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1980 15hp head bolt torque spec

Re: 15 hp head bolt torque spec

Merc didn't build a 15 horse in 1980, so must assume it's a Yamaha/Mariner - and the Merc/Mariners were headless.

So if it is the "made in Japan" version the head is torqued down in two stages.

First round torque down to 5.8 ft pounds, then second round all torqued down to 12 ft pounds. Use NO sealant between the gasket and the surfaces.

The bolts must be torqued in order (looking at the head from the back of the motor):

8 9
4 5
3 1 2
7 6
11 10
 
Re: 15 hp head bolt torque spec

That serial makes it a 1977 "A" model 15 horse which was a copy of Yamaha's own model P250A (called the 15A in the last couple years of production) built between 1972 and 1978.

The following year Yami and Merc both discontinued sales of that model and the 78-on 15 horse Yami/Mariners became carbon copies of the Yamaha model 15B which remained in production until 1989 when the Yamaha built 15 horse was scrapped from the line-up.

The heads were identical but numerous other parts are not compatable between the A and B models. So although you had an incorrect model year as long as you buy/bought parts based on the serial, you should be fine...
 
Re: 15 hp head bolt torque spec

I stated the motor after I torque down the head and I still have water in the head ,i see nothing wrong with the cylinder ,were is the water coming from
 
Re: 15 hp head bolt torque spec

The primary ways water could get in would be via a bad head gasket or in through an exhuast port.

If you have replaced the head gasket then look to the exhaust cover or powerhead base gasket as the culprit...
 
Re: 15 hp head bolt torque spec

I believe the "plate" you are talking about is the "inner" exhaust cover.

Was Merc part number 80760M - unfortunately, long discontinued along with most parts for this model (this model was last produced 32 years ago).

You can try a websearch using the part number - might be someone out there with "old stock" or you may find what you are after from a recycler (such as www.twincityoutboards.com - as one example)..
 
Re: 15 hp head bolt torque spec

Hi there i am new to this forum i were wondering what yr this mariner outboard might be as i am replacing the head gasket i am pretty sure it has made in Japan on the cowling but one can never be to sure.
684G L 333271 15ML.
Thank you in advance from Tasmania Downunder!
 
Hi there
Looking for torque specs on head gasket, side cover, and bottom gasket for this outboard 🙏 please………
MARINER 15
684C S 036382
Bottom right corner stamp is “K”

Made in JAPAN
 
galamb said:
Re: 15 hp head bolt torque spec

Merc didn't build a 15 horse in 1980, so must assume it's a Yamaha/Mariner - and the Merc/Mariners were headless.

So if it is the "made in Japan" version the head is torqued down in two stages.

First round torque down to 5.8 ft pounds, then second round all torqued down to 12 ft pounds. Use NO sealant between the gasket and the surfaces.

The bolts must be torqued in order (looking at the head from the back of the motor):

8 9
4 5
3 1 2
7 6
11 10
Click to expand...
That’s fantastic, hopefully it’s same for mine, engine plate 684C…… is there any specs for the side cover and bottom gasket cover? TIA
 
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