V8 Johnson 300 questions

[MaxxPehling]

I have a 1989 24' Superboat with a 300HP V8 Johnson on it. I have a few questions on the motor that I cant seem to track down.

First off, all tags have been stripped off the motor so I am not even able to track down a model. It is supposed to be an 89' model year. As stated it is a V8 model 300, Limited Edition. I understand there were not a lot of these motors made so I am hoping somebody will have a model number.

Second, my trim pump is having some issues. It will typically raise up with no issues other than some icky noises, but usually takes 10-15 seconds before it will build enough pressure to lower itself. I am not sure if it is a low fluid issue, or valves sticking.

Maxx

 

[tashasdaddy]

Re: V8 Johnson 300 questions

look for a Quarter sized disc(freeze plug) on the block, should have model and serial #.

 

[jonesg]

Re: V8 Johnson 300 questions

Sounds like an air pocket in the hydrolics, fill the reservoir and cycle a few times, refill and cycle again, they self bleed.

 

[tx1961whaler]

Re: V8 Johnson 300 questions

Model numbers for 300 HP Johnny are here:
http://web.archive.org/web/20010907224954/www.evinrude.com/docktalk/modref/jomodyr/JHP300.html

That is one darn big engine.......

 

[kenmyfam]

Re: V8 Johnson 300 questions

Glad I.m not paying for the gas for that one. I just looked at the parts diagrams for that motor....... 8 of everything !!!!! AAAAAGH

 

[Dhadley]

Re: V8 Johnson 300 questions

There's not a lot of difference between a LE and any other standard 300 V8 OMC. The trim units are all the same anyway. Just follow the test proceedures in the service manual.

 

[coolguy147]

Re: V8 Johnson 300 questions

woah man a v8 outboard boy would i love to work on that big boy

 

[MaxxPehling]

Re: V8 Johnson 300 questions

Sounds like an air pocket in the hydrolics, fill the reservoir and cycle a few times, refill and cycle again, they self bleed.

thats what i figured. a few issues though.

where do I fill it at?

is it filled in the up or down position? I would assume up because the ram is extended and the bulk of the fluid is spent within the system, plus that is where it has the issues "lowering"

if i do have to fill it in the up position, is pressure lost when I open a fitting to fill it? thats a heavy motor to keep up in the air, and I dont have my cherry picker anymore.

Maxx