Thanks for the follow up on it. yeah i purchased two different service manuals and both show no mention of attachment to anything so I figured it was a drain as well due to it being at the very bottom of the silencer box. My T50 is at the repair center now getting synced and tuned. I read the manuals for hours a tried over and over again but could not make all of those linkages, choke and pilot air fuel adjustments work together properly. One adjustment would throw all the rest off etc. I got it way out of whack rebuilding all of the carbs. Hoping for smoother than ever when I get it back...
Fingers crossed for you. I'm still waiting until pay day to get the vacuum gauges to balance mine so that video will still be coming eventually, but a bit late for you by the sounds of it. I still have a problem with the motor not dropping back down to idle properly so I may get a bit of professional help too in the end!
I know this was a long time ago but this was a great blog. I have a 1996 mercury 4 stroke big foot that has this same block, An I may be looking at a rebuild. My outboard runs great for a few days then it will not run under 1500 rps without stuttering and jumping all over the place.
On this video at 10:16 there is a good view of a vacuum hose that looks like it comes from a fitting at the very bottom front of the air intake opening area and goes up to the carbs area somewhere. I have it on mine as well but it appears to have been cut short by the previous owner or not put back correctly. it is connected to the airbox nipple but is just laying down near the oil dip stick area. I have not been able to figure out where it connects on the engine side or if it is even needed. Do you remember where it connects on your model? Thanks
I don't remember removing it and I can't see any reference to it in the service manual. My current thinking is that it is there for diagnostic purposes, but I'll let you know if I find out anything to the contrary.
So I've been looking a bit further into this and I've found references to an Idle Control System (ICS) that takes an input from the vacuum line on the silencer (air intake) It doesn't seem that this model has an ICS though so I'm not sure what do to with it!
I spoke to my local Yamaha guy this morning and he said that it is a drain hose to get fuel out of the silencer should the carburettors flood. Just leave the hose in the bottom of the lower cowling, or even better get it to head out through one of the grommets.
+Dangar Marine thanks for this info! I had been wondering the same thing. I didn't know what that hose connected to either. Glad to know it doesn't connect to anything
Did you ever find the culprit for the low compression?...I just picked up a F60 hecka cheap, that has low compression on cly #4....I haven't gotten a chance to dig into it yet was just curious as to what exactly was the reason on yours.thanks!
If the oil is visible in the lower cowling then I would start with the gasket below the powerhead, yes. Are you sure it isn't a bad seal around the dipstick though?
The boat is an old aluminium de Havilland, about 4.6 metres I guess. I'll do a few runs with the GPS soon, I'm not sure how quick it goes. My guess is that with one person on a flat day it would be about 25 knots but I'll check and let you know.
+Matt Karl Hi Matt, not exactly but I think they were up around 140. More importantly, they become much more even with some of the lower compression readings coming up match the others.
Hey, if I have engine oil leaking down the drive shaft and out of the water intake vents, would this be the crankshaft seal ? Any chance a base gasket would fail ?
Hi! Just foud out that my 40hp 4-stroke is leaking oil from the lower crank seal. Is it possible to pull the power head and replace the seal without splitting the engine and pulling the crank? Is the seal accessible once the power head is pulled?
Thanks for the follow up on it. yeah i purchased two different service manuals and both show no mention of attachment to anything so I figured it was a drain as well due to it being at the very bottom of the silencer box. My T50 is at the repair center now getting synced and tuned. I read the manuals for hours a tried over and over again but could not make all of those linkages, choke and pilot air fuel adjustments work together properly. One adjustment would throw all the rest off etc. I got it way out of whack rebuilding all of the carbs. Hoping for smoother than ever when I get it back...
Fingers crossed for you. I'm still waiting until pay day to get the vacuum gauges to balance mine so that video will still be coming eventually, but a bit late for you by the sounds of it. I still have a problem with the motor not dropping back down to idle properly so I may get a bit of professional help too in the end!
I know this was a long time ago but this was a great blog. I have a 1996 mercury 4 stroke big foot that has this same block, An I may be looking at a rebuild. My outboard runs great for a few days then it will not run under 1500 rps without stuttering and jumping all over the place.
On this video at 10:16 there is a good view of a vacuum hose that looks like it comes from a fitting at the very bottom front of the air intake opening area and goes up to the carbs area somewhere. I have it on mine as well but it appears to have been cut short by the previous owner or not put back correctly. it is connected to the airbox nipple but is just laying down near the oil dip stick area. I have not been able to figure out where it connects on the engine side or if it is even needed. Do you remember where it connects on your model? Thanks
I don't remember removing it and I can't see any reference to it in the service manual. My current thinking is that it is there for diagnostic purposes, but I'll let you know if I find out anything to the contrary.
So I've been looking a bit further into this and I've found references to an Idle Control System (ICS) that takes an input from the vacuum line on the silencer (air intake) It doesn't seem that this model has an ICS though so I'm not sure what do to with it!
I spoke to my local Yamaha guy this morning and he said that it is a drain hose to get fuel out of the silencer should the carburettors flood. Just leave the hose in the bottom of the lower cowling, or even better get it to head out through one of the grommets.
+Dangar Marine thanks for this info! I had been wondering the same thing. I didn't know what that hose connected to either. Glad to know it doesn't connect to anything
Love your videos man!! Keep it up.
Thanks mate!
Did you ever find the culprit for the low compression?...I just picked up a F60 hecka cheap, that has low compression on cly #4....I haven't gotten a chance to dig into it yet was just curious as to what exactly was the reason on yours.thanks!
Can I install a power trim unit Yamaha 85hp 2 stroke on my original 1991 Yamaha 85hp using the original bracket?
I may be mistaken, since the oil is leaking out, may there be a defective gasket between powerhead and oil sump instead??
If the oil is visible in the lower cowling then I would start with the gasket below the powerhead, yes. Are you sure it isn't a bad seal around the dipstick though?
22:40 not always easy to find gas trothel ;-)
Would you happen to know the torque specs for powerhead mounting to exhaust housing?
sound very nice, What size is your boat using this F50? how fast is it?
The boat is an old aluminium de Havilland, about 4.6 metres I guess. I'll do a few runs with the GPS soon, I'm not sure how quick it goes. My guess is that with one person on a flat day it would be about 25 knots but I'll check and let you know.
So I checked with the GPS and it sits at 24 knots. Not super fast but good enough for me. :)
Do you remember what the compression readings were on this after your rebuild and reassembly?
+Matt Karl Hi Matt, not exactly but I think they were up around 140. More importantly, they become much more even with some of the lower compression readings coming up match the others.
Is your shop open to the weather? How do you keep the rain from coming in? Great videos by the way.
The workshop I used to film the older videos in is under my house, so protected from falling rain but not so much wind.
Hey, if I have engine oil leaking down the drive shaft and out of the water intake vents, would this be the crankshaft seal ? Any chance a base gasket would fail ?
Yes, sounds like lower crankshaft seal.
@@DangarMarine thanks for the reply
@@DangarMarine did you replace the lower drive shaft seal in in the pan ? What is the purpose of it ? To stop crap getting into crank shaft seal ?
Hey dangar where did you get this service manual?????????
From www.readmanual.com/
thanks, you da man!
I never noticed you putting any sealer on the gaskets you installed. did I just miss it??
Many manufacturer gaskets specifically call for no sealant. Some valve cover gaskets do where they curve, but most are installed dry.
Hi! Just foud out that my 40hp 4-stroke is leaking oil from the lower crank seal. Is it possible to pull the power head and replace the seal without splitting the engine and pulling the crank? Is the seal accessible once the power head is pulled?
Yes, in some cases it is possible to pull the seal out using screws or a spike and then pressing a new one in.