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Overheating in Sacramento

RagTop

Old Grumpy
When I lived in the S.F. Bay Area I thought I had managed the overheating problems displayed by my 302. I had replaced the stock 2 core rad. with a 3 core. I installed a shroud. I had replaced the green stuff with distilled water and Water Wetter. I had replaced the 180* stat. with a 160* model. At one point I even had a Flex-A-Fan on it until the machine shop that rebuilt my short block advised me to go back to the stock 4 blade fan because they wouldn't warranty the engine with the Flex-A-Fan on it. The car always ran at about 1/3 of the temp gauge with oil pressure up toward the top of that gauge. The only time I had any problems was when the car was asked to idle for extended periods. Bumper to bumper traffic, parades and fast food drive thrus were always a challenge. Now, in sunny Sacramento, where the car sees ambient temperatures well into the hundreds on a regular basis, the temp gauge is showing half to 3/4 gauge whenever I drive it. I just swapped the 4 blade fan and the little short spacer (1.25") out yesterday for a stock type 5 blade (funny looking thing) and a longer spacer (2.25"). The fan is further into the shroud now (about 2/3 of the blade) and is closer to the core (around 1.5"). No joy. Some slight reduction in how it heats up, but no real relief from that scary approach to the dreaded "H". I'm pretty sure the real cause is the basic inadequacy of the 20" radiator to meet the needs of the engine at idle, but I'm also thinking that it is behaving somewhat like a car without a thermostat. I may swap the thermostat out, just because it's easy to do. BTW, I've returned to about 50/50 green stuff and, when I drained the radiator down last summer, what came out didn't show a bit of scale or rust. Any suggestions as to a next place to look or do I just live with this. An aluminum radiator is out of the question because I like to preserve the stock look. What to do?
 
Ken:

Some thoughts:

Other than the position of the temp needle in the stock gauge, is there any other confirmation that the engine is actually running hot when the needle rises?

Have you ruled out a faulty coolant sender as the culprit for the high gauge reading?

Have you used an infrared thermometer or mechanical temp gauge to confirm actual engine temp? (Generally when up to full operating temp, my engine runs between 200 and 210 degrees and the needle is about 1/3 up from "C")

What sort of ignition advance are you running. At idle and all in? Sometimes ignition timing will lead to a hotter running engine.

What diameter is the current "stock type" fan? (mine is running a stock clutch fan @ 18-1/4" diameter)

Any question that the fan blade is mounted backwards? (does the fan suck air through the radiator or try and push the air back?)

If I am not mistaken, the '69 radiator support easily accommodates a 24" wide radiator if your hunch about the 20" radiator is right.

Maybe the clue rests in the answer to one of the questions above..........

Regards, Jeff
 
Ken:

Some thoughts:

Other than the position of the temp needle in the stock gauge, is there any other confirmation that the engine is actually running hot when the needle rises?
Good point. It hasn't overflowed or left any coolant on the ground after being parked but it does become hard to start when the temp gauge is reading high and I shut it off. Once cooled down it fires without a problem.

Have you ruled out a faulty coolant sender as the culprit for the high gauge reading?
I haven't ruled that out, but I remember how hard it was to find a fairly accurate sender back when I first bought the car. The sender in the car, at the time, would jump around, reporting wild swings in engine temp. while cruising down the highway. I tried several aftermarket units which reported strange results before trying to locate an Autolite unit. I couldn't find one, but I did find and install an AC Delco part that worked beautifully. Perhaps the AC Delco unit has finally died.

Have you used an infrared thermometer or mechanical temp gauge to confirm actual engine temp? (Generally when up to full operating temp, my engine runs between 200 and 210 degrees and the needle is about 1/3 up from "C")
I have an infrared thermometer, but have not used it to verify the car's gauge. Back in the S.F. Bay Area (almost sounds like a Beatle title) it would show about 175* at idle with the gauge sitting at 1/3 or so. It never would rise much above that unless I stopped for traffic or a burger. Since moving up here, I'm not sure I can find it anymore. :)

What sort of ignition advance are you running. At idle and all in? Sometimes ignition timing will lead to a hotter running engine.
I've got a custom curved '68 J-code distributor in the car that I installed some years ago when I rebuilt it. The base advance is 14* and it is all in at 36* around 2500 rpm. IIRC.

What diameter is the current "stock type" fan? (mine is running a stock clutch fan @ 18-1/4" diameter)
The fan is a 17 1/2" which is the largest that will fit in a '69 20" shroud. The fan itself is one of those 5 bladed numbers with the blades not evenly spaced that you will see in the catalogs as a correct fan for a non-A/C '69-'70 Mustang. I've no idea why mine had a 17 1/2" 4 blade unit and a stubby little spacer that left it over 3" from the rad. and only about 1/4 of the blade into the shroud.

Any question that the fan blade is mounted backwards? (does the fan suck air through the radiator or try and push the air back?)
The fan is correctly oriented and most definitely pumps air back over the engine at idle.

If I am not mistaken, the '69 radiator support easily accommodates a 24" wide radiator if your hunch about the 20" radiator is right.
You may be right. The 20" radiator mounts to the radiator support with two removable sheet metal panels that probably allowed Ford to use the same support for both the 20" and 24" units. Again, I would rather not put a 24" rad in a small block, non-A/C car for the sake of authenticity, but if it means saving the engine......

Maybe the clue rests in the answer to one of the questions above..........

Regards, Jeff

Thanks for the inputs Jeff. Hope all is well with you down there in S.J.
 
Get an aluminum rad and paint the top and front black. Keep the old rad for originality sake when you want to sell.
 
Jeff has some good points, swap the temp sending unit and ensure its compatible with the gauge you are using. Some makes need their own temp sending units to read accurately, (AutoMeter).
Timing can make a big difference if too far advanced in temperature...
 
Ken:
Try to find that infrared thermometer. Consider driving your car around a set loop over your regular routes and then take a temp reading at the base of the upper coolant hose. Then retard the ignition timing to 10 degrees initial and repeat the drive and the temp reading to get an idea of how much your ignition advance affects operating temps.

Another couple of thoughts:
Is your carb running lean (which may also contribute to running hotter)?
Though you drained the radiator last year, have you actually flushed it chemically?

My guess is that there may be several factors that in the aggregate add up to a "hot" running temp. Systematic diagnosis that includes measuring the impact of each change is the likely path to your solution.

Regards, Jeff
 
Just replaced the sender. No change. I'll be digging in my garage and in the trunk of the Mustang for that infrared thermometer.
 
Eureka! (or was that Yreka?). Well anyway, I found the infrared thermometer hiding in the drawer of one of my tool chests right where I usually kept it. Who'd a thunk it? And, as an added bonus, the battery was still good. What a great day! So I took off the rad cap and dug up my candy thermometer and fired the Mustang up. I was watching for movement in the top tank to indicate that the thermostat was either working or not. My assumption was that, if the stat were stuck in some position other than smack shut I would see some movement immediately in the top tank. No immediate movement, indicating that the thermostat was closed when the engine is cold. When I began to see movement in the coolant I stuck the candy thermometer into the rad and it registered about 150*. When the movement picked up the candy thermometer said the temp of the coolant was around 160*. I checked the gauge on the dash and it was sitting at about 1/3 as usual. I checked the temp of the top tank with the infrared thermometer and it was reading 159.8* at the base of the filler neck and about the same all the way across the top tank. As I went down the face of the 3 row core I got temps of between 102* to 112* with the lower readings at the base of the core. Now I pulled the candy thermometer and stuck the pressure cap back on the radiator. The temps rose to around 175* at the top tank and about 125* at the base of the core. I am assuming that the reason for the differences in the radiator temps is because the fan is having an impact on the coolant temp by the time the green stuff gets to the bottom of the rad. If the core were plugged, wouldn't the temp at the base of the core be higher than the same as at the top of the radiator? I let the car idle a little longer with system under pressure and took another infrared reading. It was showing about 185* at the top tank and around 130* at the core base and my dash gauge was showing just under half. So I have verified that:
1) I can find my infrared thermometer and my candy thermometer.
2) The thermostat seems to be working correctly and in the right range of temperature.
3) The gauge is consistent with either sender and seems to work correctly.
4) I don't think the radiator core is plugged given the temp readings with the infrared.
5) I still have to take it out on this toasty day here in the Sacratomato area (expecting 102* ambient) and see if the fan is up to the challenge.
6) It may, indeed, be the issue of a wimpy 20" radiator.

I'll report on my experience in the heat of the midday sun.
 
Back from the drive. Everything was going just great until I got on a long, low speed mild upgrade with a couple of stop signs. On the second stop sign the temp gauge went nuts and shot up to the "H" and past it. I pulled into a parking lot and opened the hood with the engine running and threw down on it with the infrared thermo. Across the top tank left to right was from 199* - 208*, the base of the top tank hose was sitting around 164* and the core itself ranged from 178* at the top to 141* at the base. Those all seem to be pretty normal temps. for a really hot day in July. The gauge just jumped up the scale and the oil pressure was way down. I had previously assumed that the low OP reading was due to the engine heat. Now I'm wondering about the voltage regulator on the back of the dash. I had the dash out of the car about six months ago and I tried to replace the existing regulator with a solid state device. It didn't work so I went back to the old, original regulator and everything on the dash came back to life. Maybe it is screwed up though. What to do now?
 
Check your wiring to the water and oil sending units. Engine compartment heat causes wires to increase resistance. If the wires have been spliced or are in poor condition, resistance would increase sending the gauges to the lower levels. However, heat can cause a splice, if not properly insulated, to short out against metal which causes the gauge to peg high. Engine gauge feed harnesses are cheap and it's probably worthwhile replacing yours.
 
Just a few thoughts here. If you were reading 199-208 with the IR thermo on the top tank when the gauge shot up, why would you think the gauge (or electrical items), is faulty? You are getting into overheating range and it sounds like the gauge was indicating correctly. Did I miss something?

It may sound a little silly but have you simply checked your radiator cap to see if it's bad? I didn't see anything in your posts about testing or replacing it.
 
The radiator cap was tested and replaced last summer when I was looking for a cause of this problem. I replaced the gauge wiring harness around a year ago after the original one basically crumbled. When I say that my temp gauge "shot up", I literally mean that it shot up. It simply jumped from about 3/4 gauge (which I'm not comfortable with) to over "H", which sort of feels like an electrical issue rather than the physical temperature of the engine coolant suddenly jumping 1/4 of the scale. BTW, the gauge readings did not materially change after replacing the harness. Of course, the problem could exist between the factory plug for the harness under the hood and the gauge cluster. I also recently had the instrument panel out of the car to replace the dash lighting with LEDs, but this problem existed on either side of that effort. Is 199* - 208* overheating? Jeff says his car, which IIRC is a big block, runs at 200* - 210* at 1/3 gauge. That's why I wasn't real disturbed by the readings off the top of the metal tank. The core itself was showing temperatures in the 178* - 141* range, which is more like a reasonable operating temp. of a SB Ford engine. Still, the gauge is reporting overheating. BTW, the car never pukes out overflow from the radiator when stopped at these temps. I would expect a severely overheated engine to be blowing past the pressure cap when shut down, while the standing temp. builds without the fan, and puking on the ground through the overflow. That's why I'm somewhat suspicious of an electrical problem, but, clearly, I could be wrong.
 
I took it out to a cruise-in last night and, toward the end of the 102* ambient 21 mile drive there, the temp gauge was at about 7/8. As I watched it in town traffic, it pegged on "H" and, while I normally panic at that point, I took a look at my oil pressure and it was pegged on "H" as well. I would expect oil pressure to drop off with increasing temp as the stuff becomes less viscous, and that is the relationship between the temp and oil pressure gauges when the they are not off the scale. Doesn't the fact that they were both pegged to the right throw some suspicion on the voltage regulator behind the dash? I added some Water Wetter to the glycol & water 50/50 mix this morning. Drove it some but it isn't that hot outside yet. Even so, the temp gauge was still sitting in the middle or a little above.[.] I've been carrying my infrared thermometer with me these days. It is an early version of these devices liberated from Caltrans by an old friend and it's all black and angular and looks a lot like a larger taser with a pistol grip handle. Waiting for the cops to put me face down on the ground on the side of the road while I'm checking my under-hood temp. Maybe I should paint it pink.:rolleyes:
 
Many years ago the instrument circuit board on my old BMW started to delaminate where the ground posts for the instruments were connected. The result was instant pegging of the temp and fuel gauge independent of engine temp or actual fuel level in the tank. The fix was to resolder the ground posts with an added ground wire between the posts for redundancy. Problem solved. Since your '69 has a circuit ribbon, perhaps the delamination issue might be playing a role here. Not sure how to fix it if it is but.........................................
 
Many years ago the instrument circuit board on my old BMW started to delaminate where the ground posts for the instruments were connected. The result was instant pegging of the temp and fuel gauge independent of engine temp or actual fuel level in the tank. The fix was to resolder the ground posts with an added ground wire between the posts for redundancy. Problem solved. Since your '69 has a circuit ribbon, perhaps the delamination issue might be playing a role here. Not sure how to fix it if it is but.........................................
I do! I do!
http://www.stangfix.com/threads/doi...dash-cluster-circuit-board.22662/#post-274887
 
I pulled the radiator on Tuesday and took it to a recommended local radiator shop. The guy flow checked the radiator prior to taking it in for a rodding of the core. The flow check, either from the input and out the lower output or from the lower output in reverse, yielded clean, clear water without a trace of rust and flowed so strongly that the guy said "I'd love to take your money, but this radiator is about as clean as it can get." So, I've verified the radiator is clear, I've verified the operation of the thermostat visually and with a candy thermometer, I've replaced the sending unit, I've checked the temperature with an infrared thermometer and I've replaced the fan and spacer to push the new 5 bladed unit further into the shroud. What's left? Is it the gauges or the regulator on the instrument panel? I've been told by the guys at various cruise-ins that I should go to a 180* thermostat instead of the 160* that I have in the car because that would "allow the coolant to stay in the radiator longer". Since a thermostat's job is to open and close to maintain the temperature at its calibrated setting, if the radiator can't keep up with the engine's demands because it's too damn puny, then it doesn't matter if you have a 160* or a 180* thermostat. Once they are wide open it is between the radiator and the engine's ability to overwhelm it. Since my radiator is as clean as a whistle, I've gotta suspect the basic capacity of the Ford 20" radiator as the major culprit. I guess I'm being stubborn here, but I am not going to replace the 20" with an A/C / big block 24" radiator because the car is neither of those and I'm not going to pop for an aluminum box because they are equally wrong in this old stock looking engine compartment. I am also not going to dial back my timing because the car runs strongest at 14* base and it is only at base timing during idle anyway. It's all in at 36* @ 2,500 rpm, which isn't way off of the factory timing, IIRC, and the car was doing the same thing when I still had the stock 6* distributor in it. I'm blaming Henry Ford, Henry Ford II, Lee Iacoca and the entire Ford engineering department. Hey, maybe I could get one of those ambulance chaser attorneys that are constantly advertising on TV to take my case. Believe me, it could involve a ton of pain and suffering.
 
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Ken go for the alum rad and paint it black. A light coating on the front does not hurt its cooling. I left the rear au' natural. Paint the sides and top and its fine.
 
Ken, though this is a long shot, it might be possible that a pinhole (or larger) in one of the head gaskets may be allowing combustion gases into the cooling circuit which will run the coolant temp up quite a bit when the engine is working (like when climbing a grade at 50+ mph). Before giving up and parking the car in one of the local wildfire zones near you (!) , pick up one of those chemical coolant test devices (usually available for rent from O'Reilly's type stores.) You will need to buy a bottle of the testing liquid and follow the instructions. If the blue liquid turns yellow, you have combustion gases in the coolant. If not, at least that is not the problem.

Another long shot comes to mind. Is the lower radiator hose collapsing when the water pump starts to create a healthy vacuum within the cooling system? Some radiator hoses come with a thin coiled wire inside to help the soft hose retain its shape under those circumstances.

To Randy's suggestion, you could move back to the balmy South Bay where the high temp yesterday was only 97 degrees. :rolleyes:
 
Get an aluminum radiator and electric fan. You'll never have to worry about overheating again. I was driving my car on Saturday in 102 degrees in traffic and it never moved from the middle. Best upgrade you can do.
 
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