Exhaust gasket questions

V

VTBoater

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Hey guys,
I am into a complete exhaust manifold, riser, and elbow replacement job on my 88 Crusader 454. It is my first experience at this. Not going too badly, except for I made a mistake last night and put the first riser on with the gasket in the wrong orientation, so now I need another.
Did not realize it until going to put an elbow on and see only one slot in the gasket.
Question - I believe after a little searching the riser gasket is installed tab down, and the elbow is the 2 tabs up, is that correct?
I don't understand the concept of why both the riser and elbow have 4 slots machined, yet the gaskets block off some and why they rely on a gasket to redirect any flow.
???
 
Ensure that you have the correct gaskets for the application. The gasket is the key component for ensuring that the water flow is correct. There are some gaskets that block the flow between the exhaust manifold and the riser that are used in a "fresh water cooled" configuration. there are gaskets that have two slots with the other sides having small holes or none.

Again it is CTITICAL that the correct manifold/riser gasket is used and installed in the correct orientation.

Preparing to start my manifold and riser replacements tomorrow. Good luck!
 
I did not realize that I might need the blocker stainless plate, mine is set up to be a full anti freeze cooled manifold and block. I will knock apart my old riser from the manifold and see if it is blocked.
 
quote:
Originally posted by VTBoater

I did not realize that I might need the blocker stainless plate, mine is set up to be a full anti freeze cooled manifold and block. I will knock apart my old riser from the manifold and see if it is blocked.

Click to expand...

If it's fresh water cooled, you need the blocking plate. Don't ask how I know this...;-)
 
Thanks for the quick reply, I was able to cancel my order of a new gasket and got 4 gaskets and 2 blocking plates...
Must be you lost a bunch of antifreeze into the drink?
 
quote:
Originally posted by VTBoater

Thanks for the quick reply, I was able to cancel my order of a new gasket and got 4 gaskets and 2 blocking plates...
Must be you lost a bunch of antifreeze into the drink?

Click to expand...

Yup, not into the drink but internally...it will quickly flow coolant into your cylinders through an exhaust port. Went to crank over and it hydrolocked. I realized what was happening and called George from BF. He explained what I needed. This was quite some time ago. Live and learn!
 
Wow
It was pretty unclear in anything I looked at about it that this could happen. Everything written on forums I had seen to date said this was a clear cut diy job.
Glad I learned about this now before refilling the system.

Single hole gasket on the elbow still though? Placed upright at the water inlet tube?
 
Make sure you "deck" the cast iron mating surfaces. They may look flat when new but if you color them with marker then use a mill file you will immediately see how un-flat they are. The outer areas and bolt hole areas are usually proud which is not good. File until all marker is gone so pressure is even. OEM Crusader iron exhaust parts come with a slip saying decking must be done.

All new fasteners should also be used as the old ones have stretched. Torque new ones to ~~22-25??(check that figure) ft-lbs and I highly suggest re-torquing after just a few/several heat/cool-cycle runs, then about 1x a year.

Between decking and re-torquing , chances of eventual internal leak from water passages to exhaust hole at the gasket mating surfaces is substantially reduced,IMO.

The number of holes, if any, in your riser/elbow gaskets makes no difference if you have a full FWC system as you report, since you are using the SS block-off plates to separate FW coolant from RW.

( But, FWIW, on RWC applications I believe different configurations of gasket holes were often used to direct various preferred degree of RW flow to specific areas of the riser/elbow water passages, usually more toward the hotter top to help keep it cool enough . )
 
...If the SS block-off plate has a curved lip around the exhaust hole, be sure to have that lip edge oriented Up. It is there to help catch condensation and create a low pressure turbulance to recycle it into the exhaust flow.
 
Just came in from buttoning up the Boat, I have to disassemble the aft 1/3 to allow access to remove the manifolds and risers, mine is 100% Raw Water cooled. Glad that my comments triggered a you'll moment. Good luck on the project!
 
Thanks, you too.
Mine came off much more easily than expected, but were heavy and awkward as I took them out as a 3 piece assembly. Putting the new maniolds on was not too bad, the riser kits came with long studs with no head on them, perfect for holding and aligning while getting a few bolts in.
 
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