Replacing head gasket

[Arent-ned508]

Hi,

I'm replacing the head gasket on a OMC Zephyr two-stroke engine.
This engine is based on a Evinrude powerhead, I believe a 35hp.
I found a new gasket, but I'm still trying to find out how much torque I need on the gasket bolts, to get everything back the right way.

Does anyone have an idea?

Gr, Arent

 

[F_R]

Re: Replacing head gasket

?? What year 35hp are we talking about? When I hear Zephyr, I think 5.4hp 4 cylinder from the '40s.

 

[wbeaton]

Re: Replacing head gasket

Ditto. Never heard of any other Zephyr and it could not be mistaken for a 35 hp.

 

[Arent-ned508]

Re: Replacing head gasket

Right,

I can understand the confusion, this is a rather rare engine. And I was mistaken about the hp, it's not a 35hp
A little extra info:

The Sail Drive (also known as the OMC Zephyr) was built from 1977 thru 1984. It utilizes a 32 cubic inch powerhead (which commonly powers the 20/25/30 hp outboards).

The sail drive is a rather unique animal. The powerhead is "inboard" and the hull has a hole cut into it where the mid-section and gearcase end up sticking thru the bottom of the hull. I don't believe the unit pivots to provide steering, therefore steering is handled by the boat's rudder. It does use the same powerhead as the JohnnyRude 20-30 hp outboards, but it's hp is "de-rated" - the larger displacement block provides better thrust for moving large sail boats. Hope this helps your understanding of the Sail Drive a little.

I do hope it helps Mine is built around 1980, engine code is 15S10S, built by OMC that is.... I'm on this part of the forum, because of the Evinrude powerhead.

Thing is, I could buy a manual, but that covers the whole range of engines from 2-40hp and fron '73 to ?? all for a lot of money. Just need the torque and I'm fine for now

 

[Arent-ned508]

Re: Replacing head gasket

Hi,

On another forum, someone suggests 180 in-lbs, does that mean anything to you?
It is based on the 35hp.... so not completely accurate :-(

Gr, Arent

 

[ezeke]

Re: Replacing head gasket

Don't want to confuse matters but the model numbers for the Sail Drive Zephyrs are as follows, and they are 15HP motors:

[FONT=Arial,Bold]Model Number HP Year[/FONT]
15S10G 15 1977
15S10S 15 1977
15S11C 15 1978
15S13A 15 1980-82
15S14M 15 1983
15S14R 15 1984

In the 1982 service manual, both the 15HP and the 25-30-35HP list the cylinder head torque as 18 to 20 FT. LBS.

,​

 

[Arent-ned508]

Re: Replacing head gasket

Thanks, this is getting clearer Nothing confusing about the codes and production date. 1977 is around 1980 as I claimed All other engines can claim the same :-D sorry for not being really accurate....

Only confusing thing for a european like me is the torque. We measure in Nm (thats Newtonmeter). I found an easy digital way to change in.lbs to Nm, and someone suggested multiplying ft.lbs by 1.36 to get Nm, but I'm not completely sure now....

Gr, Arent

 

[ezeke]

Re: Replacing head gasket

18-20 ft lb = 24-27 N-m, so that formula is correct.

 

[Arent-ned508]

Re: Replacing head gasket

Thanks, should be fine now!