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06-01-2021, 09:22 PM | #1 |
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Rear main bearing cap oil return line question
Oil is running out of the rear of the rear main bearing cap, travels down the bottom of the cap and out of the dust cover and flywheel housing cotter pin. I finally got the bearing cap off tonight (engine is still in the car with a counter balanced fly wheel). Took out the soft plug and looked at the oil return pipe. It is screwed all the way in to the end of it's threads, with a considerable amount of threads showing in the galley behind the soft plug. Okay, here is my question...was the return pipe in further than it needed to be causing my oil stream? It's not my car so I don't know the history. And the galley is not plugged nor is the pipe. I have purchased new pipes and soft plugs. It looks like it's the 3/8" pipe.
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06-02-2021, 09:26 AM | #2 |
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Re: Rear main bearing cap oil return line question
I'm not familiar with any "soft plugs" being used anywhere near the rear main bearing cap. Where was this plug? Can you provide a picture?
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06-02-2021, 11:29 AM | #3 |
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Re: Rear main bearing cap oil return line question
There is a Welch Plug that is 90° perpendicular to the drain tube that is used that some call is a soft plug.
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06-02-2021, 11:59 AM | #4 |
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Re: Rear main bearing cap oil return line question
Ah! thank you. I found a picture that does show this. I never realized it was a plug, but I can see it's needed to drill the passage from the groove to the drain tube.
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06-02-2021, 12:17 PM | #5 | |
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Re: Rear main bearing cap oil return line question
Quote:
It is good practice to remove the plug during cleaning when the engine is rebuilt to ensure the passage way does not having any material (bearing material, sludge, etc.) that could restrict the oil from flowing out of the cap. |
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06-02-2021, 08:54 PM | #6 |
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Re: Rear main bearing cap oil return line question
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06-02-2021, 09:52 AM | #7 | |
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Re: Rear main bearing cap oil return line question
Quote:
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06-03-2021, 06:20 PM | #8 |
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Re: Rear main bearing cap oil return line question
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06-02-2021, 10:25 AM | #9 |
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Re: Rear main bearing cap oil return line question
Have you checked the (rear main) bearing clearance?
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06-03-2021, 06:31 PM | #10 |
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Re: Rear main bearing cap oil return line question
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06-02-2021, 11:00 AM | #11 |
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Re: Rear main bearing cap oil return line question
Is the crankcase free to breathe? If the oil cap is pressed on too far or something else restricting free venting of the crankcase, it will push oil out the rear main. Not that you haven't found another cause but restricted venting will confound any repairs that you make.
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06-03-2021, 06:22 PM | #12 | |
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Re: Rear main bearing cap oil return line question
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06-02-2021, 11:07 AM | #13 |
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Re: Rear main bearing cap oil return line question
For those who may not be familiar ...
Also the end of the tube must be long enough to go below the lowest level of the oil (like when a quart or more low) in the pan in order to prevent back pressure from forcing oil out the rear main. Tubes are 4 inches long end to end as I remember. Last edited by Benson; 06-02-2021 at 11:21 AM. |
06-02-2021, 11:17 AM | #14 |
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Re: Rear main bearing cap oil return line question
I was told many years ago by an engine builder to be sure the drain pipe does not go into the cap too far.
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06-02-2021, 08:56 PM | #15 |
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Re: Rear main bearing cap oil return line question
deleted
Last edited by cars2cool; 06-03-2021 at 06:26 PM. Reason: deleted |
06-03-2021, 06:24 PM | #16 |
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Re: Rear main bearing cap oil return line question
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06-04-2021, 09:31 AM | #17 | ||
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Re: Rear main bearing cap oil return line question
Quote:
Quote:
My opinion on this is the welch plug needs to be removed and that area fully cleaned using a bore brush and flushed. Next, forget about a Vee-notch in the tube and install it the correct way. The Vee or a notched groove tends to make a dam that only creates issues, -especially if some debris was to get into the galley there. If the tube's threads are loose in the cap, either use JB Weld or Loctite 620 to hold the tube in the correct location. The correct location is determined by sighting into the hole where the welch plug seals and making it as-close to flush as possible and still be oriented the proper way at the tube's exit. |
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06-05-2021, 06:00 PM | #18 | |
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Re: Rear main bearing cap oil return line question
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06-05-2021, 06:03 PM | #19 | |
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Re: Rear main bearing cap oil return line question
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