What do you think about these temps and why?

[old31]

I installed a Rex a Co temp gauge and this is what I have.

With 80-90 degree outside temps I can idle all day and stay at 185-190. Drive around town all day and stay at 185-190.

This is what I have noticed twice. On highway trips of maybe 30 miles at 50-55 mph when the outside temp is about 70 the car temp will go to 210.

But on the same trip when the outside temp gets to 80-90 the car temp will rise to 225. It does not boil over. But I can slowly watch it creep up on the highway.

I am not sure of the age of the radiator but am guessing it is 7 years old.

I am running 50/50 mix, 160 thermostat, engine pans, leak less pump, 4 blade fan, Snyder 5.5 head, a newly rebuilt engine with 1,000 miles on it.

So the question. What is making the temp get to high at fast highway speeds when the outside air temp increases.

Is it worth trying some HF floor degreaser or 1 1/2 cups of dish detergent, or Simple Green, just to try an easy something?

[Bob Bidonde]

Your car has 2 factors that cause higher temperatures, higher friction from a recent motor rebuild, and the high compression head.

Flush the radiator with a commercial product to make sure it is clean for optimum heat transfer. Straighten any bent fins.

Use 100% water instead of antifreeze until the temperature becomes normal.

Try optimizing the ignition timing beyond the stock setting to get the most spark advance without knocking. Do this by ear.

Motor oil suffers at high temperatures, so use synthetic oil.

Move your front license plate down to the bumper so it does not block air flow into the radiator. A Model A rear tail-lamp bracket is convenient for this purpose.

When the engine is hot, compare the temperature of the cylinder block at the rear (behind Cyl #4) and the front of the block (in front of Cyl #1). They should be close to the same, but Cyl #4 usually runs a bit hotter. Sometimes there is an accumulation of debris in cooling passages of the block behind Cylinder #4 which causes that cylinder to run a lot hotter.

As running time accumulates on your new engine, the friction will decrease and so should the operating temperature.

[Big hammer]

100% water + water pump lube/ anti rust !
How accurate is the newly installed temperature gauge? <<<<<?
Lose the 4 blade fan and buy the new 2 blade fan !
Use a commercial cooling system cleaner, and BACK flush the radiator!

[Art Newland]

Maybe it's worth the effort to remove the thermostat and try it?

[txkhog]

Also timing under load has an affect on temperature. have you played with the advance lever

[BILL WILLIAMSON]

Sponsored Links (Register now to hide all advertisements)

RUST FLAKES in the top of radiator tubes is the most common cause of running HOT!---Just back flush it once or twice a year.
Bill Gurgle

[Jim Brierley]

185 - 190 is good, more than that needs some attention. It may be worth a try to try a cleaner but usually the problem is the radiator itself. needing a professional cleaning/rodding out. I use a 180* stat and the temp rarely goes above 180.

[TinCup]

I would not rely on that temp gauge. I have seen too many bad ones around here. I went through two of them before ditching them for a mechanical SW gauge. We used candy thermometers to test them and have seen them 10 -15 degrees off. The last one I had stopped reading and when I tapped the glass with my finger the needle fell off. Get you a infrared gun from Harbor Freight or online and then start this process with good numbers.

[Smooth_One]

Originally Posted by BILL WILLIAMSON

RUST FLAKES in the top of radiator tubes is the most common cause of running HOT!---Just back flush it once or twice a year.
Bill Gurgle

Bill I always get a laugh out of your last names at the end of your comments!
Keep em coming.

[MAG]

X2 on Post 8... Agree with Tin Cup for the same reasons.

[hardtimes]

Originally Posted by TinCup

I would not rely on that temp gauge. I have seen too many bad ones around here. I went through two of them before ditching them for a mechanical SW gauge. We used candy thermometers to test them and have seen them 10 -15 degrees off. The last one I had stopped reading and when I tapped the glass with my finger the needle fell off. Get you a infrared gun from Harbor Freight or online and then start this process with good numbers.

X-3 on these statements/findings....except for the S&W gauge. I just changed out my NEW SW gauge that indicated engine heat...for two trips then went south permanently !
So, as said start with simple stuff first and to me that would be check your gauge against other(s)...and against a heat gun, if possible. I just installed another mechanical NEW gauge and will see how that goes.

[Y-Blockhead]

Originally Posted by TinCup

I would not rely on that temp gauge. I have seen too many bad ones around here. I went through two of them before ditching them for a mechanical SW gauge.

I had a SunPro mechanical Temp gauge that read ~15°F Hot. I replaced it with a Stewart Warner mechanical gauge and have had no problems. I like the 270° sweep gauge because it is easier to read (for me) and is accurate.

Originally Posted by Bob Bidonde

Move your front license plate down to the bumper so it does not block air flow into the radiator. A Model A rear tail-lamp bracket is convenient for this purpose.

I was working on my car's radiator just last week (crack in top tank) and took it for a test drive before reinstalling the license plate (one of the BIG CA originals). I was amazed how much cooler it ran without the plate, 10-20°F. Some may have been because I still had the hood off also.

I'm looking into a different mounting position. Right now I'm driving without the plate. Bob, Thanks for the tip on using a rear tail-lamp bracket.

[gilitos]

......and of course we can trust the HF gauges to be accurately calibrated and consistent instruments! Also, the shinyness of the metal has a BIG effect on IR gauges. BEST way to eval a temperature gauge is check two points: boiling water (212 F) and ice water (32F). And if you want to check your HF non contact gauge, heat and cool a piece of dark and a piece of shiny metal in the water and measure them.

[BILL WILLIAMSON]

Originally Posted by Smooth_One

Bill I always get a laugh out of your last names at the end of your comments!
Keep em coming.

Smoothie,
You should see all the HELL I go through, just cashing a check for "MAD" MONEY
Bill Greenback

[Beauford]

I removed Thermo and have no more temp issues.

[BN]

"I removed Thermo and have no more temp issues".

Aahhaaa - thermostat was restricting the flow and you weren't getting enough water velocity through the tubes for good heat transfer.

[Synchro909]

...

[Peyton]

Outside temp increase will increase operating temp. A water circulatory backup system which allows coolant to circulate in the engine when the thermostat is closed has helped me cool things down. Maybe the fan shroud has helped too.

After installing the backup, my temps on a hot day sure have moderated. I use 50 percent coolant, 160 thermostat, a two blade fan, and radiator shroud. So far this summer here in Jax, temp hasn't gone over 190. Good luck and try a backup and maybe a fan shroud.

Peyton

[V4F]

I use a temp gun & check the radiator in different spots to see where it is hot or cool .

[dennis lumbert]

If that radiator was used on another engine prior to the rebuild and not properly cleaned, debri from the radiator could have ended up in the engine water jacket ,most likely around # 3 or 4cylinder That would cause climbing
Temps at extended higher speeds .