[ponci]

But they are small holes, aren't they? And you know what that means. Small holes normally become big holes, except when they're not supposed to, like in our riser here. Remember the case of the "disappearing water pump impeller blades"? Yes! Now you know where all those broken pieces of water pump impeller blades end up. They go completely through the system and stop right here at our risers to make our lives somewhat less than totally pleasant, and our bank accounts a little emptier. [links]

[Endemix]

Diesel exhaust pipes have to be huge because these engines won't tolerate any back pressure, which will burn up exhaust valves. The riser, which we can also call a water induction elbow, does just that; it injects salt water from the cooling system into the exhaust piping, which is hose or fiberglass, so that the exhaust doesn't burn it up. And because the pipe is very large, a special arrangement has to be made to ensure that the top part of the hose or pipe gets enough cooling water. Otherwise, the fiberglass, rubber or silicone parts will burn up. That's not good, so they put a lot of holes all around the induction section like in the photo below. This causes a spraying action that gets all areas properly cooled. [links]

[eugene2k]

Even worse though, if corrosion makes a hole between the water jacket and the exhaust chamber, then the cooling water can go down into the exhaust manifold, flood it, into the valves and then the cylinders. This is a very unfortunate state of affairs because it can wreck the engine. You don't want this to happen because it probably is not covered by insurance, meaning you pay. Of course, you cannot see that hole because it's on the inside. One day you go to start your engine and nothing happens. The starter clicks and clunks. Water has seized the engine up. On that day, there will be much wailing and gnashing of teeth.

[donaldmoreg]

An infrared thermometer gun, that is. This allows us to "scan" the system and find hotspots that will tell us where the blockage is. Actually, you can even feel around the exhaust hose (especially at idle) and if there are spots that burn your hands, you've located the problem because the hose should not be that hot. Consequently, the moral of the story here is that even diesel systems need to be checked out occasionally, just like we know we should do preventative maintenance on our car radiator but never do, waiting for it to crap out at the worst possible moment. But car radiators cost hundreds, while we're talking thousands here, folks. A little Priority Management 101a.02b7, section DXDCIIV, Title III is in order here. Under the heading. A stitch in time saves nine. [links]

[remyroy]

Both the iron and stainless versions are shown below, along with the obvious reasons why you want the one and not the other. [links]

[billm543]

Corrosion Failures All common gasoline engines use cast iron risers, as do most small auxiliary sail boat engines. Cast iron, of course, corrodes, and is a lousy material to make risers with. Problem is, there isn't anything better. At least not that you're willing to pay for. If you have extra $$, have them custom machined from titanium and you will solve the problem. That would set you back about $5,000 apiece, so in the meantime we're stuck with cast iron.

[freetx]

Found leak at rear pass side cylinder - at exhaust manifold between the manifold and cylinder head. Suspected gasket.

[taiki]

I have a 2011 Q7 with the 3.0 TDI the is exhibiting the same symptoms. more

[jimmyrdavenport]

Iam dutch so the technical terms are maybe not so accurate, but the symptoms you describe are linked to a leaking injector, probably the o-ring. here

[Shrother179]

Exhaust manifold 807078T10 is for use on the port or starboard (left or right) side of V-8 MerCruiser engines made by General Motors. It fits 454 or 502 cid engines (model year 1981 thru 2002) . Gasket included with the manifold. Can be used for freshwater or saltwater installations.

[bugmenot]

Cast iron exhaust manifolds w/o water rail, Port or Starboard
Fits: MCM/MIE 8.1L & 8.2L non‑EC engines

[r1chb]

Exhaust conversion kit 866178A02 converts exhaust manifolds with water rails to the newer style, cast iron manifolds without water rails. For use on 496 Magnum and 8.1S MerCruiser stern drive and inboard engines.

[aaaa]

Mercruiser OEM V8 SBC 305/5.0L and 350/5.7L Exhaust Manifold and Riser Kit w/out Spacer more

[soultcer]

Exhaust manifold 807078T08 is for use on the port or starboard (left or right) side of V-8 MerCruiser engines made by General Motors. It fits 454 or 502 cid engines (model year 1981 thru 2002) . Gasket included with the manifold. For freshwater installations. [links]

[nandu661]

Mercruiser OEM V8 BBC 454/7.4L and 502/8.2L Exhaust Manifold and Riser Kit w/ 6" Spacer

[merrydaily]

Performance Product Technologies is the leading online supplier of Mercury Marine Maintenance parts. This parts table contains links that will direct you to where you can buy Mercruiser Maintenance Parts. We specialize in working with customers looking to buy Mercruiser water pump impellers, thermostat housings, water pump rebuild kits, to starters, alternators, fuel pumps, gasket sets, etc. We also handle a wide variety of Mercury Outboard Maintenance Parts, Longblocks as well as complete drop in bobtail marine engines. Clicking on the links in the table to the left will open up a new window which displays the associated Mercury Mercruiser maintenance products chart showing the Mercury Maintenance product catalog. After locating the correct part for your specific application you can either click directly on the links provided with the specific part numbers, or you can take down the correct p/n and enter it into the search entry box located in the upper left hand side of the web page. NOTE: You will need to turn pop-up blockers off in order to view properly.

[Pyash555]

here

[Naniscegine]

[dfieldshorns84]

[links]