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MGA/MGB Engine dirt trap
#1
dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
MGA/MGB Engine dirt trap

There have been several threads regarding dirt in fresh engine rebuilds.

The MGA/MGB oil pump drive gear shaft has a drilling in the upper end that feeds oil from the block to two small horizontal holes in the shaft above the gear. In the process of evaluating several used OP drive gear shafts we discovered that several shafts had completely plugged up oil drillings. These OP drive shafts had been hot tanked and pressure washed.

The upper shaft feed 1/8” diameter x 1/2” long drillings yielded a lot of debris. On some of the gears the tiny horizontal holes were open but the larger vertical hole was totally plugged with goop.

The vertical drillings were cleaned out with small brushes and a large amount of sediment and debris was removed, some was metallic. The horizontal holes were then cleaned with a .023” welding wire and all was visually inspected.


Be safe out there.
Kenny


Attachments:
OP Drive oil drillings.JPG    37.3 KB
OP Drive oil drillings.JPG

OP Drive vertical drilling.JPG    13.5 KB
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OP Drive horizontal drilling.JPG    18.6 KB
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Re: MGA/MGB Engine dirt trap
#2
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MGB567 Barrie Braxton
Ninderry, KabiKabi country, Queensland, Australia   AUS
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1966 MG MGB MkI "Money Guzzler"
1979 MG MGB GT V8 Conversion "Darkside"
Thanks Kenny; another thing I can check when it comes to rebuild (I'm one you're referring to in your 2nd line) but my OP is new. I wondered if the holes got blocked with assembly grease but then that's miscible but I'm going to check anyway.


Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Lots more as I did a nut and bolt rebuild; finished 2015. Tartan Red.

GT: December '78. VW Golf guards, flush fit front and rear valances. Torana XU1 vents, frenched indicators & Mk1 rear lights. 'Worked' Rover V8 with Monsoon ECU for EFI. GM4L60E, Lokar tiptronic & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.

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Re: MGA/MGB Engine dirt trap
#3
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fast-MG.com Dave Headley
Cortez, 4 corners, Colorado, USA   USA
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Barrie, it's not the pump, it's the drive spindle which doesn't come with a new pump and the old one gets re-used.

Kenny, good info, thanx for posting. BTW, there are two different spindles with different size holes.

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Re: MGA/MGB Engine dirt trap
#4
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riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
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1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
Good post Kenny, thanks for sharing.
This is an easy one to overlook, came across it by chance on my rebuild.

B


Life's most persistent and urgent question is, "What are you doing for others?"

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Re: MGA/MGB Engine dirt trap
#5
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dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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In reply to # 2664161 by fast-MG.com Kenny, good info, thanx for posting. BTW, there are two different spindles with different size holes.

Dave,

Have you observed any correlation between the two different spindles and failure of the oil pump drive gear? Is it possible/likely that those with the larger holes fail less frequently?

Dick


Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: MGA/MGB Engine dirt trap
#6
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fast-MG.com Dave Headley
Cortez, 4 corners, Colorado, USA   USA
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Dick, no. It's only recently that I became aware of the two different size holes.

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Re: MGA/MGB Engine dirt trap
#7
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dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Dave said, "BTW, there are two different spindles with different size holes."

Dave is correct. I have 12 oil pump drive spindles and one of the 12 has the large hole (pictured).

I don't know what engine the large hole spindle came from.


Be safe out there.
Kenny


Attachments:
Drive gear oil holes.JPG    36.7 KB
Drive gear oil holes.JPG

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Re: MGA/MGB Engine dirt trap
#8
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dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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In reply to # 2664490 by dipstick Dave said, "BTW, there are two different spindles with different size holes."

Dave is correct. I have 12 oil pump drive spindles and one of the 12 has the large hole (pictured).

I don't know what engine the large hole spindle came from.

Thanks for posting, Kenny. Do you have any anecdotal evidence as to failure rate with one versus the other?

Dick


Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: MGA/MGB Engine dirt trap
#9
MGB567 Avatar
MGB567 Barrie Braxton
Ninderry, KabiKabi country, Queensland, Australia   AUS
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1966 MG MGB MkI "Money Guzzler"
1979 MG MGB GT V8 Conversion "Darkside"
@ #3 - thanks Dave. I knew I bought a new pump back when I was buying almost everything without regard of whether the original was serviceable or not (I'm a little more circumspect today) and forgot I didn't buy a drive (same for the distributor drive) so I'll be doubly sure to check the hole in my oil pump drive given Kenny's topic.


Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Lots more as I did a nut and bolt rebuild; finished 2015. Tartan Red.

GT: December '78. VW Golf guards, flush fit front and rear valances. Torana XU1 vents, frenched indicators & Mk1 rear lights. 'Worked' Rover V8 with Monsoon ECU for EFI. GM4L60E, Lokar tiptronic & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.

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Re: MGA/MGB Engine dirt trap
#10
dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
There were two more oil pump drive spindles remaining to be cleaned up and both were totally plugged up. Just saying...


Be safe out there.
Kenny

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Re: MGA/MGB Engine dirt trap
#11
dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Dick said, "Do you have any anecdotal evidence as to failure rate with one versus the other?"

No, nothing. Yesterday from Dave's post I discovered the larger horizontal feed holes, never was aware of that before.


Be safe out there.
Kenny

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Re: MGA/MGB Engine dirt trap
#12
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dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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In reply to # 2664767 by dipstick Dick said, "Do you have any anecdotal evidence as to failure rate with one versus the other?"

No, nothing. Yesterday from Dave's post I discovered the larger horizontal feed holes, never was aware of that before.

Nor was I. It will be interesting to see if we can find any evidence that the design with the larger feed holes is less prone to failure. I'll also start watching as I disassemble cores to see if we can figure out when the change was made, and also whether it was made from larger to smaller or vice versa...

Dick


Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: MGA/MGB Engine dirt trap
#13
Steve S. Stephen Strange
Harrisonburg, VA, USA   USA
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1957 MG Magnette
1972 MG MGB MkII "The Mouse Trap"
What is the diameter of the larger hole?

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Re: MGA/MGB Engine dirt trap
#14
dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Stephen, "What is the diameter of the larger hole?"

I will check in the morning and reply. Kenny


Be safe out there.
Kenny

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Re: MGA/MGB Engine dirt trap
#15
Steve S. Stephen Strange
Harrisonburg, VA, USA   USA
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1957 MG Magnette
1972 MG MGB MkII "The Mouse Trap"
I did a quick check of the factory parts books. The oil pump drive spindle is listed as Part # 11G 12 until September of 1976. Unfortunately, my sources don't go any further. Of course, the factory parts books are notorious for their inaccuracies. From looking at the images that are posted on this BBS, the larger hole appears to have been drilled prior to machining the groove, so it might not be an owner modification. But then again, the groove seems to be wider, so the mystery deepens.........

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