Operating temp for 3.0 liter

searay sport

searay sport

New Member
Feb 21, 2007
276
Ozark Missouri
What is the normal operating temp for the 3.0 liter engine? Mine runs around 180. Also did anyone else have a problem starting their engines durring the breakin period? Mine is hard to start, and the last time we took it our, we ran it for like an hour, and turned it off, and it was still hard to start. Thats not normal is it?
 
Sounds high to me...

I think you should be in the 140 to 160 range.

I would go back to the dealer if it was bought new and have them adjust the timing and maybe make a carb adjustment. (if it has a carb). The choke may be sticking also...
 
180 sounds a little high to me, too. My 3.0L (2003) runs between 160-170. Maybe Merc is using a new thermostat these days?

Do you have the new TKS or an old-fashioned carb? Sometimes there can be a problem with cold starts, but even those can be solved by using a simple starting routine. When you're trying to fire her up after running for a while are you touching the throttle, or are you starting from idle position?
 
Mine 4.3 runs 160-170. The cold star routine that works for me is to turn the engine over for about 8 seconds and stop (to get the fuel back into the carb), then one pump all the way down and pull it back to the 1/4 throttle and turn the engine over again and she fires up in 2-3 seconds.

Once I have let it run for 5 minutes or so she will fire right back up at the touch of the key with the throttle in the nuetral or locked position.

Fuel injected/MPI engines are much easier and start at the turn of the key everytime.
 
If you haven't already, you may want to check the actual engine temp with an IR thermometer to make sure the issue is with the engine cooling and not the temp gauge.

Jeff
 
There is a good possibility that the engine temp has been raised to help combustion and emissions, my 87 3.0 ran 140, my 04 4.3 runs 170, both carb engines, your car used to run 190, today with emissions they are running around 205 to 210 if you check actual engine coolant temp, not the dash gauge. Just check with the dealer, I think you will find that to be normal, or maybe the dash gauge is off a little.
 
I have an older 3.0 engine, 1992 to be exact. I normally run at around 135-140.
:smt017 :smt017
 
Tars - You probably have a 140 degree t-stat. See midway's post above.
 
This past weekend, I took an hour out to replace my thermostat. 1995 3.0 liter. You're right, it is a 140 degree thermostat. After the replacement, and a couple days out, I am running right on 140 constantly as viewed from the dash gauge. My old thermostat was stuck upon just a bit which rarely allowed it to warm up to temp.

I do wonder though if I should/could put in a warmer thermostat? I would think a 170-180 thermostat would make the engine run a whole lot cleaner and more efficient. As mentioned most vehicles since '95 run 180-205....
 
It's hard to compare a car motor to a boat motor. Boat motors are still not governed by emissions regulations thus are not tuned that way.

I'm curious as to what they "adjusted" that was way off. Was it just the idle RPM? If so, that won't affect operating temp. They should be able to hook up the sooper-dooper snazzy computer reading thing-a-ma-jig and see if the gauge is reading right. If it's actually not running at the right temp, you may have a problem with fuel mixture also because the EFI adjusts by operating temp.
 
I mentioned boat and automotive engines in the same post just to show the differences in both from past to present, put back what the manufacturer recommends, I don't think taking a 140 degree engine and warming it up 30 to 40 degrees would be wise. Too much heat might cause something to melt, pre ignition, keep it the way it was built, unless you are throwing big bucks at it like Jim did his then you change a lot of things. :grin:
 
Hi, Scott. Have you had the impeller/water pump changed recently? If not, sounds like it might be time.

The water pumps on the 3.0L’s are the same as those used on the 4.3 and 5.0L engines. Essentially, it’s rated to supply more cooling power than the 3.0 really needs. Your pump may be operating at less-than-optimal efficiency, but you’ve been OK until now due to the volume of water moved by this system.
 
So do you think that we might have a problem? The engine temp usually sticks around 170-180ish.

How much does it cost to get the impeller or water pump changed?
 
Dang, I might have to call up the ole' marinemax and ask them about ours.


It has been 170 (all conditions) since we got it in 06'.
 
I believe the two flavors of thermostats are 140 and 160?

I do not know the merits of one over the other.

My twins have 160 thermostats and the dash gauge shows 170ish.
 
I wouldn't worry about anything in the 170-ish range. (Mine ran at approx 172 from the day she was new.) The fluctuation between 170 and 190 suggests that you might be on the verge of having a problem. If you still have the original pump and impeller, you should probably get them changed sooner rather than later. If the pump dies while you're running, you'll likely end up with either a sizeable tow bill or a cooked engine. I had my pump changed last spring and I believe the total cost (labor + materials) was either $250 or $350.
 
My 2008 3 litre warms up to 170 on the gauge & doesn't vary no matter what the load or revs. Varying between 170 & 190 sounds like the guys said, a possible problem. If the thermostat is working properly it will vary the flow of coolant to maintain a constant temperature.

I wouldn't hesitate getting cooling problems looked at. I know with car engines that overheating is one sure fire way to blow a head gasket or warp the head, both expensive to fix.
 
You must log in or register to reply here.

Forum statistics

Threads
113,173
Messages
1,427,914
Members
61,086
Latest member
MrWebster
Back
Top