Water Pump Housing to Plate Sealant?

[JohnnyGuy]

Hi all,

I will be installing a water pump kit on my new-to-me 76 Johnson 15hp this weekend.
I've watched lots of videos and have done lots of reading.

So far I have come up with the following:

Water Pump Housing
3M 847
Water Pump Housing Plate
OMC Gasket Sealing Compound (I'll be using Permatex Form-A-Gastket No.3)
Lower End Unit

I work in construction and have a direct contact with an autoparts supplier. I for the life of me cannot find where to buy the 847 except for amazon and I don't want to spend $50+ dollars on a small tube of it.

I called my local OMC dealer and they don't have the 847 or "OMC Adhesive M".
I called another local marine repair shop (Mercury) and they said they use Loctite 518 for between the Housing and the Housing plate.

Does anyone have any opinions for an alternative?
Would Loctite 518 work? What about using the Gasket Sealing Compound instead.

One of the YouTube videos I watched, the guy used a very thin layer of RTV between the housing and the housing plate? With that being said I also watched many videos where the creator put nothing...
I'm not implying that either is correct.

I'm completely new to the wonderful world of Marine motors, any advice/direction would be greatly appreciated on how you would recommend I proceed.

 

[oldboat1]

My '89/'90 manual calls for some sealant on the mating surfaces. Think the Permatex should work fine -- Just a bit on the finger tip around the housing, along with the top and bottom of the plate. Avoid the impeller area.

It's a good idea to clean up the plate and the housing mating surface. I do it the same way as for resurfacing a head cover -- piece of wet/dry sandpaper on a flat surface, and move the piece around in figure 8 fashion.

 

[boobie]

What does your local OMC dealer use ??

 

[F_R]

That thing isn't rocket science. You should use some sort of sealant between the plate and gearcase, the locktite or permatex mentioned will be fine. I've serviced many thousands of similar motors and never used anything between the plate and pump housing unless they were designed to use a gasket or such (yours wasn't).

 

[JohnnyGuy]

Thanks all.

 

[yorab]

I bought a single tube of 847 at Fastenal for a reasonable price some years back.

 

[ronward]

I have serviced several older motors and have never used so much as a drop of RTV or permatex or anything else. I listen to Boobie, F-R, Joe Reeves and the like and have never gone wrong. They know what they're saying. As oldboat1 said, surfaces should be flat and mate up for best results but it is not a sealed unit as on a car.

 

[JohnnyGuy]

I have serviced several older motors and have never used so much as a drop of RTV or permatex or anything else. I listen to Boobie, F-R, Joe Reeves and the like and have never gone wrong. They know what they're saying. As oldboat1 said, surfaces should be flat and mate up for best results but it is not a sealed unit as on a car.

I dont know who those people are you're referring to.
No sealants anywhere?
I have read so many conflicting information.
I suppose I should fork out the money for the OEM service manual.

 

[JohnnyGuy]

I bought a single tube of 847 at Fastenal for a reasonable price some years back.

I did finally find it from my autoparts dealer... it had a completely different part number in his distributors system... 847-5OZ for anyone who may be looking in the future.

 

[ronward]

I dont know who those people are you're referring to.
No sealants anywhere?
I have read so many conflicting information.
I suppose I should fork out the money for the OEM service manual.

Now you're talkin... You can't go wrong with the OEM manual.

 

[F_R]

Just for the record, I just now looked at the 1976 OEM manual for your motor. It says to use sealer between the gearcase and plate. No mention of any between the plate and pump housing.

This brings up another point. Things change. If you go back to some older OEM manuals, they don't mention any sealer above or below the plate. The change was made in later years after they realized the importance of preventing air leaks on the intake side of the pump (below the plate). But they didn't recall all the older manuals. A service bulletin may have been issued to dealers. The dealer tech is expected to remain up to date in his knowledge.

 

[oldboat1]

Before commenting up in #2, I thought I should check and see if I had any OMC instructions. Best I came up with was the OMC service manual for '89/'90 9.9s. Regarding use of sealant, the manual saith, in pertinent part:

"Inspect the impeller, housing and plate for excessive wear."

"Clean the impeller plate and gearcase."

"Apply a thin bead of OMC Adhesive M to the machined surface, on the top of the gearcase that contacts the impeller plate. Slide the plate down over the crankshaft and position it."

"Apply a thin bead of OMC Adhesive M to the impeller housing mounting surface."

(Thus endeth the recitation of the sacred text.)

 

[Joe Reeves]

(Gasket Sealers)
(Usually available at any reliable automotive parts type store)
(J. Reeves)

Do Not use any type of sealer on outboard carburetor or intake manifold gaskets as this would cause blockage of various fuel/air passageways. Also, there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers! Older style head and fuel related gaskets that are not coated with this substance are to be simply coated with oil.... nothing else.

All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.

Marprox Sealer 1000 or OMC Adhesive or Boat Armor Sealer 1000 (same substance)[See Below Note] should be used on any metal to metal (Unless GelSeal Is Called For) or metal to plastic surface (such as impeller hsg to plate, and plate to lower unit surface) to eliminate air leaks. It should also be used on the Spaghetti tubing that is used on many powerhead crankcase halves, lower unit skegs, etc. I have found that this substance works quite well on various "O" Rings such as what are found on lower unit carrier and upper driveshaft bearing housings (Note that this substance is obviously not to be used on all "O" Rings). This substance also works quite well in sealing the surfaces between the lower unit and the exhaust housing to which it attaches, eliminating the unsightly water spray between the two after completing a water pump installation.

NOTE 1: I am under the impression that Marprox Sealer 1000 and Boat Armor Sealer 1000 is no longer available.

NOTE 2: OMC Adhesive is now Bombardier 3M Product #847 which may be listed as Scotch-grip 847, part number 776964.

DO NOT use any sealer on the large "O" Rings that are used on the upper and lower crankcase heads (The housing/heads that slide over the top and bottom of the crankshaft). On those "O" Rings, use only a coating of grease.

The exception of surface to surface contacts pertains to the later model matching crankcase (block) halves (which does not incorporate spaghetti tubing) which call for "Gel-Seal", or any other surface that calls for Gel-Seal. This substance seals in the absence of air, and if called for, must be used. One other form of Gel Seal that can be substituted is "Loctite #518". Nothing else that I know of will do!

I advise against using silicone or permatex on a outboard engine. It simply will not function properly. The exception to this (as per OMC's recommendation), is to use the black Permatex (heavily) on the gasket 306242 which seperates the inner exhaust tube from the exhaust housing on the 1959 35hp and 1960 to 1970 40hp OMC outboards.

 

[JohnnyGuy]

Well I did the job yesterday, before reading some of the more recent posts. Looks like they were posted whilst i was doing the work.

I didn't end up putting anything between the plate and the impeller housing. In hindsight maybe I should have? I have one week of fishing coming up in 2 weeks and then its going away for the winter. Maybe i will fix this over the winter.

Everything went smoothly.
I did a barrel test when complete and it had a nice spray going, much better than before.
The old impellers vanes were permanently "cupped" and the housing was the older style housing with 2 bolts longer than the other 2.

A couple of newbie things I did that were not right, are outlined below. Hopefully someone can learn from my errant steps.

First, I had the wrong torque values for the impeller housing. I had based them on some information from a general OMC service manual I had found online. The torque value I had gathered from the manual was 220in-lbs. I stopped torquing when the bolts were causing the housing to creak when tightening. I only got to thinking and concerned after I had put everything back together and barrel tested it. I started thinking that plastic parts do get brittle over time and I don't want the housing to crack in the future. So I pulled the LU and backed off the 4 bolts a bit and then torqued to 84in-lbs which is a value I had found on this forum for an 80s 9.9 I believe. The good news is that its much easier dropping the LU and putting it back up after you have done it once an hour prior.

Secondly. I stupidly pulled the drive shaft out to try and make it easier to clean the LU surface with some automotive sandpaper. When I saw the black gearcase oil and smelt it (damn that stuff is potent) I realized I should have left it alone. I put a little bit of the triple guard grease around the driveshaft seal where you slide it back in, then cleaned off the drive shaft and put it back in and assured it was seated properly. I hope this error doesn't open me up for potential gearcase water infiltration issues.

I obviously also did a gearcase oil change as it was quite dirty, this was a very easy job.

It was also obvious when I dropped the LU that the drain hole at the front cavity was plugged as it was full of water. I emptied it and was able to dislodge the obstruction with the hose and got it to drain freely. There was a little gunk in the cavity which I got out.

I also did some adjusting on the lean/rich mix and the idle speed and got it to idle noticeably smoother at lower idle which I hope will be a positive for trolling.

Anyways, hopefully someone in the future can learn from me and the other informative responses in this thread in the future.
Thanks for all your help thus far.

Cheers,
JG

 

[F_R]

You didn't cause any problem by pulling the shaft out. And, glad you changed that stinky oil.

 

[JohnnyGuy]

You didn't cause any problem by pulling the shaft out.

Thanks.

And ya, when I inspected the motor during purchase, the oil ran black so I knew it needed a change, but at least it wasn't milky.
I didn't notice a smell though when I'd loosened the lower oil screw enough for some to seep out...
But boy was it potently smelling stuff.

Do they all get like that or is it a sign that it had been a LONG time since being changed last?

 

[JohnnyGuy]

So this weekend I was getting the motor ready for winter storage (basement). When I went to change the LU oil it came out milky (thick)...
I have a water problem.

I know its a piece of mechanical equipment and it's hard to say what and when it happened, but It's weird that it leaked so suddenly.
When I purchased the motor the oil was black and stinky as per my posts above. Although it was dirty, it was black which would indicate no water infiltration, correct?

The only other things I did to it were change the waterpump, during which I pulled the driveshaft out (see previous post in this thread). I then used the boat for a week.

I then checked the LU oil (by unscrewing the drain plug until oil began to seep) prior to using the boat on another weekend and the oil appeared to be a golden yellow, like the new oil I'd previously put in. Then when changing this weekend it was milky.

I'm kind of hoping that maybe I didn't tighten up the drain plug enough. Or maybe the fact that I didn't use a new plastic seal could be the culprit, that's my hope anyway.

I suppose the pressure test will identify the culprit...
However if anyone has any other ideas, I'm all ears.

Cheers,
JG

 

[oldboat1]

Think you might be on the right track with the drain/vent plugs or gaskets. If holding off until next spring, just store it upright with fresh oil in the gearcase (a few newspapers underneath always a good idea in a clean basement or garage). If thinking of pressure testing -- pretty simple to do yourself (have to pull the l.u.).

 

[JohnnyGuy]

Think you might be on the right track with the drain/vent plugs or gaskets. If holding off until next spring, just store it upright with fresh oil in the gearcase (a few newspapers underneath always a good idea in a clean basement or garage). If thinking of pressure testing -- pretty simple to do yourself (have to pull the l.u.).

Thanks oldboat1.
She's currently hanging upright off the basement wall on a bracket I made for her with a little garbage back clamped to the cavitation plate. I left it open so that air can still circulate and I did store with fresh oil in the LU also.
I suppose I will periodically check the bag/skeg to examine for leaking oil.

Cheers.