Thermostat housing hole.

[Douglasdzaster]

Thought I’d start a new thread since this is a new subject for me.
1992 40 MSHQ Yamaha. I’ve been doing a lot of maintenance catching up since I bought the boat. Also learning as I go. Today I was replacing the old thermostat and I noticed this hole in the housing behind the thermostat. I need to know if it’s supposed to be there (I hope). I’m posting a picture of what I have.
I want to thank everyone that’s helped me with this project I have learned a lot on this adventure. I just hope it’s not over due to this.

 

[Sea Rider]

Not an issue, all thermo housings have a water passage built into them, if not thermo will work dry and overheat. Which was the thermo condition found when removed from the housing ? Was the thermo cover gasket in mint cond ? Is this a salt water motor ? This pic belongs to a Yam 85 HP motor, has a larger horizontal hole...

Happy Boating​

 

[Douglasdzaster]

Not an issue, all thermo housings have a water passage built into them, if not thermo will work dry and overheat. Which was the thermo condition found when removed from the housing ? Was the thermo cover gasket in mint cond ? Is this a salt water motor ? This pic belongs to a Yam 85 HP motor, has a larger horizontal hole...

Happy Boating​

Fresh water as far as I know. There was paint still on the bolts like it’s never been changed. The gasket is going to have to be scrapped off for the new one. The water passage hole is in the back of the housing on the right side just can’t see it in the picture. Thermostat it self had some corrosion and stuck open may be able to clean it up but I have a new one. I had run a heavy mix of Seafoam with the motor in a tank with a hose running keeping cool water. The tank had a lot of grey gunk floating in it after running. Someone told me the gunk came from the water system. I then ran it with muffs and noticed way better water flow from the tale tale. Thats when I noticed the motor running a lot cooler. Sure enough the thermostat is stuck open. Before it would over heat on the muffs.

 

[Sea Rider]

Better install a new thermo along gasket cover, both are relative cheap and motor will cool much properly and pee better. Before doing so, scrape the internal thermo housing manually, looks bit rusty, If counting with a Dremel rotating tool can use small circular metal brushes to do so and much faster too. Poke the housing orifice with something rigid that won't flex to clean it.

If that motor has not been ever decarboned before, much better is to do so with a Carbon Remover Spray sprayed through the carb/carbs while the motor runs geared forward at fast idle rpm on muffs. Would recommend to get a can of CRC Engine Tune-Up Spray and soon after application go for a wot run for some minutes to burn the product leftovers in the cylinders. Can install new spark plugs after returning to terra firme.

Happy Boating​

 

[Douglasdzaster]

Better install a new thermo along gasket cover, both are relative cheap and motor will cool much properly and pee better. Before doing so, scrape the internal thermo housing manually, looks bit rusty, If counting with a Dremel rotating tool can use small circular metal brushes to do so and much faster too. Poke the housing orifice with something rigid that won't flex to clean it.

If that motor has not been ever decarboned before, much better is to do so with a Carbon Remover Spray sprayed through the carb/carbs while the motor runs geared forward at fast idle rpm on muffs. Would recommend to get a can of CRC Engine Tune-Up Spray and soon after application go for a wot run for some minutes to burn the product leftovers in the cylinders. Can install new spark plugs after returning to terra firme.

Happy Boating​

Thanks again for all the information. You’ve helped me a lot. I was waiting to scrape out the housing unit I found out about that hole. If it wasn’t supposed to be there I didn’t want to make it worse. I have a new thermostat and gasket for it. Fighting a broken bolt right now from removing the housing. The head came off and it seems to have welded itself in there.

 

[Sea Rider]

Thanks again for all the information. You’ve helped me a lot. I was waiting to scrape out the housing unit I found out about that hole. If it wasn’t supposed to be there I didn’t want to make it worse. I have a new thermostat and gasket for it. Fighting a broken bolt right now from removing the housing. The head came off and it seems to have welded itself in there.

Sometimes will break any bolt's head when being unscrewed, much worse on engines working in salt water. If the bolt's thread is visible, apply penetrant oil and let soak for a while. With a pressure plier pressed on the thread rotate it slowly sideways to loosen it little by little. Once removed, clean all powerhead's threads, install 4 new thermo bolts previously lubricated with grease, preferably marine and torque to specs.

Happy Boating​

 

[Douglasdzaster]

Sometimes will break any bolt's head when being unscrewed, much worse on engines working in salt water. If the bolt's thread is visible, apply penetrant oil and let soak for a while. With a pressure plier pressed on the thread rotate it slowly sideways to loosen it little by little. Once removed, clean all powerhead's threads, install 4 new thermo bolts previously lubricated with grease, preferably marine and torque to specs.

Happy Boating​

Just the head broke. After removing the other bolt I had to pry a little to get the cover off. I’ve been soaking it with penetrating oil. I tried 2-6mm nuts jammed together but it didn’t budge. Since there’s a good bit of bolt to grab I have a stud remover coming tomorrow. I’ll take your advice and not get in a hurry with it. I noticed a lot of people advice heating and cooling but I’m kind of shy heating aluminum. Man thanks for sticking with me on this thing.

 

[Sea Rider]

Just the head broke. After removing the other bolt I had to pry a little to get the cover off. I’ve been soaking it with penetrating oil. I tried 2-6mm nuts jammed together but it didn’t budge. Since there’s a good bit of bolt to grab I have a stud remover coming tomorrow. I’ll take your advice and not get in a hurry with it. I noticed a lot of people advice heating and cooling but I’m kind of shy heating aluminum. Man thanks for sticking with me on this thing.

Priest patience and a long soak with penetrating oil are key to remove any broken bolt's head. On extreme salted motors in which both threads are soldered as one will need a different procedure which probably won't like watching....

Happy Boating​

 

[Douglasdzaster]

Priest patience and a long soak with penetrating oil are key to remove any broken bolt's head. On extreme salted motors in which both threads are soldered as one will need a different procedure which probably won't like watching....

Happy Boating​

I chickened out and contacted a high performance auto shop near by that also does machine work. Taking her there in the morning. Depending on how long it takes I’m looking at $35 to $75. I’ll let you know how it turns out. I want to get past this and back on track.

 

[Douglasdzaster]

I drop the boat off this morning and gave him my number. The drive way sure looked empty today. Finally I couldn’t wait any more and dropped by just to check on it while I was in town. Lol They were just pulling it in the shop. I hung out and watched this man try everything. Heat didn’t budge it,welding a nut on didn’t work. Etc.etc. It finally broke off in the hole. He takes the smallest drill bit I’ve ever seen and started drilling. Changing bits one size at a time until he got it close enough to pick the threads out. 21/2 hours later we’re hooking me up to go home. No way I would have ever got it done. Here’s the kicker. Best $50 I ever spent. I love my small town. Now to get those new bolts and cover on the way so I can get back to work. If the water circulates good like I think it will. It’s on to the carburetors since I’ve replaced everything else in the fuel system might as well take care of that little bit of fuel coming out of the carburetor throat. Thanks again for sharing knowledge with me and helping me with this project.

 

[Douglasdzaster]

Quick question.. Do I need to use a sealant on the thermostat gasket?

 

[Douglasdzaster]

Thought I’d start a new thread since this is a new subject for me.
1992 40 MSHQ Yamaha. I’ve been doing a lot of maintenance catching up since I bought the boat. Also learning as I go. Today I was replacing the old thermostat and I noticed this hole in the housing behind the thermostat. I need to know if it’s supposed to be there (I hope). I’m posting a picture of what I have.
I want to thank everyone that’s helped me with this project I have learned a lot on this adventure. I just hope it’s not over due to this.View attachment 330045

Sea rider, back to this hole sir. There is a larger water passage hole on the right side back behind this small pin hole. I have a wire brush on a drill that I ran in there a little and wondering if I made the hole. I’m just wanting to make sure that pin hole is supposed to be there before I poke something in it to clean it out while cleaning the rest.

 

[Douglasdzaster]

Sea rider, back to this hole sir. There is a larger water passage hole on the right side back behind this small pin hole. I have a wire brush on a drill that I ran in there a little and wondering if I made the hole. I’m just wanting to make sure that pin hole is supposed to be there before I poke something in it to clean it out while cleaning the rest.

Could it be a vent or a drain?

 

[Sea Rider]

Quick question.. Do I need to use a sealant on the thermostat gasket?

Some issues :
Is the carb losing fuel through the throat ? happens when priming the bulb till firm or while running. I use thick grease at both gasket's sides, that way will be posible to remove the thermo any time to perform a preventive cleanig maintenance without damaging the gasket. Works for me. Retorque the new thermo gasket after one hour use. Post a pic of the hole as don't know where it could be located on the motor ?

Happy Boating​

 

[Douglasdzaster]

Some issues :
Is the carb losing fuel through the throat ? happens when priming the bulb till firm or while running. I use thick grease at both gasket's sides, that way will be posible to remove the thermo any time to perform a preventive cleanig maintenance without damaging the gasket. Works for me. Retorque the new thermo gasket after one hour use. Post a pic of the hole as don't know where it could be located on the motor ?

Happy Boating​

 

[Douglasdzaster]

Not while it’s running but afterwards it comes out of the throat a little. I cleaned it all up and primed it up good and tight and let it sit . It took a couple of hours before it started coming out the throat. Wonder if I should disconnect the line while it’s running and let it run out?
Grease on the gasket it is. I’ll post a picture of where the thermostat is located on the motor.

 

[Sea Rider]

That's a 3 carbed motor, right ? If so, which carb has fuel spills issues, the upper, middle or lower carb ?

Happy Boating​

 

[Douglasdzaster]

That's a 3 carbed motor, right ? If so, which carb has fuel spills issues, the upper, middle or lower carb ?

Happy Boating​

Middle and lower

 

[Sea Rider]

Middle and lower

To know the history behind the combo, owned it since new or it's a second/third hand one and previous owners have not performed a deep carb preventive maintenance which could account for fuel spills.

Carbs usually have a venting hole built on the upper carb, could be located around the mixrure screw area or carb's opposite side as well. When priming the bulb till firm if the needle doesn't close tight against the valve seat will spill fuel from there. Assume than in carbs that doesn't have a built venting hole will eventually spill fuel from the throat. Does Yam carbs have upper venting holes ? Were all 3 carbs previously well cleaned up or that's a new boating territory for you ?

Happy Boating​

 

[Douglasdzaster]

To know the history behind the combo, owned it since new or it's a second/third hand one and previous owners have not performed a deep carb preventive maintenance which could account for fuel spills.

Carbs usually have a venting hole built on the upper carb, could be located around the mixrure screw area or carb's opposite side as well. When priming the bulb till firm if the needle doesn't close tight against the valve seat will spill fuel from there. Assume than in carbs that doesn't have a built venting hole will eventually spill fuel from the throat. Does Yam carbs have upper venting holes ? Were all 3 carbs previously well cleaned up or that's a new boating territory for you ?

Happy Boating​

They do have vent holes in the top but no fuel coming out. Prev owner said he had the carburetors rebuilt then it sat for a year before I got it. Before even trying to start it I cleaned the tank and flushed all the lines( old gas smelled like varnish) installed a clear inline filter under the cowling and it fired right up.The only thing I did not do was drain the bowls before starting it. Why I didn’t think of it i don’t know. After replacing the water pump. I took it out and the boat flew. Idled good, great wot. Second time out noticed a couple of black specs in the filter and I stopped running it and started replacing lines installing 10 micron fuel water separator etc. I use non ethanol fuel and still mix with marine Stabil and Seafoam which is probably over kill. I’ll post some pictures of the carburetors along with the thermostat housing next.