Engine Knocking Noise From Oil Pump Area |
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gmar45
Member Joined: 27 Jan. 2022 Location: Michigan Status: Offline Points: 19 |
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Posted: 28 Jan. 2022 at 10:10am |
We have a 1946 Jeep which has an intermittent knocking sound coming from the left rear of the engine block and particularly on the oil pump.
When standing beside the engine it sounds like a rod knocking at idle. We used a long screwdriver as a "stethoscope" and found the noise to be worse around the left rear of the engine block and oil pump. The engine was rebuilt by a reputable engine builder several years ago, and has minimal hours on it since then. The knocking noise has just recently started happening, and it is intermittent. Oil pressure is around 65 psi cold, and 55 psi hot (I think it was around 45 psi hot at idle). We are thinking about taking the oil pump off to see if there is an issue with the oil pump, oil pump drive shaft, etc. But before we do that I thought I would ask the forum if they have any suggestions on what we should look for. Has anyone had this issue before? Does anyone have any suggestions on what to look for? Gene
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Oldpappy
Member Joined: 09 Apr. 2018 Location: Tennessee Status: Offline Points: 4905 |
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Well, I can't stand beside it and listen, but you have done the same thing I would do in trying to isolate the source of the knock.
That is good oil pressure, but there is still a possibility something is not within spec on the pump. Since it is not a big job to pull the oil pump, were it mine I would pull it and inspect it making sure all tolerances are in spec. Or replace it with a quality new pump and see if the noise goes away. When you reinstall the oil pump it is a good practice to prime the pump by packing the pump with light grease or Vaseline which is supposed to act as priming, others may know more about this, but it sounds reasonable. I had a mystery knock in one of these engines many years ago that had me, and all my other mechanic friends entirely stumped for quite a while. The noise would sometimes appear to come from the rear of the engine, sometimes from the front. After a lot of fooling around with it I finally pulled the timing cover and found that the cam gear had been installed without the bolt and washer, and some play had developed with the fit of the woodruff key in the shaft. Not saying this has anything to do with your issue, just saying the source of an intermittent noise can be very difficult to isolate.
Edited by Oldpappy - 28 Jan. 2022 at 3:42pm |
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If you can't get there in a Jeep you don't need to be there!
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Mark W.
Member Sponsor Member Joined: 09 Nov. 2014 Location: Silverton, OR Status: Offline Points: 7982 |
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You can not spin the pump on a 134L or F with a drill when its installed as it will be geared to the Cam. DO NOT TRY it can only cause damage. |
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Chug A Lug
1948 2A Body Customized 1949 3A W/S 1957 CJ5 Frame Modified Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962 |
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Oldpappy
Member Joined: 09 Apr. 2018 Location: Tennessee Status: Offline Points: 4905 |
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Mark is correct, the gear on these is on the oil pump and not the distributor. It has been more than 30 years since I built one of these engines and I was probably confusing it with priming a small block Ford or Chevy. Senior moment.
I have edited my previous post to remove the erroneous suggestion to avoid anyone attempting to do that. Edited by Oldpappy - 28 Jan. 2022 at 1:42pm |
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If you can't get there in a Jeep you don't need to be there!
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9651 |
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The oil pump is a rotary device, not a reciprocating one. There is nothing in it to produce a knock, except for the slight possibility of a loose drive gear or a loose impeller, neither of which have I ever seen. But it costs almost nothing to R&R the pump, so go ahead and have a look.
A rod bearing can be an intermittent thing, especially if both halves of the bearing have gotten on the same side. While it’s knocking, try accelerating the engine a little bit then let it snap back to idle. If the knock doubles up or gets louder on acceleration and quiets on deceleration, it’s probably a rod knock. While it’s knocking at idle, short or disconnect one spark plug wire at a time. If the knock goes away or decreases, probably a rod knock. I’d suspect #3. “Rebuilt several years ago and has minimal miles” Has it been sitting a long time? A rod bearing can stick to the crankshaft and then be “spun” or turned when the engine is cranked. There are other possibilities. Like Oldpappy said, I wish I could stand next to it and hear it. Good Luck. BW
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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Oldpappy
Member Joined: 09 Apr. 2018 Location: Tennessee Status: Offline Points: 4905 |
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I was wondering if a worn out bushing in the oil pump might make some noise, but that may not be likely, unless the retainer clip is missing.
Edited by Oldpappy - 28 Jan. 2022 at 3:48pm |
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If you can't get there in a Jeep you don't need to be there!
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gmar45
Member Joined: 27 Jan. 2022 Location: Michigan Status: Offline Points: 19 |
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Thanks to everyone for the comments.
Oldpappy, Yeah, this might be a tough one to track down. I appreciate hearing your experience on this. I am familiar with priming a small block Chevy with an old distributor which has the drive gear ground off it, but I understand what you and Mark W. are saying about not being able to do this since the drive gear is on the oil pump shaft of this engine. Bruce W., Thanks for the information. I think that we will pull the oil pump off and inspect it, then go from there. Thanks again to everyone for your comments. I will let you know what we find out. Thanks, Gene
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Steelyard Blues
Member Joined: 09 Oct. 2017 Location: Reno, NV Status: Offline Points: 1497 |
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Gene,
Since the pan is so easy to remove. I would suggest dropping the pan and take a look inside for something obvious. I recommend the Fel-Pro gasket;
Edited by Steelyard Blues - 03 Feb. 2022 at 9:11pm |
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1947 CJ2A 106327, Engine J109205, Tub 97077. Luzon Red
https://www.thecj2apage.com/forums/steelyard-blues_topic41024_post397981.html?KW=micah+movie#397981 1965 Johnson Furnace Company M416 #6-1577 |
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9651 |
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There’s an oil gallery plug inside, just behind the oil pump in the main gallery. It should have a lo-profile, slotted-screw type head or a modern hex socket head. A normal pipe plug may stick out far enough to be struck by a crankshaft counterweight. I would think that it would make noise from the get-go, but I reckon it’s a possibility.
BW
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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