merc help...please

[OC-PARTYCAT]

I have a 99 454mpi. It needs a new thermostat. Can I use just a regular chevy 454 therm.? what about the temp?
thanks for the help.
Dean

[Liberator TJ1984]

Dean , I think it will be the same ...when you take out the old one it should have the temperature stamped on it that it operates at..just replace with same temp. if all has been running fine..my 2*
Good Luck
Gopherrr

[OC-PARTYCAT]

heres my problem...i had a few in me when I took out the old one. The old one is at the bottom of havasu.It looked just like the standard chevy. but Im not sure of the temp. Ill call someone at a shop and ask.
Thanks for the help
Dean

[THE BOSTON SIDEWINDER]

GENERALLY YOU DON'T WANT TO USE A CAR T STAT, MARINE ONES ARE BRASS. IF YOUR ENGINE # IS BETWEEN OL086050 AND OL674000(I THINKS IT IS) USE MERCRUISER PART #807252T 2..HOPE THIS HELPS...BILL.T

[stressedout]

Automotive type will work fine and cost less than half what a marine type will cost.
Use a 160 degree.

[OC-PARTYCAT]

alright..so I go to the lake this weekend. I picked up a thermostat 160deg, chevy. I put it in (spring down). I put it in the water and fire it up. The water will not heat up. I was thinking that it was my temp sender but, when I get into the throttle the boat falls on its face. I have to gradually get on it to get the rpms up.
Will the motor run that shitty with the water being cold? I changed the oil, and fuel filters at the same time so, I know its not the fuel filter.
When the boat is on a plane cruising (3.5K rpm) I watch the temp guage sit at less than 100deg. Every once in a while it will go up to around 140 then drop right back down (within 5 seconds)
Did I forget something. I was thinking there is some type of retainer above the thermostat that holds it in place and maybe the new thermostat came up into that water manifold (block that four hoses are coming into) I had to leave so I didnt have time to take it off and check it out...What do you guys think?? :confused:

[THE BOSTON SIDEWINDER]

SORRY GUY I GUESS I'M ALWAYS THINKING O E M BECAUSE IT IS GENERALLY PRETTY GOOD QUALITY. I HAVE A BOX OF FAILED CAR T STATS AT OUR SHOP AT THE MARINA. A COUPLE EXTRA BUCKS FOR MORE PIECE OF MIND? O K I'LL BANK ON THAT...BILL.

[Sun burners]

OC-PARTYCAT:
alright..so I go to the lake this weekend. I picked up a thermostat 160deg, chevy. I put it in (spring down). I put it in the water and fire it up. The water will not heat up. I was thinking that it was my temp sender but, when I get into the throttle the boat falls on its face. I have to gradually get on it to get the rpms up.
Will the motor run that shitty with the water being cold? I changed the oil, and fuel filters at the same time so, I know its not the fuel filter.
When the boat is on a plane cruising (3.5K rpm) I watch the temp guage sit at less than 100deg. Every once in a while it will go up to around 140 then drop right back down (within 5 seconds)
Did I forget something. I was thinking there is some type of retainer above the thermostat that holds it in place and maybe the new thermostat came up into that water manifold (block that four hoses are coming into) I had to leave so I didnt have time to take it off and check it out...What do you guys think?? :confused: Any new news on this?
[ March 24, 2003, 10:47 PM: Message edited by: Sun burners ]

[OC-PARTYCAT]

Nothing. Im going back out on the 10th. I thought the old therm was at the bottom of the lake but I found it in my tool box. Ill put the old one back in and let you know what happens. Do you think the motor runs that bad because of the water temp? :confused:

[paradigm shift]

You will want to be carefull running fuel injection and low water temps. Thinks your motor is still warming up and runs in an enriched mode. Sounds like you may have other problems but thought it was worth noting. Yes there is a spacer in with the thermostat. Has to be there. Try this link.
http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=804807%2099&ivar=images/CRUISER/804807.99/12.png&inbr=4854&bnbr=130&bdesc=THERMOSTAT+HOUSING+%26+HOSES

[Tinkerer]

You should use a high flow model of the proper temp.

[DUCKY]

DO NOT USE A AUTOMOTIVE T-STAT!!!
Here are the reasons:
1) An automotive unit does not open far enough to flow the proper amount of water to keep the engine at the required temp, even if it did open at the right time.
2) You cannot buy one of the proper temp, marine engine t-stats are generally 140-145degrees. This low number is required because the incoming water is so cold, compared to a closed system.
3) a 160 stat on your motor will allow the engine to run dangerously close to 200deg. Since a raw water system is not under "pressure", this could cause steam pockets and boiling, which will fry your motor. Running over 160-180 degrees will tell your computer the something is wrong, and it could start cutting back the timing, and set off the alarm, or put it in "limp-home" mode (2500rpm)
Put it this way, run without one before using an automotive unit....

[DUCKY]

OC-PARTYCAT:
alright..so I go to the lake this weekend. I picked up a thermostat 160deg, chevy. I put it in (spring down). I put it in the water and fire it up. The water will not heat up. I was thinking that it was my temp sender but, when I get into the throttle the boat falls on its face. I have to gradually get on it to get the rpms up.
Will the motor run that shitty with the water being cold? I changed the oil, and fuel filters at the same time so, I know its not the fuel filter.
When the boat is on a plane cruising (3.5K rpm) I watch the temp guage sit at less than 100deg. Every once in a while it will go up to around 140 then drop right back down (within 5 seconds)
Did I forget something. I was thinking there is some type of retainer above the thermostat that holds it in place and maybe the new thermostat came up into that water manifold (block that four hoses are coming into) I had to leave so I didnt have time to take it off and check it out...What do you guys think?? :confused: Yes there is a spacer that goes with the themostat. Without it, water will flow right through and the engine will be too cold, and this will make an EFI motor run like crap.

[Sun burners]

Is that part #6 the sleeve
Thanks MIKE

[OC-PARTYCAT]

Thanks for the help guys. Im not sure if that part #6 is in the manifold or not. I will buy another one just in case, along with a new therm. I think that explains the temp jumping around. The alarm was going off after initial start up for about 1 minute. but all the guages where within their perameters so I just kept on and it eventually stopped. I dont get it. The only thing I can think of is that the computer is sensing the rpms going up with the water so cold? The motor is idling fine and running through the rpms good unless I get on it. that would explain the fuel mixture and timming compensating for the cold water, right?(im guessing) I hope nothings wrong other than the therm....Ill let you guys know. thanks again
Dean

[Tinkerer]

Ducky-- I don't agree-- I use 160* high flow automotive thermostats (The all brass ones) and my engines never get over 160* ever. I don't like the 140* stats because the engine runs way too cold for my likes.
[ March 26, 2003, 07:25 PM: Message edited by: Tinkerboater ]

[Sun burners]

Any newer news?

[OC-PARTYCAT]

ok... I took apart the therm housing last weekend. That part #6 (sleeve) was still in there and the thermostat was installed ontop of the manifold, just like a chevy. I guess your supposed to put it ontop of the sleeve. It made a huge difference. The boat ran great and the temp was in check.... :D :D