1999 F4 4 stroke cooling problem

[TownsendsFJR1300]

It wasnt burning oil so i'm probably not gonna tear the crankcase apart. it was running fine, so i'm just gonna fix the cooling issue and see if i have a runner.

Crank case is probably fine anyway. Looks like a simple mower engine with typical salt water crap build up over time...

You should be fine...

[Fishdeeper]

Still waiting for parts. Meanwhile, i got a sheet of glass, a couple sheets of 320 wetdry sandpaper, sprayed it w wd40, and did figure 8's with the cylinder head for 20 mins.
Cleaned right up. Cylinder head is not warped.

[vespisti]

Dear Fishdeeper, I am facing a similar problem.
Today i found that the water tube of my yamaha f4 2002 model has been broken (photo).
I will really appreciate if you can send any guidelines of how to remove the powerhead so i can install the new water tube.

Many Thanks,
Dimitris

[pstephens46]

Dear Fishdeeper, I am facing a similar problem.
Today i found that the water tube of my yamaha f4 2002 model has been broken (photo).
I will really appreciate if you can send any guidelines of how to remove the powerhead so i can install the new water tube.

Many Thanks,
Dimitris

Fishkeeper may be gone. A proper service manual will give you the steps. That little motor should be easy. No winch or lift needed.

[vespisti]

Thank you very much for your reply! I will have a look at the service manual!

[Fishdeeper]

Sorry, been away out of country. A service manual would be most helpful. I found one online and downloaded it. Shows the sequence of operations to dismantle and re-assemble, plus all the torque specs, which you need. Basically have to remove the lower unit, handles, lower cases, in gear start prevent cable, pull start assembly, fuel tank, kill switch, throttle arm, choke cable from carb, lastly 7 bolts conecting the lower unit to the powerhead. I drained the oil first.
sorry for the delay. My new watertube had to come from Japan so i had to put everything on hold and went on vacation. You will need a new case gasket too.
got it all back together and put it in the tank, still wouldnt pump water out the telltale. Arrgh! Pulled out the lower unit, and checked that the water tube was lined up in the rubber bushing at the water pump housing. yep its good. but the water tube didnt seem to be a nice tight fit into the rubber bushing, so i cut a piece of plastic tubing, slipped it over the end of the water tube, goobed it up with some gasket sealant that stays pliable, and re-i stalled the lower unit...this was the fix. Now pumps water and cools just fine... so the water pump didnt create enough pressure to defeat gravity up the water tube becuase it was leaking out of the rubber bushing sloppy fit. I used gasket sealant that stays pliable so if i ever need to get it apart again i can. But rtv or sikaflex would likely work.
Had some frustration. It ran for 5 mins pumping water, then stalled, and would not start. What did i screw up?
compression was 93, factory spec, coil tested ok, spark was ok, i reset valve clearance and coil clearance from the flywheel magnet, and took the carb apart( everything except the float jet) blew it out with compressed air, put it all back together....fric, no start. Doublechecked everything, i think its not getting fuel. but this time took the fuel system apart, cleaned everything again, and this time i removed the float and jet...found a nice piece of crud Blocking flow...everything back together again...it runs like its brand new. Starts first pull. Idles smooth at about 1300 rpm, just under factory spec.
Learned a lot, never had an engine apart like this before, then back together, then apart, then......you get the picture. Manual is a must. And patience!
So in the end, $50 for the motor, $160 in parts (water tube, impeller and insert sleeve, thermostat, thermostat anode, case gasket, cyl head gasket, sparkplug, synthetic engine and lower unit oil, gasket sealant, and ive got a runner for my 10ft jon boat. Labour was free 😉 !!

[panasonic]

I suspect you are missing a rubber grommet or sleeve where the water tube goes into the water pump. You should not have had to goop that up with sealant to get it to seal.

Sometimes all the seals are not shown on the same parts diagram. I have not looked at your particular engine parts diagram so I am only surmiseing this.

Your fix may last forever but it may be worth your while to have a close look at the parts break down again.

[Fishdeeper]

There is a black rubber sleeve/grommet, called a boot in the service manual, on the top of the impeller housing, about 1.25 inches long ( best guess as i dont have it in hand) and the water tube inserts into it directly. Its wider than the tube diameter at the opening, and tapers smaller so as the tube inserts, the fit should tighten around the tube. Nothing else is shown. Maybe it was worn, but it looked fine. as soon as i sealed it to the water tube it started working.