85 3.7 mercruiser !!HELP!!

[Tommyboy#1]

ok so i got my first boat last week took it out on the water and right in the middle of the res it overheated i know what it is im sure its the thermostat but where the hell is it located im a mechanic and i cant even find this on the boat any help would be appreciated
thanks
tom

 

[dubs283]

Re: 85 3.7 mercruiser !!HELP!!

don't assume its the thermostat, it could be the raw water impeller

guessing gets expensive!!

 

[Tommyboy#1]

Re: 85 3.7 mercruiser !!HELP!!

thats the cheapest way to start the boat has been sitting for the past year just dont know boat engines that well but i already ordered the thermostat does anyone know where its located and is there another way to see what the problem is

 

[Tommyboy#1]

Re: 85 3.7 mercruiser !!HELP!!

2 other questions the first when i close the engine cover it boggs the engine down like there is not enough air flow and another is occasionally when i try to put the boat in reverse or forward it will try to kill the engine why does it do that dont matter if you move it slow or fast like i said its my first boat got one hell of a deal from someone i know please help

 

[dubs283]

Re: 85 3.7 mercruiser !!HELP!!

if the boat was sitting for a year, i definitly would check out the water pump in the drive

do you know the service history of the boat?

impellers of that vintage can get "set" meaning the vanes do not force against the wall of the pump to push water up to the engine

I take it that this is a closed cooled engine with a heat exchanger?

 

[Tommyboy#1]

Re: 85 3.7 mercruiser !!HELP!!

as far as i know it was serviced when needed. ya heat exchanger and closed now what did you say about the impeller

 

[zospro]

Re: 85 3.7 mercruiser !!HELP!!

85 3.7 mercruiser, Is this a 228?

 

[dubs283]

Re: 85 3.7 mercruiser !!HELP!!

the raw water pump is located in the drive unit

on order to inspect it, you need to remove the drive and split the halves

head up to the adults only sticky at the top of the threads page and look under the mercruiser manual link, there you will find a link to download manual #8 which pertains to your engine

manual #6 is the one for your drive

these are mercruiser OEM manuals and have valuable info for your engine and drive set-up

 

[Tommyboy#1]

Re: 85 3.7 mercruiser !!HELP!!

im not sure what it is besides its a 4cyl 85 3.7 mercruiser

 

[Tommyboy#1]

Re: 85 3.7 mercruiser !!HELP!!

thanks alot now what about the engine bogging down and wanting to shut down when put into drive or reverse

 

[dubs283]

Re: 85 3.7 mercruiser !!HELP!!

tune-up?

fuel system?

shift cable?

shift interrupt switch?

could be one of a number of things

there is a wealth of info in the adults only section, just takes a while to read through it all

 

[gettin'even]

Re: 85 3.7 mercruiser !!HELP!!

85 3.7 mercruiser, Is this a 228?

It would be a 224.

 

[gettin'even]

Re: 85 3.7 mercruiser !!HELP!!

ok so i got my first boat last week took it out on the water and right in the middle of the res it overheated i know what it is im sure its the thermostat but where the hell is it located im a mechanic and i cant even find this on the boat any help would be appreciated
thanks
tom

The thermostat is located on the back, underside of the intake manifold. Hidden very well.

 

[stonyloam]

Re: 85 3.7 mercruiser !!HELP!!

Actually the thermostat is located on the front underside of the exhaust manifold (port side) on that engine.... http://www.mercruiserparts.com/Show...=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW+(ALUMINUM)

 

[gettin'even]

Re: 85 3.7 mercruiser !!HELP!!

Actually the thermostat is located on the front underside of the exhaust manifold (port side) on that engine.... http://www.mercruiserparts.com/Show...=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW+(ALUMINUM)

Right you are Stony. Thanks for settin' me straight. Guess my C.R.S.S. is getting alot worse...LOL!!

 

[stonyloam]

Re: 85 3.7 mercruiser !!HELP!!

You should do a compression check and a coolant system pressure check. When you overheated (iron head with aluminum block) you may have popped the head gasket. Very common for coolant to leak into #3 & 4 after an overheat. As a matter of fact If I had just picked up a 3.7 "cheap" I absolutely would plan on replacing the head gasket with a OEM Mercruiser one. Since you Know your way around engines this should be a fun learning experience. Welcome to the "470" club.

 

[gettin'even]

Re: 85 3.7 mercruiser !!HELP!!

You should do a compression check and a coolant system pressure check. When you overheated (iron head with aluminum block) you may have popped the head gasket. Very common for coolant to leak into #3 & 4 after an overheat. As a matter of fact If I had just picked up a 3.7 "cheap" I absolutely would plan on replacing the head gasket with a OEM Mercruiser one. Since you Know your way around engines this should be a fun learning experience. Welcome to the "470" club.

I got my "welcome" two weeks ago. One time on the water, now the engine is on my garage floor. Reman is coming. Good thing the local beverage center is close by...lol!!

 

[gammalight]

Re: 85 3.7 mercruiser !!HELP!!

thanks alot now what about the engine bogging down and wanting to shut down when put into drive or reverse

Sorry for chimming in so late but I have an '86 3.7L 190 and I believe what the problem may be when you are shifting is that there is a switch, I think its called the engine kill switch or something similar that is engaged to relieve the torque off the engine to allow it to go into gear. The switch is probably being held down for too long causing this bogging down problem. There is an adjustment procedure in the mercruiser manual, I did the procedure and it shifts great! I am not sure where the switch will be on yours but it was below the throtle cable assemblies on the engine on the port side. When the engine is running you can press on the switch with your finger and it will start to kill the motor.