Once Again Looking For Help From The Pool Of Knowledge

[Slimcobra]

Everyone here has been great in helping me find answers to my questions and I am going to you all again with another noob question. I had to pull off a riser to replace my steering cable. Now that I am going back together I need to replace the gasket between the manifold and the riser and mine look different than in the diagrams I am finding. The gasket I have has holes on two sides of the gasket but the diagrams are showing the gasket with the long slot on all 4 sides. Could someone have replaced the gaskets in the past and put the wrong ones in? The boat is originally from NH and I'm wondering is the previous owner could have put on more restrictive gaskets due to cooler water temps in the north.

To make matters worse on some of the parts sites that I'm going to do not find my engine when I enter in my serial number. I took a couple of pics of the number and I'm wondering if I am not reading it right. To me it looks like 656968. What do you guys think? As long as I replace both side with the same type of gasket I should be alright, correct?

 

[dvx216]

Your type of cooling system determines this gasket . If in doubt go to a local marina and they will get you the right gasket.

 

[Strecker25]

That's an odd looking serial number. Where is that plate? I thought engine SN were usually on the top cowling.

like dvx said, it depends on the cooling system. You can usually figure it out based on how many and where the hoses from your tstat connect to the manifolds/risers but getting the correct parts diagram with the serial number will be best.

 

[Espos4]

The gaskets with the slot on each side are probably for the original “non dry joint” manifolds that may have come originally on your 2000 Sundeck in your signature.

They were probably replaced with “Dry joint” type manifolds at some point and that is the reason why you have that type of gasket on it now.

Can you post a picture of the risers?
Do they have a 90° curved tube like connection from the top of the manifold to the riser?
If so, that’s a dry joint manifold/riser set up.

mercurymarine.com has an online parts look up with nice diagrams.

 

[Sun Chaser]

It looks to me that your serial number has an "L" before it. See if you can check for parts using the part number L656965.

 

[OllieC]

+1 Espos4

 

[Slimcobra]

It looks to me that your serial number has an "L" before it. See if you can check for parts using the part number L656965.

Sun Chaser you were right about the L but I am getting results for L656968. I'll grab some more pics of it tonight and post them in the morning.

That's an odd looking serial number. Where is that plate? I thought engine SN were usually on the top cowling.

Strecker25 The number was on the plastic cover on top of the spark arrestor but it's fade off. The plate in the photo is on the side of the engine just above the starter. I can't even see it. I just stuck my phone down in there to get the shot.

Thanks again for the help!

 

[ttmott]

Mercruiser has two exhaust riser designs; dry and wet. You seem to have the superior design dry riser which has the water path holes away from the exhaust path. These designs extend the replacement intervals of the exhaust system. Look up your engine S/N on this web site and contact them; they have what you are looking for http://www.marineengine.com/parts/parts.html
As a note we looked for quite a while for 3 inch exhaust spacers on a 5.0 with nobody really able to cross-reference; we then contacted these guys and they knew exactly what was needed and offered several manufacturers and alternatives to the Mercury part as well as the OEM part. Recommended from our experience.

 

[Slimcobra]

Here are some engine pics.

 

[ttmott]

Nope you have the less desired water jacketed style. Still call marinengine.com they can help.
As a note many an engine have been terminated due to exhaust water leaks; corrosion being the culprit. You should consider changing the manifolds and risers if these are in salt water and greater than 3 or four years old or in fresh water and greater than 8 years old. Based on these pictures I'd get on with replacing.

 

[Slimcobra]

I dug around on both the riser and the manifold and they are solid. I wasn't getting any heavy flakes off.

 

[Slimcobra]

In the pic if you look at the hole in the top it appears that water has been on the gasket. Like water should be passing through but the flow was restricted due to the size of the hole in the gasket. The boat was originally from NH so could it bee that a restricted flow gasket was installed to help build engine temp in cooler water? I get 2 diagrams when I look this gasket up either equal length slots all the way around or holes on 2 sides that are off set. The holes in mine are not offset.

 

[ttmott]

Restricted flow riser gasket - used to maintain raw water backpressure in cooling system and to maintain exhaust system full of water

Full flow riser gasket - used for maximum raw water flow.

Dry Joint gasket - improved exhaust design; if replacing the exhaust manifolds and risers this is the best option.

 

[Slimcobra]

So I called Mercury yesterday. The tech I spoke to said my engine should have full gaskets. I described my gasket to him and he said that it was a knock off brand restricted flow gasket. He said he doesn't know why someone would have installed them but I should be using the full flow gaskets. Thanks for the help.

 

[Strecker25]

Yup, full flow. I found the same thing on ours and they were incorrect. Here's the bulletin for your records, also specifies the torque requirements.

Now that you've found that I would pull all of them apart and replace with the correct gaskets. That includes the gasket between the riser and manifold as well. I'd only go with OEM gaskets.