94 Mariner 3.0L 225 Offshore overheat Problem?????

[davidzima]

Motor will run without problem for 10 Min or so with Temp guage steady just above 150. then all of the sudden it will start to get hot (Towards 240). Throttle back to Idle or just above and it cools back down below 150. Throttle up and it runs at just over 150 for 10 - 15min and again all of the sudden it will start to over heat.
Changed water pump / Thermostat (guy I had do it only showed me 1 thermostat....Isn't there 2??? one on top of each cylinder head?

Being that I live on the gulf coast do I need thermostats?

being that it only overheats when running, let say at 4000rpms for 10-15min, could it be that maybe the VRO pump is not mixing enough oil? and thus causing excessive heat from excessive friction? Checking reserve tank Oil level is getting lower, so maybe just not right muxture at higher RPMs.

Any Ideas would be greatly appreciated.
David.

 

[davidzima]

Re: 94 Mariner 3.0L 225 Offshore overheat Problem?????

Any Ideas?????

 

[gss036]

Re: 94 Mariner 3.0L 225 Offshore overheat Problem?????

You 2 thermostats, follow the hoses at the top of the cylinder heads. I would suggest that you check for a poppet valve being stuck closed and not dumping the excess water. Real simple to fix/check. If you are going to remove the cover and check, it just as easy to replace the components while in there, fairly cheap. The poppet cover probably will be on the lower starboad side of the block and looks like a figure "8". It has 4 small bolts, be careful when removing so that you don't break them off or strip out the holes, especially if used in saltwater.

 

[davidzima]

Re: 94 Mariner 3.0L 225 Offshore overheat Problem?????

Thanks I will check it out.

 

[studlymandingo]

Re: 94 Mariner 3.0L 225 Offshore overheat Problem?????

Being that I live on the gulf coast do I need thermostats?

Yes you do need the thermostats. Doesn't matter where you are boating, they regulate how much water flows through the block. I would go ahead and replace the other thermostat, and check the poppet valve as described. Be sure to post your results as others in the future will be able to reference your fix.​