posted 03-19-2006 05:26 PM ET (US)     

The Whaler and engines are totally fresh water use from Northern Wisconsin, and neither the boat nor engines have been used since summer of 1978. Seller tells me the engines have 5 short summers of use, mostly Lake Michigan salmon trolling, about 200 hrs on them total. They are all original, and the boat has been stored in a heated building for the last 27 years. Boat is all original, mint, no bottom paint. He says they have been started up and run on muffs every Spring.

What could I expect from an old pair of engines like this? I have not yet seen them, but he says they look factory new, no corrosion, nothing. Besides impeller replacement, would they be in need of a lot of work, such as carb tear down, head gasket replacement, new seals, etc? Any idea what a pair of classic engines like this would be worth? They are pre-mix. Are parts still available? What should I specifically be looking for as far as potential problems or warning signs?

posted 03-19-2006 05:42 PM ET (US)            

The OMC triple loopers, first introduced as a 55hp in the late 60s, were years ahead of the industry in technology and engineering. The 70hp versions were most popular and variations were made up until very recently. It wouldn't be unreasonable to call that a 50 year run. Not common for a mid range engine.

I have owned and used three "JohnnyRude" 70s and all were excellent engines. It sounds like the engines you are contemplating have been very well cared for and would have many years of good service yet to deliver.

posted 03-20-2006 08:20 AM ET (US)            

Specification wise, the latest version of the OMC 70 displaced 920 cc with a bore of 81mm and a stroke of 59.4 mm. It turned the propeller through a 2.42:1 reduction gearcase.

In contrast, the Yamaha 70, which is still in production, displaces 849 cc with a bore of 72mm and a stroke of 69.5 mm. It turns its propeller through a 2.33:1 reduction gearcase.

posted 03-20-2006 06:25 PM ET (US)            

I suggest overhaul of the carbs and replacement of the bypass cover gaskets.

posted 03-20-2006 06:29 PM ET (US)            

Yeah, you could probably run them as is, but for a few hundred bucks you can be sure your perfect vintage engines are up to snuff and wont be leaning out a cylinder any time soon.

posted 03-20-2006 06:33 PM ET (US)            

Re: Getting them started again:

Remember, plastic and rubber deteriorate with age and heat.

I'd approach the restarting of these motors with a little caution rather than just the cavalier "start them and go" mentality.

First, inspect the hoses and any plastic hoses on the powerheads. Pinch them to figure out how pliable they are, and give a gentle pull on them to make sure they're secured to the powerhead plumbing appropriately.

I'd replace the fuel delivery hoses right away, including the primer bulb. Buy BRP replacements, not the cheap tempo stuff.

Pull the props and check lube the prop shaft.

Replace the lower unit gear oil and the gasket around the drain plug.

Have the carbs rebuilt, and replace the on-the-powerhead fuel filter, if equipped.

Spray the electrical connections with anti-corrosion spray, and spray all of the hoses with a silicone lubricant.

Regrease the throttle and shift cable using BRP's Triple Guard Grease or equivalent.

Take your time...they're old engines, but a few hundred bucks and some gentle work on your part will make sure they run like new.

Plan on purchasing new spark plugs once you've done the break-in scenario.

Mix up a special batch of gasoline in 6 gallon tanks and run these through the motors for the first few hours of operation. I'd go with a heavy mixture of oil as others have specified...much like the break-in procedures. Also, for the next few tanks of gas, use Carbon Guard or equivalent fuel additives. I also like to mix a little Marvel Mystery Oil in my gasoline on older two strokes (in addition to the TC-W3 oil).

Have your dealer inspect the thermostats and check the compression when he changes the rubber hoses and rebuilds the carbs.

This will cost about $300 per engine or so. Last summer, my dad gave me the old 1972 Johnson that I learned to boat with. It hadn't been run in 8-10 years. I had the dealer inspect it, rebuild the carbs, etc. (the hoses didn't need it because dad opened the cowling every year and sprayed them down with silicone spray.) it cost me about $275 and started on the first pull.

Also have your dealer, or you if you're handy, replace the water impeller yourself...and I totally agree with Peter, inspect the fuel pump diaphram and replace it - the rubber they used in 1978 was not designed to handle the ethanol content in today's fuels.

I'd spray fogging oil in the cylinders, directly through the spark plug holes, and then turn the flywheel by hand a few times and re-apply the fogging oil and turn it over a few more times by hand.

When you start the motors, let them idle...like 8 minutes at least so that they are at full operating temperature, then pull the cowlings and make sure everything is working right...no leaks, etc.

Once you've gone through all of that without any problems, you should be set for years of operation. The 70 was a great motor for OMC. The above recommendations are only because it hasn't really been used in 28 years.

posted 03-20-2006 08:19 PM ET (US)            

Spend now or later...his choice.

That is what I would do (and count as part of the purchase cost) if I bought a 31 year old engine that hadn't been run properly in 28 years. With an engine that old, the "opportunity cost" to purchase it should be nil. Spending even $1,000 additional up front to have both motors ready to work is worth every cent, in my opinion. If proper precautions are taken and they are brought back and ready to go (and then meticulously maintained), they should last for about 2-4 thousand hours...so with only 250 hours on them, they've got a lot of life yet.

My prediction is that he'll get sick of pre-mixing before teh engines decide to die on him!