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1975 5hp air-cooled Chrysler Overheating

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Dawudfarsi

New member
Hi, I bought this outboard a while ago and it starts without an issue and ran fine for awhile, but lately it overheats (after 3-4 minutes) and seizes and I wont be able to pull the cord until it cools down. I have very little experience with air cooled outboards, I know an impeller change works for a water cooled outboard, what do I change for an air cooled one? thanks!
 
Racerone asked for pictures of the powerhead... In other words, the part under the cowling.

54HA doesn't show up in my search but other 54H* numbers are 1976. 1975 is 4.9 hp. Regardless they all are water cooled and use the same impeller.
 
Look at the first photo in that auction. On the left side of the powerhead, you can see the sparkplug going into the head. There are no cooling fins, as an air cooled motor would have.
Take the cowl off, & post a couple photos, (size them to 1Mb or less), it’s likely the impeller is shot. Continually running until it seizes will soon render that motor scrap.
Run the motor with deep water, not just the prop submerged. The pumps must be fully submerged.
Many of those older small motors had no pee stream.
 
From post #1 it sounds like it seized more than once.----A compression test is now in order.----Perhaps the original poster is now faded away.
 
Hmm, I will post pics when I can, yeah spark plugs are attached to the head as pictured. I could just be confused because there was no pee stream
 
20250427_165230.jpg
 
I believe this is an air cooled powerhead. BUT!!!! the exhaust is cooled with an impeller just like the regular outboards.
There is no pee or indicator stream.
 
it has an impeller and it is in good condition, changed the gear oil as well as it had some water in it. didn't get to test it in detail since the pull cord is now not going back and have to fix that. Should I be able to put my hand near the cylinder housing after it runs for few minutes on max? because I couldn't
20250503_120731.jpg
after 2-3 minutes of high rev?
 

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The pic(yea!!) shows the impeller. Turn the wear plate over to see the other side. The vanes should be straight out from the hub.
The corrosion and the bad vanes shows me you need to get a new impeller and maybe fill in the holes on the wear surfaces to make it water tight.
Like Racer said the impeller needs to be DEEP in a bucket for the pump to work.
It's not self priming.
 
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