OX66 225 over heats

[blindmullet]

I flushed mine with a mild acidic solution followed by a base. The motor pissed calcium. Lol

 

[Pighunter]

My order from simm Yamaha just arrived. I'm confident this will solve the overheating issue. I've ordered a impeller kit from my local dealer [30 miles from me] and its never come with everything like this kit.

 

[haywire farm]

I've got my kit too. I went ahead and ordered the lower unit oil seals as well while I'm in there. Hopefully will have everything put back together this week. The head gaskets were backordered for at least 2 weeks, so that's going to cause a delay in testing it out again.

 

[seasick]

Make sure the wavy washer goes between the two flat shaft washers.

Which oil seals did you get, the output (prop) shaft or the input, drive shaft seals?
If prop shaft, good luck with theat job. Sometimes it's not too bad and sometimes not.
On some Yamis ( my 150 for example) there are two seals. That should be installed with the lips facing opposite directions. One seal keeps oil in and the other keeps water out.

 

[Scottwd1]

I'm coming in on this a little late here but. Was the motor overheating prior to you replacing the impeller? In your case you probably did not seat everything together correctly under the impeller housing causing poor flow until you goose up the throttle a bit. Often times a slow overheat at Idle indicates the metal and plastic sleeve in top of the impeller isn't pushed down/seated well enough. Also try using quick dry silicon to seat the two 0-rings under the housing. And Always replace the metal sleeve and plastic collar. The three metal what look like shims can be re-used but make sure the wavy one is in the middle of the pile. Hopefully you are using OEM pump kits and t-stats.

Side note: I've had these motors on a couple of different boats for over 17 years now. If you are going to keep this motor for much longer definitely invest in a Yamaha Temp gauge and a Yamaha water pressure gauge. These gauges working together tell you the story to a tee sometimes as to what is making the engine overheat example: partially stuck poppet valve you will never see more than 8-9spi while underway, clear poppet 13-15 psi. When the alarm went off did you try snapping the throttle a few times in neutral (in water of curse) to see if the alarm goes away. If the alarm goes away this is often indicative of a stuck or partially stuck poppet.

Hate to have to say it but are you sure it's not the oil tank alarm! That thing has made me nuts too....
Also if you MUST run it on land with muffs Definitely remove the plastic water pick-up screen on the lower. You can't really troubleshoot a Possible overheat on land with any degree of confidence, Lauch and send it! Good Luck

 

[Pighunter]

I just removed the lower unit and I think I found the problem. It's missing the rubber bushing where the pickup tube enters the top of the impeller housing. I guess I had my head up my ass when I put it together.

 

[Pighunter]

I have felt your pain. Not great design for easy worry-free installation.
Those metal cups and o-rings suck.
Combine that with OX66s not reliably running on ear muffs and needing a Yamaha Hot Tub in order to test it..

The kit doesn't include the parts with the red arrow...some plastic sleave and metal springy shims
and the plastic housing can crack or warp.

View attachment 26738

There was a time when outboard pump was a gasket,base,impellor, and key and the housing was metal and didn't get replaced. Then they decided to "save money".

Actually after looking at your schematic it looks like I didn't have a couple of parts. The piece between 6 & 7 was not on when I originally took it apart and I don't seem to have a number 7 in my kit.

 

[Pighunter]

My old housing with the bushing still in it

New housing has a different type.

 

[haywire farm]

My housing looks the same as yours without the bushing/black seal at the top.

 

[haywire farm]

Ok so after replacing the thermostats, poppet, water pump, removing the heads and water jackets and cleaning them out, and reinstalling everything….one head is still overheating at about 190 degrees. The other head (which I found the inside anode to be broken off and I removed it for now) was running fine at around 140 degrees. Do you think the anode might be clogging up the water passage inside the head somehow? It’s he only thing that I can think of. Should I remove it and run it to see how it does before replacing both of them?

PS I had to buy a smaller torque wrench for the water jacket and head studs. The big ole 1/2 just wouldn’t get down to 2.9 ft/lbs for the first pass.

 

[seasick]

I have head of anodes blocking flow in other motors. But first let's back up a bit.
Did the motor overheat before you replaced the pump?.
If that rubber bushing was missing from the pump housing (not the top most bushing) that you wouldn't pump enough water volume.

 

[Pighunter]

I have head of anodes blocking flow in other motors. But first let's back up a bit.
Did the motor overheat before you replaced the pump?.
If that rubber bushing was missing from the pump housing (not the top most bushing) that you wouldn't pump enough water volume.

That was me that had the rubber bushing missing. We have two people here with over heat problems.

 

[seasick]

OK. was and probably am still confused. I just lay low.....

 

[haywire farm]

That was me that had the rubber bushing missing. We have two people here with over heat problems.

I have the same “new style” housing as you without the rubber seal. I don’t think that would cause just one cylinder to over heat and not the other. But it might! Who knows at this point! Haha. I’ll pull the other anode this week and check it out.
I appreciate every body’s feedback and input.

 

[haywire farm]

So I took the thermostat out of the housing on the port side (the side that is running fine) and it appears to be opening fine and getting water to it. I removed the one from the starboard side (the side that is running hot) and it doesn't appear any water is getting to that side.
Does anyone know of any other water passages that might be causing this?
Thanks so much!

 

[haywire farm]

So after pulling the rest of my hair out, I finally figured out my problem. The engine was running hot on the muffs, but when I put the lower unit in a water tub, it runs just fine and doesn't overheat. So I basically spent about 20 hours on "repairs" for nothing, haha. Just an FYI for those who might be having the same issue. Although, it is reassuring knowing that every single water passage is now clear and new parts throughout the entire cooling system.

 

[seasick]

Well I replaced the thermostats and the poppet valve and I'm still overheating at low speed.

Regarding the above post, was this overheat on the muffs?
It would have helped the suggestions to know.

 

[Pighunter]

Regarding the above post, was this overheat on the muffs?
It would have helped the suggestions to know.

No I never run it on muffs. It was in the ocean. All is good now, I ended up using my 2 year old impeller housing with the old style bushing. The new style allows water at low speed to leak past the pickup tube.

 

[seasick]

OK. good to know.

 

[dogdoc]

My mechanic that helped we out last time we pulled the boat never runs on garden hose or muffs, but always both. Says there can be overheat problems when using just one or the other.