115 Mercury 4 stroke overheating

[oboat]

Hi all! I'm new here. Here's my question. I have a 2003 Mercury 115 Four stroke. I ran on to a sand bar today and sucked up some the sand and shell. I got the boat off the sand bar and started the motor and moved to a safer area to investigate any damage. The warning buzzer sounded during the move and I shut it down. I set out the anchor and let it cool down for an hour. I restarted it and notice I had very little water out the pee hole. I went ahead and started back to the dock slowly. I noticed water out put from the pee hole increased and I felt all was good. I made a 2 mile run with no issues. Then I took off to another spot with no issues. I fished for a few hours and then when I was making my way back to the dock the engine overheat buzzer went off and I shut her down. While I was waiting to get a tow I started the engine and notice that there was no output from the pee hole. When I got the boat on the trailer I hooked the hose up to the back flush connector and flushed the motor. I hooked up the ears to the water input on the lower unit and ran the engine for around 10 minutes with no issues and good water output flow.

Is there anything I need to do with the motor like change the t'stats. I feel I need to replace the water pump but I am not sure if I need to do anything else.

 

[emckelvy]

Re: 115 Mercury 4 stroke overheating

Yeah, probably a good idea to pull the L/U and inspect the water pump for damage. The housing is a solid chunk of stainless or cres so it's not likely to be damaged, but the impeller and pump plate will likely have damage or scoring from potential sand intake. I recently worked on an '07 90hp 4-stroke and the lower unit design on that and yours is pretty much like a 2-stroke Merc of similar HP/vintage. The shift shaft is splined, so there's no linkage to disconnect. Just be sure not to move the shift shaft or control lever once you've dropped the L/U.

You'll probably want to order a pump "repair kit" which should have impeller, pump plate, gaskets & the small consumables you'll need for that job. P/N 43026Q06, $43.25 list.

I'd pull the cover at the back of the cylinder block and inspect the "pressure control valve", as sand could have become lodged in it. There's a gasket (P/N 804084, $2.10) you'll likely need, and the valve itself isn't too expensive ($5.63 for P/N 804080001). There's a grommet for the pressure control valve and you may want to replace that as well, deposits can build up and warp the grommet (P/N 804082, $.90).

The thermostat is on top of the block and is an expensive bugger (P/N 881429, almost $64!). Definitely pull that and inspect for debris.

With the sand-sucking, it would be a good idea to flush the system when the L/U is off. Hook up a hose supply to the copper water supply tube. If you have a lot of water pressure, don't run it wide open.

If you flush thru the powerhead with the pressure control valve out, it'll run out that opening and you'll get good flow thru the motor. After that you could temporarily install the little cover without the valve, and flush that way. It'll force the water to flow a slightly different path and should make for a more complete flush.

Same with the thermostat, just watch where the water's going, since it's on top it'll run all over the block. Maybe insert a rubber hose in the empty hole to divert the water, or just flush that part with thermostat removed/cover installed only.

Flush until the effluent runs clean. Hopefully it's already purged itself but there could be residual lodged in pockets. Flushing with a water supply should chase out any of that.

If it's been a while since the last impeller change, it's probably a good time to do it, anyway. Cheap insurance. Same goes for the pressure control valve, just watch out for any bolts that are hard to turn, they could be locked-in with salt.

In that case, some heat from a torch followed by penetrant should help. Use caution, drilling/tapping broken stainless bolts out of an aluminum block so you can install Heli-Coils, ain't my favorite way to spend an afternoon! :0

HTH & G'luck........ed

 

[oboat]

Re: 115 Mercury 4 stroke overheating

I took the boat to the pros. I want to make sure nothing got hurt when it overheated. Should be ready next week

 

[lawyeratlarge]

Re: 115 Mercury 4 stroke overheating

I have the same problem with my 2006 60hp 4 stroke. Idling around last Sunday with a heavy load on the boat, went to about 3/4 throttle and the buzzer went off. I let it cool down, idling for several minutes, buzzer stopped but when I opened the throttle again, buzzer goes off and engine stumbles above 1400 rpm. Came home flushed with the fresh water connector then with my "muffs". Engine ran cool with a good stream.

I decided to replace the water pump impeller as a safety measure. I found one vane was broken on the old impellor. I put in the new impellor, serviced the foot and started the engine on the ear muffs. There was a good flow through the telltale port, I ran the engine for several minutes using the cold start to increase rpm and later putting it in gear. It ran like a champ up to 3500 rpm, I would not run it any faster on the muffs. I put in the water about 45 minutes later and within 5 minutes of launching, the same problem as before.

What should I do next?

Lawyeratlarge

2006 mercury 60hp Bigfoot with approximately 2,000 hours