1973 OMC 140hp Sterndrive

[kmack180]

I just recently purchased a boat with 1973 OMC 140hp sterndrive and do not know about I/O. Doing some routine maintanance of changing plugs, oil and filters. I have a few questions. I would greatly appreciate if someone could please answer.

1) How do you change the oil in the intermediate housing. I see the fill screw on the top port side, but do not see any drain plug.

2) To change the ball gear a major job?

3) Are props still available for it? It is a one inch smooth shaft?

4) Are there any do's or don'ts?

5) Anything I should change or be on the look out for?

6) What is the best way to flush the motor? The book said there is a flush kit adapter. Do you know if it is still avalible. I've been putting a container under it, which is a pain.


Thanks

 

[futz]

Re: 1973 OMC 140hp Sterndrive

1-port side under the intermediate , there is the drain plug.

2-Ball gears easy, get a manual.

3-yes ebay

4-always put water to the drive when running, always run the drive fully down.

5- the lower unit oil is specific to that lower unit.

6-ebay has them right now.

 

[WizeOne]

Re: 1973 OMC 140hp Sterndrive

Electric shift stringer intermediate housings do not have a drain for the drive shaft bearing oil resevoir. If you want to change it, you need to get a little bulb with a long skinny snout and suck it out. Not sure of the exact volume but it is a fairly small amount.

Other important DO/DON'T's

Do drive only with the drive in the full down position. It is not a trim system. Never exceed 10-15% up tilt, at low rpm, for shallow water emergencies only.

Never hold the down toggle until the outdrive goes CLUNK. You WILL end up spitting the sector shaft out into the briney deep. Bump the toggle down in stages until the drive is fully down. Also occasionally inspect the circlip and groove that holds the sector shaft plug in on the backside of the tilt gear box. The circlip should have been stainless but if the groove corroded, it could loose the clip and out she all goes when you least expect it. There was an accessory bracket that you added that would keep that plug from being spit out. I don't know if they are still available, I should have one.

Later drives had a cap that bolted on to the termination of the sector shaft passageway but your housing will not accept that.

 

[kmack180]

Re: 1973 OMC 140hp Sterndrive

Thanks,

The drain plug, is it that plug about 3/4 inch with an allen?

What specific oil to use? I used regular OMC lower unit oil.

I saw the prop on e-bay, but do they still make new ones, say Michigan Wheel? And would it be ok to put a stainless wheel on there. The prop I took off is a 14x16.

 

[grahamh]

Re: 1973 OMC 140hp Sterndrive

Like everyone said already, only put the boat in gear when the drive is all the way down.

Stringer drives like yours (and mine) have a bit of a bad reputation. So far mine's still good, but I haven't had it that long, so fingers crossed.

 

[KRH1326]

Re: 1973 OMC 140hp Sterndrive

I went through losing a sector shaft cap, and I fabbed up a SS piece that I retrofit to hold my cap.

Also with the electric shift, make real sure that all shifts are 500-600 rpm. PROTECT THE SLINKY!

 

[KRH1326]

Re: 1973 OMC 140hp Sterndrive

PS- Use "Type C" lube in the lower unit. I don't know the absolute real reason, but have been told that the "TYPE C" is an electrically stable oil. An electric shift (remember that is where the magnets and coils are) can supposedly act real strange ( I heard that forward can become reverse and vice verse ) without the type C.

 

[futz]

Re: 1973 OMC 140hp Sterndrive

wizeone says you don't have one. the latter models have them it looks just like a regular plug such as the lower unit ones. for sure not the allen head ones, flat head screw.

 

[WizeOne]

Re: 1973 OMC 140hp Sterndrive

PROTECT THE SLINKY!

Here, Here! I whole heartedly agree! Protect the Slinky at all costs.

 

[scottrbishop]

Re: 1973 OMC 140hp Sterndrive

Never hold the down toggle until the outdrive goes CLUNK. You WILL end up spitting the sector shaft out into the briney deep. Bump the toggle down in stages until the drive is fully down. Also occasionally inspect the circlip and groove that holds the sector shaft plug in on the backside of the tilt gear box. The circlip should have been stainless but if the groove corroded, it could loose the clip and out she all goes when you least expect it.

My OMC Stringer outdrive wants to drop all the way down (and make the aforementioned CLUNK) unless I hit the toggle back up periodically to "stop" the motor from continuing straight down. I am guessing/hoping this is abnormal, just corroded contacts on the tilt motor? Any other ideas? Will dropping it this way damage the outdrive? Thanks in advance!

 

[WizeOne]

Re: 1973 OMC 140hp Sterndrive

My OMC Stringer outdrive wants to drop all the way down (and make the aforementioned CLUNK) unless I hit the toggle back up periodically to "stop" the motor from continuing straight down. I am guessing/hoping this is abnormal, just corroded contacts on the tilt motor? Any other ideas? Will dropping it this way damage the outdrive? Thanks in advance!

I find it difficult to believe that one momentary blip on the down toggle will make the drive go all the way from top to bottom. If it does, I do not have a ready explanation for it. I will say this, if you hit the up toggle when the outdrive is physically moving down, you WILL eventually snap something.

I think you better look closer at this issue. I've never really counted but I probably blip my down toggle 2-3 times before the drive fully bottoms out. As such, the last blip only has to move the drive in a few degrees before it bottoms out and there is no real momentum behind it when it does.

 

[706jim]

Re: 1973 OMC 140hp Sterndrive

Ahhh; the infamous OMC "Devil Drive"!
I had one for 4 years on an 18' Starcraft Holiday.
Change the oil often. The intermediate housing in particular tends to generate "Mushroom soup".
Baby that trim down switch. Two or three short pokes should get it down without that major "Bang!"
NEVER run the unit tilted up. Those "Ball gears" will very quickly attempt to generate themselves into gears, which in practical terms, means that they will disintegrate almost instantaneously.
The spur gear that drives the tilt sector gear will eventually wear out the intermediate housing bearing surface. The tilt shaft then tends to bind and also lets water enter the worm gear housing. This can be repaired by bushing the intermediate housing (machine shop!) or replacing it if you can find one somewhere.

The only reason that your Devil Drive is still working is that it has had the fortune to be mated to the somewhat wimpy 4 cylinder engine. Major problems ensue when this drive is mated to even the most modest of V8 engines, especially on a heavier boat. The sproinky spring tends to fail, not to mention the intermediate housing splines and those silly "ball gears".

Let's not even MENTION the rubber boot that holds the sea from sinking you in two minutes flat.

Some years ago, a malicious scuba diver sunk several OMC powered boats with a paring knife; motive unknown.

 

[WizeOne]

Re: 1973 OMC 140hp Sterndrive

......The only reason that your Devil Drive is still working is that it has had the fortune to be mated to the somewhat wimpy 4 cylinder engine. Major problems ensue when this drive is mated to even the most modest of V8 engines, especially on a heavier boat. The sproinky spring tends to fail, not to mention the intermediate housing splines and those silly "ball gears".........

A bit of an exageration here. I've had my hydro-mechanical drive for going on 30 years. It's powered by a 302 and driving a mid weight 20 ft boat. It has 100's of hours of pulling skiers and multiples with a full boat load of people. It has had only two new impellers in that time and none of them were inoperative at the time of replacement.

The outdrive has been torn apart once (3 yrs ago) to inspect all. The water pump shafts were replaced along with seals. That's the extent of it. As the boat started out as a '75 electric shift, the fine splined drive shaft and coupler had wear and were replaced with the later larger splined shaft and coupler. That was only after 31 years of use behind a V8.

Oh, and the boot and the ball gears are still the originals, now 34 years old.

So don't be in such a hurry to jump on this forum and malign a drive that many still have and in many respects is superior to the jumble of parts and myriad of issues that make up the rube goldberg black anchors!

 

[Howard Sterndrive]

Re: 1973 OMC 140hp Sterndrive

I saw the prop on e-bay, but do they still make new ones, say Michigan Wheel? And would it be ok to put a stainless wheel on there.

http://www.propcopropellers.com/omc.htm - Propco is the only company still making those props new I believe

No to stainless- too much inertia during directional shifts can break the clutch springs (slinkies as they are being called in this thread)