Need your help, I'm stumped!

[aod92]

I'm working on my 70 Deville with a 472. Something is leaking on the driver side manifold, and can't figure out where it's coming from. I've replaced both the return, and high pressure power steering hoses and that's not it. It smokes a lot after I turn the car off. Could that much oil be coming from the dipstick? It always seems the wettest around there. It's hard to figure out because the manifold always burns the oil off. I'm completely lost on this one. Thanks!

[aod92]

Update....I just took the dipstick out, and put a plug over the tube and clamped it. The smoking stopped and everything stayed dry. Why am i getting so much oil pressure out of the dipstick tube? The guy a purchased the car from has an aftermarket air cleaner on the car and the driver side valve cover plugged where the crankcase evacuation would be. Could that be part of the problem?

[n2caddies]

I  am not familiar with that engine as I am with the 390 and 429 but those motors have to breathe if you have a Pcv valve and its plugged it will blow oil anywhere it can dipstick included. If the original had a breather on the valve cover it may have connected to the air cleaner. I would check the Sevice manual and get a stock set up.
Randy

[76eldo]

That's the problem.  The oil vapor and pressure is looking for a way out and the dipstick is an opening.  Don't run it with that plugged up or you will create a gasket leak or something possibly worse.

Brian

[The Tassie Devil(le)]

G'day Phil,

I reiterate what Brian just said.   DON'T DRIVE IT until you have the breathing corrected.

Excessive breathing from within the Crankcase is also from worm compression rings resulting in blow-by on the compression stroke into the sump.

Think of the interior of the engine, the back-sides of the pistons, as an internal pump, moving air all around the sump, and then factor into the equation, the rotating crankshaft and moving of the connecting rods.   There is a lot of pressure in there.   That is why the makers created the Draft Tube initially to alleviate the internal pressures, then the PCV system was introduced to lessen the pollution that the Draft Tubes created.

Bruce.

[Scot Minesinger]

First thing to do is let this engine breath.  I have a 1970 DeVille with the 472 basically stock.  The air cleaner and valve cover is connected with breather on driver's side.  The Cadillac used parts places, such as Willington CAD, USA, Cadillac King and etc. will be able to supply a breather for you.  Drill the air cleaner housing (goes without saying when it is off the car so metal shavings do not harm anything), add the grommets (by them at Advanced Auto or any similar place), and you will be in business. 

On passenger side a PCV valve is connected from valve cover to bottom of carb behind compressor.  Make sure that is good.

Enjoy your Cadillac!, after it is breathing properly.

[aod92]

Thanks guys. I'm gonna try and find a stock air cleaner. Until then I'm gonna put a k&n breather on the valve cover that I have sitting around. Does that sound like something that should be ok temporarily?

[TJ Hopland]

That should work.   If you can find one the stock one will also work without the proper air cleaner.   The stock one was a metal box with a filter on it.  One end went into the valve cover and the other went into the side of the air filter housing. 

Is your PCV valve still there?   Its in the other valve cover and has a hose going into the base of the carb.  If the PCV valve and hose connection is missing or incorrect that too will cause issues.   I am thinking that the PCV line is the one that also goes to the air ride compressor if your car is equipped with one.

[aod92]

That should work.   If you can find one the stock one will also work without the proper air cleaner.   The stock one was a metal box with a filter on it.  One end went into the valve cover and the other went into the side of the air filter housing. 

Is your PCV valve still there?   Its in the other valve cover and has a hose going into the base of the carb.  If the PCV valve and hose connection is missing or incorrect that too will cause issues.   I am thinking that the PCV line is the one that also goes to the air ride compressor if your car is equipped with one.

The other valve cover does have the PVC with the hose that goes to the base of the carb. No air ride on my car. Didnt even know it was an option. Is the driver side also supposed to have a PVC valve?

[TJ Hopland]

One valve cover had the PCV valve.  The other cover had the breather filter.  The idea was that the PCV side would normally suck when the engine was running and draw any blow by that got past the rings back into the intake so it could be kicked out the exhaust rather than just float around in the crankcase and deposit stuff in the oil.  The breather would allow air in during normal conditions because if the engine was in decent condition the PCV would draw more air than it could get from just blow by and its not good to get the crank case under too much vacuum.  When you hit the gas hard vacuum goes away and the blow by increases so in that case crank case pressure could build so that is why its going into the air cleaner because it can still be sucked into the carb.   It was an emissions thing.  It also turned out to be an overall good thing for the engine.  If you ever work on an engine that does not have one they tend to be a lot cruddier inside.

On your car with the breather plugged the crankcase was under vacuum at idle or cruise but when you were accelerating it was likely under pressure so that is why it was trying to escape out the dipstick. 

Before they had PCV systems they had what they called a draft tube.   Typical setup was a breather on the valve cover(s), usually also was the oil fill cap(s).  There was then literally a tube that hung down usually the back of the engine that caught the draft of the air when the car was moving which then caused a bit of suction.

I think the air ride was an option on all the cars at that time.  I think it was only standard on the Eldo and maybe Fleetwoods.

[aod92]

Thanks for all the help guys. I really appreciate it.

[Steve W]

These guys are on it 100%!

Best not to drive it too much till you get it breathing properly...makes me wonder how much the previous owner drove it like that!  Its gotta breathe from both sides. Check your PCV valve while you are at it!

That's also the reason I never got the aftermarket valve covers. The ones I've seen don't have enough holes...and none of the ones I've seen have the internal baffles.

Glad you sorted out the problem!

[aod92]

I was thinking the same thing. I had to re gasket the whole motor when I got it and I wonder if that's why? Then with me putting new gaskets on it created more pressure for the oil to come out of the dip stick