454 crusader exhaust gaskets confusion?

I removed the exhaust system ( bothsides) on my 1985 454 crusader port side engine to have them boiledout because they was clogged solid. It was so bad that I couldn'tget the individual pieces apart so I took the whole assemblies (leftand right side) out in one section right up to the rubber hose that'sabout 4 inches long. If I had been able to get it all apart Iwouldn't be asking this because I would have noticed how the gasketswere situated and aligned. The rad shop that finally got it apart,didn't think to make a note of how the gaskets were placed. I founda diagram on line but it's pretty blurry. But it looks to me like itgoes as follows. Btw it appears from the diagrams, that I have theearly style of exhaust manifold and I have an 8 inch riser.
Ok so after the exhaust manifold -96108 3 hole gasket - 97295 water outlet adapter - 96108 3 holegasket - 97296 water block off stainless steel shim - 96108 3 holegasket - 97169 8 inch riser - 96562 one hole gasket - 97386 90 degreeelbow – Then that 4 inch rubber hose I mentioned and I believe thatnumber is 22221 and after that another cast elbow and then back tofour inch rubber hose and out into the ocean.
So one question is, since there are 4fresh water cooling passage openings on the exhaust casting and only3 passage holes on the 96108 gaskets, ( not really holes but morelike arched rectangular openings. If you google these part numbersyou'll see the gaskets and the cast exhaust sections.) whichhole/opening gets blocked off and why? What's the point? Should Iassume that it is the bottom one that is blocked off? It sort oflooks like it's that way from the blurry diagram. Next question is96562 gasket has only one passage hole. Should I assume that thehole or opening is on the top? Again it sort of looks like that inthe diagram.


Now I start applying logic and nothingmakes sense. Since there is the stainless steel water block off shimbetween the water outlet adapter and the 8 inch riser, and this shimdoesn't have any holes in it, why bother having any holes at all onthe gaskets on both sides of that SS shim? (It's apparent that theSS shim is separating the salt water system from the fresh watersystem.) Also I don't understand why there is only one hole/openingin the last gasket just before the last 90 degree elbow which is justbefore the rubber section? The 8 inch riser has 4 passages and sodoes the 90 degree elbow on the other side of that gasket that onlyhas one hole/opening. What's the point of only having onehole/opening in the gasket? I don't get it?? I don't evenunderstand why the other gaskets have only 3 holes/openings. Why not4? It's not like the chamber around the exhaust fume chamber areseparate individual chambers. It's all one external passage foreither salt or fresh water to flow though. So the more flow rate thebetter cooling right? So it just doesn't make any sense at all tohave anything less than 4 holes/openings in all the gaskets. Exceptthe two gaskets on either side of the SS shim and they shouldn't haveany holes/openings in them really.


I understand that the exhaust manifoldand the water outlet adapter are circulating fresh water in thepassages around the exhaust fumes. The fresh water enters at theforward end of the exhaust manifold by the one and a quarter inchhose, then travels through the outside passage, then goes into thewater outlet adapter and then from there it goes to the heatexchanger through a one and a quarter inch rubber hose? In aseparate system, (even though it looks like it's all one system), the8 inch riser is ejecting the warm salt water which comes in throughthe one and a quarter inch rubber hose from the heat exchanger, goingthrough the 8 inch riser via the external passage and then when thesalt water gets to the 90 degree elbow its blended and mixes with theexhaust fumes and is sent out the rubber exhaust system back into theocean?


One additional question. Do I reallyneed to use the dedicated gaskets? Can't I just make them out of thesame gasket material I got from the auto parts store that I used whenI made my thermostat housing gaskets?
Also I'm guessing that I would putabout 20 ft. lbs. torque on all the fastening bolts holding the exhaust sections together and about 25 ft. lbs. on the exhaust manifold boltsgoing into the block. Correct?
Thanks for any and all suggestions orfeedback.
Cheers

I removed the exhaust system ( bothsides) on my 1985 454 crusader port side engine to have them boiledout because they was clogged solid. It was so bad that I couldn'tget the individual pieces apart so I took the whole assemblies (leftand right side) out in one section right up to the rubber hose that'sabout 4 inches long.

Click to expand...

Ayuh,..... Boat exhaust is Replaced when it gets that bad,......

Not boiled out, 'n reused,.....

Yer gamblin' with yer motor,..... new exhaust pieces are relatively cheap compared to replacin' the motor,....

The cast iron carrying the raw water is what usually gets replaced - 4 to 6 years nominally....the cast iron carrying the coolant usually lasts the life of the engine as long as it is maintained correctly.

Regarding the gaskets, if you use the factory styled ones, you keep the 'tabs' up. the 3-holed gaskets go where the coolant flows, the single holes go where the raw water flows....at the block-off plates, it doesn't matter....

Thanks for your replies but I'd really like to focus on why there is restriction on the gaskets. If anyone is familiar with the parts you'll agree it's all one cavity or chamber of fresh or salt water depending on which section of the exhaust it is that flows around the inner exhaust fume cavity. So there is no need at all to not utilize the flow through those 4 holes/ slot passages. The only reason for the casting material to be between the holes/slot passages at the ends of the casting is to connect the outer wall with the inner wall. The biggest mystery is the one hole/slotted passage gasket. It's on the salt water circuit and the salt water has already done its job cooling the heat exchanger and it's about to exit the exhaust system. It makes sense to get rid of it as soon as possible and not restrict the flow and keep the exiting exhaust at a cooler temperature. Having one hole in the gasket as opposed to 4 holes/slotted passages, only slows down the flow and thus keeps the exiting exhaust warmer. Another way of making my point is why bother putting the holes/slotted passages in the casting at all if they're not being used.
Also it doesn't seem to me to be logical that there is restriction in the gaskets because if there wasn't, it would allow the fresh water coolant and salt water to flow too easily and thus make the engine run too cool. That theory doesn't seem to make any logical sense.

The one hole gasket between the riser and the elbow is used so that the cooling water is forced to fully fill the riser before being dumped out through the elbow. If you used a three hole (or even worse, a four hole) gasket there, the cooling water will take the path of least resistance and flow only through the lowest holes. The topmost portions of the riser and elbow would overheat with no cooling water there.

Thank you DJR. That's the kind of explanation I was looking for and it actually makes sense. So I'm guessing that it's sort of the same principle being applied with the 3 hole gasket and crusader closed off one passage way to restrict it enough to create a similar scenario?
So for the one hole gasket, between the riser and elbow, I should keep that hole at the top? For the 3 hole gasket between the exhaust manifold and the water outlet adapter, I'll keep the one blocked off hole at the bottom. Right?
So unless I hear different, I think I'll make my own gaskets with no holes to go either side of the SS shim.

on the closed side, you can use all four passages if you fell so inclined.....that side is different because it is pressurized.

Correct - keep the one passage gasket at the top, on the raw water side.

On the plate, you don't need any cooling passage holes...

I'm just a boat owner, not a mechanic, but I would really recommend using the OEM type gaskets on the exhaust system. If the gasket allows liquid to get past, it will make its way into the cylinders.

On the purchased gaskets, there are little ears that tell which gasket is which. You can tell even after the exhaust system is put back together. A single ear straight up is the three hole gasket (96108). Two ears oriented at 10:30 and 1:30 tell you it's the one hole gasket (96562).

The issue I have with the 96562 gasket is that it's pretty thin. Like about the thickness of a business card. The 96108 is about 1/16 of an inch thick and has a silver type look to it similar to a standard exhaust manifold gasket. The gasket material I used for the thermostat gasket I got from the auto parts store, is almost 1/16 thick. The logic side of my brain says use the auto store gasket before using the super thin 96562 gasket. Granted the 96562 gasket is by Sierra so it's aftermarket and maybe the OEM gasket was thicker. My other concern is the face of the castings is a little pitted in places. Not enough to set off an alarm bell which would make me replace the cast parts. But enough to make me think I should use RTV gasket goo. So I think I'd prefer a thicker gasket with that in mind. Any thoughts on my way of thinking?

I just checked my little stash of spare gaskets. They aren't as thick as I thought they were. I replaced my exhaust components with Barr parts two years ago. The gaskets they supply are made of material stamped "InterFace N-8094". Here is the data sheet for that gasket material:
http://www.interfacematerials.com/index.php/download_file/151/274/
It sounds like your way of thinking will be fine.

One last thing, based on information I found on this site, I didn't use any RTV on my gaskets. I think there is a concern of RTV blocking the coolant flow through the flange ports. I used Permatex 3 Aviation Sealant Liquid to attach the gaskets to the flanges.

I think I do remember seeing N-8094 stamped on the 3 hole gasket. But I don't have it right in front of me right now. I'm looking at one of the thin one hole gasket right now and it is interface TN-9005. I'm wondering if it would be a good or bad idea to double them up rather than make my own. For some reason about a dozen of the one hole gaskets came with the boat when I bought it, so I have lots to spare. Even doubled up, the 2 gaskets would still be thinner than the gasket material that I would use to make my own.
I'll pick up some of that Permatex 3 aviation Sealant liquid. Thanks for the advise.

How often should you replace coolant? on the closed system?