Running on muffs

[alldodge]

The hose you removed off the thermostat housing, take the garden hose and connect to that hose. The water should go freely back out the transom. If it flows good.

With the drive still OFF, connect the hose to the outlet port of the drive, and see if any water comes out the intake holes or the prop hub

 

[StealthQ5]

Thanks Rick - just took your advice, and ran the hose through the bell housing inlet. After it filled with water, it ran out of both relief ports like a wide open faucet, and a little also trickled out of the exhaust bellows. So this narrows it down to the drive - the water channel in the upper half and the pump itself, right?

 

[StealthQ5]

Just connected the hose to the drive outlet port - have water coming out of both inlet vents...

 

[StealthQ5]

This means the newly installed impeller is trashed, correct?

 

[StealthQ5]

One other thing - the Quicksilver kit that I bought to do this job (with housing, seals, etc.) had both the 3 gasket set and the steel gasket with overmolded rubber that was just like the one I removed. Although it may be unrelated, could that be an issue? I would think that the one-piece steel/rubber gasket would be the best of all...

 

[alldodge]

This means the newly installed impeller is trashed, correct?

Yep, its gone, but the good thing is your tube is not melted

Will let others discuss the gaskets

 

[StealthQ5]

With this comment I do thing there is a pump problem

Got to give you credit, AllDodge - you called this one on July 5th! I have learned a lot in the process, and that's a really good thing. Thanks to you and Rick for all of the help - it would have taken me a long time to get here without it. Having done the impeller change once, it's not that big of a deal having to do it again. But, this time I will be MUCH more careful...

 

[Rick Stephens]

Gasket on base, them metal plate, then housing gasket. Then impeller goes in housing offset to match hole for shaft. When you install it don't forget the key

 

[StealthQ5]

This has become a mystery. I just separated the drive halves, and the water tube was completely intact and sealing properly in the upper drive. I removed the shaft seal, and then the pump housing. The impeller looks great, and vanes are curved as they should be. The drive key was in place and lined up properly with the impeller.Impeller had been clearly in place on the drive key, too. The inner hub of the impeller was completely intact, and the impeller turns easily in the housing. The

only thing left (in my mind) is the one piece, rubber overmolded gasket I've also included a photo of the other gaskets I received: 1) thin steel "outline" gasket, 2) steel plate with cutout for water inlet, and paper gasket with bead of sealant. Could this be the issue? Mercury used the one-piece overmolded one, but perhaps that was found to be an issue, and should now be replaced by the 3 individual gaskets? If so, the instructions included with the kit are of no help. They say nothing about how the thin steel gasket should be installed (using Perfect Seal on the drive mounting surface, as some have said in other threads perhaps?).

I install all fasteners with electronic torque wrench to specified values, but I am really beginning to suspect that the single, rubber overmolded gasket is to blame, and that it leaks.

 

[alldodge]

I don't see how water will pour out the inlet ports with nothing leaking. If it dribbled out I can understand that. Guess we need an expert het achris and Bt Doctur any comment?

 

[StealthQ5]

I took the one-piece rubber overmolded gasket and laid it on my cast iron table saw top (flattest thing I have available), and it is not flat. It will rock a bit across one of the diagonals. That's an issue that torquing the 4 little pump hold-down capscrews may not be able to solve. Next, I did a trial installation of the 3 gasket system using alignment pins, and it is a VERY close fit, with no perceptible movement in any of the gaskets or the housing at all. I just don't know if the steel bottom gasket (not the plate) needs to be sealed to the drive mounting surface. In his video, achris has a paper gasket with a "tombstone" cutout, not the "outline" steel gasket I show in my photo above.

Since I chose to use the one-piece rubber overmolded gasket also included with the kit, and if it does not sit perfectly flush after torquing the pump screws, I suppose it could leak air in normal operation, leading to inefficient pumping, and also leak water when test pressurizing the drive outlet. This may be the source of the 180F temp vs 160F design temp that I was seeing last year when on the water. Also, when running on muffs days ago, I saw that 180F temperature. In part B of his videos, achris mentions that this can cause overheating.

If the one-piece rubber overmolded gasket can cause problems, why doesn't Mercury have a service bulletin out on this, telling people to discontinue use? (Maybe they do, but it is only for their dealer network - does anyone know?) I think I am like so many others who just want to do their own engine/drive maintenance, and not have to depend on dealers. I considered having someone do this a month before the 4th of July weekend, but all the local marinas quoted me times after the 4th, so I did it myself. Even bought my own sterndrive jack from Boatstands, because I will have to do this for my boat every three years. Just want to get it out on the water while it's still summer!

 

[achris]

When I did my video the steel plate gasket wasn't around. That is a new item. As you say, Merc only release TSBs to their dealers, they are not for 'public consumption'. The only reason we have access to them is community minded people 'leak' them.

I have since been using the steel gaskets and have not had any probblems with them. I have looked though this thread and can't see why you'd be getting the problemsd you're getting...

Sorry that's not much help..

Chris........

 

[StealthQ5]

Is the new steel gasket used in the same way as the previous paper base gasket, i.e., no sealant needed, just lay down the gaskets in order with the alignment pins?

Thanks Chris for all the effort to make your videos. They are far and away the best out there, and are enormously helpful!

 

[StealthQ5]

As an update, I talked with Mercury tech support, and they said that the steel gasket + stainless steel wear plate + flexible gasket with sealant bead is installed with no sealant. They are moving away from use of the one-piece stainless wear plate with overmolded rubber for the same problem that I was having (low exhaust water flow). Again, I found that my new one-piece was warped, which could potentially cause it to suck air. I'm sure that was happening in my case. I will flow the drive on muffs before reinstalling on the boat to check for leakage, anyway.

Merc support also said that it is OK to check operation after pump work on muffs at idle speed. There was an older service bulletin that said not to run at idle, but to run at 1300 rpm (just not to exceed 1500 rpm, because suction can collapse your water supply hose) so that there would be no chance of water ingestion at the engine. This may be old news to some, but may also have been confusing to others as it was for me.

 

[achris]

The issue with running at idle on muffs is a lack of exhaust back pressure, and with the overlap on the cam they pull water back into the cylinders. That was first identified by a dealer in Australia. The engine was one of the first of the vortec V6s with EFI (mid 1996). When the dealer did the first service they noticed water on the plugs on the starboard side. Initially it was suspected as tight valve guides, but after checking them they were ruled out. Fond du Lac's first response was to reprogram the ignition ECU for a later initial timing, but that didn't work either. After a lot of research the conclusion was reached that it was reversion due to lack of back pressure, and the solution was increase idle speed when on muffs. That works.

Chris. ...

 

[StealthQ5]

That is compelling reason to not run at idle (which I have been doing for the most part). It's just interesting that they would tell me today it's OK to run at idle with my 2013 engine. I guess the 2006 TSB should still be followed then., and run at ~1300 rpm...

 

[StealthQ5]

The TSB I referred to was actually Mercury Service Bulletin 99-9 "New Flushing Procedure for Alpha and Bravo Engines When Using a Flush Attachment on the Sterndrive" dated June 1999

 

[StealthQ5]

FINAL UPDATE: I assembled the pump again, using the (3) gaskets - thin steel large hole gasket, followed by the stainless steel wear plate, and then the flexible gasket that has the sealant bead on it. I used no perfect seal or any other sealant with them - just the gaskets. I reassembled the outdrive halves and filled it with oil. I then attached the Quicksilver muffs, turned on the water hose, started the engine and adjusted to about 1200 RPM. For the first time, I had full flow coming from both relief ports in the gimbal housing, along with a small trickle out the prop hub. I continued running until reaching about 165-170F and the temp remained steady. I took an IR measurement of about 155F at the thermostat housing. Clearly, the one-piece overmolded gasket was the problem, since that was the only thing I did differently this time. As laid out earlier in this thread, this problem can mimic a bad impeller. Hopefully this helps other that are considering use of the one-piece gasket - don't. I appreciate Merc tech support telling me that "they are moving away from use of that gasket", but in my opinion, they should make this information more readily available.

 

[achris]

Thanks for the update. Very happy to hear you have it fixed.

 

[StealthQ5]

Thank you achris, AllDodge, and Rick Stephens for all your support, and as a new member, I really appreciate this forum for these issues!