Over Heating Problem

[PreachRick]

New boat to me. I have a 1983 Mercedes
Model # 190SX
Hull ID # MVJM0114M83HINSII
Motor Mercury Marine
Serial # 6365879
Inboard/outboard

Yesterday on the river the temp gauge went clear over to hot, and it was boiling. I need to replace the the thermostat. Does anyone know the part number? Do these engines take a 160 degree stat?

 

[Scott Danforth]

with your new to you boat, did you do all the maintenance that the prior owner did not do?

such as a new raw water impeller?
pull the drive to inspect the gimbal bearing, u-joints and alignment?
pressure check the drive and change gear oil?
change the engine oil, plugs, cap, rotor, service the points?

you probably dont need a thermostat (would be highly unlikely that that is the issue)

you most likely need a new raw water pump (get the whole pump and not just the impeller). and because you ran hot and did not have cooling water, your exhaust went from 200F water cooled to well over 1200F flames..... so now you also need new exhaust hoses, new flappers and possibly something else

 

[PreachRick]

Thanks for answering Scott. You are talking to an OLD 83 yr old cowboy here who has no idea in the world anything about boats. Where is the raw water pump located please.

 

[alldodge]

Howdy
Thanks for the serial number, and we do need it, but in this case I'm unable to just enter it and bring up your motor. What motor is it, then I can sort down to find your exact motor

Being an inboard you should have a belt driven water pump. The pump will have an impeller of which Scott mentioned

 

[PreachRick]

Thanks alldodge (me to), I pulled the end off of the heat exchanger and this ,(if I can figure out how to upload a picture) is what I found, chunks of rubber. Have any idea where it came from? Not good I'm sure !

Rick

 

[PreachRick]

[No message]

 

[PreachRick]

Alldodge it's a Mercruiser 470 I think

 

[alldodge]

I don't find the 470 (4 cylinder) as an inboard, but over seas boat manufactures have done things and not let Merc know. Don't know which pump they used.

Looks like you found the pieces of the impeller in the HE. Can you post a pic of the pump?

The motor parts are here
https://www.mercruiserparts.com/470-...l4-1983-1984-1

 

[dubs283]

Where is the raw water pump located please.

MCM 470 sterndrive (inboard/outboard) raw water pump is located in the drive

best idea is to pull the drive, split the halves, r an r pump/base assy and pressure test drive

 

[alldodge]

Your right, he did say I/O and I'm reading inboard :facepalm:

 

[Scott Danforth]

Alldodge it's a Mercruiser 470 I think

now here is the big news......

because of the over-heat on the 470, you most likely need to also replace the head gasket in addition to the rubber bits I mentioned..... because of the open deck design of the aluminum block and the cast iron head,the motor has a propensity to spit the head gasket.

the 470's do not tolerate much more than a 10 degree overheat (170-175 range), and based on post #1, you were well over 212.

the impeller and raw water pump in your MC1 drive are located at the top end of the lower unit. you have to pull the drive off and split it.

from your pic in post #6, your impeller is toast.

 

[PreachRick]

Thanks all, looks like I may need to take it to a boat shop. Sure hate to, I'm on a very small SS check. Cowboys didn't make much in my days, (I'm 83yrs old) most of my life I worked for $40.00 a month and found. I'm also a preacher for the last 35 years, no salary, but the end results are out of this world. Will try to take pictures in the morning. Can't thank y'all enough for putting up with me !!

 

[PreachRick]

Guys can y'all help me find the water pump and head gasket (as y'all recommended) for my motor. I have looked everywhere but all to no avail, probably because I don't know what I'm doing....ya think? I would really appreciate the help, and thanks again for sharing your extensive knowledge with me.

 

[PreachRick]

Where Did This Come From?

I have never worked on a stern drive engine before, and I am new to boating at 83 years old!

I am working on my I/O that went clear to real HOT while on the lake a week ago. It is a mercruiser 470 Serial # 6365879. I took the end off of the HE and found rubber pieces (see pic below) apperantly from a rubber impeller. Some one suggested it might have come from the raw water pump impeller but on further inspection I found out the raw water pump impeller is metal on this motor.

Does anyone have another suggestion on where the rubber pieces might have come from? Does the sea water system have a water pump with an rubber impeller in line?

Any and all suggestions greatly appreciated.

Ric

 

[racerone]

The circulating pump is metal .-----The raw water pump on top of the lower gearcase has s rubber impeller.----So your " someone " is correct when telling you those are impeller pieces.

 

[Grub54891]

There is a Rubber impeller in the lower unit. That's where them peices came from. The circulation pump has a metal impeller. Your looking for the one that brings the water up to the motor.
give us a model and serial number and we will help you find the correct parts.

 

[PreachRick]

There is a Rubber impeller in the lower unit. That's where them peices came from. The circulation pump has a metal impeller. Your looking for the one that brings the water up to the motor.
give us a model and serial number and we will help you find the correct parts.

Thanks yall for answering, the make, model and serial number is in the original post. It is a 1983 mercruiser 470 Serial # 6365879.

 

[tpenfield]

I am impressed with your desire to take up boating at your age. :thumb:

As stated, those are the impeller pieces and the impeller is in the outdrive lower unit. The pump on the engine (metal impeller) just swishes the coolant around through the engine block. The impeller in the outdrive does the 'heavy lifting' of bringing water up to the heat exchanger and out through the exhaust manifold/elbow.

Lots of folks don't go looking for the 'bits' of impeller after it fails and then have cooling problems afterwards.

 

[Scott Danforth]

you get a new raw water kit for your drive from any of the mercruiser parts selling places, you get the head gasket from any of the mercruiser parts selling places. get a genuine mercruiser head gasket

do not forget the rubber bits in your exhaust that also have burned up.

 

[Scott Danforth]

We told you where the impeller bits came from in your other thread. https://forums.iboats.com/forum/eng...gines-outdrives/10930164-over-heating-problem

you realize you are starting multiple threads on the same topic