VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1941 start up part 2

if you pm "wawazit", steve would problely explain how he hooked up a pvc valve on his '38.

pm "wawuzit" and he will problely explain how he done his '38.

The road draft tube only works (sucks fumes out of the engine) when the car speed is above 30 MPH or so. This prevents sludge build-up. With positive vent the intake sucks the fumes into the intake manifold and they are burned. This works at all speeds and when standing still. This also causes a slight intake leak and a richer jet in the carburetor may be necessary. Chevrolet recommended this option for door to door delivery trucks. Not really necessary in warmer temperatures.

Thanks all for your help with the PCV. Will do some more reading and decide what to do. Am somewhat leaning towards taking the easiest way, just mounting the PCV in the cap of the oil/breather vent tube. This would also allow for using the original valve cover. Do appreciate Gene's comments on what performance changes might occur.

Still thinking things through and Wondering, Mike

P.S. Was already warned by the foreman at the machine shop that the cork gasket on the cap had to be a tight fit.

Mike,

With all due respect to everyone, including Steve, I don't think the PCV thing is the answer to your problems.

In order for the PCV to work you must have a positive pressure system. You don't right now. It is open owing to the crankcase vent.

To install a working PCV you must seal the system. Ok then, but as Gene pointed out, you don't really need to.

You merely have a non-fitting rear seal, nothing more. And, after addressing that problem it is likely that nothing more will be needed.

Best,
Charlie

I agree with Charlie. A little dab of sealer on the corners will help if the gasket does not make perfect contact. Adding a PCV system will do absolutely zero in helping to fix your problem.

Thank you Charlie and steve6!!!

I have been trying to figure this PVC thing out since it was brought up. I mean, we have this "big vent tube" stuck in the side of the block. How could there be "that much" pressure in the motor? I am glade you spoke-up.

Of course, maybe we are missing something?

too much crankcase pressure is usually a sign of tired rings and or very worn valve guides .. not an issue for you i think .. I agree with the "fix the problem first" answer .. you will be a wiser man when you have solved the leak ..

Ollie.

I have installed a pcv system on my 216 and if you PM me, I will explain it in detail. It will do nothing for your leak.

It has been my experience that the main bearing clearances have to be at the absolute minimum in order to have a good seal in affect. When I replaced my mains, I ended up with a rear main that was not as wide as the original. Some of the main journal at the rear portion is exposed. Maybe this allows the oil to escape before the seal but my rear main doesn't leak at all.

After installing the PCV won't this change my timing/idling? I seem to remember having idling/stalling problems when I disconnected my wiper vacuum line so I stick a golf tee or bolt into the end of a rubber hose and attach the hose to the vacuum line?

I want to follow the machine shop foreman's suggestions, but the question is do he and I know what we are doing???
As I have said before, there is no evidence of any oil residue in my breather tube. Is that suspicious?

Do appreciate every ones advice. Would/could not be in the hobby without all your help. Thanks, Mike

The vent tube could be plugged and not functioning so checking to be sure it's operating properly might be a good idea. By the looks of the oil spot locations it appears the oil is leaking at the bearing cap corners. I would put a little dye in the oil after cleaning everything up and it should not take long to spot the leak at the rate it is leaking. The dye is used with a light and will not take a large leak to spot. It would be nice if it were the pan gasket and not the main seal. A much easier fix.

Mike,

I just came from searching through some of my stuff to see if I had a grafite seal or not. Didn't see one. But I did find a couple of oil pan gasket sets. They contain the two halves of the gasket and the front and rear seals.

I'm wondering and I admit that I don't know, whether that aft of the rear main seal there is a way the oil that passes by the main can be dumped back into the crankcase. Thus, the seal then would help hold the oil from going on out the rear to finally drop to the clutch pan and thence to your clean floor. Maybe the cork seals were bad on the set that was installed.

Am I on to something or am I just figuring too hard? Hurts my head. Does too.
Don't really think that is the answer but something is really amiss somewhere.

You can have these cork seals if you want them. Let me know. Can't send the side gaskets. Too long. Less I break um up into little pieces...

I know that most of you out there will say that the rear seals can't be the problem. Too elementary. Well, I bet that when the problem is solved it will be, indeed, something elementary.

Best,
Charlie

The PCV system doesn't change the timing. After installing it the idle and the idle mixture should be adjusted and that is it. It doesn't allow unlimited air to pass through. There is a ball inside the valve and with a strong vacuum it clicks almost shut leaving a metered path. It also prevents a backfire from entering the crankcase.

Sorry Charlie, but there is no evidence of the oil pan gasket leaking near the rear seal. Everything continues to be dry on the transmission side of the flywheel shield.




I have been thinking of putting the car up on my truck stands and letting it run while I crawl under it to take a look. Don't know how safe that is, but I do trust the stands and will leave them at their lowest setting. I also do not know if the car needs to be driven over a certain speed to actually activate the PCV valve. I read that pressure in the crankcase is what actually opens the valve allowing the gases to be sucked up into the intake manifold. So maybe I need to drive the car for a while and then jack it up while it is still running to check for leaks.




This is the contraption I rigged up for putting a PCV on my oil/breather vent tube. Thanks Old216 for telling me that timing doesn't change. What are the symptoms that let me know to readjust the carburetor?

I also do not know if this PCV valve is the correct size for my engine? I choose the valve because it required only a 3/8" hole in my oil cap and it was threaded so I could attach it easily to the oil cap with a nut.

Thank you all again, good night, Mike

Mike,
if that is a PCV valve you can test it before you use it to see how it works. You can blow through one end or draw through the other. The PCV setup works continuously.

The vent pipe provides a passage from the crankcase to the outside air so putting a valve on the top will draw air from outside and some from the crankcase. You need to seal the holes that vent to the outside and also provide an air intake for fresh air to come in. Usually this is done with an oil cap on the valve cover that has a mesh in it.

Thank you Old216, I have the traditional valve cover with two air slits in it that came on the engines in the 40's. I am assuming that this is adequate ventilation for a PCV valve, and I do not need to replace my oil cap on the valve cover?

Before I ended my day, I started the car and ran it for about 5 minutes with the flywheel cover off and the shield between the flywheel and transmission on. I crawled under it using front jack stands and watched for leaks. It appeared that additional oil was not leaking in the areas I normally see drops forming (heads of crank cap bolts and bottom of cap). This seems to be consistent with cold starting an engine and crankcase gases not forming until the engine is warm. It is the shop foreman's assumption that the pressure accompanying the gas is forcing oil through the rear seal?

I wiped everything off. I didn't do this before cold starting the engine because I wanted to see if the leaks were coming specifically from the three points noted before, and continued leaking oil. This morning I will check for overnight oil drops then take the car on a 15 minute ride at speeds in the 30's and see how the PCV valve works and how it has changed engine performance. Wish me luck, Mike

Mike,
good luck! I must say that you take great photos. Don't get any oil on that camera!

Latest picture after about 15 minutes of driving at under 40MPH. The car sat over one hour before I took the picture. The oil pan gasket continues to be dry.

Guess this confirms that the PCV valve was not of any/little help. Will turn my attention to getting the rear seal replaced.

Thanks, Mike

P.S. If you look real close you can see the spray pattern (right to left) made as the engine idled before shut down.

old 216 I am fortunate that my wife and I share photography as a hobby. I have also, fortunately, spent the last 25 years videotaping our high school's Friday night football games on unsupervised time!

The vents in the valve cover are for drawing fresh air into the engine. It is drawn in by the vacuum created by the road draft tube when the car is maoving at speed. If equipped with a positive vaove the intake provides the vacuum to draw fres air in through the vents.
Does smoke (fumes) come out of the road draft tube when the engine is running? If so then it is not plugged up with sludge.
1954 and prior engines got the incoming air through the valve cover vents. 1955 and up had not vents but had an oil filler cap with mesh inside to bring in the air. The oiled mesh filtered out most of the dust.
I would bet $100 that the leak is caused by the seal and the engine vent. system has nothing ot do with it.

Mike,

Your car didn't need a PVC valve when it rolled off the assembly line...it doesn't need one now. I think the real problem here goes back to a previous thread that you posted several months back:
https://vccachat.org/ubbthreads.php.../Update_on_1941_216_rear_seal#Post266856

Your machine shop line bored your engine to get rid of the shims. This made the rear seal groove oval instead of round. They then went back in and reground the rope seal groove to try to correct their mistake after they realized that a 216 requires shims and probably shouldn't be line bored. You also stated that your machine shop says that Best Gaskets Graphite Rope Seal will not seal properly in a 216....yet, every engine kit sold by Filling Station and Chevy's of the 40s includes this type of gasket. Additional, I installed a Best Gaskets Graphite Rope Seal in my 216. Now after 100 miles of hard driving...it doesn't leak at all at this point. Many others have installed this same brand of rope seal too without any problems.
I think you got to look closely at how your engine shop tried to treat your 216 like a 283 V8 and it is far from that.

I hate that you're in such a spot. I too know how it feels to have to correct a major problem after a lot of money and work. I also know how it feels to keep having setbacks. It down right sucks!

I really feel your engine shop is giving you the run around on something that they really don't know what is going on. On the other hand, it's hard to find someone that actually knows how to machine a 216. I feel for you Mike. I hope you can get this resolved quickly and inexpensively.

First, I know nothing!

However, if it were me (and it ain't!) I would try one more new rope seal (do it in the car) before I took any other drastic measures. Then, if that doesn't work, I'd look at other options. Why not at least try one more rope seal???

'Sorry you're having troubles. You tried hard and spent your money and I hate it for you.

Good luck (it has to change).

PS - If the seal "groove" was a bit egg-shaped, seems that would tend to make the rope seal fit tighter on the shaft - which should have tended to prevent a leak. Wouldn't that serve to squeeze the seal tighter on the shaft? If so, how would that cause a leak? (Of course, that was before they machined the groove.)

What exactly is machined when you do line boring? Is it just the bearings? I have other rear caps so I can give them another one. If the crank and block are involved in the process I could even provide them another? Thanks, Mike

It should be only the bearing material that is cut when line boring. The process straightens and sizes the bearings to match the journals on the crankshaft.

So the general consensus is that I should order a new set of bearings, replace the rear cap and seal, and shim to the appropriate clearance .001" to .003"? Thanks, Mike