Mysterious Oil fitting on Cadillac '59-'62 390 block?

On the passenger side rear of the engine block about half way between the pan and the head is an oil fitting. My engine and another similar engine (not in a car) have a tube leaving this fitting and going up to around the rear of the valve cover where it stops with the end being open.

Not having seen either engine in a car in their stock configuration, I don't have any idea what this is for. What is it and what do it do??? Do I cap it off? Leave it open? Or run it to something?

 

Anybody know???

 

Sounds like a line for a psi. gage.

 

X2 on the oil pressure gauge line.

 

Cadillacs had an electric oil pressure gauge. There is a sender on the top of the block at the rear. I doubt somebody would drill into the crankcase to run a hard line for oil pressure. And I doubt two different guys would have done it on two different engines. Its gotta be a stock fitting. And if its stock, it can't be for oil pressure due to already having an electric gauge.

I was reading in the '59 shop manual about the oiling system. It talks about the direction and locations of oil flow through the engine. It talks about a vertical passage that ends up capped off at the end but shows no image. I'm not sure if that's inside or outside the block.

Can anyone take a look if they have a shop manual and see if this vertical passage is what I'm wondering about?

Thanks!!

 

Here's a pic. Somebody has to know for sure.

 

whats the number on your block? it should start with 59-62.
do you have the oil filter canister, it looks like you have it mounted up by your oil fill tube, chrome?
if so im gonna say, i may be wrong, but i think you have a 365 Cadillac, not a 390. the 365 had an oil fitting like your describing that ran to the oil filter canister.
if you have a screw on oil filter then its a 390.

 

I'll check the numbers tonight or in the morning.

Here's a pic from the shop manual for now. Pay attention to the vertical oil header. The manual says this vertical oil header is capped off at the top with a hex plug. The diagram doesn't show whether this vertical oil header is inside or outside the block.

 

It is inside the block. there where you are describing the vertical oil header is a 2 lobe lump directly behind the Valley Cover that the oil pressure sender sits in one hole, and the other that is right next to it, is capped off.

 

Possibly a fitting for a mechanic to check oil pressure?

 

Might it be some sort of Rube Goldberg rocker shaft oiler that someone rigged up, ala Ford Y block? Or, a solution to some perceived oiling problem that uses an external line, like you see occasionally on the 351C, or AMC engines?

Obviously missing some vital pieces, o'course.

 

The 1959 factory shop manual diagram posted above shows an oil filter canister with both lines going to the driver side front of the block. No screw on oil filter in the diagram. Later 390's ('62 only I think) had a screw on oil filter.

 

Some early Cads had a vacuum pump built as an extra layer on the oil pump, like a V-8 Packard.
Somebody will know if that is germane to this discussion...
With the end open, you'd sure know about it if it was tapped into the oil system!

 

My 62 engine has the screw-on filter, my 59 engine has the canister ports, but nothings there. I'll check and see if I have the same fitting you do when I get home..

 

I just looked at my '59 Cad & the motor I have waiting to be put in the car & niether one of them has a fitting/tapped hole in the area you describe.

 

And thanks bruce!

Thanks Dreddy!

Thanks burb!


I appreciate all the responses! We're kind of getting away from my question though. I'll confirm by tomorrow whether my engine is a 365 or a 390. But what I really NEED to know is what this fitting is and what do it do.

Here's what I know for sure...
My engine has this fitting.
A friend's '56 365 has this fitting.
A friend's '49-'54 331 does not have this.
A couple of posters' 390's do not have this fitting.

This still begs the question, what is it and what do it do? Somebody has to know!

 

Here is what I can add. I have a 365 in my 56 hearse which is all original, engine compartment wise. The fitting has a metal line running up the back of the engine to the firewall. It connects to rubber hose to the double port vacuum fitting for the wipers. In my photos you can see...
1. the fitting/line
2. metal line looking slighty bluish color. Lower left of the photo.
3. vacuum port for wipers. Mine are capped off with red caps as I switched to an electric setup.
Best I can do trying to squeeze my big hands and camera into spots not made for such items. Hope this helps. Seems you may really have a 365 not a 390?

 

Maybe its a 305.




Sorry,Terd, I had to...

 

Well Terd, it seems that it is just a matter of plugging it, since you have no need to run wipers with it.

 

Hey man, I took a pic of my '59 motor. The only thing on the passenger side was a little plug near the freeze plug.

 

Mines plugged like Dreddybear's. Hell I thought it was a coolant hole for a petcock(note mine isn't running) what comes out of there if you pull it Dreddy?

 

mine's a 365 block and has the port in question. just plugged off and 7 years no problems.

FWIW, the oil filter can be on either side depending on year and original configuration (ie AC vs non-AC car)

 

I recall those engines had a separate pump stacked onto the oil pump. The pump was used to pull enough vacuum to operate the wipers without them ever slowing down, even with a sometimes low intake vacuum signal. (it would not have been acceptable to have a Caddy owner suffer through insufficient wiper action!) I always thought it was a pretty good idea, as long as the engine was running, the wipers worked great!

 

Thanks a ton for the pics! The crankcase seems like a really odd vacuum source for the wipers? But that's the first solid answer as to where that goes. At least on your engine, lol. It just doesn't make a lot of sense to me. Can anyone explain or expand further as to why they would select the crankcase for a vacuum source for the wipers when the intake is probably easier and closer?

Hahaha! But then where's my TPI and HEI? I'll leave the 305's to JeffyJames! He's the expert.

I plugged it today. Besides, I wanted to get the chevy soup can looking vacuum canister chromed and back on the fire wall for the wipers!

That's interesting. Mine is more at the rear of the block, just above the starter. I wonder if the other 390 guys have the same plugged port as you two?

Well that's good to know!

I've seen oil filter canisters on both sides as well, along with the spin on filters in the block of the later 390's.





And for the record, the story behind my engine is that it came out of a little old lady '58. The engine and trans were rebuilt, she put 3,000 miles on it and passed away. A hamb'er in GA bought the car, drove it 1,000 miles and pulled it to swap an LS1 for cross country trips reliability. I first assumed it was a 365 based on the year car it came from. Then one night at our shop when Jeremy made some engine mounts based off a different KNOWN 365, they didn't match my engine. So JeffyJames ran the numbers as a lark and as best he could tell it was a 390. I didn't think this was too far out of the realm of possibility as it could've been a factory replacement engine if something catastrophic happened to the original back when. Or, I thought maybe it could've been a transitional engine from a car built very late in '58 and maybe they ran out of '58 blocks. This was all based on a search JJ did and I didn't pay attention to the numbers at the time as I didn't know the first two id'd the year of manufacture.

Anyway, I'll confirm the numbers on my block tomorrow for sure and post the results. It being a 365 would make Jeremy James very happy as he might then actually be faster than me.


And thanks again guys for all the pics and posts! I appreciate the help!!!

 

That explains a lot! That's a complicated solution to a then common problem. But it makes total sense I guess. Thanks!!

 

I was looking through some old Cadillac books and one had a photo of a '57 chassis with the engine. In the photo there was a line running from the oil bath air cleaner down to the area on the block in question. I have no way to scan the book without damaging it.
Also Cadillac was still using 365's in '58 so it's very likely the engine is a 365 and not a 390. It all depends on the S/N.

 

This makes incredible since! So obvious, you have a 365, has to be. Better run those numbers.

 

The plot thickens.

Here's the numbers...
5 G021190

That's right, the second space where there should be an 8 or 9 is blank. How about that?

 

Terd,
I was reading this thread with Timothy (he's 3) last night and he said Daddy, are why you looking at guns?

 

Run the head numbers then and see if those tell us a bit more.