Temp in older Mercruiser 3.0

[trooper1954]

Hi all,
Have an older mercruiser 3.0 circa 1990 that runs at idle about 140F. Is this okay for this vintage motor or should I be anticipating problems....thermostat, impeller etc.? I thought I had seen somewhere that this normal.....any help would be appreciated.
Thanks
ps. This is copied from the mercury outboard forum....sorry, posted in wrong place.

 

[achris]

60C is perfect!

Being 1990, it'll be Alpha One (generation I), so you should be checking the impeller annually, and replacing it either at that annually check, or at most bi-annually (2 yearly).

Chris.......

 

[Scott Danforth]

since this is most likely a new to you boat.

before you use it, you must assume that the prior owner did absolutely none of the maintenance

you need to do the following:

on the motor

• change the oil and filter
• change the plugs
• service the points and set timing
• inspect the plug wires, cap and rotor and replace as needed
• replace the circulating pump / alternator pulley (yes, it requires the removal of the front motor mount)

pull the drive

• inspect the bellows, replace if needed
• inspect the gimble bearing, replace if needed
• inspect the u-joints, replace if needed
• check the alignment
• grease the coupler splines
• split the drive and do a raw water pump service
• pressure check the drive
• change the gear oil
• grease the prop shaft

move on to the trailer

• pull the hubs and inspect the bearings and seals. replace as needed
• repack the bearings
• service all the rollers/bunk/etc
• service the coupler
• if applicable, service the brakes

 

[trooper1954]

Thanks to both Chris and Scott,
Glad to hear around 140f is good, and am diligently working through your list Scott....thanks both for the help

 

[FingerLaker]

Thanks for asking this question, Trooper, I was not entirely sure either, as I go to inaugurate my somewhat older 88' 3.0. (A Maxum 1700) Last used two years ago. And thanks to Scott for the useful checklists.
My understanding from the previous owner- the mechanic around here- briefly, was that at right about 140 you should hear a 'whoosh', indicating the thermostat has opened, and this can be taken essentially for a 'good to go' sign when starting up for the first time in a while, or whatever, that your cooling system is all in working order (in addition to obvious sight checks..) Does that seem to make sense for all here? Happy boating,

 

[Grub54891]

Never heard a "woosh" when the thermo opens, but a good eye on the temp gauge will tell ya when it opens.

 

[Rick Stephens]

Hi all,
Have an older mercruiser 3.0 circa 1990 that runs at idle about 140F. Is this okay for this vintage motor or should I be anticipating problems....thermostat, impeller etc.? I thought I had seen somewhere that this normal.....any help would be appreciated.
Thanks
ps. This is copied from the mercury outboard forum....sorry, posted in wrong place.

So you know the reason for 140ƒ. The cooling system is open, it builds no pressure at all. PLAIN water starts to bubble at 160 - Salt Water at 170ƒ. Yes, a gas engine is more efficient at 210ƒ, but you must both run a 15 pound pressurized system and coolant instead of water.

This is one of the best reasons to run a closed cooling system. That and corrosion.