Riser Gunk

The water passage in the exhaust manifold should have rusty water in it, not exhaust! I'd pull it off and look at the exhaust ports on the head. Check out the exhaust that I cut open and sent to Allen (81 nautique) it's in his blog under General "Torque & HP" on page 3 I just bumped it to the top of the page.

David,
Yes, on the H/M manifolds, the waterjacket is internally ported from the manifolds directly to and through the risers. At the very end of the risers is where the water is dumped into the exhaust.

I feel you should be taking a real close look at the condition of the manifolds and risers. They are noted for burn through problems. How's you oil? Any signs of water? When water enters the exhaust side of the manifold, sometimes you will get water back into the engine and then into the oil. Didn't you have a problem with this at one time or am I not remembering correctly??

I have not noticed any water in my engine oil. Just changed it and seemed OK.

There are two plugs. I pulled the ones closest to the front because they were easier to pull compared to the back ones. I drained earlier before Thanksgiving and water came out of both manifolds/risers.

Is there any problem pulling the risers off the manifolds? I assume I'll need to use a gasket sealer to reassemble?

Yes Gary, still have the HM's.

we wanted to take our risers off, but the back bolts dont have enough room for a socket head, or even a combination wrench. any ideas?? Its the pcm marinization.

vondy wrote: I have not noticed any water in my engine oil. Just changed it and seemed OK. There are two plugs. I pulled the ones closest to the front because they were easier to pull compared to the back ones. I drained earlier before Thanksgiving and water came out of both manifolds/risers. Is there any problem pulling the risers off the manifolds? I assume I'll need to use a gasket sealer to reassemble? Yes Gary, still have the HM's.

Vondy, Couple of points here. Yes the front ones drain the water jackets, the rears go through to the exhaust cavity and there's no reason to drain there unless there is a problem with water entering but you stated there isn't so I wouldn't even touch those back drains. Not sure why the backs drain holes are even there but I refitting one side to accept an air/fuel sensor for carb tuning later.

Second caution is if you are not having any leaking issues do not try to separate the risers, You'll be opening a can of worms. As Gary states you'll have to make your our gaskets but that is the least of your worries. I'm currently refurbishing a pair of HM's and they have been a nightmare every step of the way. First, took me forever and a lot of heat to get the nuts to move and three of them were previously rounded, no way to get any grip on them. Even if I could get the nuts off I still could not pry the riser off as there was so much corrosion in the riser through holes so I had to hacksaw them apart and then drive the old studs out with a drift.

Then had to drill out and retap the studs. Also we've found that these castings are incredibly brittle and when I removed the drain cocks most of the threads came with them. They just seems to want to keep falling apart, I had to use a few helicoils and also repair the threaded drain holes with aluminum braising rod then drill and retap.

I had no choice but to repair these as they were leaking but I would caution you about fooling with your set unless they have to come apart. They will certainly test your problem solving skills.

SNobsessed wrote: 74 SN - Mine had allen head screws, which were relatively easy to reach. Are yours hex head? Whoever put those on must have had a way to tighten them. A ground down open end maybe?

replace with allen head stainless steel once you gget the old ones out, but just use a good quality box end wrench, Snap-on, Matco, borrow one if you have too.

Craftsman seem to have a thicker wall due to cheaper metal I guess but I wouldn't try grinding down a onpen end wrench it will just flare and round off the head and you dead in the water then.

vondy wrote: The safe bet would be to not touch it. I'm all for that. Although I do recall a slow drip from this joint. Now that does not mean that the water jacket has a hole in it. It could simply be the gasket at the joint is failing. What do y'all think?

Unless you split the risers from the manifolds, you really can't tell what is causing the leak. It could be a gasket, a hole from corrosion or the mating surfaces corroded. Take a look at the picture of Alan's manifolds again. It's very typical of what you will find with aluminum. Lots of corrosion. It's like aluminum tie rims in snow/salt parts of the country - hard to keep air in them!!

jbear wrote: Sorry...thread jack... Pete; Where ya been? I was missin' ya. For a while there what with you gone I felt like the oldest guy on here. Glad you're back. john

John, I was up you northern Wisconsin for Christmas and New Years. I need my annual fill of lake activities when the water changes state to a solid! Drained and winterized the house and won't go back up again until the boats will enjoy the liquid water again.

I trusted you to keep the younger group here in line while I was gone!!

jbear wrote: Sounds cold up there... BTW: Only way to enjoy water in its solid state is in my Beam and Diet Coke. john

It only dropped below zero once so it was on the warm side!

You mentioning the cold and Coke reminded me that when talking to Billy the other day, I forgot to mention a little fact that I doubt he's every thought about (or anyone else in the south!). Outside soda vending machines in the north need to be heated in the winter!!!