1986 135 HP Mercury black max Exhaust not pumping water...

[easygoer]

Hi everyone . I am new to forums and thank you in advance for any help you can give. I have a 1986 135hp outboard and have just completed the required maintenance (replaced impeller, water pump, thermostats, poppet valve, lower unit lube, and temperature sender{starboard side} I had it out on the water running great for about 2 hrs or so with no issues. I had water pumping from telltail strong and exhaust ports were blowing water as well. Came back in flushed it with ear muffs and washed it down. Took it out 2 days later and after about 5-10 mins of driving 3000 RPM on plane in calm water my over heat alarm came on. As I throttled it back and brought it to neutral to look if the water stopped streaming from the back and the alarm turned off. I then resumed 3000 RPM and after 1-2mins alarm came on again. I shut off engine and checked the powerhead for heat. I could keep my hand on it without burning myself so I thought it was a false alarm. I rode at 2200 RPM back to dock and had a friend assess it with me . The water was pumping from the pee hole in back and occasionally out of poppet, but it was not blowing from the exhaust ports like before. Could this be causing an overheat issue? what would cause this alarm to sound only at high RPMs? anything I can do to troubleshoot? thanks again

 

[Dukedog]

Re: 1986 135 HP Mercury black max Exhaust not pumping water...

Water from tha weep hole in tha poppet cover? If any at all comes from that small hole there is something wrong with tha poppet assembly. Could just be not clean enough around tha seating areas. That is very important when ya change/new things inside.....

 

[CharlieB]

Re: 1986 135 HP Mercury black max Exhaust not pumping water...

Inspect the water pump again just to be sure.

Overheating at speed can be caused by a number of things including low pump output, incorrect timing, leaking adaptor plate gasket, pop-it valve sticking closed.

Check the throttle and timing levers, disconnect the throttle cable and open the throttle slowly to wide open, watch the timing lever and make sure it moves freely to the maximum advance position and is not sticking short of that which will leave the timing retarded at throttle causing heating.

Installing a water pressure gauge will let you to always keep abreast of the cooling system.

 

[easygoer]

Re: 1986 135 HP Mercury black max Exhaust not pumping water...

Thank you all for the replies.. I will look over all the repairs I have done and let you know what I find..

 

[Texasmark]

Re: 1986 135 HP Mercury black max Exhaust not pumping water...

Since you didn't mess with a lot of other things, I wouldn't be off chasing that. The book states that the poppet is for rpms above 2500 and the purpose is to allow an increased cooling water volume. Below that speed the stat controls cooling. Since the v6 is 2ea 3 cyl engines, each bank has both.

The OT sensor (tan/tan-blue stripe) may be in only one water jacket or both. Sometimes there is a thermal resistor in one of the covers for operating a temp gauge on the dash. Easy way to check. Follow the wire from it to the first junction, pull it and ohm back to the sensor to ground. If open ckt, a switch; if resistance, a sending unit for a dash temp gauge. The OT kicks in at 195 F and resets at 175 F.

The stat starts opening at 143 F. A US domestic hot water in the N position maintains 140F water for a benchmark. If you are putting around and have been for awhile (letting temps stabilize) expect the top of the block to be around 150 F. If you are up and running it will be quite a bit cooler as the popoff bypasses the stat and you are just running on ambient surface water and whatever heat the engine adds to it.

Chew on that and come back.
Mark