[jaxter]

When I rinse mine at the end of the season, I take off the prop so that I can run it at full throttle to properly check the flow.

[BitLex]

I ran the motor on the boat: about 5 NMiles, a little more than 1 hour and back, without the top cowling, continuously checking the cylinder temperature by finger. Always cool, except on the first half minute or so after starting - probably thermostat still closed. At the far end of the voyage an Yamaha dealer/boat-yard reassured me about the good working of the cooling system. He showed me on a 3hp Yam the telltale rubber tubing that mine have not. [links]

[ChesterA321]

It is essential that the water pump is properly immersed and with fixed drive engines in small tanks or bins advisable to remove the prop so that turbulence does not affect the water pick up here

[Cruzz]

Thanks to all who will either remove my fears or warn me.

[kelvie]

I had enough of this, so I popped the thermostat cover and found my problem. The inside of the housing and rubber hose were coated w/some pretty thick scale. Tried flushing w/vinegar, but I wasn't getting anywhere. Switched over to the "Works" toilet bowl cleaner. Poured it down the block through the thermostat housing, let it sit ten minutes and rinsed w/ water, and did this repeatedly (10-15 times) until foaming stopped and I didn't see any chunks of scale coming out below (had the lower unit off) or above. Cleaned up the thermostat, thermostat cover and all the hoses/tubes. Everything appears to work perfectly now. Ran it hard for 15 minutes pushing the boat..had warm water at tell tale. Motor seemed normal temp. Tell tale didnt plug again!!

[dragon]

Even though everything appears to be working fine, I have this idea in my head that the water jacket is caked with this material and I didn't get it all removed. And it could cause problems later. [links]

[motherhumper]

Now..my question. I'm worried I didn't get all the scale from the water jacket. As I was trying to flush the block, I could not get any liquids to go down the port the other end of the thermostat cover tube was connected to on the block. I could suck on it and get water and air to come out, but no flow the other direction blowing into it. Is this normal? Where is this water going? How is it going anywhere when I couldn't push air through it? here

[Mackendra99]

I have a 2002 T8 that was constantly loosing the flow on the tell tale, even after a new water pump. A wire up the pee hole would help for a while, but eventually it would plug again. Occasionally, I'd find little chunks of sand/scale in the tell tale line when I'd take it apart.

[generator]

Follow on from previous post, I bought a new Yamaha 2.5HP 4 stroke earlier this year. Used it a few times in saltwater over a 10 day period to get from boat to shore etc. Then unused for no more than 4 weeks. On next use - no water from teltale. Took it back to supplier who found in that short time, salt crystals had blocked the teltale. Suggested I run it in freshwater if not going to use it for more than a few days. here

[jenifrer]

Is this normal for these small 4 strokes? I never had this problem with the old Johnson 2 stroke that it replaced. more

[romanoza]

[jb55]

here

[Loki]

[links]

[bidcoin]

If the system is completely blocked chemical cleaning with a acid it unlikely to be effective because if the acid can't get through it wont be able to remove any scale. more

[HariposterAA]

Second one - very battered and rattly and power down, but still starts first pull, and does everything it says on the box.

[NghtRppr]

I've just uploaded the outboard motor repair scans from PBO to my photobucket page: http://s1136.photobucket.com/albums/n491/barnaclephill/

[andyc]

Ron Hale in Portsmouth is another [links]