ideal running condition merc 470

alexr254

Petty Officer 1st Class
Joined
Jun 21, 2011
Messages
262
So i have this thread going "my merc 470 rebuild" which many of you have chimed in on and helped me tremendously. The rebuild has taken quite long but we have the engine running and it sounds nice.

We were measuring Oil PSI and Water Temp, water temp was at 150f peak and Oil PSI was reading at 75PSI at high idle (2000 to 3000rpm) while we were setting seals. We are using mechanical guages from the auto store. For oil i ended up mixng some 25w40 and Diesel rated 15w40, 50/50.

What would you consider ideal temp and oil psi readings?
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: ideal running condition merc 470

Temperature range is 165 to 200 F. I like to see it down around the lower end 160-170 just to be safe;). 150 should be fine.
 

natemoore

Master Chief Petty Officer
Joined
Jun 13, 2009
Messages
844
Re: ideal running condition merc 470

Mine never goes past 160 degrees, even during very hot summers pulling lazy, thankless children on a two-person tube. My oil pressure will be up around 80 psi (according to my gauge) at higher RPMs. At idle, it's pretty much registering nada. Here's the TSB on oil pressure:

View attachment MSB 93_08 minimum oil pressure.pdf
 
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