Trojan Boat Forum

Need some help guys. Can someone explain the exhaust gasket types and stainless block off plates on a fresh water cooled engine?

Why does it matter whether you you use a three hole or single hole gasket when connecting the riser to manifold when you are using a stainless steel block off plate that blocks off all 4 of the ports anyway???

my big question is what will happen if instead of using the single hole gasket between the riser and the elbow ,a three hole gasket was used?

I just put new 3 hole gaskets and stainless block off plates between the manifolds and risers. I had replaced the manifolds , risers and elbows just before pulling the boat from the fresh water of the upper Chesapeake bay and starting my renovation so everything is in really good shape so i never unbolted the risers from the elbows. while I was looking at the gasket schedule http://www.marinepartssource.com/crusad ... 07dp25.asp it looks like the three hole gaskets have a single "tab" and the one hole gaskets have "two" tabs.
one of my elbow/riser connections has a single tab gasket (three holes) instead of the single hole gasket. since I just spent over two hours scraping off the 4 gaskets from the risers I really didnt want to scrape gaskets off 8 gaskets unless it was absolutely necessary.

I'm guessing that the single hole up top allows the water to surround the exhaust and dissipate the heat better. dam it I think I just answered my own question! any suggestion on how to verify which gasket my dumbass put in when I originally bolted them together without taking them apart????

yorklyn wrote:

it looks like the three hole gaskets have a single "tab" and the one hole gaskets have "two" tabs.


I'm guessing that the single hole up top allows the water to surround the exhaust and dissipate the heat better. dam it I think I just answered my own question! any suggestion on how to verify which gasket my dumbass put in when I originally bolted them together without taking them apart????

Can you look and see the Tabs on the gaskets ? Should be sticking out .

This page explains proper placement. The water adapter (some applications) allows water to return to the heat exchanger.
http://bpi.ebasicpower.com/faq/faqcrusa ... xhaust.htm

See also
http://www.google.ca/url?sa=t&rct=j&q=& ... 3LleCKCpNw

I can only see the tab on one and its a single tab. I must have wore the others off when I sandblasted them to get them ready for paint.
I don't have the "water heater" fitting. It would be nice to have hot water any time the engines were warn but I just figured it would also be another maintenance item.

just ordered new "single hole gaskets" for the riser/elbow connection. I hate scraping off old gaskets !!
Would still love to know why they have three holes in the gaskets with the stainless block off plates? would thing solid gaskets with no holes would be a better choice?

Ok I really need some confirmation on this. I took two of my riser/ elbow assemblies apart today and sure enough they had the incorrect three hole gaskets . here's what i have a problem with. I find it hard to believe that with the water pump running at 3200 rpm , that substantial amount of water thats cooling the engine is susposed to be pumped through that single small hole and out the exhaust?
I was running with the incorrect gasket with no obvious issues for a year. I want it to be correct but a single hole gasket does not seem like a good choice??

incorrect three hole gasket


imagine all cooling water going through one of these holes?

At least this answers my question about the block off plate, either gasket can be used. i guess im just going to follow the instructions.
http://bpi.ebasicpower.com/faq/faqcrusa ... xhaust.htm

Todd,

I just sent you an email but figured I would post here for everyone else. I just pulled mine apart after five seasons. On mine, I did use the single hole gasket (2 ears) between the elbow and riser. That blocks all but the top hole. You're right, the gasket between the manifold and riser doesn't really matter since all the holes are blocked anyway.

Has everyone else done the same on 454's? Like your pic shows, it seems like it would make sense not to limit the flow to one hole but I can attest to it working fine that way. If anything, my engines run slightly on the cooler side with 160 degree thermostats.

Bob