1987 70hp Johnson VRO

[Jill_S]

Hi all,

I'm getting ready to possibly purchace a 1987 70hp Johnson w/VRO. The seller says, naturally, that its a good motor and can demonstrate it to be running. I've worked on and am most familiar with older OMC motors from 1957to 1969, 50 and 75hp Fat boys and Big Twins. I am aware that seeing it run and checking the compression is important when making any motor/engine purchaces and ready to do so.

I chatted with a fellow motorhead who is knowledgeable on outboards and he said be sure ask the owner if it has been bored or resleeved. And to have him rev up the motor above 4200 rpm to check for pre-ignition. Sorry if my lingo or spelling is not correct I'm still new at this stuff.

Actually what Im mostly asking is opinions on these motors. I have a friend who has one and he loves it but I believe he has the VRO disconnected and puts the oil in the gas.

Thanks in advance.
Jill

 

[tashasdaddy]

Re: 1987 70hp Johnson VRO

they are fantastic motors. but if the boat is not under way, in the water do not rev it up. if on muffs, max is 1500 rpms, or you can get a runaway motor. compression, spark, lower unit oil should be check before purchasing, with a 1 hour run on the water if possible.

1987 i would eliminate the oil mixing, just do away with the oil tank, unplug the sending wire on the pump it's self, cut and plug the oil line so it does not suck air. premix your fuel.. disconnect gas line at pump, pump bulb till you get mixed gas, have a good day on the water.

 

[Jill_S]

Re: 1987 70hp Johnson VRO

Thanks,
I kinda thought reving the motor up to that high rpm was not a good pratice. Good idea also to check the lower unit gear oil but if it runs and sounds good wouldn't that be an indication that the spark is good? Won't be able to get a run on the water but I believe a short warranty is being offered.

Glad to hear another opinion on these being good motors. I'm tired of working on the old stuff and am ready to spring for newer and hopefully more reliable. I do understand that it still is a 20 year old motor though.....but at least it is 26 years newer than my Fat 75. I'll post another question on it next.

Thanks a bunch Florida Mariner for the prompt reply and the info on how to disconnect the VRO properly.

Jill

 

[iwombat]

Re: 1987 70hp Johnson VRO

On the muffs, running well is not necessarily an indication of good spark in all the holes.

Some things that are a must check:


1) Spark test
2) Compression check
3) Water intrusion in LU (remove the drain plug and let some fluid dribble out)
4) Check the condition and coloring of the plugs - look for very clean or wet plugs. Also make sure they're tan to dark brown colored or you could be looking at a lean condition in one cylinder.
5) Look at the powerhead for signs of tinkering - paint missing on bolts and the like. Ask questions if you see anything.

 

[Jill_S]

Re: 1987 70hp Johnson VRO

Thanks Comander iwombat.....more good stuff. Especially checking for signs of tinkering. I will follow up after I look at it next week.

Again....thanks a bunch guys

Jill