1970 Johnson 4Hp twin

[cid]

I have a '70 twin 4 Hp I use on a cannoe
I am doing some work and am wondering is I should replace the 36 yr old coils, wires while Im in there.

Any other areas of concern I should be addressing, the water pump points, carb I got already. It runs OK I just want it to be reliable when Im way out in the bush

thanks

 

[rickdb1boat]

Re: 1970 Johnson 4Hp twin

For the cost of both and piece of mind, I would....Did you replace the impeller or it's just working fine? Make sure to replace it if you haven't...

 

[cid]

Re: 1970 Johnson 4Hp twin

I havent replaced the impeller, but it looks like it was replaced sometime. Its nice and flexible and looks fine
as does the grommet for the tube up to the power head

Thanks

 

[Paul Moir]

Re: 1970 Johnson 4Hp twin

Go ahead and replace it anyway. It needs to be replaced every few seasons, and a new one is $15. Overheating the engine can kill it pretty quick.
I never bother replacing points. Just clean them up and they're usually good to go. Relubricate the wick with some light oil while you're in there though. Replace the ignition coils if the insulation on them is cracked.

Feel the side of the engine (not the flat plate side!) and make sure the water passage around the cylinders is still clear. The head and the flat plate will get burning hot, but the side with the fuel pump should just get warm. If not, have a look here:
click here

 

[cid]

Re: 1970 Johnson 4Hp twin

Thanks
I just got back from a long trip and It was running OK,
but I might as well check the passages

Ever try to use a radiator type boil out on these?

 

[Paul Moir]

Re: 1970 Johnson 4Hp twin

It's probably fine then. It usually crops up as dying after running at full throttle for a few minutes.

There's marine flushing solutions like Salt-Away or Salt X. I've never used them and I don't know how well they work. If the radiator flush stuff can deal with calcium carbonate deposits then perhaps it'll work too.

 

[cid]

Re: 1970 Johnson 4Hp twin

I pulled it apart and it looks pretty good
where is the best place to get a good parts list and order parts ?

 

[Paul Moir]

Re: 1970 Johnson 4Hp twin

Now I'm sort of sorry I mentioned it.
Get part numbers here:
http://epc.brp.com/default.aspx?brands=ej&lang=e
Get your parts from your local dealer or from an online J/E dealer like maxrules.com. I do not like the Sierra aftermarket head gasket because it's too thick. I'll try to get my 4hp website updated so you can see how to torque the head.

 

[cid]

Re: 1970 Johnson 4Hp twin

thanks
I cant get the web link to open.
two more questions
What is the best sealant to use or should I put it all together dry?
What is the best way to replace the top seal by the arm plate, I see a bit of leakage on the bottom of the arm plate, not bad, but.. is there a way to pull that seal out without getting into the crank?
thanks for all the help from minnesota

 

[tashasdaddy]

Re: 1970 Johnson 4Hp twin

Cid, go t to brp-evinrude, click part& accessories, click engine diagram lower right, then click your year, then model, then the section you want to see.

 

[Paul Moir]

Re: 1970 Johnson 4Hp twin

Sorry about that. That friggin' useless Iboats frame thing buggers it up. Click "Remove this Frame", then enter your email address.

Normally the head gasket goes on dry. There's a heat activated sealant on it already which gives them a shiny appearance. But there's no harm giving it a coat of gasket sealer either.

The top seal may be removed by drilling a couple small holes in the metal part, and threading in some small sheet metal screws. Those screws are then used to pry the old seal out using wooden blocking, etc. A fresh one is simply tapped in with the appropriate driver. Coat the flange with a little sealant first. Apply it with a q-tip to prevent contamination of the bearing just beyond it.

 

[cid]

Re: 1970 Johnson 4Hp twin

Got into the parts site at last
Thanks a million, where is the 4 Hp site at?

 

[Paul Moir]

Re: 1970 Johnson 4Hp twin

It's part of that one with the cooling passages. Here's the whole thing:

Click here