Tuning a 1989 Mercruiser 2.5L

[jssaville]

I have purchased the Seloc book for my engine however I find it incomplete. The idle speed is 650-700 in forward and 3500-4300 WOT. ( I dont have the manual with me so am unsure of the exact numbers). My question is, what should the engine idle at while on the trailer, in neutral with water attached? The above idle speeds are while in water, under load right?

I also found that the engine started to run close to the hot line after about 10 minutes on the trailer. Water was flowing, I was thinking thermostat?

Does anyone have any good step by step tune up directions?

Thanks

john

 

[Don S]

Re: Tuning a 1989 Mercruiser 2.5L

Get the OEM service manual for your engine. Mercruiser service manual #10 is the one you need. You can set the idle at that speed on land, if it needs readjusted in the water, then readjust it.
When was the last time the impeller in the raw water pump was changed?