I don't see where you said you're down or up on water pressure. How's that gauge looking and what pressures are you seeing. Too little and too much pressure are signs of flow issues.

Low - potential bad housing
High - still have a blockage issue

If the water dump system had a leak it would be sucking air and you'd lose your siphon and/or be dumping water in the bilge as mentioned.

A friend made a tool for me to back flush from the exchanger. Water pressure alone won't clear debris from the oil cooler. It's the only cooler that is not pass through. It has a honeycomb input. If you can't get to it directly (below port manifold) add some air to the back flush. My tool has air integrated into it. Water and then a burst of air and repeat.

The additional debris removed by adding air was staggering. All temps and pressures returned to normal. I don't have strainers. I've been fighting this for three seasons and finally have a resolution with not having strainers.

I'm not getting any water in the bilge, nor do I have any flush system or any other "T's" from the transom to the pump.

Thanks Bup, I'll look into those check valves. Never knew they existed.

I don't have smartcraft to see the water pressure numbers, and for some reason, I didn't see it on the Rinda. I'm going to go there tonight and take a second look at the Rinda and hopefully I missed something and can provide more info.

Thanks for the tips on the backflush.

Raylar 600, Whipple stage III ECU, 640 HP, Big oil cooler with oil thermostat. The temp, and knock retard are pushed way back.

Ok, so the only parameter the rinda shows is "Block Pressure". That value is 1.9 at idle and 5.8 at 3800 rpms. My other motor which is running the normal 167 degrees, that block pressure reads 1.9 at idle and 13 at 3800 rpms.

So what sensor is the Block Pressure value reading on the Rinda ?

I do believe the block pressure parameter on the Rinda is water pressure. 5.8 is much lower than I typically see at higher RPM.

Correct. 6psi at 3800rpms is not going to cut it.

So will a new Hardin pump solve this ? Or could there still be a restriction somewhere before the pump...like the gimbal hose. Boat is kept in the water and i can't really backflush through the drive.

Pull the water pump and take a look at the condition since that is an easy one to do. The mud may have done a number on the impeller and housing. Any type of scoring on the housing will cause pressure problems. If the pump and impeller check out, then you have issues in the fresh water side of things.

the drop in repair kit for the original housings are a bandaid anyways. Many people forget that the sides of the housing wear and scars as well.. Impeller housings and impellers are matched to certain tolerances to pump the correct water flow volume and maintain pressure thru all rpms. These tolerances are matched front and back along with the complete side walls of the impeller housing.

Also boat owners who do not winterized properly and or do not drain the impeller housing 100 % of water risk a change of distorting the impeller housing in freezing temps.

Does Hardin have a pump for the 496 with the water pressure sensor hole? I know they have one for the 502... and 496 without the sensor.