Normal engine operating temperature

DanG · Sep 10, 2011

Hi all,

I feel like an amateur asking this question, however it's been years since I've been in the car realm, and am trying to get back up to speed.

Anyways, I wanted to verify what a normal motor operating temperature would be for in-town/stop-and-go traffic?

Currently, I've noticed my engine temp goes to 195-200 degrees while driving through town, or during stop-and-go traffic. Otherwise, while driving at highway speeds, I'm steadily at 185 max. I'm not certain what the hottest temperature would be that I should be concerned about; ie: 230 degrees.

My cooling modifications are:
180 degree thermostat
Mishimoto 3 core radiator ( yeah, I decided to try one even though they are rumored to leak )
high volume water pump

revhead347 · Sep 10, 2011

Your doing great. The stock engine is actually designed to be at max efficiency at something like 214 degrees. It's totally normal for it to hit 200 degrees while sitting in traffic. If you have stock iron heads I wouldn't be worried about something failing until about 240 degrees. Aluminum heads is another story.

Kurt

DanG · Sep 10, 2011

revhead347 said:
Your doing great. The stock engine is actually designed to be at max efficiency at something like 214 degrees. It's totally normal for it to hit 200 degrees while sitting in traffic. If you have stock iron heads I wouldn't be worried about something failing until about 240 degrees. Aluminum heads is another story.

Kurt

Yeah that's what I am concerned about, is knowing about the threshold for an aluminum head, vs the engine temperature. I haven't really gotten into heavy boost yet, and am wondering how warm this car will get once I start hitting 10, 11psi or so.

Thanks for the reply.

revhead347 · Sep 10, 2011

For an engine like that, I wouldn't worry about it till about 210 degrees.

Kurt

Dino Dino Bambino · Sep 11, 2011

The stock t'stat opening temp. is 192*F and the low speed fan on temp. is 208*F, so the engine should run in the 192-208*F range. Sustained coolant temps. of over 220*F should be a concern and sustained temps. of over 240*F are likely to cause engine damage. That damage may be limited to a blown head gasket in an iron-headed engine but the heads may warp if they're aliminum.

DanG · Sep 12, 2011

Ironic that I posted a thread about engine temps and over heating. Saturday when I posted this thread, was the first day that I picked up the car after being worked on and tuned by a local shop.
Long story short; I drove the car home about 30 miles after test driving it with the mechanic who worked on the car and assisted on the dyno. Car ran really smooth, and I didn't have any complaints, but questioned why I could smell a coolant scent when sitting at a stop light, and when you turn the car off and approach the front. The mechanic at the shop told me to "keep an eye" on things to see if I can see any external leaking. I told him that the coolant system is obviously a closed system, so I must have a leak somewhere. Regardless, I took the car home and washed it up and waxed it, first time in nearly 8 years.

Saturday evening, my wife and I took the car out to dinner, as I wanted to put some miles on the new motor to break it in before I returned to the dyno sometime this fall or possibly next spring. On the way home from dinner, she and I were driving along when we heard a loud pop come from the front of the car. I immediately noticed the steering was tight and my battery light came on. Unfortunately, I was stuck in traffic, so I had to wait a minute before I could pull over on the shoulder of the road to shut the car down. When I pulled out of traffic and onto the shoulder, I noticed my temp gauge was spiked to 250 degrees, which seemed to happen extremely quick. I popped the hood and sure enough, the belt must have slipped off one of the pulleys, and got shredded and snapped, which explained why the power steering went out and the car got hot.
Shortly after, I walked around the car and noticed a little white steam coming from the tailpipes, which to me is an indication of coolant in the combustion chambers. Time for the tow truck.
So, this is my luck, posting a question about normal engine temps, and something like this happens. I checked the coolant and oil yesterday to see if there were any signs of contamination, but everything appeared to be normal by the visible eye.
Unfortunately, the belt on the car must have been too loose, and wasn't found by the tuner and shop. I'm a bit surprised they didn't find this, as the car was on the dyno for an entire business day being tuned, and quite honestly, when driving it for the 1 day I had it in my possession, I didn't even hit boost as I am trying to break in the new motor gently.
Hopefully the worst that happened was a popped head gasket, and the shop is willing to work with me to stand behind their work...

VibrantRedGT · Sep 12, 2011

You're having some bad luck with this shop, sucks you had someone else do the work. At this point you're at their mercy. Sounds like just a shredded belt but you never know, 250 quickly is bad for aluminum heads (warping). Not sure how long you had the car at this temp. Before all that your temps were just fine. My car would run about 175-195, mostly around 185 no matter how hot it was outside. I had a Steeda / C&R 3 Core Aluminum Radiator, 180 Stat, Fan on "High" all the time and 60/40 Water / Coolant mix. Keep us posted.

DanG · Sep 12, 2011

VibrantRedGT said:
You're having some bad luck with this shop, sucks you had someone else do the work. At this point you're at their mercy. Sounds like just a shredded belt but you never know, 250 quickly is bad for aluminum heads (warping). Not sure how long you had the car at this temp. Before all that your temps were just fine. My car would run about 175-195, mostly around 185 no matter how hot it was outside. I had a Steeda / C&R 3 Core Aluminum Radiator, 180 Stat, Fan on "High" all the time and 60/40 Water / Coolant mix. Keep us posted.

It really does suck that I had a shop do some of the work, that I could have done myself. The whole issue was, that the car sat for 8 years in a garage, which wasn't at my home. I just didn't have enough time to dedicate doing some of the small things, and I wanted the shop who built the shortblock to do the intial fire-up, and dyno tune.
So, had the car towed to the shop today, and it appears that nothing was
harmed in the motor, albeit the car being at 250 degrees+ for potentially a minute or two. When we fired up the car, the coolant level didn't budge, no bubbles in coolant when the car was idling, and the temperatures again, remained at 195 degrees steady even when climbing hills on the way home. I think I dodged a bullet with this one, and am thankful things turned out the way they did. I have a few clean up "items" and a few minor leaks that I need to clean up in the engine bay.
Thanks for the replies.

Chythar · Sep 12, 2011

Could have been an air pocket in the coolant system. The V6's have a different coolant layout, and have a bleed bolt at the top of the coolant system. Made it nice and easy to bleed the air out of the coolant system anytime. Since out 5.0's don't have anything similar, most recommend parking the car on a hill and let the car idle for a while. This should move any air pockets into the radiator.

Last5.0 · Sep 12, 2011

Using a thermostat that has a bleeder check valve (like the stock one does) also helps with air pockets. If your tstat doesn't have one, you can drill a 1/8" hole near the edge of the disc and install with hole at 12 o'clock.

Also, concerning the fans...Like someone stated above, the stock cooling fans don't kick on until over 200*. That is why your temps stay low while going down highway but come up around town in stop and go. Either switch back to a stock temp tstat (192*) so the temp stays more constant or you can have the fans set to turn on at lower temps in the EEC with a chip or tuning device.

DanG · Sep 13, 2011

Chythar said:
Could have been an air pocket in the coolant system. The V6's have a different coolant layout, and have a bleed bolt at the top of the coolant system. Made it nice and easy to bleed the air out of the coolant system anytime. Since out 5.0's don't have anything similar, most recommend parking the car on a hill and let the car idle for a while. This should move any air pockets into the radiator.

That's a good idea actually. Just to make sure all the air pockets are out, I may park the car in my driveway for a bit to let it idle, since I'm on a fairly steep incline.

Thanks!

DanG · Sep 13, 2011

Last5.0 said:
Using a thermostat that has a bleeder check valve (like the stock one does) also helps with air pockets. If your tstat doesn't have one, you can drill a 1/8" hole near the edge of the disc and install with hole at 12 o'clock.

Also, concerning the fans...Like someone stated above, the stock cooling fans don't kick on until over 200*. That is why your temps stay low while going down highway but come up around town in stop and go. Either switch back to a stock temp tstat (192*) so the temp stays more constant or you can have the fans set to turn on at lower temps in the EEC with a chip or tuning device.

Hmm, I honestly don't recall if the thermostat has a bleeder check valve on it. It's a 180 degree Mr. Gasket unit; good or bad I don't know
I currently have a manual fan switch. I keep the high speed fan running most of the time, and always turn it on when the car reached 180 degrees, which happens as you know, fairly quick. I've actually been looking into some aftermarket fan solutions to help keep the car a bit cooler, especially when under boost.

Thanks!

CoolHand244 · Nov 16, 2017

Hi everybody;
I'm New here and just purchased a 65 Mustang that has a "92" 5.0 302 in it. My question is pretty much the same, the engine ran at about 205-210 which sounds a little warm if anyone here is from the old 180 days. But if 210 is normal for this engine, I'll try not to be too concerned with it. LoL

Bill

revhead347 · Nov 19, 2017

CoolHand244 said:
Hi everybody;
I'm New here and just purchased a 65 Mustang that has a "92" 5.0 302 in it. My question is pretty much the same, the engine ran at about 205-210 which sounds a little warm if anyone here is from the old 180 days. But if 210 is normal for this engine, I'll try not to be too concerned with it. LoL

Bill

You're fine.

Kurt

Normal engine operating temperature

DanG

revhead347

Apparently my ex-husband made that mistake.

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