1987 mercury blackmax xr2 overheating

[[email protected]]

I purchased this boat and motor a few months ago and has been nothing but a headache since. Let me start with saying what I have already replaced. I have replaced the entire water pump assembly, brand new thermostats, brand new poppet valve assembly, I have had the water jackets cleaned out. Motor will never overheat on muffs. I put it in the river and as soon as I take off the motors temperature starts to rise Has been as high as 200+. I come back down to idle and the temp drops to around 160. Even when running on muffs and the temp gauge is at normal temps (140°) the alarm starts beeping and it's not a steady beep,like I've read is the over heat alarm it is a constant beep beep beep beep beep. Oil injection system has been took off so I premix and I have fresh gas and oil ratio of 50:1. I can't shake this problem so any help would be greatly appreciated.

 

[johnnygjr]

Have you done a compression test.Did you use sealer on impeller housing,installed seals,gaskets,orings,water tube aligned properly?Is water intake clear of obstructions

 

[[email protected]]

All the water pump gaskets have been replaced. I have not done a compression test cause the motor runs fine other than some minor carb issues. I do intend on doing compression test asap. I've took both thermostat housings off and plenty of water spilled out on the muffs. Is there a piece that would go over the water pick up and top of the water pump housing to secure the water pick up?