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1974 Johnson 25 hp issues

sat2mmtact

New member
Hello all, first post so please be patient. I acquired a 1974 25 hp Johnson tiller with a shot lower unit, and I just so happened to have a spare lower unit so I figured what the hell. After changing out the lower unit and doing regular maintenance (i.e. carb kit, plugs, trigger coil, fuel pump and lines, spark plugs, etc) I'm able to get it running but only at high speeds, it will not idle. I then noticed there is a small leak between the crankcase halves (previous owner clearly tried to seal with rtv), no big deal to repair even though it's a lot of work, but the thing that is puzzling me is the bypass hose. The hose from the bypass cover to the intake instantly blows a hole in itself every time I've cranked it. Is this related to the crankcase seal leak, or something else I'm not thinking of. Thanks in advance for any insight/help.

Thanks,
Scott
 
Not muck pressure on crankcases so something is wrong.----Try a better ( factory ) hose.----Any pictures of the RTV sealing attempt ?
 
Agreed, not much pressure there---normally. However, there is considerably more instantaneous pressure when it lean sneezes caused by too lean fuel/air mixture, Yes, a poorly sealed crankcase could contribute to the lean condition. Having said all that, I must say I've never seen one blow a hole in that hose. There seems to be more here than we are seeing.
 
Sorry no pics right now, I already put it in the storage unit so I can work on it over the winter (have other projects right now). I was using some of that yellow/clear fuel line since that is what was on it, but it sounds like I need to go to a braided type hose instead. Also need to check and make sure the nipple/check valve on the intake end isn't clogged/stuck for some reason. Thanks for the input...
 
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