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Johnson 35hp 1979 cooling problem

R

raksike

Member
I have bought recently a 1979 year 35hp Johnson, but it occured that it has problems with cooling. After the engine has run for about 5 minutes it is not spitting anymore water through the "pee hol" instead only white steam is coming out from there and the motor overheats. I used that same Johnson last summer with no problems but this year the last owner of the outboard has modified the shaft from L to S. Maybe something happened during the conversion? What should i check to identify the root cause of that problem. He said also that the impeller was in good shape.
 
A water pump can be fine one day and not the next... at some point, it will fail.

Remove the lower unit... Observe/measure the copper water tube to make sure that it protrudes into the water pump grommet properly. That is to make sure that it has not been bent upwards by an misalignment which would cause it to be slightly too short.

Dismantle the water pump, inspect and repair as needed.
 
What i didnt mentioned at first is that at first when i start the motor, then water is coming from "pee hole" and also from the "tell tale" would water come from these if water pump or impeller would be faulty?
 
Don't fight it, go in there and see what he screwed up. All the seals & gaskets in place? He didn't leave the drive shaft tube out, did he? Long shaft and short take different tubes.

I hope you didn't damage the motor by overheating it. The 35 doesn't like that.
 
I removed today the lower unit and found that the water pipe was pretty bent, i think that maybe is the problem caused since the pipe comes too high up on the water pump and this is blocking the water flow? I took some pictures, maybe can somebody give a comment is my theory right or not? Look also the impeller pin picture, is it OK that it is coming out so short or should it be longer? Also sorry about the bad pictures, my old Nokia is not capable to make better pictures.

Water pipe in the impeller housing: http://fotoalbum.ee/photos/raksike14/107584153/
Water pipe bent: http://fotoalbum.ee/photos/raksike14/107584147/
Impeller pin: http://fotoalbum.ee/photos/raksike14/107584143/
 
Raksike..... You need to have a serious talk with the seller. Read on.

The previous owner (or someone) has installed the wrong driveshaft. The proper driveshaft would have a Flat Spot cut into it that would accept a "round metal" or "plastic shovel like" type key to drive the impeller, one end of that plastic key would have a "filed sharp appearance to it" that would engage the impeller slot.

I notice that there is another hole drilled in that driveshaft a couple inches higher, indicating that the lower hole had to be another hole drilled to accept a older style plain "pin" type impeller drive key. Either the second (lower) hole was drilled too deep... OR... the pin was/is a makeshift attempt that is too short.

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The water pump may not be the correct kit for the 1979 35hp Evinrude/Johnson. The kit design may be identical to what is actually needed... EXCEPT... the impeller would differ.

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The water tube obviously has NOT been replaced with the needed shorter tube required for the conversion to short shaft. It has simply been cut and shortened... however it has been cut and shortened incorrectly. The cut length is in error, is too long, and as the lower unit bolts are tightened, the water pump would be pressing hard against the tube, causing it to bend.

**********
The Cure (possibly) and suggestions:

(Driveshaft)
That driveshaft might be able to be used. The drive pin that normally slides into a round drilled hole is part #300771 which is the pin that must be used with your present driveshaft.

If you want to see the impeller key that normally is used with the correct 1979 35hp driveshaft, that would be part #300611 which is a large round dowel like vertical key. Note that the newer water pumps may be equipped with the plastic shovel like key mentioned previously.

Any dealership should be able to produce both for you to see. Replacing the driveshaft with the correct one (Part #323261) is not feasible (expensive and listed as unavailable).

**********

(Impeller Pin)

The driveshaft willl simply slide out of the lower unit. Have it on your workbench so as to be able to view the following properly. Purchase the impeller pin that would be needed with your present driveshaft (pin #300771). Slide it in the hole of that driveshaft, make sure that it is all the way in the hole! Slide the impeller over the pin, then observe carefully... is the head of that pin close to the end wall of the groove in the impeller? If not, then whoever drilled that hole drilled it too deep, in which case you will need to make your own impeller pin/key of whatever length needed to drive the impeller.

**********

(Water Tube)The proper short shaft water tube is part #319674 but has been superseded up to part #322077. It appears to be listed as unavailable BUT can no doubt be found at various dealerships or other shops.

Keep this figure in mind: The difference in length between the short and long tube is exactly Five Inches (5")

FYI, the long shaft water tube is part #319675, superseded up to #322078 and is still available according to my books.

If you can't locate the proper short shaft water tube, you can determine exactly how much to cut from your present tube as follows: On the workbench, measure from the top surface edge fo the lower unit to the bottom of the water tube grommet of the impeller housing. Be sure of the measurement and make a note of it.

Straighten the obvious bent portion of the water tube as good as possible, then... with the top of the water tube inserted and seated into the upper grommet in the exhaust housing... have a flat edge laying across the bottom surface edge of the exhaust housing. Measure up from that flat edge to whatever the measurement is you made a note of... That point must be the bottom edge of the water tube so that it sits and seals perfectly within the impeller housing grommet.

**********

Should you decide to purchase a new long shaft water tube to cut (it happens)... it is then a simple matter to cut exactly five inches 5" off from the bottom of it... that is from the extreme taped bottom point up.

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If I've left anything out, get back to me
 
The previous owner said that he used a 33hp Johnson driveshaft and that it fitted properly to that 35hp outboard, but it seems that he was not right! I think i have to do a new impeller pin myself, maybe i find somewhere a new driveshaft. I have a 55hp Johnson also for spare parts, maybe is there something that would fit to my 35hp outboard. I will update this topic with new posts if i have any progress with that issue. Many thanks to yoereeves.
 
kimcrwbr1 said:
The 33hp was discontinued in 1970. As long as the shaft diameter, length and splines are the same then just fab up a pin to fit the 1976 impeller. Get the water tube to fit correct and then put a little permatex on the outside of the upper tube so it fits tight in the upper grommet. Put a light bead and let it set up for a couple hours and fits nice and tight. If you cant get a tight fit up top you will need to replace the upper grommet.
Click to expand...


So i need now to order a new impeller for a 1976 35hp Johnson? Is it correct?
 
raksike said:
So i need now to order a new impeller for a 1976 35hp Johnson? Is it correct?
Click to expand...

When i look at the pictures at the internet, then all the other impellers are looking bigger, can someone confirm that the dimensions are the same with a diffrent impeller and which one should i order?
 
raksike said:
When i look at the pictures at the internet, then all the other impellers are looking bigger, can someone confirm that the dimensions are the same with a diffrent impeller and which one should i order?
Click to expand...

In double checking and viewing very closelt your picture of the water pump kit, which includes the impeller which was what I wanted to examine up close.... I see that the impeller and the kit in general is for the 1979 35hp driveshaft which would have the flat spot cut into the driveshaft to accept the plastic shovel like impeller key.

This is going to create a problem as that impeller is not designed to operate or be driven with that small metal round pin. If you could locate the proper short driveshaft at a reasonable price (Part #323261) , that would be the ideal way to go (but expensive). Should you think you've located one, the part number would be imprinted directly on the driveshaft somewhere... look for it closely.

Note that you cannot use the 1976 impeller as it's diameter is too large and it height is not high enough.

Ask your dealership to let you view (impeller in hand) the impeller part numer 388702. What would be the cheapest way out of the predicament you're in would be to have a impeller of the proper outside measurements BUT to simply have a rectangular slot cut into the inner portion for the pin... OR... instead of a rectangular slot, to simply have a half round slot cut there.

As a last resort.... you would need a new impeller of the same type in your present impeller housing, the 388702 impeller, BUT do design a pin in your driveshaft, cut to a proper length on your workbench as stated in my previous reply.

Let us know how things work out for you.
 
I have now two options:

Option 1: The local spare part dealer offered me a impeller that should be with the same dimensions what is needed, impeller code 6H3-44352-00

Option 2: I got the original long shaft drivetrain, i think that it is possible to make it 5 inches shorter and use the original impeller.

I dont know which option would be better?
 
Last edited:
I sent the driveshaft yesterday for rework, now i want to order the impeller key, should the key with part no. 330619 fit to my driveshaft?
 
joereeves said:
This rework of the driveshaft... you don't say what's being done to it.
Click to expand...

Sorry, the guy who made the rework, he made just a cut into the driveshaft like the original one has, he sayd that we can anytime make the long shaft shorter but not the otherway around, so he suggested that we will modify the short one, i have forgotten to take a picture from that modifyed shaft.

Today i got it assembled and it seems that it is working! I had also to bend the water pipe so that it fits correctly into the impeller housing. After running in the barrel for 15 minutes it didnt show any marks of overheating anymore, i try it tomorrow on the river. I added also 2 videos from the motor running.


 
I was today at the river, it seems that it is now better then before but now i have another problem. It is starting very hard when warm/hot, sometimes are the spark plugs wet, but the most time are they dry, like it would not get any fuel! I noticed also that sometimes it is much harder to pull the rope to start and some times it is like normal. Could this problem be caused by a bad head gasket?
 
I have today disassembled the cylinder head and the gasket is bad, inside the cylinders was pretty much water. And i found one bigger issue with this engine i think. The pistons are wobbling inside the cylinders pretty much :(

Now i dont know what would be the most reasonable solution, to scrap the engine, or try to change piston rings and use the engine in this condition? I think the pistons would be very expensive to replace.

Here is a video of the current condition https://www.youtube.com/watch?v=j3ay...ature=youtu.be
 
Now is the head gasket replaced, the motor runs, but the upper spark plug goes still wet! I think, that it is water, since the motor runs pretty good with both cylinders. I didn`t had a wrench with a torque meter, but i have tightened them pretty hard, could there be some problem, that the head is fastened wrongly?
 
Did you make absolutely sure that the sealing surfaces of the head and block are in perfect condition. There can be no bad pitting or grooves that would allow water to flow by. The head gasket you installed was a new one?

I'm not sure what the bolt torque should be on that engine but someone will jump in here with that info... it is important.

Also, the bolts must be torqued a little at a time up to that torque setting in the following sequence:

9...10
5....6
1....2
4....3
8....7
 
I have to take it apart again, and check it again, but in my remembering was everything okey, today i tryed to tighten the bolts and one bolt cracked so i have to disassemble it anyways.
 
Look at the cylinders when you have it off to see if the aluminum casting as pulled away from the liner as these years are bad about this if severely overheated. This will cause water to be suck down beside liner and into intake/exhaust ports, if so block is junk as to expensive to repair.
 
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