Mariner 75 4 cyl or Johnson 70 3 cyl

[gkm24]

I have been offered a Mariner 75 Hp 4 cylinder and a Johnson 70 Hp 3 cylinder. Both run fine but are old engines. The Mariner Serial is No 6468810 and the Johnson No's are B7668578 Mod BJ70TLCCA.
Anyone have any advice as to which one would be best? I am tending to like the Johnson as it is 3 cylinder(not so high/heavy) and it is Autolube. Don't know much about the Mariner and neither does the owner. Both engines are also very clean in as much as no corrosion. Mariner control box is also the wrong handed i.e. it is mounted on its left side and I need it to mount on its right.
Any info greatly appreciated.

 

[JB]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

The JohnnyRude 70s were 20 years ahead of the industry when introduced as 55s in ancient history, gkm. Your 70 is not so old, however. It is a 1988.

The JohnnyRude triple loopers are great, reliable, powerful and economical engines. I have run 3 of them on different boats and been pleased with each one.

That would be my choice, without doubt.

 

[gkm24]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

Thank you for your reply. It is my favourite of the two. I think I will go for that one.

 

[Chinewalker]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

Yep, the Johnson 3-holer, hands down...

 

[Home Cookin']

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

go for the Johnson. I'm on my second, a little older than yours (both of them) and No. 1 did not fail due to its mechanics.

I assume by "autolube" you mean VRO where the oil is mixed by the motor. I'v ehad that system and it is fine, although some would recommend by-passing and mixnig your own, especially considering the age. But you can't just unhook it; there are conversion steps that I don't know.

 

[Texasmark]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

The JohnnyRude 70s were 20 years ahead of the industry when introduced as 55s in ancient history, gkm. Your 70 is not so old, however. It is a 1988.

The JohnnyRude triple loopers are great, reliable, powerful and economical engines. I have run 3 of them on different boats and been pleased with each one.

That would be my choice, without doubt.

If you do, put yourself in a new water pump and thermostat. I had a '75 70 Rude that I lost the powerhead on because I was young and ignorant about such things and there was no over temp alarm to warn me that the stat was stuck shut like you have in today's engines. Otherwise, it was a nice running, easy starting engine and on a little Kingfisher 15' Bass Boat, like BB's were designed when the first came out in the early 70's, after I jacked it up one notch on the transom and put a high rake SS prop on it, twas a real joy to operate.

The Merc 4 is probably a spinoff of the original 4 banger 40 hp Merc Mark 55 that came out in the '50's. Very reliable and smooth engine, had several, but was cross flow charged and was not near as efficient as is the OMC triple that is a looper.

So it looks like a moot point. You have your answer. Grin.

Mark

 

[phillnjack2]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

Is this 70hp for your orkney dory ?

i have a 3cylinder 1995 60 on my 4 metre orkney and its a flying machine.
ive had the mercury mariner 80hp 4 cylinder engine and they were very nice and smooth, But seemed to be very big for what they were.
the evinrude or johnson 3 cylinder is more compact and i think a faster engine that dont drink as much fuel.
i think the johnnyrude is a better engine

Would like to know what performance you get from it on the bigger brother to my boat.

phill

 

[ajgraz]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

Take it from a Mercury owner...

Go for the Johnson.

 

[jimmbo]

Re: Mariner 75 4 cyl or Johnson 70 3 cyl

I'm partial to the merc. 66.6 cubic inches vs 56.1 for the johnny. Bulletproof engine.