Follow up to 1956 Caddy Overheating Post

[Ron Draper]

Due to sickness and in turn money problems I was not able to respond to initial posting on this problem.

The engine overheats in less than 10 minutes.  I am guessing it is a crack some place in the heads or block.  No water in the crankcase.  No steam out of the exhaust that I can see.  Seems to run all cylinders but I have yet to run a compression check.

The fellow that I bought the car from replaced a head but I did not ask him which one.  Is there a means of looking for a casting number to determine this?

How do you determine which head (left or right) or if it is the block or if it is a head gasket that is causing the problem?

I think I could remove just the water pump and try to test the heads to see which one is a problem?

Is there a head gasket that will "bolt on" but be wrong for this engine?

Can the head gasket be installed incorrectly?

Thanks for you thoughts.
Ron

[Otto Skorzeny]

Hi Ron,

Let's not get ahead of ourselves. There are a lot of reasons your car could be overheating that don't involve a head or head gasket problem.

You say there's no water in the crankcase and no steam in the exhaust. That's all good. You say it runs well. That's good, too. So far no indication of head or head gasket trouble.

Check for oil in the exhaust pipe. Stick your finger in the pipe and wipe it around. Is it oily or greasy black? If so you've got oil leaking into the cylinder(s). Take out each spark plug one by one and check for oil fouling. Are they oily, black and greasy looking?  If you do, it could mean you have ring or valve seal problems.

Before worrying about what head's what or what kind of gasket was used, you'll need to perform both a compression test with a pressure gauge and a leakdown test.

When doing the dry test, make sure you run the engine until it reaches normal operating temperature. Crank the engine for at least 4 compression strokes. Do this on all cylinders and for the same number of strokes on each cylinder.

What matters most is uniformity of readings across all cylinders with less than a 10lb variation between them. Check the readings against the shop manual. When the compression is low in only one cylinder, suspect valve or ring leakage in that cylinder. If it's low in two adjacent cylinders, the headgasket is likely leaking between the two.

If your tests indicate that there is no head or head gasket problem, then you will have to start looking at the many other causes of overheating.

[Ron Draper]

Hello,

I have not done the compression test yet but I did want to thank you for your response and to post a few "extra" bits of info.

The overheating occurs quickly and I even have the thermostat removed and it quickly boils the water out.

I tried running the engine on 4 cylinders with the spark plugs removed on the driver side and still quickly gets the water boiling over.

I ran out of time and energy before I could do the other side.

So i topped the upper thermostat neck to check for water loss this morning and tonight it was down about 1/2 inch - i have topped again and will check in the morning.

There are still no signs of water in crankcase or other leakage and no oil in the radiator either.

Thanks again
Ron

[buicksplus]

An engine overheating that fast with no thermostat in place is odd. A leaking head gasket or cracked head usually will not overheat unless the engine is under load.

I think you have either a badly plugged radiator, radiator hose,  or a water pump with a rotted impellor.  The most likely is a plugged radiator.  I suggest removing the radiator and having it flow tested by a good radiator shop.  I would do this before removing any of the heads.

[Otto Skorzeny]

I agree with Buickplus. It sounds like something other than a head problem.

I forgot to ask earlier, has the engine been rebuilt? Was the car running and driving normally then suddenly had this problem?

[baxterculver]

Ron,
If you can get or borrow an infra-red temp gun, shoot the radiator, water pump housing and water outlet and both heads while the engine is coming up to temp--from cold.  That should tell you where the problem is.  Also, check the ignition timing and make sure the lower radiator hose isn't collapsing.

[dadscad]

You might have a test performed on the cooling system to see if there are combustion gasses in the cooling system. You can buy a test kit from NAPA and perform it yourself or have your mechanic do it for you. If there are combustion gasses in the cooling system you most likely have a head gasket leak or a crack in the block or head.

One time, I had a car with a leaking head gasket that would spike a 260° reading on the gauge during warm up, just before the thermostat opened, after the thermostat opened, it would not overheat any more. Over many miles it would require some additional coolant to top off the overflow bottle.

Hope this helps, Good luck,
David

[Ron Draper]

I posted the compression pressures in an email but don.t see them here - did they go to some one else?

Ron