G3 oil pump guide pin screw/body
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G3 oil pump guide pin screw/body
I am in the process to complete my G3 which was partly restored by the previous owner. By chance I noticed that the guide pin screw does not abut against the boss (I could see about 8mm of thread). First idea was that the previous owner might have missed to screw it fully home. But the screw was quite tight, obviously tightened with a spanner. To make sure that incorrect positioning of the guide pin (collision with plunger) wasnt the reason, I unscrewed it and took the guide pin off. But surprise, surprise: Even without the guide pin it wasnt possible to screw it fully home, same result as before - about 8mm of thread visible. It would be very helpful if anybody experienced this or could give me hints, ideas solutions etc.
Thank you very much, Peter
Thank you very much, Peter
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Re: G3 oil pump guide pin screw/body
This is my G3 engine. The pump guide pin screw screws in fully.
NOTE.... The red fibre washer should NOT be there and was subsequently removed.
NOTE.... The red fibre washer should NOT be there and was subsequently removed.
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Re: G3 oil pump guide pin screw/body
Hi Peter
Why not compare the depth of the hole in the crank case and the length of the thread on the guide screw thread? - this should indicate whether the crank case thread is damaged or the guide screw is the incorrect length.
Does your guide screw match the design of the one shown in the manual?
Do you have the tooling to identify the thread?
Regards Mick
Why not compare the depth of the hole in the crank case and the length of the thread on the guide screw thread? - this should indicate whether the crank case thread is damaged or the guide screw is the incorrect length.
Does your guide screw match the design of the one shown in the manual?
Do you have the tooling to identify the thread?
Regards Mick
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Re: G3 oil pump guide pin screw/body
Welcome to the Forum, Peter.
What year is your engine?
In 1947 the guide pin diameter was increased from 3/16" to 1/4".
The Guide Pin and the Guide Pin Screw (the pin holder) both have completely different part numbers to those of the earlier (pre-1947) engines.
You say it was 'partly restored' ( ) by the previous owner so maybe, (depending upon the year of your engine), you have the wrong Guide Pin Screw? If so, you will have the wrong Guide Pin as well.
This is the assembly for 1947 and later engines. No dimensions unfortunately but it looks longer than the screw in Mick D's photo above......
What year is your engine?
In 1947 the guide pin diameter was increased from 3/16" to 1/4".
The Guide Pin and the Guide Pin Screw (the pin holder) both have completely different part numbers to those of the earlier (pre-1947) engines.
You say it was 'partly restored' ( ) by the previous owner so maybe, (depending upon the year of your engine), you have the wrong Guide Pin Screw? If so, you will have the wrong Guide Pin as well.
This is the assembly for 1947 and later engines. No dimensions unfortunately but it looks longer than the screw in Mick D's photo above......
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Re: G3 oil pump guide pin screw/body
Hi Peter. It would help to identify the year of your G3. And welcome.
clive
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if it ain't broke don't fix
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Re: G3 oil pump guide pin screw/body
Thank you all for your prompt replies.
Sorry for not providing the year, engine no as per the stamp on the crankcase is: 56/16MS28374.
I measured the diameter of the guide pin: 6.4mm (~1/4"). Guide pin screw measurements: Overall length 26mm, head height 8mm, thread length 15mm, and 3mm bare/without thread (smaller in diameter compared to thread, there is no shoulder between thread and head). Thread size, outer dia. is 9.5mm which I believe is a 3/8" thread. I dont have the tooling to verify the thread, but hopefully the 3/8" estimate is ok.
I will also try to compare the depth of the hole and the length of the thread.
Unfortunately I wasnt able to upload an image showing "my" guide pin screw so you could check the design. Any approval needed for uploads, or where is the magic button?
When looking at the above measurements, do you think I have the correct guide pin screw???
Regards, Peter
Sorry for not providing the year, engine no as per the stamp on the crankcase is: 56/16MS28374.
I measured the diameter of the guide pin: 6.4mm (~1/4"). Guide pin screw measurements: Overall length 26mm, head height 8mm, thread length 15mm, and 3mm bare/without thread (smaller in diameter compared to thread, there is no shoulder between thread and head). Thread size, outer dia. is 9.5mm which I believe is a 3/8" thread. I dont have the tooling to verify the thread, but hopefully the 3/8" estimate is ok.
I will also try to compare the depth of the hole and the length of the thread.
Unfortunately I wasnt able to upload an image showing "my" guide pin screw so you could check the design. Any approval needed for uploads, or where is the magic button?
When looking at the above measurements, do you think I have the correct guide pin screw???
Regards, Peter
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Re: G3 oil pump guide pin screw/body
Hello,
Please see image - "my" guide pin and screw/Body. Can you please check the design of the screw and let me know your comments etc.
Thank you ...
Regards, Peter
Please see image - "my" guide pin and screw/Body. Can you please check the design of the screw and let me know your comments etc.
Thank you ...
Regards, Peter
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- clive
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Re: G3 oil pump guide pin screw/body
Both the pin and body look correct for a 56 single to me. The stepped section goes into the holder. So if the holder does not screw home without the pin the logical conclusion is that the thread is damaged. May well be recoverable with a tap (cannot help with the thread form). I would grease the tap to try to pick up the swarf reversing it out and cleaning and regreasing regularly and clean up throughly afterwards. Someone else may be able to help with the thread.
clive
if it ain't broke don't fix
if it ain't broke don't fix
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Re: G3 oil pump guide pin screw/body
Hi
The thread in the photo is 3/8" x 24 TPI which is a standard UNF thread and I'm pretty sure that's correct for the engine.
I'd have a look up the hole in the crank case with the aid of a strong flashlight and mirror before I introduced a plug tap, there may be something obvious blocking the thread or the travel of the guide pin.
Regards Mick
The thread in the photo is 3/8" x 24 TPI which is a standard UNF thread and I'm pretty sure that's correct for the engine.
I'd have a look up the hole in the crank case with the aid of a strong flashlight and mirror before I introduced a plug tap, there may be something obvious blocking the thread or the travel of the guide pin.
Regards Mick
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Re: G3 oil pump guide pin screw/body
Hello,
I will follow your hints later today or tomorrow by trying to look up the hole with a flashlight/mirror (tricky enough because the engine is still in the frame and proper positioning seems difficult).
Regards, Peter
I will follow your hints later today or tomorrow by trying to look up the hole with a flashlight/mirror (tricky enough because the engine is still in the frame and proper positioning seems difficult).
Regards, Peter