cover. Note the 3 square holes. They held square nuts which the outlet neck is screwed down with. So, when tugging on a stubborn upper hose to get it off, some of the strain is placed on the gasketed joint, because the 3 round metal tubes are a loose fit in the upper cover! You can still see remnants of the gasket left on between the two pieces, though I scraped and wire-brushed it before I knew the dang thing was available at O'Reilly's. I was going to try re-sealing it with RTV Silicone or Trim Cement, glad I didn't try that! Of course, the 3rd. piece is the outlet neck, missing in the pics 'cause it's residing on the replacement part in the truck! imp