over heat

[rick l f]

i have a 1985 or 86 mecury mr2 , 150 it was running fine 2 years ago, but i have had a problem iwith the eng . what it does when you push and go to full power . it shows to over heat. i have changed the popit valve, water pump, whater pump houseing, head gaskets, temp.gage sending unit, checked tub from water pump. timing, plugs, new gas , the alarm is the temp knot the oil alarm. it shoots a very good stream out at idle and full speed, the alarm will go off a full gas and stop when you slow it back down . you can idle all day long and it show cool but from 3000 and up it show hot . but the water is warm but you can still hold your hand under it . what should i do now. i have had 3 shop look at it and it still does the same . but i have been out about 1000 in cash ( i need help )

[rick l f]

i have a 1985 or 86 mecury mr2 , 150 it was running fine 2 years ago, but i have had a problem iwith the eng . what it does when you push and go to full power . it shows to over heat. i have changed the popit valve, water pump, whater pump houseing, head gaskets, temp.gage sending unit, checked tub from water pump. timing, plugs, new gas , the alarm is the temp knot the oil alarm. it shoots a very good stream out at idle and full speed, the alarm will go off a full gas and stop when you slow it back down . you can idle all day long and it show cool but from 3000 and up it show hot . but the water is warm but you can still hold your hand under it . what should i do now. i have had 3 shop look at it and it still does the same . but i have been out about 1000 in cash ( i need help )

you can email me

[rgsauger]

When you had the heads off, did you put diverters in the cylinder liners? 2.4's benefit from flow diverters as an fyi. Do you have a water PRESSURE gauge in your boat? What pressure do you see at speed?

[Go Time]

You did not mention that you had tried replacing the temperature alarm sender. I had one do the same thing and it was a alarm sender that actuated at too low a temperature.

[rgsauger]

Excellent point, Go Time

[bigbluechevy454]

The water pump transfer tube have a issure i had one before that got push up in the adpater place and wouldnt allow the water to follow correctly. Have u tried pulling the lower unit off and hooking a water house to that tube? It may give u a idea where your problem is

[rick l f]

i have put 3 water pumps in and 1 new housing and pool the tube and checked it for crakes every time, and had others check it also thanks

[rick l f]

i dont have a pressure gage. but it shoots about a 4 to5 ft streem out the pee hole

[rick l f]

when i took the poppit out it must have been stuck because it pop so it was stuck closed.

[bigbluechevy454]

Id say your sender is bad. I miss read. Your post eailer. I thought it said steam coming from the pee hole. Sorry

[rick l f]

i am going to see if the popet fixed it , if knot i will change the sencer thanks for the help every one

[CharlieB53]

If the pop-it or temp sensor do not fix it you may consider lifting the powerhead and replacing the adaptor gasket. Sometimes the gasket fails under higher pressures allowing cooling water supply to dump straight into the exhaust. I often take a centerpunch and very small ball-peen to make a series of 'raised'' dots along the center of the divider creating 'tooth' to hold the gasket.

[rick l f]

the tuning gasket was changed , is that what you are talking about .