1938 - Odd coolant behaviour...

[DBT]

Well this one has me stumped.

I topped up the coolant yesterday afternoon before a run as the car had been standing for a while.

All was well during the run and I parked the car back in the garage. The car had ran for about 2 hours, had reached normal running temperature and had not approached overheating levels. Left the car and went out for tea for a few hours.

Came back home some hours later that evening and checked in on the car. Again all was well [no leaks or wierd behaviour].. nice and dry below too.

Went out this morning at 7am and loh and behold a fresh pool of coolant on the floor still dripping from the front [water pump or lower - cant tell easily]. So fresh infact that the cardboard underneath had yet to absorb any of it..

So why did that take a whole night to occur? And why did it occur? It has done this to me once before and again after the same series of events [top up, run, overflow the next morning].

Free tour of Singapore to the person who can solve this one.

[Guest brh]

It can't be a pressure issue as this would overflow after the car is shut off. Not real knowledgeable on 38, does it have a bypass on or around the pump that has sprung a leak? Or is it leaking from around the pump itself (the bearing)? Here is the most important question, on the free tour will this be in the 38?

[Steve_bigD]

Here's one WAG:

If the puddle of coolant was near the front of the engine perhaps the water pump packing seal leaks after it fully contracts. This might take many hours due to residual heat and even then the coolant may take time to find its way past the seal.

Have you pressurized your cooling system? 1938 Buicks did not run any pressure and the old style packings may not stand up to pressure.

Steve D

[Mark Shaw]

I think Steve D is probably right about the leak happening when the cooling system finally gets cool enough to leak.

The engine block will retain heat for long periods when the ambient temperature is relatively high. Since you are in Singapore, I expect it would take overnight to get cool enough to leak.

What was the ambient temperature difference day and night?

[DBT]

Each day [every day!] its 32 deg C [90F] and each evening [every evening!] its 25 deg C [77F] and I dont think the system is pressurised going by the cap which isnt rated - but how do I tell exactly?

The car goes to the mechanics tomorrow so will ask them to look at the leak source.

Now does this mean I have to offer two tours of Singapore?

Regards

David

[DBT]

The mechanic identifed a leaking seal around the waterpump and agreed with the theory suggested.

So will be taking the opportunity to do a water pump overhaul.

Anytime you guys want to collect your prize let me know!