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I want to know if anyone can help me with a cooling water pressure problem. I have a 2005 Z300turd. After about 25 hours I tagged a sand bar with the lower unit. No visable damage to the lower unit. But I did notice that my water pressure was reduced to around 2psi at idle and 5psi at 4500rpm. So, I changed out the water pump impeller thinking that I may have cooked it. I inspected the old impeller and found no damage. I check the dicharge tube from the pump to the block and the ports on the lower unit and found no restrictions. So I went ahead in installed the new repair kit. Impeller, plate, gasket, woodruff key. I tested the engine again and still had only 4psi at idle and 5psi at 4500rpm. So I checked both themo's (one for each bank) both open and closed at the right temps. (hot water in pot with temp gauge) When I removed the thermo's I can see nothing under them as far as sand or debris both banks are clean. I then removed the water pressure gauge on the control panel and with the engine running the water just barely trickles out. Ok with that said, at both times before and after the water pump replacement the pisser as I call it was showing a flow of water coming out of the engine....but it seems to be weak in flow. Now at higher RPM's it shoots out pretty good. And while I run the engine with the muffs on I can feel the cool water on both sides of the banks running through the block. After a quick run I went back with the engine running and put my hand in the flow to check to see if it was hot and it was not. And as for the line running from the top of the power head to the pressure gauge I removed the line and I can blow through it with easily. So at this point Im confused. The pump is working I think due to the flow observed out of the pisser but why dont I have the 12-15psi on the gauge that I once had. And if the flow is reduce why dont I get a overheat alarm from the engine. I dont want to cook the engine but I not sure were to look next. Thank you I can use any advice given.
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Check the pressure control valve at the bottom of rear exhaust plate to see if valve has debris under it keeping it from closing completely. -
Yes, I would think you got some shell fragments or other debris up in the pressure control valve seat, jamming it open. Make sure you have the new style mushroom headed pressure control valve installed, it helps prevent debris from getting stuck in the seat area and allowing this loss of water pressure. It was a mid-'05 model year update so you may or may not have it in your motor. Its only about $5 at the dealer.
Mike......... Miami, FLComment
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Thanks for the great advice guys!!!! I will check out that pressure valve friday and give you update! Thanks again!!Comment
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Im having the exact same problem!!! I have a 2005 Z300TURD. With less than 20 hours on it. I have 2psi at idle and 4psi at 3500rpm. I replaced the entire water pump, impeller, housing, woodruff key, even the gaskets with no results. Same pressure. Some one on this board did have some good advice and commented on checking the Pressure Relief Valve. Some debris can get between the rubber seat and the popit and cause it not to close completely. Makes sense to me if the Relief Valve is stuck open you arent going to get the pressure, but you would still see the flow at the pisser. You see, I have good flow at the pisser when running anything above 1000rpm but at idle it just pisses a little. The pressure relief valve is located at the bottom the block if your facing the back of the motor. But let me warn you!!! It is a spring with a plastic popit that seats against a rubber bushing that when the pressure reaches 20psi or more, it pushes on the spring and opens to bleed off the pressure. Sounds simple enough. But it is located in a position that requires the plastic covers under the motor cover to be removed. I had to remove the right bank of plug wires and push up on a wiring harness at the same time while I had my hand on top of the engine exuast plate trying to remove the bolts to see the prv. And once you get the cover plate removed there is not enough slack on the discharge hose for you to get a straight shot when you install the new valve. And you have to hold down the spring and the plastic tip with one hand while you line up the installation all while your trying to get a bolt started!!! Very poor design. I bet needless shop hours and money are wasted on checking or replacing this $3.00 Yes thats three dollar valve! You will need some fancy socket swivels to even think about getting to the bolts. And after all that... I still only have 2psi at idle and 4psi at 3500rpm. And yes I did check the gauge..even removed the hose from the gauge and blew back to the motor to see if I had a blockage. I could blow through it with no problem. I even followed the line back to the engine, its connected to the top of the block above the right cylinder bank. I removed the two bushings and looked down into the engine..its clean as a whisle. I also checked the height of the cavitation plate on the lower unit in relation to the bottom "V" of the boat. It is perfectly lined up parallel. So Im at my wits end!! And your right about the three weeks of missed fishing...my shop told me it would be 5 weeks before they could "LOOK" at mine. Plus they are no help at all over the phone. They cant charge you for a phone call so I dont get any advice from them. I would like to talk to you or anyone else that I share Idea's with on this subject. It cant be that complex. Its the same water cooling design that have been used for 50 years!!! Any Idea's from anyone?????Comment
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