59BlueSilver

Hopefully I'm at the end of resolving this problem. Had trouble last summer idling in the Texas heat, 95+. PO bought & installed a Dewitt radiator which helped enormously but still overheats in slow traffic & at long stop lights.
Contacted Dewitt's & bought an electric fan. Last month I converted to an alternator in support of the fan and now just finished installing the fan. Driving temps are about 195-200 at 40-50mph, ambient temp. Is 72 deg. The fan comes on at 185. Strange thing is, after the trip, when I'm idling in the garage, the temp drops to 180. Can someone explain this? I'm used to this being the other way around!

Geralds57

Sounds like you're still running too much temp. Was anything done to the engine recently to cause it to overheat? If not, I would check the hoses with an IR gun to see if it's reading like the gauge. Check timing and the carb. Running lean can cause overheating too.

59BlueSilver

It's been doing that for several summers. The IR gun on the gauge sensor in the head matches the gauge temp pretty close. However, when the gauge is reading 185, the thermostat housing reads 156.6 deg.

Wade Mahaffey

If it runs hotter going down the road, I would check to see that the fan is turning in the right direction. The easy way to tell is by holding a piece of paper in front of the radiator. It should suck it against the radiator if the fan is drawing correctly. To maximize your cooling you should have a shroud, something like this. My 383 stroker runs below 170 degrees with a 17 X 17 radiator core.



Wade Mahaffey

tach drive 61

How's the dwell holding on distributor.my car was giving me cooling troubles.turned out bushings were gone causing turning
to change/and overheating.

BobT59

I've had my '59 over a half century.... over the years it developed a serious overheating problem to the point it was undriveable. Tried everything possible including a many flushings and a recore..to no avail.

Finally broke down and bought a Dewitts radiator a few years ago...talk about an instant cure...she now runs about 170 without a thermostat on a typical 75-80 degree day. I do have an electric fan (not Dewitts) hooked up which I manually turn on/off in heavy traffic/ hot summer days. Even then, it will keep it in the 170-180 range.

Love my Dewitts...

59BlueSilver

You must be running a regular fan also, with shroud?

59BlueSilver

Changed over to Pertronic III last year.

BobT59

yes..original fan...original shroud...

rich5962

It sure seems like the fan direction like Wade mentioned. With stock fan and electric fan they could be fighting each other.

Engine off, I'd turn on the electric fan and make sure the airflow is front to rear.

I'd make sure the rad is sealed around the support mounts as well. You are running the stock fan shroud? Not sure if you said that or just asking BobT about his setup.

59BlueSilver

The puller fan is turning in the correct direction. I removed the existing fan and stock shroud and used the SPAL fan with a shroud developed by DeWitts for my car.

rich5962

Okay, got it. This is certainly a strange occurrence then.

....That 30* difference at the therm housing and dash gauge is suspect after reading your 2nd post again. I'm wondering now if you have some intermittent instrument function going on. Your sender is in the head, or the manifold near the housing?

What's the IR gun reading at the sensor base vs the gauge?

Rich

59BlueSilver

Pretty close. The sender is in the head, 185 gauge, 177 sender. The 185 fan sensor is in the other head and fan comes on pretty close to 185 gauge reading.
I've read several posts about overheating and wonder why everyone takes the IR reading off the thermostat housing. That's not where the gauge sensor is? And, in every case, my housing temp is way lower than my gauge.

rich5962

And when doing a comparison, it's best to point the IR gun at the sensor base, then compare to the gauge. You're somewhat close(8* cooler at the head sender), but when the gauge reads 200+ it'd be interesting what the IR gun would read there.

THe gauge/sender reading isn't linear over the whole range. It may be reading very high at higher actual temps, and you may be chasing a ghost.....just thinkin' a possibility. I've been there before and had false gauge readings.

When it gets to 200, can you pull over real quick and shoot the IR at the sender, then upper rad hose(black is best for IR guns), etc and see what you get? That 156* reading at the therm is actually too cool IMO. Ideal to me is 180* coming out of the block.

Rich

59BlueSilver

Yea, maybe I can do that today. I think you're right, need to chart it & do a correlation. What my main concern is, if the gauge is reading 200 at ambient 72, what is it going to read at 100 ambient?

59BlueSilver

Just got back, outside temp 75. Gauge does weird things, on warm-upit gradually goes clear to 220, stays there just long enough to panic, then drops to 180, goes up to 210, drops back to 180. Finally stabilizes at approx. 190-195. Fan comes on as it should at 185, never shut off.

Cruising at 40-50mph, gauge reads 190. Sending unit reads 182.3, housing 155.7, hose 151. What would you say that mark just before 220 represents? It stays just to the left of it, except when stopped, then drops to 180-185. I stopped to get gas and it puked, expected that.

Gotta tell ya, it is such a relief to go driving & not overheat. If it will stay that way at 95+ deg., I'll be a very happy camper!

Frankie the Fink

I haven't kept up with this thread but the warm up should be when the thermostat opens and if you are watching closely you'll catch the swings of the gauge....both my cars will ramp up to about 190 or so as the thermostat open and then settle down to 165-175 (I run 160* thermostats). The only time I've seen the gauges swing into the 210*+ area is when I was refilling the entire coolant system after flushing the radiator, heater core and block. This happened as the added fluid 'chased' the air out of the system until full.

I'm wondering if you have an air bubble lurking around in the system somewhere.

59BlueSilver

That makes sense about the gauge swings. There is such a disparity b/t the head temp & housing (30+deg) that it's going to read 210-220 before the stat gets hot enough to open. Wonder if I need to go back to a 160?
Thought about the bubble, but it took almost the exact amount of antifreeze specified, and I thought it would disperse the first time it warmed up, especially if it puked. If I have a bubble, how do I purge it?

JohnZ

Remove the radiator cap, start the engine, let it warm up until the thermostat opens (upper hose gets HOT), and let it run for about two minutes after the hose gets hot.

Using a lower-rated thermostat (160 vs. 180) will have zero effect on operating temperature - the thermostat only controls the minimum temperature.

http://www.lbfun.com/warehouse/tech_...em/cooling.pdf

59BlueSilver

Okay, just did that. Turned the heater on also. There was a lot of gurgling & bubbling going on after I shut off the engine. After it settled down, I put the cap back on. Hopefully that took care of that!
Will take it out again in a little while.