1980-1981? Mercury 140HP S/N 5739168

[GT1000000]

Hello Fellow Boaters,
Thanks for existing, I am a super NOOB to boating and this site has already answered many questions.
I just purchased my first new USED boat and am in the process of getting it ready for fishing.
It is a 1988 Glasstream with a 140HP Mercury O/B.
I purchased the Seloc Manual for the engine, and am going through it.
I could not find the build plate anywhere, but according to the Seloc Manual, the engine serial number is embossed on the powerhead. After removing some covers, I found what looks to be a good number, but would appreciate any "decoding" of it.
S/N 5739168
According to the manual, any Serial Number greater than 5625108 is a 140HP, 1980-1981, EL or ELPT.
I would also like to verify that the fuel/oil ratio IS 50:1??? And I can use any 2 cycle oil that is Rated TC-W3???
Thanks for any help.
Gus

[Chris1956]

Gas oil ratio is indeed 50::1. Any TCW-III oil is fine.

Check maxrules.com model guide for year of motor. I do not think the 140HPIL6 was made past 1979. How do you know it is 140HP? Inline sixes had HP range from 90 - 150 HP, in the 70s and 80s.

[GT1000000]

Check maxrules.com model guide for year of motor. I do not think the 140HPIL6 was made past 1979. How do you know it is 140HP? Inline sixes had HP range from 90 - 150 HP, in the 70s and 80s.

Thanks for the quick response...

According to the Serial Number Chart, and the Seloc Manual, the 140HP Inline 6, was made until 1981??

As for the HP, I am only guessing, because that is what the engine cover has on it...Looks to be original? It is the type that has a front cover with a twist-type lock, then then engine cover is a wrap around type with three hook clasps that hold it in place...I don't know if that helps...

That is why I was hoping the serial Number could be decoded by someone...

[79Merc80]

The number you posted shows it as an 1980/81. There was no changes between those 2 years and they show as the same.

[GT1000000]

BTW, according to the Seloc manual...the serial number is supposed to be on the top of the powerhead...after removing most of the coverings around the powerhead, the number I found was located on the port side, approximately between the number 1 and 2 cylinders. It was the only number that even remotely looked like a serial number...I hope it is correct...If anyone knows differently, Please, advise...Thanks,gt.

[Chris1956]

You mean the starboard side? The port side has the exhaust cover on it

[GT1000000]

You mean the starboard side? The port side has the exhaust cover on it

Hi Chris1956, As I stand at the rear or stern of the boat, looking forward to the bow, the number I found is on the port or left side of the engine. If I am incorrect, please, advise. Thanks,gt.

[carholme]

GT;

Are you sure that it is a Mercury 140 as mercurypartsexpress shows that s/n as a 90/115 and the model number says it is a:

7115640 MARINER 1980 115

Gerry

[GT1000000]

GT;

Are you sure that it is a Mercury 140 as mercurypartsexpress shows that s/n as a 90/115 and the model number says it is a:

7115640 MARINER 1980 115

Gerry

Hello Gerry,

To be quite honest, I am only sure of death and taxes...

As for the serial number, the sources I have checked, list both U.S. and Canadian numbers. You may have gotten that listing from mercurypartsexpress, because you are looking up a part in Canada, instead of the U.S.??? Maybe? As far as I can tell, this is a U.S. number on my engine.

I am still trying to make sure of two things...
1- Did I get the correct number off of the engine in the first place ?, and...
2- What are the specifics of that number, as in the decoding of it ?

Best Regards,gt

[carholme]

Well that looks like a valid s/n and the search engine does not care where the engine was made, if it is in the database, it will come up and clearly identify what engine it is. There is no decoding of the s/n other than engines of your era were roughly broken down by the first number, eg;

Canada 7

Australia 8

Belgium 9

USA lower than 7

However, I leave it up to you and good luck with it

Gerry

[GT1000000]

Gerry,

I must first say thank you for your information! The more I try to get information, the more confusing things get...

I have entered my serial number into the mercurypartsexpress and tried every concievable prefix of 1's and 0's and you sir, are correct. The only engine that comes up with that serial number, plus a 0, added to the front of it, is the 90/115 HP Inline... The few diagrams that are shown do indeed look just like my engine.

I am going to attempt to contact Mercury Marine directly and try to get this verified.

I am still quite confused because of the Engine Cowling {looks original and has the Mercury Decal around the mid section and the 140HP decal just below that} and a couple of other sources listing that engine as a 140HP...Personally I don't care if it is a 90 or 115 or 140 HP engine...I just want to make sure that I get the right parts for it.

Most Confused,gt.

[GT1000000]

I have contacted Mercury Marine with the Serial Number and they have confirmed that the powerhead is from a Mariner 115 HP...
However, it turns out the rest of the engine is bit of a "Frankenstein"...

I had my neighbor, who is a Mercury mechanic, who knew?, come and check it out...

He confirmed the powerhead as being a Mariner, but the shaft is originally from a 140 HP inline, circa late 70's...and the Lower Unit is from an unknown Mercury of a larger displacement with an interesting water intake [he has personally never seen this type of configuration]...

As soon as I can figure out how to post some pics, I will...

Thanks to all for your help and understanding...

Good Fishing and Smooth Sailing,gt.

[Joeshow]

Hey, I just got the manual for my '80 115 and noticed both '80 and '81 90, 115 and 140hp all had the same bore, stroke, carb, timing and wiring! The only differences I've seen are carb jets! I'm wondering if the exhaust is different? It's pretty interesting!

Good luck!

[jimmbo]

This comes up ever 2 or 3 weeks. Yes the carb jets are different. So are the carbs, blocks, reed valve blocks and reeds, pistons, and exhaust tuners too. It gets confusing comparing crank rated 90s and 115s to prop rated 90s and 115s. Then the rumour that prop rated 115 is the old crank rated 140 comes up. One of the most knowledgeable persons regarding Inline sixes was a gent called Clams Canino.

[Joeshow]

Oh ok sorry!! I'm a newbie to these engines.. Yeah it's a bit of a pain that they went from crank to prop ratings!!
Its too bad that fellas not around anymore!

GT, did ya get her in the water?!