Keeping 95 5.0 Cobra cool in 100+ weather?

mike8066 · Jul 26, 2011

Guys,

I'd like some input, advice, ideas, etc. on keeping a 95 Cobra 5.0 cool in 100+deg heat.

Year round the normal operating temp is between 210-212. I am in Oklahoma and we are into week 8 of 100+ deg weather. Average daily temps are around 105 with 60-70% humidity...IT'S INSANELY HOT! The engine temp has been more around 212 on hiway, and 215 in town, but when I kick on the AC, it levels out at 225-230!! Maybe it's my own paranoia, but that's way too hot for my taste.

I'm running a Mishimoto (yes, I know...but no probs yet. LOL!) dual core 3" aluminum radiator, a Mark VIII electric fan, and a Mr. Gasket 180 thermostat. I have no major mods to the engine, pretty much stock. I've replaced the stock dash temp gauge with an Equus mechanical temp gauge. The oil is changed on a regular basis and there are only about 2000 miles on this motor. With gas prices the way they are, the timing is set to the stock 10* to allow for use of regular grade gas.

I've heard people on this site rave and swear by Water Wetter, saying that they saw major reductions in heat using two bottles with a higher water-to-coolant ratio mixture. So, I flushed my system, put in a 25/75 coolant/water mix and 2 bottles of Water Wetter. It gave me about a 2 degree drop, not much.

I do have a dual scoop hood (Stormin Normin style), and have had a couple of people tell me to block off my scoops because it is throwing off the air flow under the hood. Any truth to this?

Any ideas, or am I just stuck with driving my POS truck during the summer and the Cobra the rest of the year??

Thanks!

Mike

4rdnut · Jul 26, 2011

How are you controlling the fan, with the computer or separate control module and relays? If you have a mark VIII fan with a stock engine and those temps then something is wrong. It sounds to me the fan isn't spinning at 100 per cent speed and are you sure the fan is blowing toward the engine. Also did you check the upper radiator hose to see if it gets hot when your temp gauge reads 188 degrees, thats when the t-stat fully opens.

mike8066 · Jul 26, 2011

Right now, I'm not running a controller. It's wired straight to battery through an 80A relay, triggered by key-on ignition 12V source. I have an on/off bypass switch in the console.

If it's not running 100%, then I'd hate to hear 100%! LOL! That thing is so loud that my buddies always laugh saying that they can tell when I'm coming because they hear the fan before they ever hear the car.

BlownFiveLiter · Jul 26, 2011

What was wrong with the stock fan that you replaced it with the Mark VIII fan? Why not hook it to the stock wiring, so the CCRM turns it on at the preset temperatures? The Mark VIII fan should have a similar setup that has a high/low speed like the Mustang's stock fan would. You shouldn't have any trouble keeping it cool in 100 degree temperatures, even with the stock radiator.

mike8066 · Jul 26, 2011

The motor bearings on the stock fan went out back in March. At the time, I couldn't find a replacement motor and people on eBay were actually asking more for that fan than the Mark VIII, so I went with the Mark VIII based on it's past reputation. I've since learned that NAPA sells the stock fan motor for about $65, so if needed, I can go back to the orginal fan configuration. Truthfully, I never noticed a difference in the fans (with the exception of the VIII being louder). They both kept the engine at about 210-212*.

HISSIN50 · Jul 26, 2011

In case I missed it, what are the cut-in and off temps for the fan controller?

Are you sure the fan is pulling air?

You don't use slow speed on the fan, do you? As I recall, the Mark VIII fan's low speed was PWM via the EEC.

Zero Signal · Jul 27, 2011

Run higher octane gas AND pull timing. It will kill your power but should keep it cooler.

mike8066 · Jul 27, 2011

Hissin,

There are no cut-in/cut-off points. I have it set for ignition on (all or nothing). I was going to get it put on a controller before fall/winter, but with as hot as it's been, I just have it wired to run all the time. I'm on the high setting. When I got the fan, I hooked each wire to the battery to determine low and high settings. I wired it to the high. It's definitely pulling air. Damn thing is like a Cesna taking off!! LOL! But, someone on another site made a good suggestion. I've never messed with the condensor sitting in front of the radiator. With this car being 16 years old, there's always a chance that there is a lot of crap in the condensor coils. So, I'm going to spray that out and see if it helps. It won't matter what kind of fan I have if the flow is obstructed.

mike8066 · Jul 27, 2011

Pull timing to what degree? It's at 10* now.

BlownFiveLiter · Jul 27, 2011

You still didn't say why you're not letting the CCRM control the fan?

mike8066 · Jul 27, 2011

To be honest, I have no real reason for it. Just wired the Mark VIII directly to a relay. Is there an advantage of having the fan come on at certain times vs. running all the time? (not trying to sound dumb, just curious.)

chaos254 · Jul 27, 2011

have you had the system pressure tested? The only time I had an issue with running hot is when there was a small leak in my radiator. I replaced it with an aftermarket radiator from summit and I have had no issues living in Arizona and Northern CA. Both areas see temps of 100+.

I've heard good things about water wetter but I would only use it as a temporary fix. good luck

mike8066 · Jul 27, 2011

Gonna have it pressure tested today.

five0xpres · Jul 27, 2011

I've always heard that the front lower lip spoiler was important in making sure that our 'Stangs run cool in hot weather. But after living with my '94 in North Carolina the past 2 years and not having one on mine, I can't say that my water temp has ever been past the middle of the stock temp gauge during the heat of the summer.

I did have an issue though in the spring of last year with some of my gauges going through some fluctuations at weird times....like the temp gauge reaching the upper 3/4 of the range on my way to work at 2AM along with some "surging" of the dash lights under differing engine loads. I took a guess and ran another ground wire from the top of the intake assembly to good ground spot on the firewall and that solved my gremlin. Probably not the same as your issue, since you're using an aftermarket gauge but I thought I'd share my experience in case it might be helpful.

Good luck on tracking the cause down.

HISSIN50 · Jul 27, 2011

Your plan sounds good. It sounds like you have an issue with absolute heat rejection.

Just to be explicit, are you sure the fan is pulling air through the radiator (not pushing it forward)? If the wires are backwards, this can happen.

mike8066 · Jul 28, 2011

Hissin, just to be absolutely sure, I checked the fan again. Yes, the airflow is blowing toward the engine (pulling through the radiator).

five0expres, my gauge is a mechanical, not electric, but I did check it against another gauge and it does seem to be accurate.

Here's what's been done since the last post:
I cleaned out the AC condensor in front of the radiator and had the system pressure tested. The pressure test revealed a pin hole in the upper rad hose. After changing the hose, pressure held good. I decided to swap the 180* stat with a 195*. My luck couldn't be worse! I went through TWO of them that wouldn't open!! Since the stat wouldn't open, it wouldn't allow me to burp the system! The first one was a Murray brand from O'Reilly's and the second was a Stant from Advance Auto. I thought it was strange that 2 stats of 2 brands from 2 places would be bad, so I broke out the pan of water on the stove. The Murray never opened, even after the water was boiling. The Stant did open about 1/16", but not until the water was over 220*! Out of curiosity, I repeated the pan test with my original 180* Mr. Gasket HiPo, and it promptly opened fully at about 190* or so (pan water temp). So, rather than continue buying more 195's, I just put the 180 back in and it allowed me to burp the system. Still haven't fully tested yet. Will let you know after a test drive. I do still plan to go to a 195, but I'm going to order a Ford Motorcraft stock replacement and will try again next week after it arrives.

VibrantRedGT · Jul 28, 2011

Are you saying the fan is spinning and the heat is going towards the front of the motor? If so, its going the wrong way. It should push the air forward through the radiator. Maybe that's why it's so loud and can be heard for blocks. Your best bet is to put the stock fan back in it, 50/50 mix, Water Wetter and 180 Stat. I live in S. Florida and my car never went over 185 degrees ever. Although I also had a 3 Core Steeda Aluminum Radiator.

HISSIN50 · Jul 28, 2011

Joe, I know you know what you're saying and meant (and maybe it's just me) but your last reply reads weird to me. We all know that the fan pulls air - the air is pulled towards the rear of the car.

Mike, a balanced stat should be fully open by the rated temp. Generally, the balanced 180's should start to open just over 170* and be fully open by 180* +/- 2*F or so.

mike8066 · Jul 29, 2011

Thanks, Hissin, for the info. I've always had much better luck with actual Ford Motorcraft or Ford Racing parts, but unfortunately, no one around here carrys them, so I'm going to order the Ford Motorcraft OEM 195 replacement stat and go back to my stock fan (after replacing the fan motor) wired into the CCRM.

VibrantRedGT · Jul 29, 2011

Ok, my reply didn't make sense. Which way is the fan turning? My fan was never so loud it could be heard over the engine. Plus I had it set to come on high at 140 degrees which means it was on high just about all the time. The Steeda radiator was really the game changer in my temps, dropped 40 degrees.

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