1991 70 Beto Possible Overheating issue?

[R3V3R3NT]

Went out yesterday and as soon as we launched we were having what I can only assume is an over heating issue. Initially the alarm beep was sounding from the Yamaha Throttle remote especially when throttling hard then we were in the safety go slow mode. Not long after this Engine was running fine again. Later as we headed back into shore we were kicked into go slow mode again.

The whole time water was flowing strongly out the pisser and today I checked the thermostat by putting it in hot water, and it worked correctly. I also changed the water pump about a month ago. I found this thread ( http://www.yamahaoutboardparts.com/f...p-th15480.html ) that has similar symptoms, and indicates a blocked cylinder head.

Should I go down the same route, remove and check the cylinder head. Or is there something else I can do first? Also I noticed that the water coming out the pisser has never been warm even after long runs. Could this be related to a cylinder head issue?

Thanks

[vr4rhoads]

I recently had the same issue, only thing I could think was that there was something clogging up a water jacket inside somewhere, so I removed my lower unit and use high pressure water and sprayed up inside the motor from the bottom and up through the thermo housing as well. Then I ran a few things of salt dissolver through and it worked like a champ. I had the same exact problem you had as well, strong tell tale and all.

[99yam40]

Went out yesterday and as soon as we launched we were having what I can only assume is an over heating issue. Initially the alarm beep was sounding from the Yamaha Throttle remote especially when throttling hard then we were in the safety go slow mode. Not long after this Engine was running fine again. Later as we headed back into shore we were kicked into go slow mode again.

The whole time water was flowing strongly out the pisser and today I checked the thermostat by putting it in hot water, and it worked correctly. I also changed the water pump about a month ago. I found this thread ( http://www.yamahaoutboardparts.com/f...p-th15480.html ) that has similar symptoms, and indicates a blocked cylinder head.

Should I go down the same route, remove and check the cylinder head. Or is there something else I can do first? Also I noticed that the water coming out the pisser has never been warm even after long runs. Could this be related to a cylinder head issue?

Thanks

Did you replace the impeller only or the whole kit?

Tell tail does not get hot, water come out of it before running through the block very far on the Yamaha's I have seem.
I did see a few posts on a product called Rydlyme that got good results to keep from having to open up a motor to clean cooling passages. you might do some searching for those

[R3V3R3NT]

Did you replace the impeller only or the whole kit?

Tell tail does not get hot, water come out of it before running through the block very far on the Yamaha's I have seem.
I did see a few posts on a product called Rydlyme that got good results to keep from having to open up a motor to clean cooling passages. you might do some searching for those

Yes replaced the whole kit. I will look it up thanks.

[R3V3R3NT]

I recently had the same issue, only thing I could think was that there was something clogging up a water jacket inside somewhere, so I removed my lower unit and use high pressure water and sprayed up inside the motor from the bottom and up through the thermo housing as well. Then I ran a few things of salt dissolver through and it worked like a champ. I had the same exact problem you had as well, strong tell tale and all.

Thanks I will remove the lower unit later this week and give it a try. Not sure how to test the engine without dropping it in the water though? any ideas?