Overheating and stumped?!!

[69.5Mav]

Before replacing your radiator check the temperature of the top and bottom tank with an IR temp meter and stick a cheap dial thermometer in the radiator cap opening that can be bought at any grocery store.

You seem to have covered all the bases. It sounds like you rebuilt the engine. If so did you bore it out and how much?

Any new radiator will out perform any old radiator of the same capacity, but you might cover up some other problems that could came back to haunt you in a few months as the new radiator ages and loses some performance.

The cooling system must dissipate the heat the engine is making to produce the horsepower to meet demand; if not the temperature of the working fluid (coolant) will rise until the dissipation rate matches the production rate of heat, within practical limits. Simple thermodynamics. You can increase the dissipation rate by increasing the surface area of the heat exchanger (radiator) the coolant flow through the exchanger, the air flow through the exchanger, decreasing the temperature of the air through the exchanger, increasing the temperature of the coolant flowing through the exchanger and or increasing the coupling coefficient of the exchanger from coolant to air.

 

[mustangsilly]

The engine was bored .020. That was the minimum I could get away with.

The delta between top and bottom tanks when the gauge pegs on "H" is 35 deg (top tank is 216, bottom tank is 181.)

 

[69.5Mav]

Mustangsilly

Well It seems you still have some meat on the cylinders.

The temp drop between the upper and lower tanks seems to small.

I have a 69.5 Maverick with an 170 never broken apart with 170K on the clock. It has a weber 5200, roller rockers and a 10" electric fan (no mechanical fan) with a sentra thermo switch in the bottom radiator hose that turns on the fan at around 180, a 195 thermostat with 50/50 Preston and one bottle of water wetter.

Today I let it idle till everything came into thermal equilibrium. It settle out at 191 degrees at the radiator cap and 148 at the bottom tank with the fan on continuously. The outside temp was 75. When I drove the car the engine temp dropped back to 195. I have driven this car up and down California and even three year daily driver in Sierra Vista AZ. This car is notorious for running cold. The only time it over heated was when the thermostat stuck closed.

I believe you need a new radiator at this time however if you have not already you might try water wetter as a short term solution.

Good Luck

 

[mustangsilly]

Thanks 69.5 Mav. Just a quick question. What is "water wetter' and where do I find some?

I ordered a new stock radiator from NAPA and will let you know if that cools things down. Keeping my fingers crossed 'cause that's the only part of the cooling system I HAVEN'T replaced!! :|

 

[JackFish]

Does that include the heater core?

 

[MPGmustang]

Does that include the heater core?

this is important, when i replaced mine i flushed the old one by running the garden hose backwards to what the engine was doing, and ALOT of gunk came running out. if this was connected as is, i wonder how much of that gunk got into the engine.

Have you tried a hose flush? what i did was disconnect the top radiator hose so it spilt everywhere, pluged a garden hose to the top of the radiator and ran it until all collant was gone, then drained the engine and radiator to do it again. i did take off my fan because i was running cold water into the radiator...

just my $0.02

Richard

 

[mustangsilly]

Hey - It's worth a try.

I did back-flush the radiator after the engine rebuild. I also put a solution of muriatic acid in it and left it for a few days. Can't remember where I heard this, but it's supposed to be an effective flush.

I'll try the reverse block flush, but the block was boiled when the shop bored and decked it, so I would hope the crud around the cylinders and water jackets would have been cleaned out. Thanks for the advice.

 

[69.5Mav]

Mustangsilly

Remove the thermostat. Disconnect the upper and lower radiator hoses from the radiator. Run a garden hose in to the upper radiator hose and flush till it runs clean. Next try it at the lower hose then go back to the upper hose and keep switching till they both run clean finishing with the upper.

Do the same thing with the heater core.

Reassemble using new hoses and thermostat and test with 50/50 mix antifreeze and Water Wetter from Kagens or Auto Zone. You might also try some water pump lube and anti corrosion treatment from Preston at the same store (Kagens).

Good luck and let us know how it turns out.

 

[66 Fastback]

What was the guage reading when you read the top tank at 216 deg and 185 deg on the bottom tank?
That does not necessarily sound like over heating to me. What is the thermostat rating?

Have you verified that the balancer has not slipped? Retarded timing will overheat the engine.
Doug

 

[FALCONAROUND]

I've said this before somewhere and I'll say it again. (gosh I love that phrase)

The Myth about thermostats is not a myth! The engine will only run cooler until you shut it off, at which point the heat soak will raise the temperature of the coolant drastically.

I see it all the time. It don't really do any harm to the engine, I ran my old Maverick stat-less for a while, but it's not correct.

The thermostat regulates the flow and the temperature. Not having a thermostat means there is no temperature or flow regulation. Furthermore, once you begin to overheat without a t-stat, you are helpless.

 

[mustangsilly]

I put the 180 thermostat back in. I just took it out to verify it was NOT the thermostat causing the problem.

As for the balancer, I had not though of that as a reason for overheating, but it makes sense. I did not change the balancer when I did the engine build. I guess there is really no way to check for a slipped pulley is there? I did check the timing with the light and set it to everywhere from 0 deg to 12 deg BTDC and the OH problem never went away or improved.

 

[69.5Mav]

Any Progress.

You check the balencer by putting a Top Dead Center (TDC) checker in the number one cylinder and following its dirrections to get number 1 to TDC then checking the balencer timing marks to see if they line up. If not then it has slipped. J C Whitney sells a TDC ckecker so does Eastwood.

 

[MPGmustang]

my over heating problem was due to not enough gas... i richened the idle screw on my 1v and it really cooled the car down. another thing that helped me was the vacuum advance diaphram being replaced...

i felt like i was beating a wall but it was just the wall beating me...

 

[mustangsilly]

I've thought about jetting the carb a little richer. The plugs are a good color, though, so I don't want to go to larger jets unless it's a last resort.

I replaced the distributor when I put on the 2bbl (went with a rebuilt from a 1968) non-Load-o-Matic version. I think the vac advance would be replaced when they do a rebuild. Is there an easy way to check to see if advance is coming in at the right time? Should idle change when the vac hose is removed or plugged?

 

[mugsy]

To check the vac advance there are two things you need to do. First is to disconnect the tube between the carb and dizzy, plug the port on the carb and then apply vacuum (I use a Mity-Vac) to the dizzy. The engine should be running when you apply the vacuum. You can either use a timing light to see if the timing has changed when the vac was appied OR you should notice the idle speed increase. Also you should also apply a few inches of vaccum to the diaphram and see if it holds vacuum. It might leak and any advance be lost (goes back to static timing)

The second thing to test is to put a vacuum gauge on the port connected to the carb. Then move the throttle and see if the vacuum gauge needle moves. This test is more for a ported source than one connected to the intake manifold. It's still usefully information if conencted to the intake mani; at least you'll know what the vac level is at idle. This is a good indication of the health of the motor and intake timing event.

If the is vacuum to the dizzy AND the dizzy advances when vacuum is aplied you can then assume that this system is good.

 

[69.5Mav]

Congats.

Turn the engine off.
Remove the vacuum line to the distributer from the carb.
Remove the distributer cap.
Apply vacuum from a vacuum pump to the distributer vacuum line.
Watch the breaker plate to see if it moves.
If your distributer has two vacuum lines then one is for advance and one for retard.
The retard line will move the breaker plate in the opposite direction then the advance line.
The advance line will make the points open earlier in the piston stroke.
Leave the vacuum attached two the vacuum port (both) for a while to see if the vacuum drops indicating a leaky diaphragm.

 

[MPGmustang]

well to see if my vacum advance is leaking i just blow (very gently) from the line at the carb keeping it connected... no vacuum for me because i'm afraid that vacuum could be too strong... and if it slowly leaks then you have a leak, if it can't hold air then it can't vacuum properly is what i think.

Richard

 

[FALCONAROUND]

that's correct for the most part.

 

[LaGrasta]

Any updates?

I've been dealing with this same situation for the last two years and have replaced just about everything Mustangsilly has. My symptoms are identical! Read my sig for my set-up.

Also, how can I tell if my hoses are collapsing? My car only overheats at speed such as being on the freeway for 15 minutes straight at high speed. If I pull off an exit, it begins to cool. And yes my pump is new, brand new, not even a rebuild.

 

[64falconsix]

the things that come to mind are a lean condition, ignition timing , or even cam timing can have an effect on operating temps. in your post you say it overheats at idle also and you said you checked the bottom radiator hose, even hoses with missing or rusted (springs) usally only collapse while the rpms are up and not at idle. just more food for thought.

charlie