2003 ox66 225, ? about water intakes

[KCLOST]

I'm having a bit of a problem with my dealer/service in regards to loss of water pressure at WOT..
Let me give you some background info... I purchased this motor with my TR20 of the same year about a month and a half ago. During the test drives we had an overheat alarm come on and the dealer obviously put in a new water pump before I picked it up. Now this boat/motor are new, and have been sitting around for 3 years or so, so that was nice of them...
Anyway, I purchased the boat and started the breakin... Eventually I opened her up and adjusted the motor height. At 6.5" above the transom and a 8" detwiler jackplate I was reaching 75-76mph and showing 5800 rpms with a 27P Tempest. The water pressure was holding steady at 16-17psi. My trim was at 3/4 up according to the guage... I did this several times and was very happy and everything worked great.

Now hear is the problem... One day a few weeks back I was running at WOT about 1/2 way trimmed out and I looked at the guage and was runnning 20psi. I look ahead and continue for a few seconds and happened to glance at the guage and it is reading ZERO. :^ So I immediately decelerate and I gain water pressure again back to 20psi.. I retested this a few times and the same thing happens. It will hold at 20psi for about 10 seconds .and then the guage just drops down to nothing. (however I shut it down before it actually bottomed out). My dealer says the motor was too high so they lowered it about 3". I go to retest, and the same thing happens. I'm only about 3" above the transom now. Each time this has happened I have not gotten an overheat alarm, which is good! Caught it early enough I guess.

So I take it in again and they now say that I have the wrong water intakes!!!.. Have any of you heard of this? Is there a newer style out there. I still don't understand why everything was fine and now it's a problem... Could I have fried the impeller and that is the real issue when at WOT?

 

[rodbolt]

Re: 2003 ox66 225, ? about water intakes

there is a tech bulliten out on the high performance 3.1 intake grates.
it may take some hunting but they should have it.

if your going to continue for max performance you will need to have the case modified for low water pick up.
5800 is a bit on the high side.

 

[KCLOST]

Re: 2003 ox66 225, ? about water intakes

Rodbolt, It's not about max performance anymore... I just completely lose water pressure at WOT with very little trim and the motor is relatively low with an 8" jack plate...

Are you aware of intake issues that will cause a complete loss of water pressure, even though they are completely submerged with the 3.1's?
My tech is saying I have the wrong intakes. And I have seen several other motors on co-anglers of mine with the intakes I have on them.. So I'm a bit confused....
This motor should run well at 6.5" above the transom (this is recommended by Todd Morgan with C&O marine). And it did! But now there is a problem I can't understand... Could an overheated impeller cause this, because that is possible with the heavy grass we have in my home lake. Maybe that was the initial cause..

 

[rodbolt]

Re: 2003 ox66 225, ? about water intakes

could be, or it could be yamaha reccomends a height of 1" above or below the bottom of the hull.
if ya wish to vary then the gearcase may have to be modified accordingly. could also be your guage is failing.
if you suspect the pump is bad it takes 1 hour to drop it,inspect/replace it and reinstall the case.

 

[Ray Neudecker]

Re: 2003 ox66 225, ? about water intakes

Since the alarm didn't go off, I would want to first test the water pressure guage and hose. I first would take the hose loose at both ends and blow it out. Then reattach to the guage and with a metered air hose bring it up to different PSI's to check the guage.
Obviously you are getting best performance at a high transom hieght, but I agree 100 percent with Rodbolt. A wise investment would be to have an aftermarket nose cone with the proper pickup for your application installed.
Bob's Machine Shop has been a leader in this for many years.
That can be a very reliable strong performing motor properly set up. With the limiter disconnected, they seem to like to turn up to 6400 for long periods with out any problems.

 

[rodbolt]

Re: 2003 ox66 225, ? about water intakes

think about it.
if the motor was at operating temps and full load, how long would it take with a total cooling system failure to over heat? and trust me that over heat WILL rapid and WILL be catastrophic.
without actually riding with you its hard to say, does the tell tale from the block go away?
test the guages and insure they are accurate.
couple weeks ago I got called in to find a "sudden"problem on a pair of 3.1 250's.
after extensive and expensive chatting with the customer I finally got the story.
that mombo combo transducer he and his friend installed was areating the water flow. for proof we made a run with and without the transducer.
it set him back about 400 dollars of my time to prove it.
my motto is always go back and look at the last service, half the time its a bingo.
god I wish my industry actually had standards.
seems any idiot with a tool box can be certified.

but if your set up allows the anti-ventilation plate to rise more than 1" out of the water all bets are off cause you are running a transom hieght higher than factory specs.
its just a fact o life.
ya wish to run outta engineering specs ya gotta pay more.

 

[KCLOST]

Re: 2003 ox66 225, ? about water intakes

This has been the wierdest thing I have ever seen.

Well it's been several days since I last posted, so here is what has happened.

The dealer changed the water pump (again), they have lowered the motor repeated times and now have it at it's "lowest" position (well within engineering specs). The new intake screens were installed, and they have changed my prop from the 27 tempest to a 25 Yamaha M. The guage was checked out ok.

Take it out to test, and the same freakin thing happens. After getting up on pad and going to 1/4 trim according to the guage, the water pressure drops to zero. I did turn around and look at the tell tail and it was peeing water but it looked weak to me. I did get an overheat alarm on my test run Friday when I decelerated after a WOT run of about 20 seconds and then made a turn.. But it doesn't overheat while running straight I ran for 10-15 seconds with the guage reading zero and the alarm didn't sound.

My dealer took it out yesterday and raised the motor all the way "up" (way out of engineering specs) and he says it held pressure ok :/. He has talked with yamaha and they are sending another type of intake screen that are designed to be used on a Triton hull....
There must be something going on with the pressure wave that doesn't work well with the Yamaha lower unit...????

 

[budm59]

Re: 2003 ox66 225, ? about water intakes

I have a 22' flatsboat w/a 225 V-Max, my motor has always run high. I recently replaced the water pump and now I lose water pressure every time I break over on plane even jacked all the way down. I replaced the pump assemby two more times with the same results. Since then I have replaced head gaskets, t-stats, prv and am at the end of my rope. I went to PorMansfield, Texas and talked to the locals with Yamaha engines. They told me there was a design change in the factory pump and they had the same problems. Also stated they had spoken with Yamaha and was told Yamaha doesn't make lift pumps. One of them replaced his pump with an aftermarket Sierra and problem was fixed. I'm about to try it myself, anyone heard of this?

Buddy

 

[budm59]

Re: 2003 ox66 225, ? about water intakes

I've replaced the water pump again with an aftermarket Sierra pump. The Sierra impeller is much stiffer, larger in diameter and the impeller cup is smaller in diameter. The housing is also shallower and the impeller thicker.It is difficult to get the impeller in the housing compared to the OEM part. This thing is tight and like others said it will drill a hole in concrete at idle now. The pressure guage will hit 30lbs when I nail it and then the PRV holds it at around 22 to 25lbs. I never had this much pressure. Yamaha knows they have a problem. The motor has to be deep for their pump to work, this isn't possible on a shallow water boat. When I plane the motor is to high for it to work. Sierra fixes it!!!!