Logo
FULL SITE MENU

Mercruiser 165 inline 6 1977 or 78 Serial Number

P

PeterDE

Member
Well, I thought I knew the answer to this but apparently I don't and I read through a lot of threads and did not find an answer.

I recently replaced the 72 Mercruiser 165 6 cyl, I had in my Sea Ray (it died) with the same engine out of a 1978 boat. So the engine is either a 77 or 78. model. The problem? The engine serial number plate is missing. I have read through the service manual and can find no information on any other location for the serial number. It is not the same as the one on the sterndrive because that is the old engine number. It is not on the Flame Arrester (the old engine had the engine serial number on the Flame Arrester) And it's not on the valve cover.

So is there some other place.

Or should I just order parts using the old engine number and take my chances? I need to replace the two solenoids. Are they the same? One list I looked at gave two different part numbers for pre 78 and 78 and up.
 
I think you will be fine.....you may need to make minor adjustments but they shouldn't 't be significant...

You can always use the parts diagrams available at the top of the www page and do a comparison if you are worried about it....

its been a while but when we had one of those (originally the 160hp version), the only significant delta between it and the newer 165 was the carb and the combo manifold...
 
Thanks for the reply. I am surprised they didn't put the serial number in more than one place, especially on a plate that can be removed?
Basically that's what I did. I have narrowed down the range of serial numbers based on the model year. I used the originally parts diagrams to get the original Mercruiser parts numbers and went from there. I agree, there's not a lot of difference. The 77 has a different fuel pump, and carburetor, but everything else seems to be the same as the 72 I had before. I don't know why they changed those two parts, but I would be willing to bet that the fuel pump and the 2CV carb would work just fine. The Wiring diagrams are the same and the fuel system as well.
 
Mercruiser typically rivited a metal tag with serial number to engine casting above the starter.

Not 100% sure on '72 or ' 77 but newer from '80 up anyway all have them.

If block was ever replaced then its a chance it was not transfered as it should have been.
 
PeterDE said:
.... . The 77 has a different fuel pump, and carburetor, but everything else seems to be the same as the 72 I had before....
Click to expand...

Yes, you jarred my memory on the fuel pump...our 160 had the old original pump which had a clear bowl on it.....I believe the shop providing the replacement said the new one was a redesign for safety considerations.....so that is consistent to me.....
 
The metal tag is gone. The rivet is still there. The glassbowls went out because they could break and leak. The newer ones are design to not leak. If the diaphragm develops a hole then some have a second diaphragm, others have a containment bowl that keeps fuel from leaking into the boat. Plus they had to meet a 2 1/2 minute fire test which automotive fuels pumps don't have to meet and glass bowls can't meet. Anyway, both the 72 and 77 had marine fuel pumps, but they are different types. I think the 77 is a double diaphragm pump and it has a different style filter built in than the 72 one.

According to the person I bought the engine from it's original to his 78 Fiberform, but he doesn't know what happened to the tag and he doesn't know the serial number.
 
Back
Top