56 TBird 312 Overheat at speed.

[pismo10]

Lots of threads about overheating at idle but my problem is after about 15-20mins it drifts up and up to 205-210F at the thermostat housing with an IR gun. Not bad but still too hot. Have flushed coolant thoroughly, 9 flushes until it ran completely clear and all new Prestone 50/50 coolant. Replaced thermostat hoping it was old and clogged but it was fine. Old was a 180, new is a 160 but made absolutely no difference, just a bit longer to overheat. Setup is totally original 312, stock radiator front not covered in leaves etc, and 3 blade fan, no AC, hoses are fine and not collapsing, started about 2-3 years ago with no major work/changes done except for a TPot carb rebuild and tune ups, points, plugs etc.


Thinking check timing and advance next.


Any suggestions appreciated.....
Thanks,
Steve

 

[RKS.PA]

Steve, that's not good. Not sure what was original, but my '56 T Bird 312 had a 4 blade fan when I got it 2 years ago and because I live here in southern Arizona, I changed to a 6 blade. I've done all the things you have in terms of flushing, and mine runs about 180* on a 100* day, according to my IR gun. After checking to see where your timing is, maybe think about a different fan?? Also, is your fan shroud in place?

 

[miker98038]

If it’s tied to the carb rebuild it tune up, I’d start like you said with the timing. But you also might want to run the infrared over the radiator, to to bottom. Should be pretty even across and cooler at the bottom. Usually heating at speed is airflow or timing advance,
but I suppose a couple blocked tubes might just reduce the total enough to overheat at the heavier load at speed.

 

[Fairlane56]

If you’re still running the Loadmatic it sounds like its running without enough advance at speed. Also I believe, since our cars did not over heat early in their lives, that today’s formulation of the gasoline has a lot to do with it. The bumper thru exhaust on mine never gets black.

 

[Charlie Stephens]

I had the same problem on my '57 TB. Turned out to be a leak in the diaphragm that is mounted to the distributer. Chased it forever until one day I was driving down the street and noticed a pulsing in the power which lead me to investigate and find the problem.

Charlie Stephens

 

[KULTULZ]

A car that overheats at speed usually indicates poor airflow through the radiator or a partially plugged radiator.

If a LOAD-O-MATIC SYSTEM is on it, incorrect/no timing advance is also a possible cause.

The radiator fan is only suspect at street speed/idling (well that and the design of the water pump). BIRDS are bad for air-flow.

If after warming and the thermostat is open, when you look down the cap opening (be careful here), do you see coolant flow? Also, if no spring in the lower hose, it may collapse at high-RPM speed.

Blocked coolant passages in the block and heads is another factor.

 

[pismo10]

The shroud is in place. The lower water hose is about 160 and the thermostat housing is 200-210. Will measure temps across radiator. Seems like it is making less power as well so will check advance.


Thanks for the tips!

 

[miker98038]

It’ll vary with ambient temperatures, but a 40-50 degree drop is pretty good. If memory serves me correctly, the 56’s had the dual diaphragms for advance. I’ve never used one, but was told the larger did the Venturi (mimicking mechanical) and the smaller was a manifold vacumn (or load related). If so, the manual hopefully gives a procedure to check both. Probably worth doing.

 

[40cpe]

The shroud is in place. The lower water hose is about 160 and the thermostat housing is 200-210. Will measure temps across radiator. Seems like it is making less power as well so will check advance.


Thanks for the tips!

You stated that the lower hose reads 160. Infrared temp guns measure the temp of different materials differently. If you are reading the rubber hose temp, try reading the radiator close to the outlet and inlet so you will be reading a similar material on both locations. I know from experience that a rubber hose doesn't read like metal.

 

[KULTULZ]

And another little diddy, the OEM COOLANT TEMP GAUGE has it's sender in the left cylinder head and measures coolant temp as it comes out of the block at that point. It may be hotter there than at the thermostat. It also doesn't actually read the coolant temp on the right bank and only after having the two sides meet at the cooling crossover point (thermostat housing).

Another thing that can happen is corrosion buildup in the cylinder heads coolant passages between cyls 2&3 and 5&6 as the FYB runs the exhaust valves next to one another at those points and causes extra heat.

EDIT -

If the cyl head(s) was ever off, check to make sure the head gasket was installed correctly.

 

[Gene F]

I have 2 things I would do; 1) change that fan to a 6 blade (concourse parts). I have never seen a T-bird without a lot more blades than what you have., 2) the vac advance is hanging up. Change it, and make sure it rotates free including where it joins the breaker plate. This includes even if your dist has been updated to electronic. (concourse parts). And change that vacuum hose while you are at it with the right size.
Sometimes as a step of diagnosis you can play around with smashing the throttle all the way down when getting on the expressway at the next ramp, and see if the temp moderates. I have seen this happen. Especially when you car has been fine, and now it is not.

 

[dmsfrr]

The original Loadomatic distributor in a '56 T-Bird has timing advance that is only operated by a vacuum signal from the carburetor. They have no mechanical / centrifugal advance.

If the vacuum canisters have failed or the points mounting plate is stuck you're get no timing advance.

"Probably the most over looked item on 1955 & 1956 Thunderbirds is the vacuum advance mechanism. It is the only control that advances the timing. When it fails, the engine runs at the setting of the distributor, which is 3 to 6 degrees B.T.D.C"
Quote from this link...
https://www.ctci.org/gilsgarage/cracked-exhaust-manifold/

Edited to add the second image. To explain why timing advance is needed in the distributor. And it also notes that later carburetors ('57+) aren't compatible with the '56 and earlier distributors.

.

 

[KULTULZ]

I have 2 things I would do; 1) change that fan to a 6 blade (concourse parts). I have never seen a T-bird without a lot more blades than what you have.,

The 1955 and early production 1956 BIRD came through with a 3-blade fan. The WP PULLEY DIA also factors into all of this. But the fan should not be a factor at highway speed(s).

The 55/57 BIRD had cooling problems straight from the factory.

The biggest problem(s) being the engine front cover design (volute) and use of a PASS CAR WP on the front cover. That and the LOAD-O-MATIC not being serviced correctly (retarded ignition advance).

 

[Gene F]

Can anyone help me? The Mallory distributor 3838701; is that a drop in electronic replacement for my 1957 292 Fairlane? Where can I get one? I'd like to get out of vacuum controlled advance without the box.

 

[miker98038]

Since the OP is looking at timing, I guess this isn’t too far off the topic.

If you want a start on Yblock replacement distributors, this link is a good start.

Half way down is a series of links by Ted Eaton

http://forums.y-blocksforever.com/Topic166810.aspx

 

[KULTULZ]

Can anyone help me?

The Mallory distributor 3838701; is that a drop in electronic replacement for my 1957 292 Fairlane? Where can I get one? I'd like to get out of vacuum controlled advance without the box.

Why would you want to defeat the DUAL ADVANCE DIST on a 57 FYB? If you go entirely mechanical advance it is going to eat into your mileage.

It would be easier (IMO) to ensure your present DIST is in good shape and install a PERTRONIX II (w/ matching coil) for the street.

MECHANICAL ADVANCE only is for race or hot street.

 

[dmsfrr]

Can anyone help me? The Mallory distributor 3838701; is that a drop in electronic replacement for my 1957 292 Fairlane? Where can I get one? I'd like to get out of vacuum controlled advance without the box.

Gene F,
An oem '57 distributor has built-in mechanical timing advance, with flyweights under the points.

What "box" are you wanting to get rid of? Would posting a photo of it help us out?
.

 

[dmsfrr]

. . . The 55/57 BIRD had cooling problems straight from the factory.
The biggest problem(s) being the engine front cover design (volute) and use of a PASS CAR WP on the front cover. ....

There is an upgraded water pump spacer available for the '55/'57 T-Birds that much improves low speed cooling. Photo 1, oem part on the left, upgraded part on the right.
At this link...
https://thunderbird.us/

There are also water pumps available with oversize vanes, specifically for '55/'57 Birds.
Some older oem water pumps may have their vanes corroded / worn off.

A car that overheats at speed usually indicates poor airflow through the radiator or a partially plugged radiator.
. . .
Blocked coolant passages in the block and heads is another factor.

Running hot is a Very common problem with '55/'57 Birds. The timing problems aren't as well known. In town I drive my '55 with the hood unlatched for more air flow.

pismo10 has the radiator been removed and taken to a radiator shop for an inspection and cleaning? Blocked tubes won't show up with a casual flush.

With poor coolant flow over the years debris can build up around the cylinder walls in the block and have to be dug out manually; coat hanger wire, scraper, screwdriver, etc. It's not always possible to remove it with a chemical flush.
Photo 2, looking in thru a freeze plug opening, before & after a manual cleaning.

There are also instances of excess casting flash on the timing cover obstructing the opening to the block. Photo 3

I thought the 3 blade fan was only original to '55 but could easily be mistaken.
After too many previous owners the '55 I have has a 4 blade fan.
.

 

[TedEaton]

Lots of threads about overheating at idle but my problem is after about 15-20mins it drifts up and up to 205-210F at the thermostat housing with an IR gun. Not bad but still too hot. Have flushed coolant thoroughly, 9 flushes until it ran completely clear and all new Prestone 50/50 coolant. Replaced thermostat hoping it was old and clogged but it was fine. Old was a 180, new is a 160 but made absolutely no difference, just a bit longer to overheat. Setup is totally original 312, stock radiator front not covered in leaves etc, and 3 blade fan, no AC, hoses are fine and not collapsing, started about 2-3 years ago with no major work/changes done except for a TPot carb rebuild and tune ups, points, plugs etc.


Thinking check timing and advance next.


Any suggestions appreciated.....
Thanks,
Steve

Steel shim head gaskets? If so, then it's possible that the front sections of the head gaskets have rusted through thus preventing adequate coolant flow to the back of the engine.

 

[KULTULZ]

Steel shim head gaskets? If so, then it's possible that the front sections of the head gaskets have rusted through thus preventing adequate coolant flow to the back of the engine.

... hmmpf ...

Never thought of that.

Every time TED EATON posts I learn something new.