84 60 hp Johnson cooling system problem

[lmbr]

84 Johnson 60 hp restoring. Compression on both cylinders is 115 - 120. After overhauling carbs and completely cleaning fuel system engine started right up. But when I started the motor, there was no Tell Tale so I overhauled the water pump and replaced the impeller. I am using earmuffs. When I had the lower unit off, using a water hose and nozzle, I ran water thru the Tell Tail hose and water came out of the tube the water pump connects to. I know running the water thru that hose is the opposite direction of normal operation but I was trying to see if the cooling system was blocked. When I originally got this motor and used earmuffs the tell tale worked. 2 questions: Is there a way to run water thru the system to flush it without having to pull the lower unit again. And do I just need to put it into the lake to try it. (Closest lake is 30 miles away I also could put the motor in a horse water trough if that would. I do know not to put the prop in gear when doing this.)

 

[interalian]

Running on muffs pressurizes the cooling system so it doesn't really prove the system is working properly.

As long as you can have the water level in the trough is higher than the impeller you'll be fine test running. Reason being the water pump is not self-priming - it needs to be submerged.

 

[Bosunsmate]

If you didnt have it submerged properly you may have burnt up the impellor. The water level needs to be quite high on those when the boat isnt moving through the water. When you a going fast the water momentum pushes it up in the pump when the boat lifts up on a plane.
Also on those you can get air bubbles at the top of the crankcase cooling chamber and it will make it run dangerously hot. Theres a simple mod you can which ive done here to mine.
Its pretty much a must do
https://forums.iboats.com/forum/engi...ng-a-tell-tale

 

[lmbr]

I'ma little nervous about the modification you are suggesting. The bulletin you posted is for an in line 3. My engine is a 2 cylinder. The cooling system was operating fine prior to letting it sit idle for 3 years. I have not run the engine very much since I overhauled the water pump so I think that is ok but should I be able to flush water thru the tell tale system using a water hose? The telltale hose does connect to the engine down low behind the starter then goes up over the top of the engine and then to the outlet. Guess I will have to pull the lower unit and make sure the impeller is ok and working and go from there. If I were to add the mod on top of the engine, don't know how I would get to the existing outlet to block it off.

 

[racerone]

Correct ---the modification is for the early production 56 cube 3 cylinder motors.----Never a service bulletin for the 2 cylinder motors.

 

[lmbr]

In looking at the photo of your motor it looks like the CD3 and CD2 are basically the same on the top. If I end up doing the modification, would I install it right behind the lifting eye?

 

[Bosunsmate]

In looking at the photo of your motor it looks like the CD3 and CD2 are basically the same on the top. If I end up doing the modification, would I install it right behind the lifting eye?

Yes mine is the 2 cylinder and its absolutely crucial its done. I was chasing an overheat at idle for weeks on it- new waterpump, I cleared out cylinder head etc etc and still the IR gun showed she was getting too hot.

The design of the original system definitely does not allow for thorough evacuation of air bubbles trapped in the top of the crankcase.
All you have to do is yes install it right behind the lifting eye. I did not have a tapping thread so i just drilled the hole and then used the lifting eye as kind of a platform to help keep the new outlet pressed in. I used heat resistant epoxy which is about $15 here in NZ so cheaper in US to seal around it. Its never given me an issue and has made the outboard now run at perfect temps, i dont worry at all about overheating anymore, i just check now again the pisser is working and i test the horn every few trips.
The heat resistant epoxy i just rolled up into a ball and squished it into the old watertale outlet to clog that up.
All you do is drill through the top casing and you stop when you get to the empty area between the top of the crankcase and the top of the cylinder. The outer crankcase cover is a few mm thick and then your drill will come in to free space, its very evident so you stop then and then install the new outlet. You can put grease on the drill bit too which stops filings going into the motor but thats not critical its just good practice to do it. I picked up a outlet T from a boating shop for about $3

Let me know your plan as if you do this modification which i totally recommend as it saved my motor then i will give you the exact measurement to drill from behind the lifting eye that i did mine at, but im pretty sure anything not too close to the eye or to the rear of the crankcase would be fine.

 

[Bosunsmate]

And to answer your other question, if you put a hose onto the tell tale then it will just put water into the start of the cooling system in the exhaust housing jacket before it falls away out the intake pipe, so it will tell you only as much as that not the rest of the cooling system such as the head or crankcase jackets

 

[Rustywrench]

You mentioned you ran water thru the telltale tube. Did you check the fitting in the pan? It is the most restrictive part of the system. A small rock or trash will block it. With the hose off run a small wire thru it. Just wouldn't want you chasing a ghost.
I would NOT do the mod on top of the block. It will vent the block of any air, but that is unnecessary. It will cause your engine to run cold. Just as bad for cylinder & ring wear. Circumvents your thermostat operation. Might not hurt to give it a look after all these years. Thermostat, seat, & poppet seat.
If the telltale elbow needed moving OMC would have moved it!

 

[Bosunsmate]

My engine heats up to normal temperature 95% as quick as it use to except now due to no air bubbles it doesnt go past that into danger. Venting that air is totally necessary, the proof was in the pudding

 

[jakedaawg]

My engine heats up to normal temperature 95% as quick as it use to except now due to no air bubbles it doesnt go past that into danger. Venting that air is totally necessary, the proof was in the pudding

But isn't your motor a 3 cyl? He has a two cylinder and no mod is necessary or reccomended.

 

[Bosunsmate]

But isn't your motor a 3 cyl? He has a two cylinder and no mod is necessary or reccomended.

Nope, ive the two cylinder and it was overheating until i relocated the telltale. That instantly fixed it, i had done everything else recommended to fix overheating problems until i did this. The water is warm here but not markedly so and the sea often has short waves meaning i do possibly get more air in the system than in other areas but still if the motor is able to evacuate air efficiently it should have no problem with the occasional momentary ingress of air

 

[lmbr]

OK, I removed the lower unit again today. Couldn't find anything suspicious. Water pump looks OK. With the lower unit off I put a water hose in the input tube coming up to the engine. Nothing from the tell tale. So I'm thinking there is something in the cooling system stopped up. So 2 questions: Is it possible for the whole system to be stopped up? & wouldn't adding the modification be just installing another tell tale? Wouldn't this confirm if the original tell tale is stopped up? The original fitting is a nylon L fitting and VERY tight. I'm afraid if I put too much pressure on it that it will break off causing even more of a problem. If I install the modification and it works I'm OK. If not then I'm not sure what to do other than scrap the motor. If the mod works I can always just plug the original hose. I am somewhat able to work on this motor, but if it involves removing the head or going deep into the motor I'm not sure. If I had ever seen it done or watched a video I pretty sure I could do it but otherwise seems like I a working blind.

 

[lmbr]

Another update. I used my air compressor to shoot hp air (140 psi) thru the fitting the tell tale hose connects to. I could hear air going thru the fitting so at least it tells me the fitting is not blocked. So now I'm feeling a little like I'm into more than a simple blockage.

 

[oldboat1]

take off the head cover and check cooling passages -- scrape them out if you find blockages.

 

[Bosunsmate]

Dont worry about the mod as of yet, you need to find out why the water isnt going through the engine. WHen you connect the hose you should get some coming back down the internal exhaust outlet inside the leg.
If its not doing that then you will need to remove the head cover and maybe the head too as Oldboat says.
Dont worry its easy. Everyone here will give you tips.
Just take photos so they remind you where things go and then back out the bolts by starting in the middle and working your way up and then a bit down a bit up again until you have got to the outside. Post photos of the cooling channels and also remove the two ignition coils and put them up and out of the way.
I use to be cautious about ripping into an outboard but its saved me thousands and a lot of time since i finally made the decision to do things myself, they are very easy once you look at them straight in the eye

 

[Bosunsmate]

If you get really stuck i can probably make a quick video. But all you a doing a moving the little bolts on the back cover of the motor and looking to see if things a clogged in there.
To remove the head you just undo the larger bolts on the head which are like 1/2 inch i think

 

[lmbr]

Taking head cover off. All bolts but one came out easily. One at the bottom really tight and no room to get to it. Any suggestions. Sure don't want to break it off.

 

[Bosunsmate]

You can undo the bolts that hold up the lower cowling at the rear and that will drop it somewhat.
Tightening then loosening then tightening then loosening helps when the threads a full of gunk

 

[lmbr]

Actually I got it out by drilling a small hole in the cowling just big enough for a 1/4" drive extension to fit thru and then put the socket on the bolt and then slid te extension thru to the socket. The bolt was still really tight so I used a small propane torch used for heat shrink tubing to heat the end of the bolt and then by tightening and loosing got it to break loose. Underneath the cover everything is really pretty clean. Nothing stopped up but the thermostat seemed to be in bad shape and it might have not been opening. But I haven't run the engine long enough for it to open. Opened the water pump again and the nylon key seemed really worn so that could be the problem. Finding the correct impeller with the nylon wedge key has been a big problem. I've ordered two and neither one was the right one. I have another one coming along with a new thermostat and gaskets so hopefully these will fix the problem