Yamaha T50TLRX - Steam from auxiliary exhaust port

[Sigi]

Hello,

About 3 years ago the Yamaha T50TLRX started exhausting what I think is steam from the auxiliary exhaust port. This has gotten worse over time where it is now a very noticeable "cloud" at all times. I did ask a local Yamaha dealer once about them and they suggested it is normal and not to worry.

A second change is that around the auxiliary port there is now evidence of heat and the rear top cover of the engine is also discolored.

Apart from the items mentioned above, the engine runs fine and stars easy. The compression on the cylinders is average with #3 a bit lower than the other three, at #1: 90, #2: 80, #3: 70, #4: 90. I am now planning to investigate and do any necessary repairs to the engine before the boating season starts again in the spring.

Based on the symptoms above and in the pictures what is the problem with this engine?
Is it a problem with the head gasket and would replacing it solve it?
Is it a problem with plugged exhaust ports and would "Salt Away" clear it?
Will the powerhead need a full rebuild?

Appreciate any feedback and help.

Andy

 

[racerone]

Those compression numbers are not encouraging for a 4 stroke.-----Test with another gauge with throttle open.-----Perhaps there is a compression release on it too.

 

[Sigi]

I understand, but it may be just the way I measure the compression. We had this engine for the last 10 years and there has not been a significant change in compression. Assuming that we do not have an issue with the compression, do you have any suggestions and solutions that relate to the steam issue? What causes a steam cloud to come from the auxiliary exhaust port?