Radiator cap

[Phil Waterman]

Hi Gilles

I've got a 180F thermostat in my C60S with the 261 cubic inch engine and it has trouble getting up to operating temp takes a good hour on the road to get the oil up 180F, if anything it is over cooled.

I've run all three engines 216, 235, 261 in the trucks and on the test stand, and if the rest of the cooling system, radiator, fan, and water pump are working correctly and the cooling system is clean, think you may discover that without the thermostat the engine will not get up to temperature long enough to keep the condensation in the crankcase and oil evaporated. Take a look at the photo below which is of the side valve gallery of the 261 with a clear cover, the fog is water vapor which dissipates once the engine is fully warm.

I've done flow and temperature test on all three engines with and without thermostat and all three of my trucks have thermostats.

What is the average outside temperature for most of your planned driving? Which fan and pulley sets are you using?

The only reason I don't run a low pressure radiator cap is to protect the radiator which wasn't designed for it and as look as the engine doesn't boil I don't feel I need the raised boiling protection.

Cheers Phil

[hrpearce]

If you are using the original Blitz radiator with the overflow pipe soldered into the top of the tank the radiator cap has no influence on system pressure.

[Stew Robertson]

Thanks Grant and Phil
It all makes sense
of all the ones I have worked on I never really though about it
just always run no presure cap
See never to old to learn, now all I have to do is remeber it
Stew

[Harry Moon]

Well I've always thought i might have an intermittent water leak into the crankcase as a pasty white film accumulates sometimes on the dipstick and oil filler cap. Nothing showed up this weekend. It was a hot dry day and about 100 minutes running time and no sign of any moisture when I checked it. Shorter rainier trips had been common for the previous couple of trips. Is moisture in the crankcase normal?

[Bob Carriere]

...... and the engine is not running hot enough.

My 261 with a cardboard infront of the rad can hardly get above 162-5 degrees with the 160 thermostats....... I will no doubt replace with a 180 F

If water boils at 210 F .... you need to have the engine hot enough to evaporate the water vapour..... which should be sucked out in the PCV connection on the 261. Now your engine oil will always be about 40 to 50 degrees hotter than the coolant...... Most older engine suffered from sludge deposit which in combination with a high ash content in the older oil and water vapour would actually plug up the oil return openings in the overhead engines.... a 1/4 in. thick deposit was not unheard of.

Harry...... are you running some kind of PCV system on your engine..? and how hot does your engine run up to....? have you used the hand held infrared thermometer from Princess...?

The Dodge flat head six had the same problem...... could hardly get it to heat up....... and never boiled over....

Bob

[Harry Moon]

I wonder if the pasty white only shows up when I take the rad cover off? I usually have it mounted and that covers the lower half and does raise the temp a few degrees. What I do think now is that I don't have a leak!