02-11-2015, 03:06 PM | #1 |
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Oil drain tube
I have a pretty good leak at the back of my engine. I read something about the possibility of the drain tube on the rear main may be plugged. I see in Les Andrews' book that the drain tube is threaded. Can this drain tube be unscrewed without dropping the main bearing cap? John
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02-11-2015, 03:21 PM | #2 |
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Re: Oil drain tube
Tube is threaded but usually "spot welded" to prevent it backing out and ending up in the bottom of your oil pan.
Joe K
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02-11-2015, 03:36 PM | #3 |
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Re: Oil drain tube
Thanks, John
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02-11-2015, 03:56 PM | #4 |
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Re: Oil drain tube
Yeah, you can unthread it easily. I put blue thread lock on mine. Some ,probably most , do not use anything. Even if a spot of 'weld' is present, you can remove it and then unscrew it.
BTW...stick something up thru tube after unscrewing it...to ensure that it is clean. Mine would let air pass thru, but was still about half crudded closed. caveat: the tube/pipe threads are very fine and prone to being cross threaded. Use patience/caution to thread back into cap . Last edited by hardtimes; 02-11-2015 at 03:58 PM. Reason: .......... |
02-11-2015, 04:34 PM | #5 |
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Re: Oil drain tube
thanks, John
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02-12-2015, 09:46 AM | #6 |
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Re: Oil drain tube
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02-12-2015, 11:43 AM | #7 |
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Re: Oil drain tube
Several years ago I also had a bad leak at the back of the engine. I removed the oil pan and looked at that tube and found that the previous owner had squeezed the tube and dropped a ball bearing down the tube to restrict the oil flow. I removed the tube and no more leaks. Ed
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02-12-2015, 11:45 AM | #8 |
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Re: Oil drain tube
I forgot to say I took the ball bearing out and replaced the tube. Ed
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02-12-2015, 12:52 PM | #9 |
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Re: Oil drain tube
That ball bearing'ed tube may have been a factory install on an engine headed for AA truck use.
The Service Bulletins describe the one-way drain tube variant for "trucks in service where the angle of incline is found regularly greater than 15 degrees" or some such descriptive. Sort of the reverse of the cotter pin in the flywheel housing IMHO. I expect a LOT of these were removed/retro'ed after getting plugged up on the ball. Joe K
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02-12-2015, 05:14 PM | #10 |
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Re: Oil drain tube
I dropped the pan today and inspected the oil drain tube. The engine appears to have been rebuilt. The drain tube looks like a replacement type (pipe nipple about 2 1/2 inches long). It was in so tight that I had to remove it with vise grips. I am hoping that Bob Bionde is correct about it being in too much. I was able to blow air through the opening, and it appears to be clear. There is absolutely no sludge in the engine or valve galley. Once I get the pan and oil pump back on, I will let you know if the problem is corrected. Thanks to all. John
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02-12-2015, 06:10 PM | #11 |
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Re: Oil drain tube
2 1/2" sounds a little short..........isn't it? I'll have to see if I have a spare original tube to measure.
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02-12-2015, 06:11 PM | #12 | |
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Re: Oil drain tube
Quote:
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02-12-2015, 06:37 PM | #13 |
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Re: Oil drain tube
Mine is definitely a brass pipe nipple. I looked at Snyders' catalog and their tube has a bend in it, but I can't tell the length. I will check with them tomorrow. By looking in the catalog, and comparing the picture with my tube, mine seems to be shorter than the longer part of theirs before the bend. Guess I'll have to call them. John
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02-12-2015, 07:44 PM | #14 | |
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Re: Oil drain tube
Quote:
A-6328-A -- Pipe assy (crankshaft rear bearing oil) - ball check type - 5/16" O.D. 1 required Pass, Comm & Truck (4 cyl) 1928-30 A-6328-B -- Pipe assy (crankshaft rear bearing oil) - ball check type - 3/8" O.D. 1 required Pass, Comm & Truck (4 cyl) 1930-31 |
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02-12-2015, 08:04 PM | #15 | |
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Re: Oil drain tube
Quote:
You mean yours does not have a bend and the entire pipe is made of brass? |
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02-12-2015, 08:08 PM | #16 |
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Re: Oil drain tube
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02-12-2015, 10:57 PM | #17 |
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Re: Oil drain tube
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02-13-2015, 08:50 AM | #18 |
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Re: Oil drain tube
I ordered he drain tube today. I am assuming he bend is toward the front of the engine so that it sits in the dripper tray. Is this correct? John
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02-13-2015, 01:24 PM | #19 |
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Re: Oil drain tube
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02-13-2015, 07:39 PM | #20 |
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Re: Oil drain tube
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