f115 cooling water route

[benzico]

hello all, i have a merc 115 efi which i believe has the same power head as the yamaha f115. i am having some problems tracking down a overheating problem. can anyone tell me the route of the cooling water from pump to pee hole. i think i might have a problem where the water tube joins the power head but to check this i would have to remove the motor and go in from the top. i was wondering if it is safe to remove the lower unit and put a hose into the bottom of the water tube and then disconnect the the water pipe just before the stat and turn the hose on to see if i am getting a good flow. i am just worried about water going where it should not. sorry for the long post.thankyou

 

[benzico]

Re: f115 cooling water route

just found the cooling water diagram, everything is alot clearer now. i think i have a supply and or restriction problem between the water intake and the power head. has anyone had any problems with the water tube where it joins the power head. i have a new impeller and the bottom water tube seal looks ok but i am getting very little water from the pee hole and have no water pressure at the test point just next to the pop off valve. thanks for any input.

 

[99yam40]

Re: f115 cooling water route

Just curious as to where you found the cooling water diagram.

Not sure about your motor ,but I have seen the rubber grommet (seal) on the top of the water tube where it meets the power head swell up and cause the flow to be restricted on a 15hp Evinrude.

I do not see any problem with putting a water hose to the tube to check for water flow, but I never tried on that motor or any Suzuki.

 

[rodbolt]

Re: f115 cooling water route

wont hurt anything using a hose directly on the water intake tube.
any excess water pressure will simply open the pressure control valve and be dumped.

 

[benzico]

Re: f115 cooling water route

thanks for the replies, I tried the hose on the water tube intake and still had very little water flow. I then removed the water jacket and poked a flexible poker down the inlet hole on the power head and found a restriction/build up of salt. after a lot of gentle pushing and pulling i cleared the salt build up. it now has good flow out of pee hole and doesnt seem to over heat, however when testing on the water the boat feels good upto about 3000 rmp then the engine stalls for a split second, feels like the ignition switches off then on again.whilst running with this problem i fitted a pressure gauge to the fuel rail but the fuel pressure remains good (43psi) during the stutter/stall, maybe the guage doesnt drop quick enough? Before i had the water flow problem the engine would rev freely , i dont think the engine is overheating now, i could place my hand on the engine after a 5 min run albeit under 3000 rpm, no buzzer and engine idles @750 not 900. any ideas does the water temp sensor or oil pressure sensor have the ability to cut ignition for a second? thank you for any input ps the diagram is in the service manual along with the wiring diagrams

 

[sdsaw]

Re: f115 cooling water route

Glad you found found the cause of the poor water flow.
I have the same motor with a water pressure gauge hooked up.
At idle, my gauge reads "0" but will increase up to 10lbs as the RPM's increase.

What year motor?

I have a 2001 and have had the "intermittent" cutting out for a split second.

Under warranty, my mechanic chased the cause for 3 months.
Running out of things to clean or replace, we replaced the main relay
That was it!

It would lose contact as it was getting warm.
After it surpassed that certain temperature, it would not lose contact until I shut down and it cooled down and it would happen again at that certain temperature.
This might be what is happening to your motor.

Anyways,
Good luck

 

[benzico]

Re: f115 cooling water route

thanks for the reply, my problem seems to be rmp/fuel flow related, the engine will run really smooth but at around 2.5-3k it will stutter for a split second then run smooth again for a few seconds sometimes longer then stutter again, however it will run at around 2k fine. when the engine stutters it really stops the boat. if it was a starvation problem wouldnt the engine gradually slow down or is it more "on,off" with a fuel injected engine. can i unplug some sensors and then test the engine (tps,cps,mps). cheers all

 

[sdsaw]

Re: f115 cooling water route

Have you been inside of the VST and clean the filter?
Check the thermostat?

Recently, someone here had running issues with his Mercury 115 fourstroke
Ended up needing a new high pressure fuel pump
http://forums.iboats.com/showthread.php?t=360336