I cannot find my SN to save my life!!

[deerhuntre]

I have a new to me 1972 Cruiser's Inc. with a Mercruiser 165 inline 6. I've looked above and all around the starter motor and do not see any tag or other indication of a serial number. I also cannot find any serial number or tag on the outdrive either. Did all these motors have the SN affixed in a way that it should still be there or was the tag removable? Is it plausible its not there?

So, the motor has 2018 champion plugs in it, but I want to verify that's the right one, as this motor apparently could also have used plug RN5C.

Are there any other clues to help me figure out the approximate year of this motor so I can get the right parts for it?

By the way, this is my first I/O and so far I really like it. The Mercury manual arrive yesterday and I can't seem to put it down!!

 

[Bt Doctur]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

can aslo use #44 or #45 plug. serial number should be in the rectangular area on the port side of the upper drive. May have to remove the decal and scrape .Most drive parts are NLA, so brake things carefully

 

[deerhuntre]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

Thank you...for the warning and the info!!

What are people doing if parts break/wear out on the drive? Are there other drives that can be used?

 

[Bt Doctur]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

upper gearset NLA
lower driveshaft NLA 8 spline vs 13 spline
complete drive with the correct ratio can be swapped with the correct length input shaft

 

[deerhuntre]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

Good to know.

Any suggestions for verifying the age of the motor?

 

[Bt Doctur]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

if all original , using the 13/16 ths size spark plug, I`d say 1972 vintage

 

[deerhuntre]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

I'm not sure I understand: I used a 5/8" socket to remove the spark plug.

 

[Don S]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

Remove a spark plug and look at the seat in the head. Is it tapered or flat?

 

[deerhuntre]

Re: I cannot fine my SN to save my life!!

Re: I cannot fine my SN to save my life!!

I think it looks flat, but I'm not sure what I'm looking at. Here's a photo. If you can't tell from this picture I can try to get a better one. You can also download the full resolution picture so you can zoom in your view. The picture is located at http://thedubins.com/showntell/IMG_4338.JPG.

The threads certainly look like they are for the shorter plug...the two possiblitites look like long threaded flat or short threaded tapered.