engine help 175 yamaha

[fshlbi]

I was hoping to get some help with an oil problem. I posted about this last season and there were some very helpful suggestions. I have tried many of them and was hoping with a more detailed summary, maybe someone could have the magic fix I am looking for.

I have a 1993 175 that I bought used. The engine runs strong. I had no problems at the beginning of last season, but I have since developed a problem where the engine seems to either overpump and then overfill the tank on the engine. The symptoms appear to be that the oil fills inside the cover that is in front of the three carburetors. Then when the engine is tilted, the oil pours out and inside the cowling and drips all over the splashwell

I have replaced the oil pump, a sending unit that is in the engine oil tank, and a rocker switch that apparently tells the pump that engine is tilted (this is near the trim and tilt on the transom). I then talked to a yamaha mechanic that I've known for years and he mentioned a 'check valve' that is in each oil line that feeds each cylinder. I replaced two of the six of these and it still appears to be leaking oil.

The only things I can think of to attack next time I can work on it are: a sending unit at the reserve oil tank (boat side), and the other four check valves.

Anyone have any other suggestions or experience similar to this? I am reluctant to keep trying to problem solve as I am now in for almost 1000 bucks on parts.

 

[seasick]

Here are a few things to check:

With the motor tilted down and ignition off, remove the cowling. Tale a look at the oil tank on the motor and note the oil level.
Turn on the ignition but don't start the motor.
If the oil level was below the full level, the remote tank pump should pump oil. When the oil level reaches the full level ( not filled to the brim) the pump should stop.

Of course using the manual pump toggle switch should cause the remote pump to operate.

So if all the above is working then the logic, switches and sensors at the motor are working.
If on the other hand, the main tank over fills, then either the manual switch or wiring is bad ( no electronics are involved) or the tank sensor is bad(or wiring). That is fairly easy to check with an ohmmeter.

Newer yamis do not use the tilt sensor for oil logic, Some older ones do but I don't know what year the logic changed. Regardless, if the ignition is off(and the motor main relay is not stuck) than even if the tilt sensor is bad, the remote pump will not pump.

That leavs two more things to look at: You should check the synchronization level and adjustment at the oil pump. It connects to the throttle linkage and adjust the amount of oil that is injected into the carbs. The linkage cab break and that causes the pump to pump max oil. There is a lever and a stop. The lever should rest against the stop when the throttle is at minimum.

Finally, the engine oil tank sensor cap itself is prone to leaking when the motor is tilted up. This does not cause oil to run into the carbs but will cause oil to pool in the bottom of the cowling. Usually the oil pools but does not leak out until the motor is lowered.

 

[suzukidave]

have you confirmed it is oil and not mixed gas you are seeing? mixed gas will look similar to oil but be thinner. if it is mixed gas then your problem is likely one or more carbs needing a rebuild.

you don't seem to have identified a leak source, which makes me suspect it is just leaking out of the carb throat.

 

[fshlbi]

thanks to seasick and suzuki dave for suggestions. seasick: i can tell you that it is not leaking out of the oil tank. it is definitely pooling in the carburetor cover and it is leaking out of that cover.

suzuki dave, i will check next time to see if it is oil or mix. i am pretty sure it is oil though.

i won't be able to get there for a couple of weeks, but i'll let you know what i find out.

 

[Tucker]

Unless I missed something you didn't mention the oil pooling after running or while sitting with engine tilted. If your seeing what appears to be oil running out of the silencer after running the could be the 2-stroke slobber we all experience. Usually happens when varying the throttle. Not sure why it happens but the carbs or throttle body spits during throttle changes. In my case it usually amounts to enough to absorb a few paper towels midway through the season. You may think it's just oil because the fuel has evaporated. If you see oil after the motor has been sitting tilted, I would bet the check valves are bad, yea you replace 3 but one of the other one's may be bad. While in there you should think about replacing the oil lines with weed-wacker fuel line and make sure the pressure clamps are on tight. To check for sure, you have to remove the oil lines on all the carbs and see if any drips out the ends. Cheeez, $1000 in parts?! With that vintage engine, I would disconnect all that crap and premix. The piece of mind is worth it to me.

 

[fshlbi]

Thank you to all of you for all of your help. yes, it's a lot of money to invest in an older engine. it wouldn't have been that bad if the first mechanic wouldn't have replaced the oil pump. i really didn't think that was the issue, but.....

and it's definitely not slobber. it is pooling significantly in the bottom of the carburetor cover (i guess some are referring to this as the silencer). it is pooling to the point that it is coming out of the silencer/cover and dripping all over the cowling. it is not just a couple of paper towels. it usually is three to four oil absorb towels.

it is not every time the engine is run, either. this past weekend we took it for a ride and while under way it ran fine at cruising speed with just a couple of misses. stalled at idle. then we came back to the house, tilted the engine and the entire bottom carb intake was submerged by oil that collected in the silencer.

i agree that the only thing that seems to make sense is the check valves. it seems to match all symptoms. however, it also does seem that the oil pump is overfilling the tank as well. i plan on trying to get the boat and work on it this weekend, but with mother's day, it may not be very conducive to working on it.

 

[seasick]

Unless I missed something you didn't mention the oil pooling after running or while sitting with engine tilted. If your seeing what appears to be oil running out of the silencer after running the could be the 2-stroke slobber we all experience. Usually happens when varying the throttle. Not sure why it happens but the carbs or throttle body spits during throttle changes. In my case it usually amounts to enough to absorb a few paper towels midway through the season. You may think it's just oil because the fuel has evaporated. If you see oil after the motor has been sitting tilted, I would bet the check valves are bad, yea you replace 3 but one of the other one's may be bad. While in there you should think about replacing the oil lines with weed-wacker fuel line and make sure the pressure clamps are on tight. To check for sure, you have to remove the oil lines on all the carbs and see if any drips out the ends. Cheeez, $1000 in parts?! With that vintage engine, I would disconnect all that crap and premix. The piece of mind is worth it to me.

There are six check valves but to be honest I am not sure what function they serve. If they are spring loaded they may limit oil flow until a certain pressure is sent but I don't see them regulating oil flow per se.
I am also not sure on the carbed models where the oil gets pumped. Is it into the fuel bowls or into the throttle throat? ( I am a lot more educated on the SX fuel injected motors)
If it is into the bowls, I guess it could be possible that one or more carbs is not using fuel at the same rate as the others so in effect gets too much oil that overflows. In that case, the carbs assuming they are in good shape, need to be synched. Of course, if the synch is off and the carbs are OK, I would expect rough idling or problems at speed under load.

 

[gw204]

have you confirmed it is oil and not mixed gas you are seeing? mixed gas will look similar to oil but be thinner. if it is mixed gas then your problem is likely one or more carbs needing a rebuild.

you don't seem to have identified a leak source, which makes me suspect it is just leaking out of the carb throat.

My money is on this.

 

[Tucker]

have you confirmed it is oil and not mixed gas you are seeing? mixed gas will look similar to oil but be thinner. if it is mixed gas then your problem is likely one or more carbs needing a rebuild.

you don't seem to have identified a leak source, which makes me suspect it is just leaking out of the carb throat.

My money is on this.

Naaa, the OP said it isn't slobber. And...I'm taking back the check valves being the problem. The oil feed hoses connect to the intake, not the carb. The check valves are there to keep the oil from draining backwards hence running the engine "dry" upon start up after shutdown for a while. They would not stop oil from "feeding" the intake, just the opposite they would open up. Fshlbi, you had the engine mounted oil pump replaced, correct? Not the pump in the onboard oil tank? We have confirmed 2-problems: 1) The engine mounted oil tank overfills. 2) Too much oil is being delivered to the intakes. And...the freakin' problem is intermittent! Next thing I would do is run the engine hard with the cowl, an silencer off. If these are original oil lines, I'm wondering if there's a leak somewhere. this still wouldn't explain the problem being intermittent.