Re: over heat question
if the impeller housing shows any signs of melt its toast. yes the poppet and presure control valve is the same thing. key is to carefully clean the grommet pocket and replace the grommet, its under the t-stat housing looking thing on the lower stbd side of the exhast cover.
there were several styles of tachs, the one with the arrows shows oil level only. and only oil level in the remote tank is ok, when the remote level gets low the center arrow illuminates and no automatic oil transfer can occur. when the engine tnk level is low and the remote level is ok all the arrows may flsh or just the farthest to the left may flash indicating a low tank level.
a clogged filter in the remote tank will create a condition at higher speeds were the engine can use oil faster than it can transfer creating an alarm at higher speeds that goes away at low speeds. a bad trim sender can create a no transfer condition as well.
I think in that year range the overheat visual was in the speedometer with the low battery visual but I cant remember.
low battery,overheat and low engine oil level will all use the same horn and all will set RPM reduction in that year range.
when you first power up the tach you should see 3 arrows for a second or so while the tach self tests.
if you get a tone and no flashing arrows on the tach odds are its either overheat or low battery.
a bad connection anywhere from either battery post to the ECU can trigger a low battery alarm.
you cant miss a melted housing as it will look rather bubbly and discolored some. first place they melt is at the cup edges and where the shaft passes through the housing.
make sure you turn the drive shaft clockwise when reinstalling the impeller housing/cup assy, there is not enough room for the blades to properly orient themselves if installed backwards. I just use grease in the oring groove to retain the oring on that model.
no need for any speacial sealers. the other cause of low presure can be the rubber dam just aft and below the wear plate. remove it and the holder and clean any corrosion from them.
sometimes the corrosion will lift the dam slightly and create an air leak that is most noticible at low speeds and will cause low pressure at idle.
