Resealing Lower Unit

[newf1]

I am in the process of resealing the lower unit of my 1980/82 Evinrude 20 HP. Upon getting the unit ready while waiting for the parts I require a little help in the removal of the bushing for the shift rod as well as the removal of the main oil seal located below the water pump. What is the best way to remove these parts? It appears that I may have to reuse the shift rod brass bushing and just replace the O-Ring so I do not want to damage it.<br /><br />Any tips on this project will be greatly appreciated. <br /><br />Also, if anyone knows for a link to a digram to aid in this project please let me know?<br /><br />Thanks

 

[rolmops]

Re: Resealing Lower Unit

I take them out by using a 1/4 inch threaded rod.I guess you can use 3/8.Just lower it down on that bushing and give it a fairly gentle knock on the head.If it does not move,heat it up a bit and hit it again.In a worst case scenario you can tap a thread in the bushing(not all the way through) and screw a heavy bolt in there.Get it out that way.These bushing do not cost a lot of money so you should not worry to much about ruining one.

 

[newf1]

Re: Resealing Lower Unit

Thanks for the info.<br /><br />While installing the new seals (O-rings/oil seals/etc) should I dress them with some light oil or should I install them dry. Mainly concerned with the upper oil seal, seal in the water pump housing, O-ring on the propeller shaft, and the shift rod bushing.

 

[Paul Moir]

Re: Resealing Lower Unit

There's a diagram in the GLM Marine Catalog for your lower unit. If you're not working out of a service manual for your engine, you're causing yourself an awful lot of grief. If you're reluctant to buy one for whatever reason, you can often borrow one from the local library. It's nice to look at them anyway - sort of a 'try before you buy'.<br />Factory manuals are the best. You can reprints here:<br />TheOutboardWizard<br />Mastertech<br />Marine Engine<br />Ken Cook

 

[umblecumbuz]

Re: Resealing Lower Unit

Answering your question about 'O' rings ...<br /><br />These are designed to be lubricated on assembly - either with 'mounting grease' or with silicon oil, depending on the ring material. It is bad practice to assemble dry.<br /><br />Ciao

 

[newf1]

Re: Resealing Lower Unit

I have started to install the water pump and seal kit last night.<br /><br />I was just wondering if there was supposed to be a seal for the top of the water pump housing? It has a large recess where the shaft goes down through the top.<br /><br />Also, when I removed the 2 oil seals located under the water pump plate I had noticed that the seals were not as deep as the new ones. The diameter is right for the shaft and If I install both seals (one over the other) the top one would not be flush with the housing but would still be below the plate. It appears that it would not adversely affect anything if I installed it that way. Should I do this?

 

[R.Johnson]

Re: Resealing Lower Unit

I'm wondering if you have the correct upper drive shaft seals here. With out looking at the service manual, I can't recall when they went to a double seal. When they used only one seal, that seal was thicker in height, and I'm wondering if you may have two of those.I did'nt see it mentioned, but be aware, those two seals are placed back to back, not both facing the same way. The first, or bottom seal face's lip down, the top! lip up. I coat the outer edge of the seal with OMC gasket sealer, then fill the space between the two seal's with triple guard grease. There is a spacer, or sealing tube that slips into that large cavity on top of the water punp. It seal's between the pump, and exhaust housing. It probably stayed stuck in the exhaust housing when you dropped the gearcase. It has a o-ring on both ends. Next! and I don't mean this for just you, but for anyone doing this repair. There is a puller for removing these seals. Trying to remove these seals with what ever you may have handy can cause a lot of grief. That recess the seals fit in is not very thick. I have seen them badly gouged, and even cracked from using the wrong tool. That gearcase casting alone is about an $800 component. You don't want to damage that to save a few dollars on seals.

 

[newf1]

Re: Resealing Lower Unit

Thanks for the info R.Johnson.<br /><br />I got everthing back together. I had emailed the parts supplier and asked about the double seal. He said that I was to use both of these seals even though the top seal would be purtruded about 3/16 of an inch. After installing put the new water pump housing back together and the plate did not contact the top seal. I forgot to put some gasket glue around the seals but all surfaces were perfectly smooth and the seals made a perfect fit. I tapped them in gently with a large socket.<br /><br />I did however notice that the o-ring and bushing for the shift rod is rally tight. I used some mounting grease during istallation but is still pretty tight.<br /><br />I was also looking at the water pump assembly and was just wondering where exactly does the water come in from. Below the water pump is a plate with 3 small holes in it. When I blow down the tube I hear the air escaping through this area but it seems that there should be more.<br /><br />One more question. If I place the impeller in the wrong direction, will the fins realign in the prooper direction on their own? Not sure which direction. I put it in clockwise looking down at the housing.

 

[R.Johnson]

Re: Resealing Lower Unit

There is an inlet passage behind this plate, there is also an inlet screen on the front face of the exhaust outlet. As you have found, the shift bushing is made of brass, and is quite soft. If you don't have the correct driver to remove, or install, this bushing can get peened in. This is what will cause the tight feeling on the shift rod. You put the impellor in correctly. It is also a good idea to gease the impellor, and pump housing so that it don't have a dry start. On this small pump, the blades will correct them selves if put in the wrong direction.