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Overheat buzzer goes off when getting up on plane

K

kiwi_dave

Contributing Member
"Desperate for help, My 140843

"Desperate for help, My 1408430 1978 140 horse, . I recd some advice some months ago re the above problem. I was advised to Chk water Pump, Done. Check Thermostats, Done (after doing these boat ran on a plane for about 1 1/2 minutes then buzzed) . Check, service / replace my water deflectors, (about to do), however, the SELOC Service manual I have, doesnt really give any information on how to get to them, and replace them. The book does mention the deflectors, and shows them as a passage around the top of the cylinder, but from the prev advice I had recd from Joe Reeves, ( I think t was joe ) the deflectors are a small length of rubber pipe runing in between the top and bottom cyls ?
Anyone got any info as to where I best start ???
I"
 
Did You just check or replace

Did You just check or replace impeller in pump?
(Max impeller life time 3-5 years)
Did You just check or replace thermostats/pressure valves?
Seal between exhaust tube and lower gearcase?
 
"Checked the impeller and was

"Checked the impeller and was advised it was fine.
replaced the thermostats as they were seized closed... dealer inspected pressure valves, advised they were fine no heavy wear, all looked good. Rplcement of stats made some difference as was able to gun it up to plane twice for short periods1-2 minutes ( great fun !) , the second time obviously shorter, with the old familiar song ... BEEEEEEEEEEEEEEEEEP !!!! ppowered off for 15-20 mins .... bugger started and cruised home 6-8 knots."
 
"Do a voltage check of battery

"Do a voltage check of battery charging first.
Then do an OHM test of both temp switches to determine if they really 'close' and set off the alarm. It might be one that closes on too low temp.
I have never liked mechs 'inspecting' the impeller and stating it is 'fine'. If not changed last 5 years, change it! Another thing that puzzles me is that opposite the Yamaha thermostats the OMC thermostats gets stuck OPEN and not closed, or are You running Yamaha thermostats?
Perhaps time to change mech and impeller."
 
"Voltage,on a 78 140,..is not

"Voltage,on a 78 140,..is not gonna affect hot horn operation.....period.......omc's will.stick either open or closed.I NEVER inspect......if i go in there...i replace,as morten suggests."
 
"u may have a control box prob

"u may have a control box prob,instead of eng,....turn key on,spin prop while shifting into forward and throttle,eng not running,...and see if horn goes off...many times,objects ground horn and make it go off this way."
 
Has the motor been updated wit

Has the motor been updated with the later model fuel flow sensor or VRO system?
 
"David.... If the engine was o

"David.... If the engine was overheating previously which prompted you to drop the lower unit to have the water pump inspected, and if the water pump has not been replaced in a couple years or so, install a complete new water pump if for no other reason.... peace of mind.

This eliminates the possibility of having a pump that looks great, but in reality has a flaw which leads into a false trail of looking for a problem elsewhere that may not exist.

Pertaining to the deflectors......

(Water Deflectors)
(J. Reeves)

Water deflectors are actually lengths of 3/8" outside diameter rubber hose, installed between the top cylinder and any cylinder beneath it, and also between the bottom cylinder and the block. The purpose of the deflectors is to have the water follow a definite path around the cylinder walls. Unfortunately the deflectors between the cylinders will at times swell sideways due to either a previous bad overheating problem, or simply due to age and salt corrosion. This causes a water flow restriction which usually allows the water to cool sufficently at low rpms but not at the higher rpms.

This hose material can be purchased reasonably at any automotive parts type store if you care to make your own, or you can purchase individual deflectors at any Evinrude/Johnson dealership at a somewhat higher cost.

Removing and installing them can be a hassle at times, but not always. I use a sharply pointed scribe with about 1/4" of the tip bent at a right angle whereas I can reach in, jab the tip sideways into the rubber, then yank it out. It's necessary to clean the seating surfaces where the ruber contacts the block with a small rat tail file to eliminate salt deposits etc. When installing the new rubber deflector, coat the deflector and the metal surfaces with WD40 which will act as lubrication to allow it to go in as easily as possible.

Make sure that you insert something into that deflector area before cutting and installing the deflectors if you make your own so that you will be certain that they are the right length and also that they will be seated properly. Usually a very small amount will be left extending about the block sealing area..... simply cut the excess off with a single edge razor blade.

When time permits, visit my store (copy/paste) at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
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