Yamaha 60 HP Two Stroke Overheat Frustrations

[Supercaiber]

Ok,, the basics. At low rpm's the pump must work 100%. Any air leak into the impeller area will do what your described. I use a loctite sealant on the complete SS waterpump "Cup" water is 900 more times dense than air. So even a little leak can cause issue's.. When up and on plane the water is being forced/jammed thru the pump, flexing what is now considered a centrifugal pump... As in at higher speeds you can take out the impeller and run fine..

Thanks. Can you tell me what loctite you are using? I have another new impeller kit in route.

[zenoahphobic]

Looking at your photos of the stainless steel cup and base plate, they seem marginal. It loooks like grooves and blackening, this seems that the impeller may have run dry to itself overheating. Running without water can do this. This could also mean the (a previous) impeller could have broken apart.

So, your passages from what you could show are OK, this could mean some impeller fragment is lodged and could move to shut off cooling water. The sudden onset of alarm and hot pee water could suggest this.

If that the case the blockage is low below where the pee hose comes out.

Suggest you renew everything of your water pump, paying attention to what BajaKeith highlighted.

[Keithbaja]

Also if the old impeller was missing a "vane" you need to pull the copper pipe that goes up to the pwrhead and clear the pump discharge pipe. If it passed into the motor,, don't worry much about it till it plugs a therm or telltale

[Keithbaja]

loctite #1525607 careful that's 16 fl oz big ass can.. They sell it in smaller sizes. It's not supposed to Thoroughly drive out...

[Supercaiber]

Also if the old impeller was missing a "vane" you need to pull the copper pipe that goes up to the pwrhead and clear the pump discharge pipe. If it passed into the motor,, don't worry much about it till it plugs a therm or telltale

Thanks I’ll grab some for the new kit.

I will also provide an update on the thermostat temperature testing.

[Keithbaja]

Btw,, goober up the complete side and up over the curve on the Cup. A bit on the upper O ring
use it sparingly on the top as there are vent cutouts

[Supercaiber]

Btw,, goober up the complete side and up over the curve on the Cup. A bit on the upper O ring
use it sparingly on the top as there are vent cutouts

Thank you sir.

This morning I tested the thermostat at 130, 135, 140 and 160 degrees.

130 - Barely open, if much at all
135 - 1/8” or so open
140 - not much more that 1/8”, let’s stay 3/16”
160 - significantly open.

This leads me to believe the thermostat is opening much later that it should? Agree?

I have a new one scheduled to deliver tomorrow and will test with the same temps at the same time to see how they compare.

Again, I appreciate all of the knowledge you guys have shared.

Stay tuned.

[zenoahphobic]

Atleast thermostat is opening fully, don’t think that’s the problem.

[99yam40]

Just a thought,
but my brothers C60 has a problem running wide open( overheats) but runs fine for as long as you want at lower throttle.
there seems to be stuff in the cooling passages the ends up in the stat plugging it off while running WOT.
shut it down, pull the stat and clean it out and it runs fine for awhile again.
I have flushed it out several times, but it keeps happening.
Problem is he rarely runs the boat.

might check to make sure you do not have stuff building up around the stat when you get the alarm.
or do a chemical clean

[panasonic]

https://www.boats.net/catalog/yamaha...casing-drive-2

Reference above parts diagram. Are items1,4, 10, 11 and 16 all in place? Especially the three seals that go in the water pump housing where the water tube connects.

[Keithbaja]

Super caliber, some tips on w/p replacement. Take the driveshaft key and grind down one flat side. Install with grease. Use a small screwdriver and put grease in the four water pump bolt threads on top of lwr unit.. Do not use any Sealants. Use fresh grease on driveshaft splines,, but not on the top of shaft.. Pull up and slowly turn driveshaft clock wise, while tapping down impeller and keepers.. This preload the gears and stops clunking.. Best with two people..don't watch YouTube outboard repair videos..ain't seen one done right yet... There are a lot of tricks to do the job correctly.......after just rereading complete post,, I noticed you replaced w.p housing. On a complete new kit or new housing they dont give you the last (top) grommlet.. Its round with two sideways locking tabs. I've seen 100's of them missing..font know why yammy does that,, but you have yo salvage the old one out other top of your old pimp housing

[Supercaiber]

https://www.boats.net/catalog/yamaha...casing-drive-2

Reference above parts diagram. Are items1,4, 10, 11 and 16 all in place? Especially the three seals that go in the water pump housing where the water tube connects.

This is an interesting observation. Looks like I am missing 1&4. Not sure exactly how they fit and stay in place, but I’ll order them. Thanks!

[Supercaiber]

Super caliber, some tips on w/p replacement. Take the driveshaft key and grind down one flat side. Install with grease. Use a small screwdriver and put grease in the four water pump bolt threads on top of lwr unit.. Do not use any Sealants. Use fresh grease on driveshaft splines,, but not on the top of shaft.. Pull up and slowly turn driveshaft clock wise, while tapping down impeller and keepers.. This preload the gears and stops clunking.. Best with two people..don't watch YouTube outboard repair videos..ain't seen one done right yet... There are a lot of tricks to do the job correctly.......after just rereading complete post,, I noticed you replaced w.p housing. On a complete new kit or new housing they dont give you the last (top) grommlet.. Iround with two sideways locking tabs. I've seen 100's of them missing..font know why yammy does that,, but you have yo salvage the old one out other top of your old pimp housing

More good advice. I’ll orders the necessary parts and keep y’all posted.

Really appreciate all the feedback.

[Keithbaja]

super caiber, part # 1 is the one yammy dosnt give you.. #4 isn't used on the bigger motors which is the bulk of my work.. To install #1,, large lip facing up. On the side of #1 gromlet is to round nipples that go inside and
thru the top round part of wp housing to lock it in place. Write back when done.. F-ing Yammy leaves this part out to mess with folks and will cause low rpm overheat. Grrrr

[Supercaiber]

super caiber, part # 1 is the one yammy dosnt give you.. #4 isn't used on the bigger motors which is the bulk of my work.. To install #1,, large lip facing up. On the side of #1 gromlet is to round nipples that go inside and
thru the top round part of wp housing to lock it in place. Write back when done.. F-ing Yammy leaves this part out to mess with folks and will cause low rpm overheat. Grrrr

You are the man! Ordering today.