15hp fastwin issues

[madbasser]

I just started working on a 15hp fastwin, I replaced the coils cause they were shot and a new impeller. I then went to get I started. I starts and ildes fine but then when I throtle it up in neutral it starts to pop and even sounds like it knocks a bit then it stalls out. That's the first propblem. The second problem I saw was that there was a little water coming out of the plate were the shift linkage is located. I popped it open and sure enough there was a coat of water everywere in there. What do I do next? Is it stalling because of a carb issue or ignition issue or a timing issue? Is there a seal I need to replace in the lower unit or is it ok to water in there? There seems to be plenty of water coming out of the pee hole. Thanks for the help.

 

[madbasser]

Re: 15hp fastwin issues

I think the water problem is being caused by a tweaked water pump groment. Does anyone know the Sierra part number? I might as well also replace the lower seal. Anyone have a number for that too? Thanks again.

 

[lindy46]

Re: 15hp fastwin issues

The leg is not sealed and it is normal for water to be in there. I'd check compression before doing any more to the motor. If compression is good, then sounds like a carb clean/rebuild is in order.

 

[madbasser]

Re: 15hp fastwin issues

Really? I didn't think you were suposed to have water in there. I thought it was for exaust only? On my 69' 9.5hp i don't recal seeing water there when i replaced the impeller. I do see that after just running it for 10 min. i got a lot of water in the gear case. Would replaceing the seal under the water pump fix that? Whats it called? I cant seem to find the number to replace it.

I opened the carb up and it looks clean. All the seals are new, looks like it was done before storing and i got it soon after. I heard that some times a condenser can make that happen? i will try again today.

FYI the motor is a 1955. not sure if that makes a huge diff.

 

[lindy46]

Re: 15hp fastwin issues

There are several seals in the lower unit which could be leaking. The most obvious and easiest to fix are the washer/seals on the drain and vent screws. I'd make sure you have new ones, refill the lower unit with oil, and try running it again. If water is still getting in there, it could be the driveshaft seal, the propshaft seal/o-ring, or the shift rod seal. A pressure test of the lower unit will help determine which seal is leaking.