Over heating in 4ADT

[Paul Wilson]

I was wondering if anyone had some suggestions on overheating in my 4ADT.

I have tried all methods known to me ....radiator flush and block (three or four times)
Water is now clear and stays that way. My last resort was Water Wettner, but to
no avail.

The strange thing is that it only overheats on hot days - above 20 degrees.
Engine is fine and purrs along, which would not indicate timing.
The radiator remains cool - with no hot spots - and I only want to remove it as
a last resort - all other methods failing.

The radiator capped fitted to it is AC W7 which could be the cause as the book recommends
a 4. Could this be the cause.

The engine was re built before I bought it and I would hope that the brass tube fitted inside
the water jacket was replaced....if not I am in for some major work. If it wasn't wouldn't the car
overheat all of the time ? As it is I can safely drive it all day, once I know the temperature
will be below 20 degress.
While you boys are settling in for winter I want to feel the wind in my hair on 30 degree days.

[indian301]

Paul,

Running only water is not a good idea. A 50/50 mixture of water and antifreeze actually raises the boiling point. Also a 10-12 pound radiator cap should also help because the extra pressure also raises the boiling point. I have used the water wetter in my motorcycles and it seemed to help. Maybe the above suggestions and the water wetter might do the trick.

Dave

[Mark Thompson]

Since your car is a 4ADT, I am assuming it is a later model. In mid 1952 (starting with model no. 4AD900V) the cooling system pressure recomendation was raised from 4 psi to 7 psi. Also, the twin carburetor models should have a properly working thermostat.

A non-contact infrared thermometer is very useful in diagnosing overheating problems and they are rather inexpensive at discount stores (Harbor Freight). I have rebuilt three SM 1500 engines and they all had heavy sediment buildups in the lower regions of the block around the cylinders. A clear flush does not necessarily mean that there is not a sediment buildup because it can be very solid and not easily flushed out, especially if the car has set for extended periods without being used. The cooling space around the cylinders should extend approximately 5 inches below the head gasket. A thermal scan should be able to detect if this is a problem. With proper circulation, the temperature should be fairly consistent in this region.

If you start the car up with the radiator cap removed you should be able to determine if you are getting circulation. You shouldn't have circulation until the temperature in the block gets warm enough to open the thermostat. Normally, thermostats fail in the open position and typically open around 160-180 degrees F when working properly.

Best Regards,
Mark Thompson
1952 4AD & 1953 4ADT

[mikeyr]

check the thermostat and also make sure its facing the correct way. I ran my twin carb without a thermostat for many years including 90+ degree days and it never overheated. I always felt the real reason for a thermostat on the twin carb was to get it hot faster since the car runs so much better when fully warmed up.

Also I am not sure what you are thinking when you say "brass tube inside the water jacket", can you identify it on this drawing ? http://www.singercars.com/4ax/pone.html or this one http://www.singercars.com/4ax/ptwo.html.

It would not hurt to have the radiator cleaned also.

[Phillip]

Hey Paul,

Mark makes a very good point about hard sediment in the water jacket. This problem affects the 972cc and 1074cc engines also. I boiled out my spare '35 972 engine and discovered there was still a lot of solid matter in between the cylinders and at the bottom of the water jacket that was only removed by 'rodding' the block manually with a hard welding rod and various homemade picks. The amount of crud left after boiling was very surprising.

I'd agree with Dave's comments also re 50/50 mix. Up here we go 70% antifreeze, given our horrendous winters. I've used Water Wetter also and found it to work quite well.

[Mark Thompson]

Where are you located? Are you talking 20 degrees Farenheit or Centigrade? If you are talking Fahrenheit, you might also want to test your radiator cap. It might be possible that at temperatures 20 degrees Fahrenheit and below your thermostat never opens. When the temperature is 30 degrees and above your thermostat is opening and the resulting pressure in the radiator is relieving at a lower pressure than the rating on the cap.

Mark Again!

[Paul Wilson]

Thanks boys....looks like the radiator may be the starting point.
I imported the car from NZ and he assures me he had no heating problems. Probably wouldn't given the
climate and over here it ran perfectly durng winter . Now with tmperatures in the 80's and 90"s it takes
half an hour or so of driving to make it boil.
On a cool day I have driven it all day without boiling with the critical point being about 70 - under that it is fine.
I have ordered a new radiator cap ( Fergy tractor ) but went for a 4 lb rather than the 7 lb which was on it. May be worth a test run just to see what happens. I know that the 7lb is the correct one for a 1955 model ...thanks again.

According to the Service Manual " ...a brass tube fitted inside the water jacket, extending along the entire lenght of the distributer side of the head. Holes in the tube direct the water onto the combustion chamber's walls . around the exhaust valve guides and sparking plug bosses. The tube is inserted from the rear of the head...."
Accessing this would mean a motor transplant - and as I said the motor was supposedly done up ( which I have no reason to disbelieve because of its performance) and any self respecting mechanic would have attended to this when doing the motor up.
With the radiator out, I will be in a better position to flush the block out and look for sediment that may be there.
Christmas will hold this up as my soldering skills are not what they used to be and I will give the radiator to professional.
I would have expected to feel hot spots in it if it was unduely clogged...water circulation seems fine...but the once clear water now has a murky colour to it ..despite four or five flushes.

Is it worth removing the welsh plugs to secure a good block clean out? They are bright and clean, indicating a re build
1,000 miles ago.
Will keep you informed...thanks again and a Happy Christmas to all.