I hear these 5.0s run hot...

SableSal · Sep 27, 2009

Well, I have heard and experienced these mustangs running high temperatures. I personally don't really like how warm the engine gets when at a stand still, or even while driving in stop and go traffic.

My goal is to keep the temp gauge at half or just below. I installed a 160 degree tstat, and flushed the coolant.

The fans kick on, and all. But it still reads at times (on the NORMAL scale) M and almost to A.

Is there something that I can do to try to keep it at O-R?

Thanks guys!

Sal

sgarrelts01 · Sep 27, 2009

Something imo is wrong because when mine was stock it never ran past the R, most of the time it was on the 0, and now with the stroker it still doesn't run that hot.

yukisho · Sep 27, 2009

I had the same issue. I changed my tstat to a 180, new hoses, new radiator and a full flush. now it never goes past the start of the O.

Chythar · Sep 27, 2009

The stock gauge is not very accurate, you really can't base your opinions on whether the engine is "hot" on the stock gauge. For example, my GT goes all the way to the "A" before the fan kicks on. I hooked up a code reader to check and see what the actual temperature was, and it was 208*. This temp is usually around the "R" on a properly working gauge. Either my gauge is off or the sensor is bad (more likely), so I just ignore it.

The only way to keep the temp gauge lower is to get a chip that changes when the fan turns on and off. Stock settings are:

Low Speed on: 208*
Low speed off: 204*
High Speed on: 224* or 228* (two settings in the PCM)
High speed off: 220

HISSIN50 · Sep 27, 2009

I'm with Matt. Gotta get a real gauge, lower the fan-on threshold, and possibly upgrade some parts.

To add to Matt's thoughts, you can install manual fan switches, use an aftermarket temp controller or thermoswitch, or use a Delta controller interface that lowers the fan on/off temps to accomodate a 180*F t-stat.

Here's some general cooling system info and stuff to consider

Good luck.

SableSal · Sep 27, 2009

Chythar said:
The stock gauge is not very accurate, you really can't base your opinions on whether the engine is "hot" on the stock gauge. For example, my GT goes all the way to the "A" before the fan kicks on. I hooked up a code reader to check and see what the actual temperature was, and it was 208*. This temp is usually around the "R" on a properly working gauge. Either my gauge is off or the sensor is bad (more likely), so I just ignore it.

The only way to keep the temp gauge lower is to get a chip that changes when the fan turns on and off. Stock settings are:

Low Speed on: 208*
Low speed off: 204*
High Speed on: 224* or 228* (two settings in the PCM)
High speed off: 220

I was thinking the gauge or coolant temp switch is bad. It never went that far before, and all the cooling system seems to be working pretty well.

Anyhow, I'll try that next weekend. I'll let you guys know what I found.

Thanks!

revhead347 · Sep 27, 2009

The design temperature is between 212 deg and 222 deg to keep the efficiency up. Changing the thermostat to a lower temperature won't make the car run any cooler.

Kurt

HISSIN50 · Sep 27, 2009

I'll respectfully disagree with the above statement.

toyman · Sep 27, 2009

revhead347 said:
The design temperature is between 212 deg and 222 deg to keep the efficiency up. Changing the thermostat to a lower temperature won't make the car run any cooler.

Kurt

It may or may not. If opening the flow to the rad at a lower temp along with the rad's ability to keep the coolant at that temperature then the answer is yes a lower rated T-stat will help. However, if the engine is generating sufficient heat and the rad can only maintain cooling to a higher temperature than the answer is no it won't help. Since the stock T-stat is, I believe, rated at 195* and isn't fully open until 205* than a lower rated T-stat may be helpful in keeping the temps a little lower under normal driving conditions.

SableSal · Sep 27, 2009

You know, one thing popped into my head just now. I remember a good smell of radiator fluid coming from the radiator cap. I'm thinking it should be best to replace it. If it's losing any sorts of pressure, I'm sure it could give me the results I am getting at this time. Maybe I'll send the wife to pick one up on the way home.

Thanks for the input guys, I'll let you know what I find.

Maybe a Griffin Radiator is in my near future!

89 ST4NG · Sep 27, 2009

Mine runs between R and M stays on R mostly. Which isn't accurate anyway but just to let you know.

SableSal · Sep 28, 2009

I'm going to replace the radiator cap and then go from there. I'm replacing it with a factory ford cap. I'll report my findings there after.

Thanks for all the great input!

Zero Signal · Sep 28, 2009

If the top hose is pretty tight one the motor is hot, the radiator cap is probably fine. If it's still squishy, then a new cap would be in order, but not necessarily the problem. Definitely get a flush. Who knows what kind of crap is built up in the radiator. If one side of the radiator is really hot and the other side is cool, it may be clogged up. Happened to my Bronco. The clogged radiator caused my timing cover gasket to blow twice. Never had a problem once I replaced it.

SableSal · Sep 29, 2009

Anyhow, I think I've figured out my dilemma. I think what was wrong the whole time was the cap. I think the 160 tstat is now causing my new/old dilemma.

This is what I've observed. I replaced the radiator cap. I did catch it leaking on me. There on after the car did run pretty cool until I pushed higher RPMs. It then started to heat up. I think this is caused by two things:

1: The 160 tstat is not working with the stock 195 temp set for the fans to come on. So what's happening is the coolant is flowing through, but not cooling off as it should through the radiator. So in reality the 160 tstat is heating up more the car than cooling it down.

2: Ever since I required a jump start for being a dumbass and leaving lights on... I've noticed the volt meter is reading low near the "O" in NORMAL. Where before it would be at "R" or very close to "M". I think the Volt regulator or Alternator may be taking a dumb. I have noticed when the fans kick on, there's a lag in voltage and the temp will then shoot up torwards the "M" in NORMAL. I think the extra load plus my stereo isn't helping the situation. I even verified this with the stereo off. BTW the battery is reading 12.3 volts which is a bit on the low side. The alternator output is 13.75 volts while the battery reads 13.65 volts. Not bad at all, but still a bit on the low side. I'm too used to seeing 14+ volts on a charging system. Is this not the case on the SN95s?

Anyhow, I'm starting off with a new tstat this weekend. I was curious if anyone has tried the Mr. Gasket tstat which is supposidly more flow?

Here's a link:
Mr. Gasket 4365 - Mr. Gasket High Performance Thermostats - Overview - SummitRacing.com

Anyhow, any input would be much appreciated.

Thanks!

HISSIN50 · Sep 29, 2009

How and when were those readings taken?
You should stay above 13.6V in near all situations (idle output depends upon idle RPM, alt pulley size, E-load, etc). But at 1500 RPM, even with a full load, it should be over 13.0 V.

I run older Mr G t-stats. Some folks have reported supposed issues with newer ones but I cannot comment on that.

SableSal · Sep 29, 2009

HISSIN50 said:
How and when were those readings taken?
You should stay above 13.6V in near all situations (idle output depends upon idle RPM, alt pulley size, E-load, etc). But at 1500 RPM, even with a full load, it should be over 13.0 V.

I run older Mr G t-stats. Some folks have reported supposed issues with newer ones but I cannot comment on that.

I took the readings with a DMM last night. I'm thinking something weird is going on here. I may have a couple of issues on my hands.

I honestly think 13.0V is a tad too low. What do you guys think?

revhead347 · Sep 29, 2009

I have an older Mr. Gasket Thermostat, and it works great. Just understand that if you run the oversize thermostat, you are basically not going to have heat anymore. The thermostat allows all the water to go to the radiator, and nothing gets up into the heater hose.

Charge voltage should be around 14.8 volts. Basically all the gauges in your car are volt gauges, so you might be onto something with your theory there.

Kurt

HISSIN50 · Sep 29, 2009

13.0 V may or may not be low, depending upon what RPM and load the alt was under.

How and when meant what accessories were running and what was your RPM. We don't know if you're seeing this with no load at 2K RPM, which is cause for concern, or at idle with every accessory going.

This is why it's helpful to give numbers with an articulated list of accessories, taken at 1500+ RPM.

SableSal · Sep 29, 2009

OK, I think I'm getting somewhere here. I checked voltage again at the alternator and it's pushing 13.9 volts. At the battery was 13.85 volts. I'm forgetting the alternator. I'm going to call it good.

I did find today that the temp hit "M" on the NORMAL. Found that the fan wasn't turning on. Shortly after discovering that, the fan did turn on. I turned off the car and checked the plug at the fan. I found that the plug clips were broken at one time or another and the plug is zip tied to the fan motor. I attempted to push the plug further in to the fan. Didn't feel like there was any play. I turned on the car and started driving home (I was at my parents house). They car was cool, and didn't go past "R". I think cause I was driving freeway.

This is my NEW theory, I don't think this fan is coming on when it should. I wonder if this is a two speed fan? I think the fan is not coming on at the low speed setting. I think the fan is only coming on at the high speed setting, which by then is too late to try to cool down to "R" on the NORMAL scale. I think one of two things is going on here. I think the CCRM is needing replacing or the motor. Also there might be an issue with the connection at the motor.

I needs some help pretty badly! Can someone show me what I should test on the CCRM to make sure that is my issue? I'll try and test voltage at the fan motor this weekend and go from there.

I once again appreciate everyone's help! Thanks a million for all the information shared so far!

SableSal · Sep 29, 2009

UPDATE! Also reading a little more into the CCRM conditions. Once which I have... I have no power to the A/C clutch! Which is part of the CCRM functions! Also the car JUST started taking a tad bit longer to start. I think I'm replacing the CCRM tomorrow!

I hear these 5.0s run hot...

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