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Discussion Starter · #1 ·
Just before the lockdown I acquired a 20hp Johnson, which ran, but was not pumping water very well. I ordered a water pump impeller and associated gaskets and grommets. Being very hawkish about lubricants and sealants, I would like to know what is best where.

The Clymer manual mentions about half a dozen different products, but I'd like to take care of it with what I have on hand, if workable. Every reference I've read recommends a light coating of oil on the the water tube grommet, but most are not specific. I was thinking lower unit oil. I would expect gasket sealant to apply to all the gaskets, and of course intend to use anti-seize on screws, nuts, and bolts.

I have gasket sealant, an assortment of light and heavy oils (water-cooled 2-cycle, air-cooled 2-cycle, lower unit, fishing reel, chain saw, 5-W30, 10-W30), marine grease, and fishing reel grease, as well as various culinary and nutritional oils.

Any info and tips would be much appreciated.
 

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Just before the lockdown I acquired a 20hp Johnson, which ran, but was not pumping water very well. I ordered a water pump impeller and associated gaskets and grommets. Being very hawkish about lubricants and sealants, I would like to know what is best where.

The Clymer manual mentions about half a dozen different products, but I'd like to take care of it with what I have on hand, if workable. Every reference I've read recommends a light coating of oil on the the water tube grommet, but most are not specific. I was thinking lower unit oil. I would expect gasket sealant to apply to all the gaskets, and of course intend to use anti-seize on screws, nuts, and bolts.

I have gasket sealant, an assortment of light and heavy oils (water-cooled 2-cycle, air-cooled 2-cycle, lower unit, fishing reel, chain saw, 5-W30, 10-W30), marine grease, and fishing reel grease, as well as various culinary and nutritional oils.

Any info and tips would be much appreciated.
I use Sil-Glyde on all o-rings and rubber connections. Oil can be hard on rubber.
https://www.napaonline.com/en/p/BK_...dDjy_viaiiABb2VHkZ9VRH5cR2Nd_TNoaAllREALw_wcB
 

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Discussion Starter · #3 ·
I figured gasket sealant would be fine for any gaskets and o-rings.
 

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I wouldn’t over think this.

The water tube never sees gear lube. I wouldn’t use it for that location. A thin smear of motor oil, doesn’t matter what kind, might be helpful.

What do you mean by gasket sealant? Do you mean RTV/Permatex type of product? I wouldn’t use it. Gaskets are seals. That’s what they do, they seal. A potential downside to using RTV or similar is getting the unit apart in the future.
 

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Discussion Starter · #5 ·
I wouldn’t over think this.

The water tube never sees gear lube. I wouldn’t use it for that location. A thin smear of motor oil, doesn’t matter what kind, might be helpful.

What do you mean by gasket sealant? Do you mean RTV/Permatex type of product? I wouldn’t use it. Gaskets are seals. That’s what they do, they seal. A potential downside to using RTV or similar is getting the unit apart in the future.
Thanks. A gasket lubricant like Permatex is exactly what I had in mind to prevent sticking. Mainly for the large, flat gaskets that could get stuck. O-rings wouldn't need it. All the references recommend a thin smear of oil for the water tube, the stated reason being to prevent is from expanding and covering a small passageway, or some such.
 

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You mentioned sealant and lubricant. Which product do you mean? Neither are required. I would not use any of these products.

No gasket on an outboard motor falls into the “large” category. If down the road a gasket needs removed, remove it whole or in pieces. If it sticks to the mating surfaces, a razor blade and patiences handles that job well.

Also for o-rings, no assembly lube is strictly required. These are static seals, nothing like a valve guide, crankshaft bearing or piston ring. O-rings and gaskets are designed to be one time use and replaceable. Have you rebuilt engines in the past? Curious where the interest in these products comes from.
 

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Discussion Starter · #8 ·
Have you rebuilt engines in the past? Curious where the interest in these products comes from.
I certainly haven't, very new to all of this. That is why I posted this, to get some info and pointers from folks with more experience help sort out what the references such as the Clymer Evinrude/Johnson manual and the Cheap Outboards book said was correct or BS. Cheap Outboards has the clearest and simplest info.

My interest comes from wanting to have my boat powered as inexpensively and reliably as possible and knowing what to do and not do to accomplish that.
 

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You mentioned sealant and lubricant. Which product do you mean? Neither are required. I would not use any of these products.

No gasket on an outboard motor falls into the “large” category. If down the road a gasket needs removed, remove it whole or in pieces. If it sticks to the mating surfaces, a razor blade and patiences handles that job well.

Also for o-rings, no assembly lube is strictly required. These are static seals, nothing like a valve guide, crankshaft bearing or piston ring. O-rings and gaskets are designed to be one time use and replaceable. Have you rebuilt engines in the past? Curious where the interest in these products comes from.
"outboard motors don't die, there owners kill them"
 

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Clymer does not make the best manuals. The best is an OMC Shop manual for your exact model of outboard. They can often be found on ebay for very reasonable prices. Second choice would be a repair manual from Seloc. They are pretty good. BTW I always use silicone reel grease on the water tube grommet.
 

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Just before the lockdown I acquired a 20hp Johnson, which ran, but was not pumping water very well. I ordered a water pump impeller and associated gaskets and grommets. Being very hawkish about lubricants and sealants, I would like to know what is best where.

The Clymer manual mentions about half a dozen different products, but I'd like to take care of it with what I have on hand, if workable. Every reference I've read recommends a light coating of oil on the the water tube grommet, but most are not specific. I was thinking lower unit oil. I would expect gasket sealant to apply to all the gaskets, and of course intend to use anti-seize on screws, nuts, and bolts.

I have gasket sealant, an assortment of light and heavy oils (water-cooled 2-cycle, air-cooled 2-cycle, lower unit, fishing reel, chain saw, 5-W30, 10-W30), marine grease, and fishing reel grease, as well as various culinary and nutritional oils.

Any info and tips would be much appreciated.
That model year OMC motor does not have a "Pee" hole it has a spitter port on backside of exhaust housing.You can add a "Pee" port if kits to do that are still available,that makes it easy to see if it's pumping well...
 
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Discussion Starter · #12 ·
Clymer does not make the best manuals. The best is an OMC Shop manual for your exact model of outboard. They can often be found on ebay for very reasonable prices. Second choice would be a repair manual from Seloc. They are pretty good. BTW I always use silicone reel grease on the water tube grommet.
Thanks. I haven't found the Clymer manual very easy to work with, either. I'm mostly using the parts diagrams from the dealers from whom I've been ordering the parts lately.
 

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I use dish soap and water to pre lube the impeller , that way upon start up the impeller isn't running dry until water gets to it
The impeller is in water if on muffs or in a bucket,cup fills with water upon submersion...
 
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Just before the lockdown I acquired a 20hp Johnson, which ran, but was not pumping water very well. I ordered a water pump impeller and associated gaskets and grommets. Being very hawkish about lubricants and sealants, I would like to know what is best where.

The Clymer manual mentions about half a dozen different products, but I'd like to take care of it with what I have on hand, if workable. Every reference I've read recommends a light coating of oil on the the water tube grommet, but most are not specific. I was thinking lower unit oil. I would expect gasket sealant to apply to all the gaskets, and of course intend to use anti-seize on screws, nuts, and bolts.

I have gasket sealant, an assortment of light and heavy oils (water-cooled 2-cycle, air-cooled 2-cycle, lower unit, fishing reel, chain saw, 5-W30, 10-W30), marine grease, and fishing reel grease, as well as various culinary and nutritional oils.

Any info and tips would be much appreciated.
Not meaning to change subject fishinthed ,but what is the status of the 18hp Mercury from a previous post before this one?
 

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Impellers should be coated with Vaseline prior to inserting the cap while rotating the Impeller in a clockwise rotation. To the original OP, you bought all the items and did not know if your housing is still good? Will chew up a new Impeller even after Emery Clothing it.
 

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Discussion Starter · #17 · (Edited)
Not meaning to change subject fishinthed ,but what is the status of the 18hp Mercury from a previous post before this one?
Caught up in other things, so no progress on the Merc, though it's probably an easier repair -- once I have the parts. I'll almost certainly have to order parts, most likely a reed valve assembly, so the Johnson jumped ahead in the queue.

Speaking of which, I've got the water pump system dismantled and mostly cleaned out. It wasn't easy to get the linkage bolt out - had to squirt Free All on the bolt and use a long-handled socket wrench - and the gearcase was a real bugger and a half to pull out - had to use a pry bar, which I padded by duct taping plastic lure box divider pieces to both sides of the flat end so it didn't damage any metal parts.

There was flow through the entire water tube, but there also may be leakage along the line. Hard to tell, because the nozzle I shot up the water tube wasn't tight enough.

The impeller itself actually looked OK, but may as well replace it while I have it open. Likewise, the housing looked fine. The water tube grommet was very much shot, and the drive shaft is encrusted with black crud. Wonder what that was all about? The O-rings didn't look bad, but a few seemed a bit loose.Good thing I ordered the associated rubber parts.

Automotive tire Motor vehicle Automotive exterior Bicycle part Bumper


cleaned up parts:
Dead bolt Wood Material property Gas Household hardware


Other side cleaned up
Wheel Rim Circle Auto part Automotive tire


Impeller housing inside, brighter pic:

Automotive wheel system Circle Auto part Metal Machine

Old impeller:
Finger Thumb Bicycle part Tool Nail
 

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You will be installing a new impeller, grommet and o-ring, correct?
 

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Discussion Starter · #19 · (Edited)
Yes. And cleaning things up as best I can without additional dismantling above where I've already taken 'er apart.

I also plan to refresh the lower unit seals and gaskets, than filling the lower unit with fresh oil. That should be much easier with the lower unit already detached. And anti-seize on all bolts and screws that are not inherently lubricated is standard operating procedure.
 

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Discussion Starter · #20 · (Edited)
Well, I got the parts cleaned up, the lower unit filled, and the impeller changed; and as expected, dealt with some more things that came up, and she pumped water like a champ, but it was not easy, to say the least.

First cleaned up the metal parts, especially the water intake screen, which was really clogged and crusty. In fact, I think that was why she wasn’t pumping water very well, much more than the impeller or anything else. Figured CLR would do the trick, since the crud was evidently mostly lime and corrosion; and that proved very correct, got the parts really nice, much better than the previous pic. All passages were clear and surfaces clean and ready. Used a small bottle brush on the intake screen while turning it around; then oriented the screen where it was clearest, opposite the overlap.

Upon seeing just how bad of shape the plug washers for the lower unit were (the top had 2 beat up ones sandwiched together!), figured out those were probably why so much water got in the lower unit when checking 'er out, and decided to just change those washers, fill the lower unit, and see how things go. But having filled it while detached and more horizontal than vertical, ended up filling it with a bit too much oil, which I had to clean off. Note to self: keep the lower unit more vertical, however more difficult to contain the oil and get the plug screws in.

Then after replacing the worn out parts and impeller, reattaching the lower unit was a real bugger. Since the drive shaft came off in the lower unit, it was especially difficult to get the drive shaft key to align with the notch in the impeller and housing, however carefully I "eyeballed" it based on its position relative to the water tube. I was wondering if I’d even get it done at all, or perhaps have to take the drive shaft out at top. But kept at it. Then once I finally got it to go in, the shift rod missed the linkage, and I had to back the gearcase out a bit to get 'er in. But it eventually got done. Many lessons learned, next one won’t be so difficult. I hope.

Then I noticed the prop was very loose and a bit bent around the edges in a few spots, so I had to take care of those issues – and when taking the prop off the cotter pin broke! Pushing the broken piece through with an awl and hammer was easier than expected, so I got the prop out, filed and hammered the edges back into shape pretty well, lubed things up, tightened the prop to spec, put in a fresh cotter pin, and she was ready for a spin.

Or so I thought. I expected some difficulty starting, though she started right up after putting new plugs in when I checked ‘er out, because the gas wasn’t run out of the carb due to ‘er not pumping water. Just shut ‘er off, figuring I’d take a tough next start over a blown engine any day. But this was the mother of all tough starts, had to repeatedly remove the plugs and shoot increasingly liberal shots of carb cleaner in, typically getting a few coughs, but not getting the choke fast enough to get ‘er going. Having dealt with a real hard starting Merc I was thinking: “Bloody hell, here we go again.”

But eventually she got going and ran very smoothly, idled well in neutral and forward (didn't push my luck with reverse, which I never use anyway), pumping water like a champ, and the water remained cool. And started right up subsequent times, after the gunk had evidently been cleared from the carb. Now hoping the prop turns out alright on the water, having experienced a run of bad luck with spun props with my older 18 horse Evinrude, which is still awaiting a prop rebuild, which may be awaiting once Lockeman’s reopens properly. No way to really tell in a bucket.

Pumping water like a champ!
Automotive tire Motor vehicle Automotive exterior Cookware and bakeware Gas


However, there was one remaining problem I couldn’t figure out, which I don't consider a "show stopper", by any means: I was unable to turn ‘er off using the throttle. She idled as far clockwise as the throttle would go, and the only way to shut ‘er down was running the gas out of the carb (which I did 3 times), or presumably with the choke, as when checking 'er out. Talk about kicking it old school! But as long as she runs well on the water and can troll slow enough I can live with that if there’s no easy fix such as an idle adjustment. The throttle was also a bit out of alignment, and I found the inner nut and bolt had come loose. So I got that straightened out, too.

So it looks like another one is ready to go, prop willing, maybe with a little tweak or three to go. Appreciate all the tips, everyone.
 
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