2 Identical SHO's and 2 different temps!

[Arc Angel]

Hello again, SHO gurus. Briefly, I have a strange problem. I have two 94 ATX SHO's. Virtually identical. I've gone over both of them and replaced the thermostats, upper and lower hoses, temperature sensors (both of them), flushed each one's coolant system, refilled each with the proper mix of Prestone and even added a bottle of Redlines 20 below to each. The problem?
My car #1 runs at the very top of the "normal" temperature range. I'm worried that if I see ambient daytime temperatures above 90 degrees up here in PA, this thing may just overheat.
My car #2 runs just barely inside the bottom of the "normal"...so I have the one car basically running hot, and the other running quite nicely at the lower temp range.
What's going on?
Car #1 gauge will fluctuate pretty drastically, i.e. when going up steep highway hills, the indicator will rise, and then come back down when coasting down hills (from say the "N" in normal, down to the "M")...car #2 is rock solid at just below the "L" no matter what type of driving I'm doing. Doesn't move.
Car #1 seems to run cool only when it's below 70 degrees outside. The fans on both cars ARE kicking in. Any clues as to what would make #1 run so much hotter than (I would assume) normal? Thanks again to all this forum's help on such a mundane topic. It is appreciated, for sure.

Frank

 

[Racer X]

(1) Radiator. Are they both flowing the same? One older/ more clogged that the other?

(2) Alternator. Are they both putting out the same 13.8v? Low voltages cause the gauge reading to appear higher than normal.

(3) The temp gauge sender. Replace it in both cars. The hope here is that with two new senders, the gauge reading will be a bit more acccurate.

 

[Yamaha V6]

Trans resistance? One generating more heat than the other?

 

[NiNeTy Fo SHO]

Has someone replaced the gauges in 1 before and had to remove the needles? (Hence they placed the needle wrong when putting it back on.)

 

[sho'd]

ford's temp guages arn't that acurate, i don't think you'll find many cars that will be exactly the same. i could be wrong.

 

[SHObill]

Temp gauge sensors,both are new correct? Swap them & see if they exhibit the diff your seeing! Get one of those lasor temp reading devices & bring each car up to temp & check. OR put a REAL temp gauge in & do not worry about the factory idiot gauge!

 

[naval-avi8or]

Hello again, SHO gurus. Briefly, I have a strange problem. I have two 94 ATX SHO's. Virtually identical. I've gone over both of them and replaced the thermostats, upper and lower hoses, temperature sensors (both of them), flushed each one's coolant system, refilled each with the proper mix of Prestone and even added a bottle of Redlines 20 below to each. The problem?
My car #1 runs at the very top of the "normal" temperature range. I'm worried that if I see ambient daytime temperatures above 90 degrees up here in PA, this thing may just overheat.
My car #2 runs just barely inside the bottom of the "normal"...so I have the one car basically running hot, and the other running quite nicely at the lower temp range.
What's going on?
Car #1 gauge will fluctuate pretty drastically, i.e. when going up steep highway hills, the indicator will rise, and then come back down when coasting down hills (from say the "N" in normal, down to the "M")...car #2 is rock solid at just below the "L" no matter what type of driving I'm doing. Doesn't move.
Car #1 seems to run cool only when it's below 70 degrees outside. The fans on both cars ARE kicking in. Any clues as to what would make #1 run so much hotter than (I would assume) normal? Thanks again to all this forum's help on such a mundane topic. It is appreciated, for sure.

Frank

Are you sure you replaced the correct temp sending unit. There are two on the SHO (one for the ECU and one for the Gauge) both of which are located close to each other on the thermostat housing.

 

[dantheman68]

also check with some other sort of temperature tool (like another gauge) to see if the gauge in the dash is off.

 

[clindahl]

Some of the new Ford gagues are very accurate, cold or hot and thats about it, and oil pressure, you have it or you don't.

Yeah I know that doesn't help at all, but I have seen this covered in many Forums that car manufacturers are getting away from real gauges and using switches, or idiot lights, in some cases nothing....

 

[Arc Angel]

Thanks for the input. What gets me on this - the FLUCTUATION on car#1 (the one seemingly running hotter). I'm not kidding...take it out for a long drive on the highway, and start climbing hills, and the guage is nearly always riding on the "N" in normal...then start coasting at 65 mph and/or going down hill, and it will drop down to say the "M"...
On my "other" car #2, that guage doesn't budge. It stays right on "L" no matter what's going on.
Anyway...yes both temp senders have been replaced in both cars, and both radiators are "clean" and flowing good. I am just baffled why car #1 is running so much hotter. I'll hit it with an temp gun and see what the actual engine temp is, later today.
Thanks!
Frank

 

[Storm-Chaser]

Catalytic converters - that's the one thing you haven't checked, changed, or addressed. While your cooling system may be "flowing" well, it is only one-half the equation. It sounds like the catayltic converters are not flowing well, which restricts exhaust flow and in-turn results in higher internal engine temps when under a load. You may also begin to note somewhat higher engine temps even on a level road, when at high-speed (ie. greater than 75 mph, not that I would know anything about that.... <= Johnny Law !).

And yes this is a problem, especially for an ATX. Check the transmission fluid, as the heat build-up will be transferred to the transmission as well.

Are you also noting any difference in fuel economy?

 

[Arc Angel]

WOW! I decided to do the "what the heck" side of the equation and replace the CATs as I was pretty darn sure they were bad...sure enough - they were toast. All the guts were blown back towards the outlet pipe and clogging everything up pretty darn good. Glad you suggested the CAT's because I doubt I would have even checked. THANKS! Let's see if this does anything to the temperature. I'll post after I've taken it out for a cruise.
Frank

 

[doclees]

WOW! I decided to do the "what the heck" side of the equation and replace the CATs as I was pretty darn sure they were bad...sure enough - they were toast. All the guts were blown back towards the outlet pipe and clogging everything up pretty darn good. Glad you suggested the CAT's because I doubt I would have even checked. THANKS! Let's see if this does anything to the temperature. I'll post after I've taken it out for a cruise.
Frank

Does that mean you have a set of near gutted atx cats you want to get rid of?

 

[Storm-Chaser]

I diagnosed it - I get dibbs :laugh_ti:


Arc Angel - you need to inspect the exhaust manifolds to ensure none of the catalytic material was sucked back into the engine - as it can damage or destroy it. Do a search, as several have posted here about this problem.

 

[Arc Angel]

Actually, I'll have two sets of gutted CATs. Out of curiosity, I checked my other SHO...same thing. CATs were wacked, so I'll be replacing both sets of CATs here shortly. For now, there's just two flex pipes in until I can order two sets of Y-pipes from SHOBros...
Frank

 

[AREA 91]

I always found that a new temp sensor will read higher at the guage, than an older one.