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Mercruiser 5.0L riser & rister block gasket restricted and non-restricted?

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BackEastDon

Member
Screen Shot 03-26-20 at 06.18 PM.PNG

Did a quick look up using the serial number and noticed the exploded view shows restricted on the bottom between manifold and riser block and non-restricted on the top. Just checking that this is correct. Got the kits but forgot the top gasket. Just want to be sure to order the right thing.
 
Think I figured it out. Non restricted with a riser, both gaskets? I can cut the gaskets I got and order two more of the right ones if I have this correct.
 
depends upon which version/configuration you have.....when I worked in the shop, we put the full flow under the riser and the restricted flow under the elbow....on the RWC systems....
 
makomark said:
depends upon which version/configuration you have.....when I worked in the shop, we put the full flow under the riser and the restricted flow under the elbow....on the RWC systems....
Click to expand...

2nd that.

think of it this way,

You want as much cold water to go as high as possible and restrict at elbow.
DO NOT MODIFY the restricted gasket. Orient as shown in picture.
 
Thanks, was looking for confirmation as the diagram give both gaskets the same reference number and is a bit confusing. Probably would have figured it out once apart except my luck would be to have the wrong gaskets. I bought two full sets so could steal from the second and cut but will instead just order 4 of the non-restricted so I have a set for next time. Was replaced before I bought the boat two years ago. I want to repaint the riser block as the little bit of rust is bothering me everytime I look at it. At home for the next month, might as well get to all the little projects I've not had time for.
 
FWIW, the parts diagrams are not always accurate in the details of the individual components....they will reuse a drawing whenever it is 'close enough' to save a few bucks. I noticed the reference numbers were the same in your posted pic....they usually catch those errors but not always....
 
OK.... If you have a four hose system, one on each elbow and on the bottom of the exhaust manifold, you use a restrictor gasket between the elbow and spacer and an open gasket between the spacer and manifold.

If you have a two hose system, hose only attached to the bottom of the manifold all gaskets are non-restrictor type.
 
Docksidemarineservices said:
OK.... If you have a four hose system, one on each elbow and on the bottom of the exhaust manifold, you use a restrictor gasket between the elbow and spacer and an open gasket between the spacer and manifold.

If you have a two hose system, hose only attached to the bottom of the manifold all gaskets are non-restrictor type.
Click to expand...

Went out to double check as I've only ever noticed the two hoses below and confirmed it. I ordered 4 non-restrictor types this morning.

Thanks
 
Docksidemarineservices said:
OK.... If you have a four hose system, one on each elbow and on the bottom of the exhaust manifold, you use a restrictor gasket between the elbow and spacer and an open gasket between the spacer and manifold.

If you have a two hose system, hose only attached to the bottom of the manifold all gaskets are non-restrictor type.
Click to expand...

Took it apart and found the upper gasket was a restrictor type. The previous owner replaced them as part of the sale conditions.

One of the reasons I'm pulling these apart is that the riser was rusting. Nothing bad just surface. but now wondering. Surveyor didn't indicate any issues with temp when we did the sea trial. He used a thermal scanner while we spun the boat up to WOT a few times. This was the boat I had asked about with stuck valves a couple years ago. Motor has been running great but I just didn't like seeing the rust and wanted to clean up a few other things as I didn't like the way the previous owner left them. A little bit of OCD on my part I guess.
 
BackEastDon said:
Took it apart and found the upper gasket was a restrictor type. The previous owner replaced them as part of the sale conditions.

One of the reasons I'm pulling these apart is that the riser was rusting. Nothing bad just surface. but now wondering. Surveyor didn't indicate any issues with temp when we did the sea trial. He used a thermal scanner while we spun the boat up to WOT a few times. This was the boat I had asked about with stuck valves a couple years ago. Motor has been running great but I just didn't like seeing the rust and wanted to clean up a few other things as I didn't like the way the previous owner left them. A little bit of OCD on my part I guess.
Click to expand...

Two hose system has Non restricted gaskets. PN 863726
 
Docksidemarineservices said:
Two hose system has Non restricted gaskets. PN 863726
Click to expand...

Thanks Chris. My comment was just being curious about the paint on the riser block. I took it apart, cleaned it up and painted it with engine paint yesterday. I've got the non-restricted gaskets ordered but it would be easy enough to just cut out a couple restrictor gaskets. Wasn't having any issues with over heating but I didn't put a lot of hours and I've not been running it hard either. I'll pull off the other side and clean up the exhaust port surfaces then tape them off so I can clean up the engine bay.

Thanks everyone for the input.
 
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