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runs cool

93 mustang coupe, 2.3T swapped.  Engine came from a Merkur, not that it matters.

Won't really warm up.  Runs about 145-150 deg going down the road.  If I let it idle for a long time it will get to 200, fan kicks on at 205, cools right back down, takes forever to repeat the cycle. 

Thermostat is a new Motorcraft 192° for the turbocoupe.  Thermostat housing is an original, in great shape with no pitting inside or outside for that matter.  Thermostat seals against the housing, verified by blowing into the housing and no air escaping, of course I had plugged the heater line fitting during testing.   Only thing I haven't done is actually test the thermostat in hot water; don't have a great way to do it at this point because my thermometer is dead for the DVOM (thermocouple).  This evening I removed the stat from the housing and stuffed an o-ring between the housing and thermostat, kinda help seal it to the housing.  Once bolted back to the head, verified that no leakage happens past the thermostat by blowing into the hose/housing while blocking the heater fitting.  Refilled, started engine, within a minute or so (just enough time to put up my ratchet and socket), I came back and put my hand on the radiator and it's warm-nowhere hear hot, gauge in car shows right on the 130 mark.

I've fought this for several months, several different motorcraft thermostats (all new from the parts store). 

Y'all got any ideas?  Have I gotten 3 "bad" thermostats?  I had a '93 Ranger at one point, all OEM, sucker would heat up quick and stay warm, but this stupid thing...completely different story.
'93 Mustang 2.3T swapped. LA3, Stinger FMIC 3" down elbow and 3" exhaust.

Todd, my 1986 SVO has always run cool...barely to the "o" in Normal on the stock gauge. The man from Washington state who sold me the car had placed a piece of cardboard in front of the radiator to increase the temp. I removed it since I live in CA's Central Valley where it is a LOT warmer.
IMO, running cooler is a plus. I also wonder is the turbo water bypass at the thermostat housing doesn't have some affect on the engine temps?
I now have no problem keeping temp above 150, as I installed a FMIC, which affects the radiator cooling flow.
1986 SVO daily driver. PiMP v1.4.2/3" Stinger exhaust/FMIC/Schlodes Manifolds/Boport 1.5 and head/GM 3700 stall 200-4R auto trans
1963 2.3T Ranchero Project

Running cooler is not a plus if it runs below the "warmup threshold" and therefore is constantly feeding it additional fuel enrichment. It also needs to get warm enough to burn off any condensation inside the engine or you'll end up with contaminated oil and such.

Most likely cause is the wrong thermostat style, or a poor thermostat seal.
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Did you get all the air out of the system?
'86 SVO, ported head, ported intake, Bo 1.5, .040 block, Pimp XS.

My Tbird never gets over a quarter or so up on the gauge, cant remenber at the moment what it was saying in tuner studio. Wish I knew why too! Also running a motorcraft thermo for an 88 tbird.
88 TC in Canyon Red
Walbro 255, AEM wideband, CP Pistons, FMIC, PIMP, SVO T3, Ranger roller, 3" Stinger exhaust, AFPR, RFL BOV, Gutted upper, Ported lower

(02-01-2020, 02:27 AM)jimtash Wrote:  Did you get all the air out of the system?
'93 Mustang 2.3T swapped. LA3, Stinger FMIC 3" down elbow and 3" exhaust.

ASSuming all coolant plumbing is routed as it was from Ford (as shown in the bottom diagram) AND your temp gauge is accuracte, I suggest using a pair of needle-nose ViseGrips to temporarily squeeze shut (close) the hose attached to the t/stat-housing nipple. If the coolant temp still  doesn't warm quickly to the s/stat's temp threshold (180°, 192°, etc.)......I'd say your t/stat is no good OR it's installed incorrectly. If a replacement is needed, I suggest one of the two depicted below:

[Image: zKEkAfp.jpg?2]

Note that the integral rubber gasket should be seated firmly against the (clean/smooth) counterbore inside the t/stat housing AND that the two metal tabs protruding from either side should be resting against the edges of the bore in the cyl head.

If the temp DOES rise quickly to the preset t/stat's "threshold" when the hose is squeezed shut......you need to figure out if there's something in the heater-core or oil-cooler circuit(s) that's allowing too much cooling to take place. I.e., a lack of restrictor in one of the heater core's nipples, etc.. GOOD LUCK! [Image: confused0024.gif]

[Image: 0AGaeYM.jpg?3]
Placerville, California
(former)  '78 2.3T Courier w/blow-thru carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI

Ray I have the restrictor in the heater core. I made SURE to put that in when I replaced the core. Started the engine cold this morning with the hose that feeds the heater core blocked with a pair of those hose crimping pliers. Within a minute, the upper radiator hose is/was getting warm, indicating (to me) that the thermostat is opening sooner than expected. Local parts store is going out of business and had a Robertshaw thermostat that just happened to be on the clearance stuff, fits Rangers, etc (2.3 and 2.5) , I gave them the $4 plus the darn tax and ran with it. No time to install it today, probably be a few days with moving the shop to another location but I'm certainly gonna try this new stat & see if there's any change. I might be able to find a thermometer to test it in hot water while I'm packing/moving stuff. We'll see.

My other car (92 mustang, 427w), when the engine is started cold, the upper hose takes forever to get warm, and when it does, it gets hot real quick and then cools, repeats, until the temp stays mostly the same. Takes 4-5 minutes idling to get the first heat in the hose. This little 2.3....takes about a minute to start feeling warm to the touch (but never really gets "hot".) I know, they're totally different applications but a thermostat should work mostly the same regardless, or I'd assume that anyway.
'93 Mustang 2.3T swapped. LA3, Stinger FMIC 3" down elbow and 3" exhaust.

There are probably dozens - if not 100's - of different brand t/stats available for the 2.3 Lima engine and none are contingent on turbo vs non-turbo. The closeout "Robert Shaw" version you purchased may well be a quality piece......dunno. I only suggested the two depicted in my last post because I KNOW  of their reputation for quality.

As for the original cooling circuit used by Ford (depicted above), the only "valving" that the t/stat performs is to block the flow of coolant/water to or from the radiator. The t/stat being open or shut doesn't affect or alter cooling that can occur in other parts of the coolant circuit, i.e. subtracting heat via the heater core, oil cooler or other means.

Clamping off the smallish hose attached to the t/stat housing does this by eliminating all means of cooling EXCEPT the t/stat &/or radiator. If, therefore, the engine temp warms and fluctuates in a "usual" and predictable manner with the small hose clamped shut.....then any "fault" or defect resides with the "small-hose-circuitry" and NOT with the t/stat or radiator. 

Sooooo.........proceed according to your own desire. However, assuming correct cooling-system plumbing, I suspect that you're gonna "fix" this so-called eng-temp/warmup issue with the proper installation of a quality/working 2.3-specific t/stat. [Image: happy0034.gif]
Placerville, California
(former)  '78 2.3T Courier w/blow-thru carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI

I got the thermostat in (robertshaw) earlier and am in the middle of changing them. One thing I noticed about the robertshaw thermostat is that it has a tab on it that "clocks" the thermostat, the tab fits into the heater outlet. Once pressed into the housing, it will not turn-and it fits TIGHT between the housing and the head. The two "legs" are beefier as well, the motorcraft thermostat's "legs" are kind of thin and bend pretty easily. Time will tell. I have to let this sit a while to let the sealant cure up before I go beat on it. Hope it works.

I chose the robertshaw brand because I have used them in the past and they've always been much better quality than any of the other aftermarket thermostats. Have one in my '92 GT and it's been absolutely perfect. One in the Maverick, also perfect. Just put one in dad's 93 Mustang 5.0 to replace a failed (stuck open) stant super-stat. I don't think robertshaw offers them anymore; so when I saw this one for my application, I jumped on it. At one time, they were selling them under another brand but I do not know now.
'93 Mustang 2.3T swapped. LA3, Stinger FMIC 3" down elbow and 3" exhaust.

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