1992 nissan 9.9hp gearcase /cooling problem

[nissan]

Can someone help me?
After renewing the water cooling pump. no water flows when the gearcase is securely thightened in position.When the 4 hold own gearcase bolts are loosened and a small gap (approx.1/16 inch)exits between the mid section and the gearcase the cooling system works perfecftly.What must I look for??

 

[Sea Rider]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Welcome to the forums,

Very strange, if the impeller housing seal is well seated and properly matching water tube should have a nice pee, how have you tested loosening for a small gap to show to work well, with muffs ? You could have water tube coupling issues where tube connects with exhaust upper pipe, there's a rubber seal that's probably worn out.

Happy Boating

 

[pvanv]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Yep, probably have the water pump outlet grommet jammed against the tube.

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Welcome to the forums,

Very strange, if the impeller housing seal is well seated and properly matching water tube should have a nice pee, how have you tested loosening for a small gap to show to work well, with muffs ? You could have water tube coupling issues where tube connects with exhaust upper pipe, there's a rubber seal that's probably worn out.

Happy Boating

Thanks for your reply.
I have loosened the 4 bolts holding the gearcase with the midsection whilst the motor was in operation in a water tank.Obviously I get exhaust bubbles coming from the created gap.Re tighting the nuts whilst in operation in the watertank cooling water flow stops immediately.Strange I know but that's whats happening!.
I have also tried it outside the water tank using muffs and it works ok but I think thats because I have more pressure coming from the water mains.
In the meantime a friend lent me a replica gearcase which I installed on my motor and tried it in the same water tank and it worked perfectly. This means that there is no water tube coupling issues and whatever is wrong is in the gearcase itself.
I dont understand what you mean by "where tube connects with exhaust upper pipe, there's a rubber seal that's probably worn out"
Any more suggestions welcomed with open arms as the boating season has already with us over here.

 

[Sea Rider]

Re: 1992 nissan 9.9hp gearcase /cooling problem

If have tested with another same leg and works perfect, not an issue with upper water tube that connects to lower crankcase by means of another grommet, this part is not visible as will need to remove middle leg and exhaust tube to check it.

Is the impeller housing black grommet well seated at housing, doesn't clear upwards by hand, it's locked to base by means of 2 small pins that securely locks it.
Have you installed a new impeller, if so, is key well seated on shaft and impeller rotated CW while lowering housing to base ?

Happy Boating

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

If have tested with another same leg and works perfect, not an issue with upper water tube that connects to lower crankcase by means of another grommet, this part is not visible as will need to remove middle leg and exhaust tube to check it.

Is the impeller housing black grommet well seated at housing, doesn't clear upwards by hand, it's locked to base by means of 2 small pins that securely locks it.
Have you installed a new impeller, if so, is key well seated on shaft and impeller rotated CW while lowering housing to base ?

Happy Boating

thanks for your reply.
the answer to all of your questions is yes all checked to be correct.
May I add that to remove the gearcase a substantial amount of heat had to be applied to the case.A little bit of filing was also made to the surface of the gearcase matching face so that the imperfections caused by the steel wedges ( used plus the heat to remove the the gearcase) were smoothed down. could the heat stressed or deformed something? visually and phyisically all seems ok externally.

 

[pvanv]

Re: 1992 nissan 9.9hp gearcase /cooling problem

If you removed a substantial amount from the top of the LU by filing, you could be ramming the water tube too far into the upper pump housing. Likewise, if all that heat distorted the wp housing some, it may need to be replaced. Did you do the complete wp kit, or just the impeller?

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

If you removed a substantial amount from the top of the LU by filing, you could be ramming the water tube too far into the upper pump housing. Likewise, if all that heat distorted the wp housing some, it may need to be replaced. Did you do the complete wp kit, or just the impeller?

the pump was replaced as a kit together with the oil seal.The oil seals for the shift rod were also replaced.
my problem seems lack of water when in water tank because with muffs (higher water pressure ) it works ok.
I noticed that on the borrowed LU(which works perfectly in water tank) in the exhaust compartment a small tube connects the water pump compartment with a secondary water inlet at the bottom of the LU flange.This pipe has what seems two hard rubber/plastic grommets one at each of its ends ( inside the exhaust compartment)-My LU (which only works well with muffs) has this pipe but no grommets. Could this have something to do with the lack of water flow??
Thanks for all your patience

 

[Sea Rider]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Water pump sucks water through lateral intakes and also from lower AC plate, not sure if the tube is locked with grommets, what you can do is apply a generous amount of mega grey silicone to both tube ends and shape them accordingly to seal properly against leg wall. Should work better..

Happy Boating

 

[pvanv]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Might be it. What is your actual model? Did you change the upper wp housing when you installed the wp kit?

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Water pump sucks water through lateral intakes and also from lower AC plate, not sure if the tube is locked with grommets, what you can do is apply a generous amount of mega grey silicone to both tube ends and shape them accordingly to seal properly against leg wall. Should work better..


Happy Boating

I'l try your suggestion, thanks.One problem , never used mega grey silicone- what is it exactly and where can I get it from ?.

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Might be it. What is your actual model? Did you change the upper wp housing when you installed the wp kit?

model 9.9B2.
Yes the upper wp housing was replaced

 

[Sea Rider]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Mega gray is a high heat automotive silicone, but could use any other good silicone intended for water use, just apply evenly around tube extreme and let cure/dry for 24 hours.

Happy Boating

 

[nissan]

Re: 1992 nissan 9.9hp gearcase /cooling problem

Mega gray is a high heat automotive silicone, but could use any other good silicone intendeed for water use, just apply evenly around tube extreme and let cure/dry for 24 hours.

Happy Boating

Thanks just ordered a 3oz.tube from Amazon.Will let youknow the result when I receive it and use it.