I've been chasing an issue with the '59 292 in my model A running hotter than I would like for a little while now.  I swapped in a 180* thermostat and it gets up to about 210 in the thermostat housing and (if I believe the electric Stewart Warner gauge) 230 in the head.  

Is it possible that the water pump impellers are no good anymore and that's the cause of all this?

I'm also not sure if it's real.  People on here say that the Thermostat housing should be hotter than the rear of the driver's side head, but according to my gauges, that isn't the case.  I have a new temp sending unit on the way so I'll be able to verify that, soon.  There's also teflon tape on the threads of the sender- could that keep it from reading correctly?

I'm running just a stock replacement thermostat and I'm shocked at how small the opening is when it opens.  I just ordered that NAPA #6 that Paul has recommended that is supposed to be a larger hole.  I'm tempted to remove the thermostat again, make one of those "water restrictors" by knocking the guts out of one of the ones I have here.  

Today I played around with the timing because they say that if it's too far advanced you could run hot.  I idled the engine and retarded it back until it changed the idle for the worse and ran around town a bit with no effect on the temp gauges, so I'll rule that out.  

Now, when there was no thermostat, it would stick around 165 all day long.  

Any thoughts?  Thanks in advance.  

I don’t know what Paul suggested, but I’ve used the Robert Shaw ones, I think they’re listed for a mopar. Bigger opening. It’s been years, but if they don’t have a small hole for bypass I drill one 3/16” or so. No matter what it is, bring it to a boil suspended in a pan of water. If you’ve got a meat or candy thermometer use that too to check the water temperature. Thermostats vary a bit when they open and when is full open. It’s an easy way to check before installation.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

My Tbird is not a Model A, but I have had my share of over heating problems.  Early Tbirds are notorious for over heating and my 55 was no exception. Summers in Central Florida are hot and traffic is heavy.  The first thing I did was change to an aluminum radiator.  Those old radiators don't cut it today.   I used a $200 Champion radiator electric fan combo and it helped a bunch.  I then changed to a wider thermostat. It helped some, but my engine still heated up in traffic.  Not hot enough to boil over, just hot enough to make me nervous.  The best thing I ever did was change to the deep finned water pump.  Casco sells these and they work.  Tbird engines have a 1" spacer behind the water pump and this newer unit has deeper fins, so it may not work for you.   My 292 is relatively new with 57 "G" heads, distributor and "B" intake.  My timing is set at 35 degrees all in with the vacumn advance disconnected.  Yesterday, I went to a car show with about 20 other early Tbirds.  There was an accident on the way and we sat in traffic for some time.  My SW gauge got up to 210 a few times then went back to 180 as soon as we got rolling. There were about 300 cars at that show.  Six of them left on tow trucks.  Thankfully, mine wasn't one of them.

If not overheating with the thermostat out, then this sounds like a thermostat related problem.  Is the thermostat installed in the correct direction?

Here are some random thoughts that may or may not help.

The reading taken at the front of the engine is typically 10-15°F higher than what you will read if monitoring the temperature at the back of the head.

Is it the same overheating issue when driving at various speeds?  Boiling out water?  In the grand scheme of things, if you are not losing coolant, you are not overheating.

Top of the list is to check the accuracy of the existing temperature sending gauge.  Electric gauges are notorious for their inaccuracy and much of this is related to the voltage input.  As the voltage input varies from what the manufacturer deemed to be a standard input signal, so to does the reading.  An infrared gun measuring the temperature at various points on the radiator and engine may help to determine this.  A temperature probe inserted into the radiator fill opening while bringing the engine temperature up and comparing that to the temperature gauge reading is also another option.

Lorena, Texas (South of Waco)

Thanks to all for your continued attention with this issue.  

Yes, the thermostat is in correctly and the upper hose gets HOT to the touch.  I am really looking at another thermostat that I have and marveling at how restrictive it would be for flow...not a large opening to begin with when it opens and there's a big metal restriction right in the path of the flow.  Maybe it slows the coolant down too much and it can't make its way around fast enough?  I hope it's THAT.  

I agree, Ted, I've never trusted aftermarket electric gauges.  The mechanical gauge that I have that matches the rest of the set that's currently in there doesn't appear to have the correct fitting to screw into the head, and I feel like I checked out the thermostat housing when I had the system drained and it wasn't right, either.  

As for the overheating issue...still not sure I'd even call it "overheating."  It isn't boiling over and, in theory, 50/50 antifreeze and a 16lb cap should get me to a BP of 265*.  I'm about 30 degrees from that...then again, according to Summit, the sending unit range is 100-230* so maybe that's reached its limit.  It's just a little off-putting when the temp goes up so much higher than the thermostat value and never goes down.  

Why is the thermostat housing that's in a raised "air gap" manifold hotter than the water surrounding the explosion and the piston.  Is it just because it's already absorbed the rest of the heat along the path?

Thanks again.  

Have you pressure tested the cooling system?



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Lord,
I am not sure I know what you mean...I have a 16lb cap on it and there were no leaks.  The oil looks like oil and there's no milky oil in the antifreeze.

I drained it again tonight and am trying something else out.  I found Moroso water restrictors online- basically the diameter of the thermostat but with various sized holes in them to sort of slow down the flow but negate the thermostat.  They had good reviews...  No surprise- they're for a SBC.  I'd be surprised if they made them for a Y block so I gutted a thermostat I had here so it's basically a 1" hole in the middle of a flat restriction.  I'll report back.  

Yes.  Once the coolant has made it to the area of the thermostat housing, it has absorbed all if the heat it can and is therefore, hottest.  Even with an "air gap," the surface area and airflow will not be sufficient for measurable temperature reduction.  The "air gap" design is intended to keep the airflow portions of the manifold as cool as possible, not for engine cooling.

The temperature sender is over the combustion chamber of #8 cyl and still has to pass over #s 7, 6 and 5, absorbing more heat which is why the intake / thermostat housing is always hotter than the sender location.



Lawrenceville, GA

We’ve used those restrictors in dirt track cars for years but never on the street. The thermostats with more flow are for MOPAR products and are definitely different in the size of the opening. If your heating up in traffic then not getting it back down by moving to recover I would check for water flow thru the radiator at idle. Install the thermostat, leave the coolant 1” low in the rad tank and start the engine leaving the cap off.  Bring it to operating temp and are sure the thermostat is open . I use a heat gun. Look in the radiator for coolant movement; if you see none raise the idle maybe 100 rpm, if you now see coolant movement you need to speed up the water pump. Let it go back to idle and if an automatic do this in gear.
Many on this site have done this and it’s has helped a lot of them. I bought a 302 Ford Mustang (late 60’s) from Summit and a spacer kit. My original pulley was over 7” and the new one just over 5”;  my problems were solved because the engine no longer heated up at idle then tried to recover while moving in traffic. I have a 3 core copper/brass radiator, AC, fan shroud and a 6 blade fan. Some state the pump will cavitate but my engine runs at 2200 rpm doing 70+ because I’ve added a 2.74 rear gear.
A restrictor washer would definitely have flow at idle just like no thermostat but way longer to reach operating temp for your engine. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Pressurize the cooling system with the device/tool that replaces the radiator cap and is connected to a hand pump with a pressure gauge. Pump up to desired pressure (16 lbs) and wait to see if pressure drops. If it does you have a cracked block/head or a blown head gasket that is introducing combustion gasses into st system causing the engine to overheat...you won't see water in the oil or coolant leaks.

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