Plug/Fitting In Block near Oil Pan

[hawkfan]

I came across this brass fitting/plug in the block close to oil pan on the drivers side of engine.  Does anyone what its purpose is?

Thanks
Brian

[The Tassie Devil(le)]

Looks like it is a fitting placed there in order to easily drain the coolant from the block when storing for winter.

A Brass Plug will be easier to remove than the factory steel plug.

Bruce.

[Lexi]

I believe Bruce is correct. There is also another one on the other side. There is also a drain cock on the radiator, lower RH side for 1956. Clay/Lexi

[Roger Zimmermann]

Looks like it is a fitting placed there in order to easily drain the coolant from the block when storing for winter.

A Brass Plug will be easier to remove than the factory steel plug.

Not only used to drain the coolant during winter time, but also for repairs like cylinder head gasket. By draining the coolant at the radiator, all coolant in the "V" is still there, creating a mess when a head is removed.
During the fifties, those plugs were brass from the factory.

[The Tassie Devil(le)]

With the shape of that fitting, it wouldn't surprise me if on the side that is hidden from view there could be access for the installation of a fitting to put a hose on to direct the coolant into a container, when the "Tap" is opened.   Thus, saving the coolant and not making a mess.

I know that when I release the taps in my boat, the coolant just flows into the bilge.

Bruce.

[Lexi]

Not only used to drain the coolant during winter time, but also for repairs like cylinder head gasket. By draining the coolant at the radiator, all coolant in the "V" is still there, creating a mess when a head is removed.
During the fifties, those plugs were brass from the factory.

Yes, both are brass fittings. Clay/Lexi

[hawkfan]

Thanks to all for the responses!  I thought it may have been that elusive temperature port for the temp gauge that was never machined into my engine block.  My car has a built in temp gauge in the dash but no port in the block.  I had my radiator re-core'd and the re-builder installed a threaded port on the coolant return neck so I can at least get a real close engine temp reading.
I climbed back under there today and yes, there is a similar brass plug in the block on the passenger side.

Thanks again,
Brian

[Lexi]

Hawkfan! I have been thinking about your missing temperature port and I think I have the answer based on the presumption that the head in question on your car is indeed for a '56 Cadillac. Here is my explanation:

I believe both heads were cast the same but were drilled out to go on either the left or right hand side of the engine block. 1956 Cadillac heads were notorious for cracking, and it seems that your driver side head failed at some point. Looks like only a passenger side head was located, which when flipped would work but it would LACK the port for the temperature sensor as it never had one to begin with. One port if I recall correctly would also have to be cut in the replacement head to accept the water pump, with the now rear facing port needing to be covered (now facing firewall).

I know for a fact that they did this sort of thing when the correct spare head was unobtainable as I have had one engine like that in the past, i.e. 2 RH heads used. In my case with my spare engine, someone went to the trouble to make a port for the temperature sender while at the same time having to block a now dysfunctional water port facing the rear of the engine.

At this time this is the only explanation that seems likely if yours is a '56 Cadillac head, unless of course the factory omitted to drill and tap a temperature sending port. Clay/Lexi

[Poncholover]

BTW, that "freeze" plug will lead to some excitement on the road in the near future!

[hawkfan]

Lexi,

Your assessment is well thought out and probably correct!  Makes the most likely scenario!

Thanks
Brian

[hawkfan]

Poncholover,

I thought the same thing regarding the freeze plug.  That is one thing I never had to mess with in all my years.  I guess now I'll have to educate myself on how to tackle replacing it.

Thanks
Brian

[Lexi]

Lexi,

Your assessment is well thought out and probably correct!  Makes the most likely scenario!

Thanks
Brian

Brian you should check the rear of your driver side head at the firewall and see if a plate has been fabricated to cover the now dysfunctional water pump port. That should confirm my above explanation on why you are missing the temperature sending port on your cylinder head. If a passenger side head was used and flipped, the water pump port would have to be blocked off and a new one drilled. Also, that rear cylinder head area is where one of 2 short engine grounding straps are normally located on your engine. There is probably not one there (unless fastened to hardware from a "cover" plate?). Tough area to work in as virtually no room. If there is a plate there it would be a good idea to ensure that it is not leaking. Clay/Lexi

[hawkfan]

Clay
There is a plate as stated but it is so close the the fire wall one might get a wrench on on the bolts but theres not enough room to back them out.

Thanks
Brian

[Lexi]

Brain that is great news as that mystery is now solved. As I said in my last post just pray you don't develop a coolant leak at that improvised plate. If you have access to a borescope have a look to make sure all is fine. I  know what you mean by no room as just working on a ground strap there is tough, let alone your situation. Attached is a shot of my old spare 1956 365 engine with such a plate as it also had a "flipped" cylinder head. Plate was very well made and quite thick. Clay/Lexi