OX66 225 over heats

[Pighunter]

I just replaced seals and impeller and housing in my 99 ox66 225. Yesterday I launched for a day of salmon fishing. I motored out the fishing grounds about 5 miles, then switched over to my kicker for trolling. After about 4 hours I fired up the main and ran north about 15 miles, steady steam of water being pissed like normal. Finished up and ran back to the salmon grounds again. After trolling again with the kicker I fired up the main and it sent the overheat alarm after a few minutes. I ended up trying to come in on my kicker, after an hour I was able to start the main with no alarm. I got back to the launch ramp about 10 miles with no overheat alarm but at the ramp sitting at idle the over heat alarm sounded again. Any ideas? I guess the only thing to do is pull the impeller again?

 

[SkunkBoat]

idk, if its pissing good the impellor is working.
try poppet valve. Replace thermostats just for S&G.

See if its just one side of the head thats hot?

 

[Pighunter]

idk, if its pissing good the impellor is working.
try poppet valve. Replace thermostats just for S&G.

See if its just one side of the head thats hot?

It's been 2 seasons since replacing poppet valve and thermostat,, i will replace those this week would that cause it to over heat at idle but okay when under full power?

 

[SkunkBoat]

If a poppet is stuck open you will have problems at idle

if the telltale is pissing then the pump is pumping water to the top of the block. That water heats up and the tstats open to let the water flow through the heads to cool. Your motor has two tstats One could be not opening or clogged with salt gooo.
worse could be clogged passage or a leaking gasket

 

[seasick]

A stuck open poppet will cause overheat at low revs but normal cooling at higher revs

 

[Pighunter]

Just ordered thermostats and poppet valve assembly, hopefully be here Friday

 

[seasick]

Poppet assembly is a little tricky. Make a note of the order of parts when disassembling. Note that when you remove the bolts, the internal spring pressure will tend to 'pop' the unit open and parts can fly
Also make sure that the rubber poppet seat get inserted correctly into the block. If correct the neck of the poppet stem will slide in and out without binding.

 

[Pighunter]

Poppet assembly is a little tricky. Make a note of the order of parts when disassembling. Note that when you remove the bolts, the internal spring pressure will tend to 'pop' the unit open and parts can fly
Also make sure that the rubber poppet seat get inserted correctly into the block. If correct the neck of the poppet stem will slide in and out without binding.

I replaced it two years ago when I bought the boat. I found a video on line showing it, I remember using a 3/8" dowel to help insert it. I'll search for the video again.

 

[Pighunter]

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

 

[seasick]

I reread your first post. If you didn't overheat before you replaced the impeller and housing but do overheat now, something got messed up during the pump rebuild. It could be several things, like a spun impeller. the wrong impeller, wrong order or missing gasket/wear plate, impeller rotated the wrong way during installation, missing or cracked seal on water tube, running the impeller dry even for a very short time ( did you grease the housing's inside)etc...
You will probably have to drop the LU and check your work

The pee stream kind of tells you that you have pressure but it doesn't tell you if you are pumping enough volume, which it seems you are not doing.

 

[Pighunter]

I reread your first post. If you didn't overheat before you replaced the impeller and housing but do overheat now, something got messed up during the pump rebuild. It could be several things, like a spun impeller. the wrong impeller, wrong order or missing gasket/wear plate, impeller rotated the wrong way during installation, missing or cracked seal on water tube, running the impeller dry even for a very short time ( did you grease the housing's inside)etc...
You will probably have to drop the LU and check your work

The pee stream kind of tells you that you have pressure but it doesn't tell you if you are pumping enough volume, which it seems you are not doing.

Yes I'm going to pull the LU this week. I greased it during install, It doesn't overheat at high speeds and the pee stream is not as powerful at idle as it was before impeller replacement. It's possible I put something in the wrong order but I didn't think so? I'll order another impeller kit and replace it again.

 

[seasick]

Did you pre bend the vanes of the impeller by turning the driveshaft clockwise while looking down on the LU as you squish the impeller into the housing

 

[Pighunter]

Did you pre bend the vanes of the impeller by turning the driveshaft clockwise while looking down on the LU as you squish the impeller into the housing

Yes I did

 

[SkunkBoat]

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.



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".

 

[seasick]

Make sure you have part # 6 have part # 22 facing the right way and have the o-ring part no. 10 correctly seated. some grease on the o-ring will help hold it in place

 

[Pighunter]

I just ordered a new kit from Sim yamaha

 

[haywire farm]

I'm having the same problem. I replaced both thermostats and the poppet valve (note the new style is shaped like a dome rather than the old "t" style that came out." I just pulled my lower unit and my impeller looked to be in great shape. I just pulled the heads and the water channels around the cylinders looks clean. I was going to pull the water jackets off the heads and of course one of the bolts snapped off.

 

[blindmullet]

How was the scale in the motor when you removed the thermostats? I had to descale a 115 Yamaha and the 225 on my Grady. The passages needed to be cleaned up.

 

[haywire farm]

Mine wasn't bad at all, which is kind of unsettling after thinking the scaling might be the issue. I was able to get one head and water jacket off yesterday and they didn't look too bad either. At this point I’m not sure how to pinpoint what was causing it to overheat.

 

[haywire farm]

So I’m going to probably have to weld a nut to the end of the one water jacket bolt that snapped off. The inside of the other one didn’t look too bad.