200hp 2.5ltr Xri - water preasure too high?

[strelitz]

Having replaced the water pump due to ripping the hub out of an impeller (probably due to high rpm's on a low pitched prop - 18p) and stripping and cleaning the poppet valve assembly at the same time (was fairly dirty) the water pressure gauge now reads 6psi at idle, 15psi at 3000 rpm and 24psi at wot. This is twice what it used to read, which was on spec???? The manual states a minimum of 12psi at 5000rpm so why all of a sudden the higher pressure readings, and is this normal?

 

[Dukedog]

ya might revisit tha poppet stuff... higher than normal (you say it is now) pressure usually leads to a blockage and/or poppet problems......

 

[strelitz]

Problem Solved - I think.

As I have been running the engine for 2 years, even though I had rebuilt the cooling system I had not serviced or cleaned the poppet and was accustomed to a water pressure of 3psi at idle and 12psi at WOT now that it is working much more efficiently it reads 6psi to 24psi - so no problems I hope. (the manual does say a MINIMUM of 12 psi at 5000 rpm) so I am assuming that anything above that is OK.

Dukedog thanks for the reply.

 

[Chris1956]

Your water pressure is more than expected. Check the poppet. Can you connect another gauge to compare the readings? Sometimes over the winter a bit of residual water will change the way a water pressure gauge reads...

Also, I have never heard of excess RPM ruining a Merc impeller. I suspect the impeller was older, or was turned over and reused, which will cause it to fail as your reported.

 

[Shawnmm]

Makes me wonder if you have a chunk of the bad impeller stuck it one of the heads or thermostats. A super heated t-stat can sometimes stop working totally or partially. It might not be enough to over heat but just restrict the water.