Yamaha 300 HPDI 2005-2006 Waterpump

[pjlexydaddy]

ID10T,
Which exhaust gasket?
Will this cause a low water PSI issue?
When I ran the new hose for the PSI gauge the water was barely trickling out of the hose. Since its connected directly to the top of the cylinder head I figured it should be plenty of water pissing out. But, once again, the strange thing is that the piss hole has plenty of pressure.
Can this be a thermostat issue?
The heads do get pretty hot to the touch. Shouldnt it just be warm?
If the waterpump was weak I should notice it by a weak pisser. Correct?


Thanks ,
John

[pjlexydaddy]

I GIVE UP! Time for the PRO's to conquer this beast.
I checked the Water pump which reveiled nothing, Thermostats are working as they should, Poppit wasnt clogged and is mushroom type, The exhaust gasket wasnt installed properly(I fixed it) and still the same problem.
My water PSI is way too low.
There is no water exiting the exhasut port behind the engine. Just hot air. Is that normal?
Plenty of water out of the piss hole.
I tried to peak at it while traveling about 3500rmp but didnt see any water coming out.
Somehow, this engine is losing water pressure and is driving me nuts.
I'll keep you guys posted.
Thanks for all the good tips.

JOhn

[IFish4Tuna]

My 250 had the pressure relief valve stuck open from salt build up, but it didn't affect water flow from the pisser. It did however affect EFI fuel. It was same effect as stuck open thermostats. Engine will shake at low speed but be ok while cruising.

Ed

[pjlexydaddy]

I finally brought the boat to a certified yamaha shop.They changed the PSI gauge and hose which did not fix the problem. They installed a temp gauge which showed no overheating problems.
They proceeded to take the boat out on a test run at wide open throttle and the PSI only reached 5-8PSI. But the water temp was cool. There final answer was "Some engines simply have low PSI and since its not getting hot to leave it alone". At this point I really dont care since I am covered under warrantee. Being that the engine was serviced by a certified yamaha tech thay cannot deny a claim if I blow the engine due to overheating since I brought it to them for a cooling problem to begin with.

I just find it hard to beleive that no-one else out there is having the same problem as me, since my brother-n-law has the same problem with his engine. We bought the same package at the same time.

Thanks,
John

[Ken]

John,
There should not be much water at all coming out the relief holes that are at the top back side of the upper casing, UNTIL the pressure control valve opens up. This happens when water system pressure exceeds 20 psi, OR the PCV is partially stuck open for some reason (debris, broken spring).
I have read back over your posts, and it is still a mystery why your water pressure is so low .
I know that when the thermostats open up, the pressure will drop considerably, and this is normal. But at WOT, I would think you should still have at least 10 psi.
I've had an over heat problem with my little C115 for some time now, and I installed a water pressure gauge after doing a water pump repair to make sure my pump was doing its job. Sure 'nuf, I had 5 psi at idle and 20 at anythng over 3500 rpm.
But I still got an over heat alarm at 4000 rpm.
Long story short, after checking EVERYTHING, I removed the 'stats, and replaced them with stainless washers to give me more water flow than wide open stats, yet still give me enough restriction so that the cylinder jackets completely fill with water. To my surprise, my water pressure was cut by over half - 2 psi at idle and 8 at WOT.
My point here - removal of the thermostats can shoot the heck out of your water pressure. Are you sure thermostats are in those heads?
Ken K

[pjlexydaddy]

HI Ken,
Thermostats are in the head and was tested.I picked up the boat from being serviced this saturday and used the boat all weekend with no problems. The PSI was 0 at idle and around 5-8max over 3500rpm.
They installed a temp gauge just to be sure I'm not overheating and to my surprise it was cool all weekend even though the PSI is low. They told me not to worry about it since its not overheating.
Maybe one day I will find that missing water seal somewhere(in my opinion).
Thanks,
John

[dtacmed900]

[QUOTE=pjlexydaddy;n37695]I finally brought the boat to a certified yamaha shop.They changed the PSI gauge and hose which did not fix the problem. They installed a temp gauge which showed no overheating problems.
They proceeded to take the boat out on a test run at wide open throttle and the PSI only reached 5-8PSI. But the water temp was cool. There final answer was "Some engines simply have low PSI and since its not getting hot to leave it alone". At this point I really dont care since I am covered under warrantee. Being that the engine was serviced by a certified yamaha tech thay cannot deny a claim if I blow the engine due to overheating since I brought it to them for a cooling problem to begin with.

I just find it hard to beleive that no-one else out there is having the same problem as me, since my brother-n-law has the same problem with his engine. We bought the same package at the same time.

[boscoe99]

What is the problem?

[Keithbaja]

There a black rubber bushing that isn't included with whole new waterpump kit. U have to take the one out of the old water pump and install it on the new housing. Very top of housing.
outside pump. A lot of folks miss it. I can't for the life of me reason why they sell you a complete wp kit with every part except that part. Kind of goofy imo