Mercury Mark 5, Water Inlet Cap Assembly

[Steve Justice]

The Mark 5 Swivel Tube is conneted to the Crankcase as an assembly. Deep down in the attached swivel tube is the Water Inlet Cap Assembly with both the crankcase oil seal and the bushing / seal for the water inlet tube. I would like to replace both seals, but stumped on how to get at this. Anybody done this before?

Steve Justice

[frankr]

I’ve never done it, but I sure learned a lot of new cuss words while watching somebody else do it.

[Buccaneer]

I’ve done it on the Mark 6 / Silent Six. Presume it’s the same idea.
It was no fun, and required a torch, pipe wrench, big vise, etc.
Frank, I didn’t know you could hear me swearing 1500 miles away!

I “think” the job can be done without removing the swivel tube,
but I like to do things the hard way, lol.

Prepare to be boarded!

[dave-bernard]

A long Philips screwdriver.is the merc tool takes the assembly out. as said no need to remove the tube.

[Buccaneer]

If you don’t take the tube off, you may have to get creative
to clean the old gasket. Mine was a mess and stuck on the
bottom of the powerhead. I think that’s why I took the tube
off in the first place.

Prepare to be boarded!

[billw]

Assuming the screws don’t snap off, the gasket surface can be cleaned by grinding a sharp edge on the end of a steel bar and scraping it back and forth until the surface is clean enough, then vacuum, etc. This takes a lot of patience and time; but that is a standard requirement for the Mark 5 and Silent Six, in general. I like Mercs, but let me tell you, most of those engines are truly silent for a REASON.

Long live American manufacturing!

[jeff-register]

I’ve don a Mark 5 before & never again! Replaced the lower bearing too. That requires crankshaft removal & the bearing has a tight tolarance, for crankshaft end clearance. I didn’t remove the tube but had a fiber optic light sourse to see what  I was doing & a long 1/4″ extretion to tap the seal in. What a pain in the arse!!!

[frankr]

Add to all the grief, another small item around these parts:  Salt water.

[Steve Justice]

Thanks to all! I have a couple of approches here.  I did not look to me that the Pilot cap would come out of the swivel tube.  But learned that it can. No matter which way, Full on Open Heart  Surgery or Arthroscopic, I am in for a Mark 5 surgical session. I think I will delay until the next long Ohio winter to begin (not long a long wait).  Fun!

[billw]

If it helps any, they run really good when you’re done flogging them.

Long live American manufacturing!

[Author]

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