Just Got My Glasses Clean - TEST

J

jsilvestri

Member
1931 S/W 160B

Running very well....but distributor locked in...rusted single shaft...
Oil Leakage minimal....typical Model A droplets.

Pulled the head to get the distributor out from the other side...did so.

Cleaned up everything thoroughly....assembly grease where applicable.....
re-installed head with new copper gasket.....installed New distributor.....

Fired it up....very disturbing engine noises (mostly low-pitched banging type)...smoothed out after about 30 seconds....

Car ran very well and peppy......B-U-T.....

An apparent HUGE back-pressure in the crankcase caused oil to gush out the cotter hole in the housing (not drip, gush). We dropped pan, Checked rear main bearing, crankshaft: Fine.

Further check: Bent the oil breather tube baffles straight up and down... Yep, much less oil UNDER the car, but a faceful (and eye-glasses full) of oil visibly spraying up the tube........

TEST QUESTION: What the hell happened to my car???!!!

Any help/theories from the A Brotherhood greatly appreciated....happy to answer any questions about what was done/not done or whatever...

John Silvestri :confused:
 
Compression Currently: 60 / 60 / 58 / 50 front to back...

Pulled head off again today.....no surgical instruments left behind...
 
I can't solve your problem, but. Both my engines have a bit of spray out the breather, since I drive them hard. Here's a tip. To keep the engine compartment free from oil mist, I simply slip a white cotton sock over the breather pipe. Keeps the entire compartment totally oil free. I used to use one of those flexible tube things, then some mist got on the underside of the car, especially the battery.
 
sounds like compression getting into sump. hence question on compression, that solved , better take head off & check no damage, bore damage ?? need more history but its blow by causing preasure in sump. so is the oil level way to high?water getting in causing the level to high ??The low pitch banging could be a numberof things, , always check centre main, That usually lets go 1st. Keep us updated.
 
Had the steel wool in up to the point of the problem....now it's out. Oil level about 3/16" under Full on dipstick.

In case I understated it, here's the power of this back-pressure: With the oil tube breather baffles normal, pressure/oil goes to the bottom of the engine and out the cotter hole under the car - almost a constant flow up the inclined driveway. With the breather baffles vertical (open tube, basically) the oil spray/mist is 18" high.
 
Too much oil and too much incline on the drive way. You are counting on a small slinger and not a seal. Turn the vehicle around and see if it will pour out the front too. I would either reduce the oild level to about halfway or drive it til it calms down (Constatnt loss style). You may want to check and see it the tube draining the rear main is still in place on the cap.
 
Has the rean main seal been changed to a modern seal and in the process removed the slinger or added a rope type seal between the main cap and slinger . The fellow that rebuilt my "B " engine added a six cylinder chevrolet seal in between the rear main cap and slinger . After 1,000 miles ,the seal disintegrated into fuzz and plugged up the normal rear main drain system . The engine pumped oil out the rear main. Pulled the engine cleaned out the reminants of the rope seal put engine back in . NO oil leaks at all . If the crank and babbitts are within spec the system ford designed works.
 
Looks like you have ok compression at cranking speed. Could be that at cranking speed the oil is sealing the bore but once the engine is running it blows off the walls and pistons builds up pressure in the crankcase.
The oil coming out the flywheel drain hole, could be the drain tube is plugged up or the aluminum insert is very loose or someone has modified it for a modern seal which is not in place.
 
Sounds like one of the top two rings on #4 is frozen in it's land. Run it about 1200rpm with the filler cap off and short Plug lead #4 to ground. If the oil spray reduces after a few seconds you have a stuck compression ring in that cyl.

You may want to attach a temporary short hose to the filler to direct the blowby sideways, away from the engine compartment.

I learned this diagnostic dirt racing SBC's in the '70's.

Didn't see you at the Ill. Region meeting last night. :(
 
The driver side(left side) of the inside of the crankcase is the "dry side"! If you
have oil coming out the breather and need to put steel wool or rag the breathe, you
have blow-by.
 
Sounds like a rebuild is in order. Any cylinder with a drop of 10% or more is getting to the point of worn out or some other problem. A leak out the cotter pin hole like you describe is usually because of cracked or severely worn babbitt or the drain tube has fallen off. I weld all the tubes on my rebuilds.
 
I hate that when that happens...oil on your glasses from the breather tube! :(
I agree with MikeK...#4 compression is way to low when compared to the others. It should be within 5-6# max difference. When the head was removed, carbon particle(s) may have dropped down on the top ring and it was forced between the ring and the groove to cause a "stuck" or it was frozen prior as I think Mike suspects. You may be able to free the ring with an additive but if you are game, the sure fix would be to remove the pan and head and then pull the piston out of the top of the engine. Carefully remove the rings and then clean the ring grooves. Re-install the rings as close to the original orientation to the cylinder walls as possible and try it. You may get many more years out of your engine. With steel wool in the breather and a stuck ring, you would build enough crankcase pressure to push the oil backwards through the rear cap drain tube. Comment: If you can get #4 compression back up close to 60# by cleaning the grooves, you could have a good running engine once again. If you continue to need to stuff steel wool into the breather even after you free the ring, you have additional issues you will need to chase. I'd check the valve guide wear next if the problem continues after freeing #4 ring. Let us know what you find.
Good Luck with your project!
 
Dave, Mike and everyone...

Thanks so much for the thoughtful responses. That's the wonderful thing about this Model A community we're part of - it's life at its best.

The rear main tube was fine...and the rear main. Valve #8 spring was "leaning over" some and we found that it would not seat all the way.

We're going to be trying this, per your suggestions: replacing all 8 valves (since they're also not concentric/centered on the seats for some reason) and we're dropping the pan (again) to pull down #4 piston, as you guys suggest, and seeing what the rings look like. Regardless of how it looks, we'll probably pull all 4 for rings....then we shall see what happens.

It's a tough thing to think that, when we cleaned up the block face, piston heads, valves, etc (trying to do it right) that we left enough carbon particles in there to cause all of this mess. It certainly is an argument for truly assessing (as say doctors do) whether the risk of "going in there" outweighs the potential benefits. I will weigh that much more in the future.

Again, thanks guys - and I will keep you posted on what we do and what we find and how it ends up.....

John S :)
 
To all my helpful friends:

So far #4 piston had stuck rings....#3 did not...which surprised me because #3 and #4 were both the low compressions ones at 50.

I wish I knew that it might be worth "unsticking" them via various methods while driving....I understand that they sometimes will become "unstuck."

In any event, we are now replacing 8 valves, all the rings and the timing gear (which has a few teeth with pieces missing)....all with engine in chassis.

Will keep you posted on progress....and what else we find.

John S. ;)
 
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