54olds

I did a quickie leakdown test on several of my cylinders on my '54 a few days ago. On both tests, there was a strong rushing of air out of the oil filler tube (I did make sure each piston was at TDC before testing.) Also, when I put my hand over the filler tube and blocked it, I could hear the air escaping from somewhere around the back of the motor (I have not been able to determine where, though.)

Is this an indication that my rings are bad? The motor does burn a some oil.

Oldsguy

It very well could be. If you were to squirt some oil in the cylinder being tested and get a better reading and/or less air passing into the crankcase then you definitely have bad rings.

54olds

The thing I don't understand is, when I did my compression readings, they were all between 103 and 115. When I squirted some oil down in one of the spark plug holes, the reading stayed the same.

Texascarnut

Chances are your crankcase breather tube is clogged up. The engine may not actually be using oil in the traditional sense, however; excessive crankcase pressure from a clogged vent tube can create similar situation. You should also check the oil filler cap. If it is full of oil it is almost assured the crankcase breather is clogged. The circumstance is identical to what happens when a PVC valve on newer vehicles clogs or otherwise fails.

54olds

I think I went through this before - where is this crankcase breather tube at? I looked for it before, but couldn't find it.

Texascarnut

You'll find it at the rear of the block. If you get beneath the car you shouldn't have any trouble finding it. Its about a 1" diameter pipe sticking downward. Typically about 2" lower than the bottom of the oil pan. Bad news is there maybe a filter at the top of the tube that looks a bit like a chunk of Brillo pad. Access will be likely be through the valley beneath the intake manifold. More than likely the filter is really the culprit if there is one in that year model engine. Sorry I don't have Olds shop manuals that go back to 1954.

Before you do anything as rash as removing the intake examine the oil filler cap for oil running from it if you put it on a white paper towel and let it sit for a few minutes.

You really need to get on eBay and buy a shop manual for this guy. Printed or on CD run between $30 and $50. You'll be glad you did.

54olds

Thanks. I'll check that out tonight.

54olds

OK, I looked all over the rear of that motor, both on top and from underneath and could not find anything at all that looked like a crankcase breather tube. Could it be possible that it was taken off and never put back on? Where does it connect to the engine at? If it's missing, wouldn't there must be some kind of connection or something?

Texascarnut

Well, let's put it this way if there were no breather tube of some sort someplace on the engine you wouldn't want to be in the car more than about 2 minutes with it not moving, the crankcase fumes would run you out. Wasn't much better than that with an old engine with a breather tube.

If there is no breather tube or PCV valve on an engine the crankcase pressure would be blowing oil out from any point an even very minute opening to the crankcase is found and right slap smack out of the oil filler tube as well.

Go look again!

Aside from the fact you need to find the breather tube, after reading your original post again I would conclude that the engine has worn rings or tapered cylinder walls, maybe both. Meaning your oil loss is from blow-by. The fact you mentioned hearing air escaping from the rear of the engine following an attempt at a leak down test confirms there is a breather tube there someplace unless it has fallen out or been knocked off the engine (not likely).

88 coupe

If Texascarnut knew anything about '54 Oldsmobiles, he would know that, since air follows the path of "least resistance" this is the normal place for it to escape.

And he would have called it a "road draft tube".

He would also know, that at the rear of the block, below the distributor, and above the bell housing, is where the fumes escape through the "road draft tube" when (and only when) the car is moving. If the tube is missing, there should be a hole where it was originally connected.

My guess is: Someone removed the tube, and plugged the hole with steel wool.

If so, those fine folks at Radiators.com can probably fix you up with one, for about 1/3 what the dealer charges.

Not by itself.

How much air was escaping, from the oil filler, during your tests? During normal driving, how much oil accumulates in the breather (filler) cap?

More than 1 quart in 1000 miles?

Right where they should be.

Norm

Texascarnut

Norm the last time I checked the term "Crankcase ventilation tube" was a valid term. You can call it whatever you desire. Oh, and vent tubes are not unique to Oldsmobiles. Vent tubes do function when a car is sitting still believe it or not. If you had sat in bumper to bumper traffic on freeways in the 1950s as I have you would be well acquainted with the fact all the fumes from crankcases of cars just sitting in a traffic jamb was far less than pleasant.

I think you need to get over yourself. You'll certainly have a lot better relationship with people with a different attitude than you seem to consistently have.

54olds

I can't measure i, but it was a fair amount. There is a little oil on the breather cap.

I've only driven it about 50 mile since I bought it, so I don't know the usage yet.

54olds

BTW, I found the hole where the breather tube is supposed to be. It isn't there, so someone must have taken it off and thrown it away.

I did find this curiosity hooked up to the vacuum line and dangling between the firewall and the engine:



I guess it wa supposed to be some kind of vent tube, but it wasn't connected to the crankcase, just the vacuum line.

P.S. - this part also had a plunger inside, much like a PVC valve. I don't believe the '54 had a PVC system yet, so I'm pretty sure this part doesn't belong there.

88 coupe

Back in the day, the practice was not uncommon.

Maybe an old guy, who was alive at that time, can tell us why.

There should be two ⅜" bolts, holding a flange to the block, in the area I described. It should either have a 1" (or so) hole, for the tube to "plug" into, or a ⅜" tube, similar to the one on the PCV valve, in your image.

Not from the factory.

Beginning in the late fifties, AC sold a "retrofit" to replace the, often messy, original setup with the more efficient, PCV system.

Norm

59-59-59

Ok, I laughed so hard that I needed an underwear change!!

88 coupe

Read the following thread:

https://classicoldsmobile.com/forums...e-madness.html

Then ask me if I care, what you think.

Norm

Texascarnut

GM's A/C Delco Divison began selling PCV valves in September of 1960.

http://cases.justia.com/us-court-of-appeals/F2/366/389/

88 coupe

With the engine idling at operating temp, remove the oil filler cap. Look for puffs of smoke. If you don't see any, your rings are in good condition. More smoke = more blowby = not good.

And you didn't notice the smell of burning oil, or see smoke from the exhaust, during that time?

Norm

Texascarnut

The item in the photo is most certainly an early PCV valve. How early I can't say. The first PCV valves were used on WW II tanks and were patented by a man named Hanks in 1944.

Where did the vacuum line this thing was attached to go? It would be interesting to see how they had it attached to the block in place of the vent tube.

88 coupe

Makes sense. Open PCV systems were required on all '61 cars sold in California.

Norm

88 coupe

I'm glad you agree.

Maybe I should have added the part about it being AC or equivalent.

According to the following:

It would be '60 or newer.

Norm

redoldsman

I just went out and looked at my friends 54 that is in my garage. The vent tube comes from the top and rear of the engine (top is hard to see) and down the right side right in front of the motor support. Near the bottom is a built in filter the is about 2-3 inches thick and about 5 inches in diameter. The filter is not serviceable and can become clogged. We had to have this one cut open and then actuall put brillo pads inside and welded it back up. The pupose of this downdraft tubes (or what anybody else wants to call them) id to carry crankcase emissions down below the car where the draft under the car would keep them out of the interior. With the exception of California, most cars used them until 1963 (I could be off a year on this) when the PCV valve was used. Obviously this was the first emissions control device. Hope this helps.

54olds

When it's warm and running, I do see some smoke from the blowby opening on the rear of the motor, not so much out of the oilf iller tube. After the motor's shut off, however, it does smoke for about 10 minutes or so.

Oh yea, it does smoke when it's running, sometimes a lot and sometimes just a little.

54olds

I know this is a pain, but is there any way you could take a digital photo of his vacuum lines and post it here? After finding that A.M. PCV valve just laying there, I'm suspecting that the vacuum lines may not be hookoed up correctly.

Here is a pic I took of the vacuum lines on my car:




BTW, Norm and everyone else here - I really appreciate all your help!

redoldsman

I will try and do that this weekend. They may be little off since we are running a vacuum pump for the power brakes.

Texascarnut

Not necessarily! Who ever put that thing on the car might have come up with a PCV from or for an old WW II tank, some of which were still floating around in National Guard units as late as 1960.

Texascarnut

If your power brake booster is requiring a vacuum pump to function, there are three possibilities. All of which will affect engine performance.

1. Massive manifold vacuum leaks (gasket and/or bolt torquing issues)
2. Check valve between vacuum source and booster non-functional or installed backwards.
3. Valve timing way off.

To get things to where it is possible to set engine timing to specs you are going to need to plug all vacuum lines/ports at the engine and set the timing to original factory specs. You have to have a level point of beginning to run tests and without the engine being in time you are just wasting your time.

Texascarnut

What color is the "smoke" from the tail pipe? Light gray would usually indicate valve stem seals and/or valve guides have it given up. Somewhat verified by the fact it stops or appears to abate once the engine has been running for a while. Black smoke typically indicates an excessive amount of fuel entering the engine. Typically does not stop because the engine has warmed up. The latter can be resultant of both incorrect carburetor adjustments and/or timing issues.

Beginning to sound like that old girl needs to be yanked out and rebuilt or at least the heads pulled and refreshed.

Texascarnut

You are dead on with the time frame. Olds did a mid production year change in 1962. Early '62 production had a vent tube from the passenger side valve cover, which was replaced with a PCV valve from the same valve cover location where the tube had been mounted.

tarps3

very intersting thread.
How hard is it to access the bolts holding the road draft tube/crankcase ventilation tube in place?

I had a '60 TBird that had this tube and I converted it to a closed PCV system. It was much more pleasant to drive without all the fumes.

I'd like to do the same for my '53 Olds but that darn tube is way back behind everything...is there a reasonable way to access it??

thanks,
Casey

88 coupe

Doesn't sound like anything I saw on my '54.

I wonder why they would put a filter on the "outbound" side of a ventilation system.

Interesting. A clogged filter that is not serviceable.

Must have been designed by a "drunken blacksmith".


Same mistake I mentioned earlier:

Plugged, is the operative word.

Any competent mechanic, would have simply removed the tube, cleaned it with solvent, and replaced it.

Little to do with the interior. Everything to do with keeping the engine alive.

In addition to hot oil vapors, crankcase gases contain water, acids, and unburned fuel, partially from the fumes that "blow by" the rings during the combustion process.

"Road draft tubes" were used by all manufacturers, to send these "emissions" into the atmosphere. By design, its placement in the air stream, caused a vacuum (only when the car was actually moving) which, in effect, evacuated the crankcase and replaced its contents with fresh air, drawn from the filler/breather cap.

It worked very well, when the car was moving.

At the other end, the breather/filler cap was placed at such an angle, that the fan could "push" air through it, into the crankcase (and out the road draft tube), when the car was not moving.

It did not work as well, but it was better than nothing.

Not possible for a "road draft tube" to function, unless there is enough airflow to create a vacuum. Under normal conditions, the car would have to be moving for that to happen.

Norm

88 coupe

Line A = Sends manifold vacuum to the inlet of the vacuum pump. Should be another line, sending it to the wiper motor.

Line B = Manifold vacuum for the power brakes = As it should be.

Line C = Vacuum originating from the "ported" source, at the carb, for use with vacuum advance only. The other line should go from the wiper motor to that "other" port on the vacuum pump.

Norm

88 coupe

A small amount is normal after a few years/thousand miles. Since you didn't mention it, in your opening post, I don't see a problem.

Out the exhaust? Driving? Under load?

When accelerating, after slowing down or idling?

Norm

88 coupe

Funny too.

At the top, it's a "slip fit" into the flange, at the rear of the block.

From the bottom, you will see where the tube is attached to the flywheel/starter housing. Remove the bolt and it should come out easily.

Norm

Texascarnut

Yes they do function when a car is just sitting! There is always a certain amount of pressure in the crankcase created by piston movement. If you don't believe that just crawl up under a car having a crankcase vent tube with the engine running and enjoy the vapors puffing out the tube. The performance of a crankcase ventilation tube is indeed enhanced with vehicle forward movement.

54olds

Light blue.

54olds

Out the exhaust. It smokes light but steady when idling, and of course increases considerably when raced. The smoking seems to be about the same as idling when you're driving.

54olds

I should also note that I got in my leakdown tester that I ordered. I was only able to check the 4 cylinders on the driver's side. On two of them, I got 25% leakage, on the other two it was 40%.

I don't yet know what the cylinders on the passenger side look like yet - I'll try to check them this weekend.

Also, I've taken the car out a few times, driving it around the neighborhood to get it nice and warmed up and to see how it performs after its been running for a while.

It seems to have a pretty bad idle problem. It idles fine when it's cold, but once its warmed up, when you're stopped at a stoplight, the idle will run rough and drop to the point where it will stall if you don't give it some gas. I don't think it's a carb problem as I just put a factory rebuilt carb on it about a week ago and I was having similar problems with the old carb.

marcar1993

Was the rebuilt carb from a parts store or done by a rebuilder? I have had HORRIBLE luck with parts store rebuilds. They are junk.

As for the road draft tube, though the topic has been beaten beyond recognition, does effectively evacuate the crankcase at idle. All my knowledge of them are on mopars, but the theory of how they work is the same. + Pressure evacutes the crankcase, in motion there is a low pressure area below the tube making it easier to evacuate. Do olds road draft tubes have a small square of sheet metal on the front (at the bottom) to create more of a vacuum? (Low pressure area)
On a mopar, the air is deflected off the sheetmetal below the tube and creates a low pressure area (boyle's law, the thing that makes aeroplanes fly)to use the + pressure of the crankcase to push the gases out the tube. I'd suppose it couldn't be much of a different principal.

Texascarnut

I really hate to say this, but with a constant light gray or bluish gray emission from the tailpipe and the results you got from the leak down, the engine needs a major rebuilding, which may require boring the cylinders. It is for certain the heads need a major rebuild and there is no reason to do that and put them back on when it appears you have one or more cylinders that are no longer true. If you haven't already you should do a compression test on all cylinders. I suspect the results of a compression test are not going to be good, unfortunately.