Another question for the evinrude experts

[hondaatc]

I just picked up a 1956 7.5 hp that the previous owner swapped the the complete lower unit from a 1958 5.5 he went right through it but he has given up because it pumps water out of what looks like a freeze plug on the head and i see something bubbling on one of the other head bolts but i doesn’t pump water out of the normal spot on the lower unit my question is are the compatible ? Or is something maybe plugged up ? I have the 5.5 power unit so i might swap it back but the i was wondering first thanks

James

[Mumbles]

Both exhaust housings are the same so the powerheads interchange. No problem there but if water isn’t coming out of the exhaust relief, insects may have crawled up in there and built a nest. If the water pump needs servicing, the powerhead will have to come off and that would be a good time to make sure the water passage (blue arrow) is clear. You should be able to see daylight when you look down thru it.

The 7.5 cylinder heads have two Welch plugs and the lower one likes to rot out or fall out causing a leak. Water shouldn’t be coming out from under a bolt head either as the threads are dry and don’t go into the water jacket. I’d suspect a leaking or blown head gasket, P/N 203034 as the culprit. Or possibly the head is corroded thru into a bolt hole or it isn’t torqued down properly.

[hondaatc]

Thanks again mumbles time to take it apart

[hondaatc]

Just pulled the power head off brand new base and head gasket and i can see right through the water passage on the lower unit i did see that he had tried to silicone the freeze plugs in not sure why i think I’m gonna buy some new gaskets and put the 5.5 back on its original lower unit i did notice that the paint on the 5.5 looks like it might of over heated so i guess I’ll find out soon enough

[JOHN HOLBIK]

Pretty well all the pre thermostat 5.5 hp OMCs I have saw over the years had brown colored plates as though they had over heated .

[fleetwin]

Are you sure it is a 1956 unit? I’m asking because 1955 powerheads/exhaust housings were a little different, and you can not mix/match 55 and prior with 56 and later years…Post some pictures when you pull the powerhead…
Like others have said, and you have discovered, the water pouring out is most likely due to the bottom head welch plug falling out, which short circuits the water path out of the normal relief on the exhaust housing.
Post a picture of just where the other minor leak is also.
And yes, burned paint is normal on the older 5.5hp exhaust covers. This area was not water cooled back then, so normally gets pretty hot….

[crosbyman]

make certain you have the proper base gasket for your base

see different gaskets./year

..https://www.vintageoutboard.com/collections/johnson-evinrude-gaskets?page=2

Joining AOMCI has priviledges 🙂

[hondaatc]

Hi all so I’ve replaced the impeller on the 5.5 new base gasket new head gasket pumps water but not like my other evinrude/johnsons and the water gets hot in a few seconds plus the exhaust cover gets hot enough to boil water on it almost Immediately any ideas ?? Thanks

• This reply was modified 2 years, 7 months ago by hondaatc.

[frankr]

I guess I’m confused by now. Are we dealing with a 5.5 or 7.5? The 5.5 exhaust cover do get burning hot. I remember starting them up, fresh out of the box when new. That paint stunk terribly as it burned off for the first time.

[hondaatc]

Yeah sorry i was referring to the 5.5 I’ve kinda put the 7.5 on the back burner for now

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