87 Mercury 70

[TD_Maker]

Glad to be back in the boating forums once again. The recession hit me hard and I was forced to dump all my play toys; however, I am once again back in the saddle.

I just came across a nice 1987 16' McKee Craft with a 1987 Mercury 70 outboard. The boat has been very well maintained by the previous snow-bird owner (one owner) and the old Merc looks pretty good under the hood. The boat sat for a few years, but the motor is free. I have not attempted to start the motor YET. I am draining the fuel tanks this weekend. I am also installing a new impeller this weekend as well and sticking in three new plugs. From here, I am a little unsure about the oil injection from Mercs of that era. Is there anything special I need to do before I start the motor? Should I replace the oil in the tank before I start it? How reliable is the oil injection system? How hard would it be to disconnect it?

I am sorry to return with so many questions, but I am pretty anal about doing something correctly.

Thanks

 

[ajgraz]

Re: 87 Mercury 70

If it was me I would ditch the oil injection and premix my own. Especially since I don't KNOW it works.

 

[Maxz695]

Re: 87 Mercury 70

That would be great for testing but the oil pump reduces and increases oil flow for the RPM of the engine as needed for the intake of fuel to give poper ratios. I,m not very educated on oil injected other to have stripped one for parts to sell. I have heard alot about the injections purpose and wheather it should or could be eliminated. I would as ajgraz said use premix until you can see if the hole system is up to par. The major issues with the oil injection are the float sensor in the resevor setting off the alarm the alarm having cracks and allowing moisture into the electrical componant creating a short and setting off the alarm, and the cylinder of the pump itself wearing down and not pumping the correct amount of oil nessecary or becoming air bound. If the system is good I would use it if not then premix is the alternative unless you want to spend $$ on repairing it at that time

 

[oldman570]

Re: 87 Mercury 70

I have the same motor as you, and have gone to premixed fuel with vary few troubles. The easyiest way to buypass the oil injuction is to cut the oil line from the tank and place a T in it and run the oil line from the fuel pump back to the T that has been placed. Be sure to plug the oil port on the fuel pump to prevent it from causing any trouble. Mixing a 50/1 fuel will be fine and the most that can happen is the plugs will want to foul out if the motor is idled for long perids of time. Keep oil in the tank to prevent the alarm from sounding and this way the oil pump just recurlates the oil and the system can be hooked back up if so wanted. Any oil that is over about 1 year old should be replace as it will lose some of its abilty to do the job correctly.IMO
Oldman570

 

[ajgraz]

Re: 87 Mercury 70

...Mixing a 50/1 fuel will be fine and the most that can happen is the plugs will want to foul out if the motor is idled for long perids of time...

Which is no different than any Merc prior to the Autolube thing.

Sounds like oldman570 has got you covered. I'd rather have to wipe off plugs every so often than rebuild a powerhead due to a failed autolube system.

 

[Dave1027]

Re: 87 Mercury 70

My '88 has oil injection that still works just fine today but I did have to replace all of the clear oil hoses which had broken down from age and were leaking like sives.