Home › Forum › Ask A Member › 1959 Johnson RDSL21 35hp issues
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October 7, 2024 at 8:24 pm #291402
Hi: After 2 years of flawless running, this past weekend surprised me with problems. The motor quit while at about 3500 revs and then flew up as if I hit a sandbar. We were in deep water and no underwater obstructions. This happened 2 more times within about 1/2 an hour. Seemed to start OK after this each time but did require a bit more cranking time to start. Monitoring the engine while running, the discharge cooling water was warm/hot up to about 3000 RPM then got scalding hot above that RPM. Finally quit altogether and had to tow her home. Out of the water now at the shop and was hopeful someone could point me in a direction to look for problem(s?). Thanks Tom Alexander
October 7, 2024 at 9:11 pm #291403you may want to check the impeller or water passages for obstructions. check thermostat
hopefully it is not seized !
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October 9, 2024 at 4:23 pm #291442Except for the high temperature discharge water the symptoms sound like fuel starvation.
October 14, 2024 at 7:49 pm #291498Thanks Crosbyman and Vintin! Took a few days but I got to looking at it at the shop. No, it’s not seized, a good thing! I removed the thermostat and found it frozen is ‘an open’ position and replaces it with a new one from Sierra. Both had 143 stamped on the end. I did find that the crankcase vacuum hose was quite loose at the crankcase end so I removed the orig spring clamp and put a regular hose clamp on it. That could have been the fuel starving issue, I hope! I started it today with hose water into the water portal on the stbd side down low, turned up the water volume to max available here and hardly any water spray came out the discharge port. Water was going everywhere at the bottom because the water portal into the engine from that side also back feeds the ‘forward going’ water pick up, so the water was gushing out from there pretty well but I am pretty sure enough was going into the engine that if the water pump was working there was sufficient water available for a very healthy spray from the discharge port would have been happening. But it wasn’t, so I think I am going to have to remove the lower unit and explore what the hell happened to the water pump. Only about 40 hours on the motor since i last rebuilt the lower unit, with all the pump pieces replaced with new. Not a cheap exercise I can tell you!! Thanks again and if you guys can think of anything, especially causes (other than the obvious like a bag over the inlet) please let me know? BTW, a friend out here in the SF Bay area has a couple of 4 cycle rebuilt outboards that were derived from Crosby auto engines. I think they are Homelite?
October 14, 2024 at 11:33 pm #291500try it on the open water before you tear into the LU
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October 15, 2024 at 1:59 am #291501Crosbyman: I will see what I can do, but my only option will be a half barrel filled with fresh water. But that will get both water pickups immersed and won’t take the whole day. I might be able to do this tomorrow. Wish me luck, I’ll report back. I have had very good water output several times in the past with using the screw on cover with a hose fitting in it that replaces the SST one with the 6 or 8 holes in it. I think I read somewhere that this is where the engine picks up its water when in reverse. Thanks again. Tom Alex
October 15, 2024 at 2:27 am #291502I am curious too, as to how much water actually is supposed to exit the above water discharge port. I have been looking at videos I took at the yard after getting it all back together and running it with only the hose attachment on the side plate and looking carefully now I think I see WAY more water coming out the underwater exhaust port that the spray coming out the above water discharge port. I can’t find in the literature I have any mention of cooling water paths. Anybody know anything about this? Thanks Tom Alex.
October 15, 2024 at 7:56 am #291507first find out if it is heating up…. run it and check the PH heat with a IR gun (cheap tool these days)
if it is not overheating it is cooling fine .
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October 15, 2024 at 8:15 am #291511above pages are from the BIBLE…aka RED book… best thing to service oldies covers your RD extensively
https://watercraftmanuals.com/outboard/johnson/manuals/johnson-302231.htm
20$ cheapest book around just download to tyour hard drive and print locally double sided pages with a spring binder 🙂
BTW… top discharge (rear) only spits water from the thermostat while it opens around 145F all the rest goes out the bottom discharge
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October 15, 2024 at 9:12 am #291516It is not abnormal for the engine to kick up out of the water when it stalls out like that at higher RPM. Does it seem like it overheated? Is the paint on the powerhead burnt/smells burnt when you remove the engine cover? Post pictures if that will help.
Hoping it is just a simple issue like fuel starvation.
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