Big oil loss on rear sid

Werner

Werner

Well-known member
Good evening everyone.


My Green Roadster has recently developed an oil drip problem. Within about 1,000 miles, the oil loss on the rear clutch side suddenly increased to more than 300 ml/0,6 pint on 100 miles, and the trend is increasing.



It's not dripping down the oil pan, but from the clutch bell housing bore = rear crankshaft bearing.


It's thick 60-weight oil, and I keep the oil level in the lower quarter of the dipstick.


If I've read and understood that correctly, it's due to a blockage in the oil return tube on the rear crankshaft bearing. However, that's unlikely, since I change the HD cleaning oil (API SC) every 1,000 miles and use an oil filter.


Does anyone have any other advice?
Thanks in advance!
 
My car started leaking more oil a couple of years ago. When I inspected the rear main bearing I found the babbitt bearing had come apart and the thrust surface broke off and lying in the pan. Sounds like you have the same problem but I hope not.

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The Master Cylinder said:
My car started leaking more oil a couple of years ago. When I inspected the rear main bearing I found the babbitt bearing had come apart and the thrust surface broke off and lying in the pan. Sounds like you have the same problem but I hope not.

41645031084_eb50ebc4bf.jpg
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This is kind of what I found last year also, and that is what I expect Werner will find.

Drop the oil pan and see what you can see.
 
Make sure your breather oil fill pipe is not restricted somehow which would cause crankcase pressure to build up and force oil out the rear bearing.
 
The oil return tube on the rear bearing might be clogged, but it also may have broken off, which will cause a leak too (ask me how I know). You need to drop the pan and inspect the situation.
 
Fullraceflathead said:
Make sure your breather oil fill pipe is not restricted somehow which would cause crankcase pressure to build up and force oil out the rear bearing.
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DITTO.


1. Be sure that someone did not stuff a "pot cleaner" (green plastic or copper mesh) in breather cap on top of breather tube.

Water vapor collects in cap and mixes with combustion by products and then dries out to become a "gooey glue" which dries and plugs up breather. Then too much crankcase pressure then forces oil out rear main cap.

If plugged enough, 5 quarts of oil can be forced out rear main cap in about 70 miles of driving.

This has happened two times that I know about.

2. Anything which restricts air flow out of the breather tube will force oil out rear main cap.

3. Did someone install breather cap and slam cap down with their fist, which damages cap and blocks air flow? (that is bends tabs inside cap).

4. See Service bulletin 326 for photos
 
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Good evening Model A friends,
Thank you all for the initial advice. It's a pleasure to read them.


The oil used is labeled like International SAE Class 60, or SAE 20W-50.


Since I electrically preheat the engine before every start, the thick SAE 60 isn't the cause.


The crankcase breather is free-breathing; I have the attachment with a flexible pipe at the rear.


I'll remove the oil pan and try to figure out how to remove the rear main bearing. It's unlikely to be an easy task, as I've unfortunately become a bit unfit myself.





 
Good luck. I use the 20W-50 oil too. It does not need to be warmed up as it behaves as 20 weight oil when cold.

I am a little unfit myself, mostly because of my advanced age. I found it easier to remove the engine and put in on an engine stand to work on the bearings while the engine is up side down.

My club will have technical days where we invite all the club members over to a member's house to analysis a problem and effect a fix. The host will supply food and drinks to the participants. This can be instructive for all involved and usually gets a problem fixed.
 
Werner, I would remove the rear cap and check the clearance with plastic gauge (green) if you can get it. Another option is to use aluminum foil. A strip folded to about 3/8 x 2 inches (measures .002 of an inch thick) in the rear cap. Turn with hand crank just a little to see if it moves. It should not. It should hold with 2 strips and turn with 1 strip. Remove shims as needed. If the thrust is broken in the block check out Berts Model A Store on-line for a bronze rear main seal with thrust. Part # A-6336. Good Luck! Dan in Reno Nedada
 
Werner said:
Good evening Model A friends,
Thank you all for the initial advice. It's a pleasure to read them.


The oil used is labeled like International SAE Class 60, or SAE 20W-50.


Since I electrically preheat the engine before every start, the thick SAE 60 isn't the cause.


The crankcase breather is free-breathing; I have the attachment with a flexible pipe at the rear.


I'll remove the oil pan and try to figure out how to remove the rear main bearing. It's unlikely to be an easy task, as I've unfortunately become a bit unfit myself.
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As I said in post 8, item #2 above any restriction in air flow will force oil out rear main.

There have been several versions of these devices made over the last 90 years.

Some are more restrictive than others.

55 years ago I had one installed which increased the amount of back pressure and leaked oil out rear main bearing. After removing "draft tube attachment", the leak was about 1/3 as much (2/3rds less)
 
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Good evening and thanks to all!


What please are the advantages of using a bronze main bearing oil seal compared to the aluminum version?


My problem is that Mikes Shop doesn't ship (the bronze version) to the EU/Germany. I can currently still easily get the aluminum version from MACs and probably also from Don Snyder. -




I checked the crankcase breather; it's completely free and clean, without any sludge. -




Regarding my comment above about oil viscosity: The term "weight" is an American expression and has never been used in Germany. "Weight 60" essentially means "heavy oil," which generally means "thick." The correct term is the international SAE designation, which refers to the standardized viscosity grades.
"Weight 60" does not directly correspond to SAE 60.
 
Werner said:
I can currently still easily get the aluminum version from MACs and probably also from Don Snyder. -

Regarding my comment above about oil viscosity: The term "weight" is an American expression and has never been used in Germany. "Weight 60" essentially means "heavy oil," which generally means "thick." The correct term is the international SAE designation, which refers to the standardized viscosity grades.
"Weight 60" does not directly correspond to SAE 60.
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I think you are going to find anything Model A related hard to get from MAC's.

Help me understand. You walk into an auto parts store and ask for "Heavy Oil" for your engine?
 
Yes, it has become more difficult for end consumers to obtain US spare parts here. The customs and import declarations have become so complicated and extensive that many companies no longer want to deal with the considerable paperwork involved. -


Regarding the oil specifications:
No, it's the other way around.

I specify the SAE viscosity grade. For example, SAE 20W-50 (a multi-grade oil for summer and winter use). Or SAE 60, a thick, single-grade oil (for worn-out engines).


In addition, I specify the API class. For modern gasoline engines, this is, for example, API SM. For modern gasoline engines, this is, for example, API >SM. For classic cars, API SC is the best choice. It doesn't corrode non-ferrous metals like copper, bronze, or brass, and it's compatible with old rubber seals.
And yet, it still provides some wear protection, has corrosion protection, and also contains cleaning additives to prevent sludge and deposits.


From API SC upwards, these were known as "HD" oils, meaning Heavy Duty.



Beste Sommerwettergruesse!
 
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