1939 Leyland TD5 [1635 DD]

Norman Julian 1st Dec
This is the overflow pipe for the radiator.
You can see where it connects to the underside of the top tank and it has a length of tube that goes up inside to a certain level which means overfilling can't be done.
This got me thinking about old and new technology as far as cooling systems are concerned.
When I work on this stuff and I'm a little bewildered on something that really I want to understand I do research.
Sometimes things are complicated and other times are black and white. What I'm leading to is the cooling system itself.
Way back when just about all engines were not pressurised like these engines, compared to todays engines which are pressurised.
The old stuff relied on a pretty basic cooling system with galleries right through the block just like modern engines but and it is a biggy the water
circulating through was being pushed by a waterpump just like modern engines but not consistently and has
areas of nothing where heat can accumulate and can cause problems.
This in itself isn't a problem because the older engines made adaquate power at low revs.
If though the engine is put under strain it can heat up which means the cooling system can struggle.
The newer engines are built to finer tolerances and have much bigger cooling galleries and having a pressurised system means the water
or coolant can cover every millimetre of the galleries.
This needed to happen because as engines developed more power they developed more heat at greater revs.
Now this is the nuts and bolts of this and is much more involved.
This is a basic understanding of it.

Robert Stevenson
Apparently earlier engines didnt have water pumps.
They relied solely on convection.
The radiators were lots bigger compared to newer engines.
But in theory, convection circulation would reduce any hot areas, as the hotter water would naturally flow to the highest point in the system.
Norman Julian
Robert Stevenson that's probably why I have seen some inline water pumps in the past.
Pablo E. Laredo
Thermosiphon was the term you're looking for. it was almost adequate for the low compression low horsepower engines of that time.
Pablo E. Laredo
Having battled cooling issues in my time, (Ford Cleveland V8's with the wrong type of thermostat)
I've discovered that its all about the balance between overall volume & coolant velocity.
not enough volume, too fast(or too slow) flow and there'll be insufficient heat transfer.
While not applicable to your busses Norman,
Modern Truck/Bus Engines have radiators which have 8+ rows of very small tubes to slow down the velocity to maximise the water/air heat transfer.

Norman Julian 3rd Dec
I have turned the radiator over to my bodies dismay.
I didn't notice that 4 bolts had no thread left or broken down flush so time was spent getting
the old ones out and retapping new ones that hold these freshly painted black components.
I also braced the overflow pipe so no rattling occurs, Also new gaskets were made but I also made some blanks to go over the top of them.
In the summer we get annoying mud wasps that like to fill any little orifices up with yet more young pesky little buggers.
They build a nest made of mud and lay their young in the middle with paralyzed prey alongside so the young have something to eat when their born.
I don't need these guys getting deep inside this radiator after I have finished it off.
They could get into one of the tubes and block it up.
I don't know how long it will sit before going back onto the bus.

Robert StevensonRobert Stevenson
Looks fantastic.
Are you going to coat the cleaned up alloy?
Norman Julian
Robert Stevenson probably not

Norman Julian 8th Dec
This radiator is very similar to the later OPDY series buses in the way they function.
For those that didn't see that go back together you can see it through this.
First the rubber seal which has an outside dia. of 5/8" and a inside dia. of 3/8" and a depth of 1/4" is made of a special compound that is capable of heat up to 90 deg. C.
The old seals being at least 65 years old were too hard to be of any use so I got these ones made, the same with the OPDY one.
Firstly I grab about 6 "O" rings and roll lube on the rubber which wont hurt it.
I push it into the theaded hole and get it all the way down.
Then I put the threaded brass piece over the tube at both ends.
Then the longest end of the tube gets pushed into the hole which has the seal and gets pushed in far enough that you can get the opposite end of the tube into the brass piece at the opposite end and then get the tube equal at both ends.
Then you tighten the nuts up on the threads and that squashes the rubber seal down to form a seal.
There are 56 tubes to do.

Pablo E. Laredo
I've found "Personal Lube" ideal as it's water based..
John Lidstone
You do fine work.
I'm puzzled, forgive my ignorance, but why is a radiator seal capable of temps up to 90c when radiators' top seals would surely have to contend with beyond 100c (not in design, but through life)?
and what of those seals after such heat?
Intrigued.
Norman Julian
Norman Julian
According to the manual the radiator temperatures can get up to 180 degrees fahrenheit.
That converts to around 82 degrees cel.
Rubber when exposed to prolonged heat will go rock hard with heat and age.

Norman Julian 9th Dec,
Apart from the front grill which covers these tubes this job is finally done! The grill is fairly ordinary.
A fair bit of thinking to be done on how to attack that job.
One more radiator to do and I have done the set.
For now though I want to start on the back of the bus which includes reinstalling the route number box mechanism, place new panelling on and making the new staircase.

Stuart Brown
Very nice
Norman Julian
Just to answer the question on the screws in the Leyland badge, they will be painted black so they blend in with the rest.
Fred Holland
You have done a great job on it Norm.

Norman Julian 20 Dec
I have looked at this and I have decided to make a new one.
I could try and straighten the verticle fins but at the end of the day it will still be ordinary to look at.
The thing I can't fix is the position of the ones that sit near the mounting holes.
I will still have to do something with those anyway.
Some sit right over the top of the mounting holes and have been pushed out of the way to put screws in.
I wont bother making the folded over type fins.
I will just use solid steel ones.
I know it will be heavier but the later model radiators do it this way.
Comparing this one which has 52 verticle fins with the TS7 which has 34 the weight will probably balance out anyway.
The TS7 fins being further apart fit much better between the mounting holes.
I will save the round flange which the crank handle goes through to put back on the new one.

Rusty Ian Holton
and Merry Christmas,