1986 Evinrude 90hp Overheating help please

"Hi All,
I've been trying

"Hi All,
I've been trying to fix this motor on and off now for over 1 year with on/off success. Its been to many mechanics who have charge me a lot of money with minimal improvement. Decided to pull heads, open water jackets and find problem for myself.

I now believe the problem is actually in the water pump. I have attached bilge pump to copper tube with lower leg removed and get great water flow through the heads. With leg on flow is nill to minimal. Pump is NEW!. Looking in the discharge of the pump I can see the grease stain from where the copper tube sits when lower leg is assembled. It appears very low to the point where it may be bottoming out on the pump base plate, hence limiting the water entering the tube. Is this possible? has anyone seen this before? what is the fix? I hoping it could be this simple as I've spent considerable money and time on this engine now.

Thanks in advance

cheers
rr"

"One critical item is the big

"One critical item is the big rubber seal preventing exhaust from going into the pump.
Pos #21 on attached pic.
"

"i believe I have those rubber

"i believe I have those rubber seals in place however will double check tonight, thanks

any idea on the required clearance between the copper tube and the pump base plate?"

"Ryan, the water tube itself s

"Ryan, the water tube itself should not extend below the guide tube on the waterpump cover. If the water tube was replaced somewhere along the line with something other than the correct OEM piece it may be too long.

The arrow on the diagram points out the guide. The water tube should insert about half way into the guide upon assembly...

"

"With the lower unit removed a

"With the lower unit removed and set aside, lay a straight edge across the exhaust housing and measure from the mating surface of the exhaust housing to the bottom of the water tube. Make a note of that measurement.

Now, take note of the exact location of the water tube grommet that is located in the water pump impeller housing. From the mating surface of the lower unit, measure up the exact measurement that you've made a note of. That measurement should be within the water tube grommet at its lowest sealing point...... indicating exactly where the tube would be with the lower unit installed.

The term "plate" pertains to the plate beneath the impeller. The item that the impeller installs within is the "cup". Perhaps you are referring to the cup as the plate which can be somewhat misleading.

If the water pump is installed correctly and no misalignment exists pertasining to the water tube, and you're sure that the thermostats are operational, it's possible that a problem exists with the water deflectors as follows.

(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

You haven't actually stated exactly what the engine is doing. I can only assume that it is overheating. It would help if you defined the problem somewhat more."

"Hi Guys,

Thanks for the as

"Hi Guys,

Thanks for the assistance. I have measured and checked alignment of copper tube into pump, it is as per origional manufacture, the grease markings must have washed down into the pump giving me a bum steer.

I have reassembled leg and heads temporarly on until new gaskets arrive. Turning over on starter motor without plugs it seems to be pumping well now, to the top of the head and out the top water galary hole (i have cover plates removed from head).

The problem has been cyclinder block getting to hot to touch at idle and eventually steam comming out the tell tail. Previously I have removed the hoses which run from the head to the thermostat and no to little water has been pumping through. Deflectors appear in surprisingly good condition.

There are some very small holes running through the block towards the exhaust for water on each cyclinder, I've been rodding these out with wire the best i can. How on earth do you ever stop these from blocking with salt? are these critical? is this a bad design?

thermostats are new. bypass pop off plugs and springs seem to be very firm. When undoing the thermostat cover, i struggle to hold the springs compressed, does this sound right? will these be forced open with pump flow at idle? I'm guessing these pumps work as positive displacement giving massive discharge pressures as required?

Haven't really found a problem as yet so am hesitent about putting everything back together fully.

Exhaust rubbers are present and installed as per drawing.

Thanks
RR"

The springs being hard to comp

The springs being hard to compress is normal. The springs and the related parts are water bypass valves which allow water to bypass the thermostat when needed.

Possible problem areas:

Head gasket not sealing properly due to improper torque specifications or improper tigntening sequence. This should show up as slight burn travel marks at leakage points.

Custom sealing O Ring on bottom of water pump impeller housing may have slipped upon installation. This allows the impeller to draw air into the pump assembly.

"When testing, are You running

"When testing, are You running with muffs or in a barrel? To get a correct picture, please run in a barrel with water level ABOVE the water pump."

"yes purchased a barrel yester

"yes purchased a barrel yesterday for the test, previously have been running down the boat ramp, I have never had much success with ears on this motor.

parts arrived today, will assemble over weekend and post results next week.

cheers"

"g'day all again,

about

"g'day all again,

about to reinstall the heads and am confused to which way the new head gaskets go. There are absolutely no markings on gaskets. There are the small tabs which stick out at one end, i believe these are to be on the top? The gasket metal ring is thicker on one side then on the other side of the gasket. Does anyone know if you install the thicker side to the block or the head? The gasket also has additional holes which look like they might work in conjunction with the water deflectors to direct water to the top of the head, I still can't be sure on where these are to be. Can anyone help please? thanks"

There is an arrow ( should

There is an arrow ( should be ) on the gaskets and the arrow point to the exhaust.The tabs are on the top and towards the outside of the motor. If you are not sure on this do not install them untill you get a proper manual.

"my old gaskets had arrows and

"my old gaskets had arrows and a label saying to point towards the exhaust manifold. the strange thing was both of the old gaskets were identical so to have them both pointing to the exhaust, one had to be flipped and therefore the metal gaskets sealing ring was different width for each side of the motor (hope that made sense). This just doesn't look 100% right to me..."

And WHY does it not " look

And WHY does it not " look right " to you.Both tabs are at the top and to the outside.AND AGAIN if you look closely you will see that this all has to do with the way the water flows thru the motor." looking right " to you has nothing to do with what is right.Sorry to be somewhat blunt.

"Ryan....It doesn't matter

"Ryan....It doesn't matter which way the metal sealing rings face. The important thing is that the water passages are aligned properly, hence the flipping of the gasket."

"ok thanks guys, I have them r

"ok thanks guys, I have them right in that case, I appreciate the feedback. cheers"