Another Riser/Cooling Question

[kwoolard]

This weekend I took my risers off to clean and inspect and to replace the gaskets. This is the first time since I have owned the boat, and of course out of the 12 bolts I had to remove, 8 of the heads broke off. <br /><br />Anyway, getting to the point of discussion. I noticed that the riser-to-manifold gasket did not have any holes in it. It was the block-off gasket, if that makes sense. And I was wondering if that is the right gasket to use for my application? The riser and manifold set up that I have is on page 38 of the following OSCO catalog.<br /><br /> OSCO Risers and Manifolds <br /><br />I have raw water standard cooling. And gasket number 10 on that web page is what I have installed currently. Is that what I should have, or should it be the open gasket? What is the difference for my engine?<br /><br />Engine is Ford 302/188 Mercruiser.

 

[Bondo]

Re: Another Riser/Cooling Question

I have raw water standard cooling.

Don't Start It !!!!!!!<br />Without holes, You're going to pump water Into your motor,<br />With Nowhere to Go...... <br /><br />It appears you Need gasket #8......

 

[kwoolard]

Re: Another Riser/Cooling Question

Bondo, the engine has been run with those block off gaskets for about three years. I know that the previous owner had an overheating problem, and I was wondering if it was due partially to the block off gasket. He never had any problem with water in the block though.<br /><br />I don't see how water could get pumped into the engine. It would seem like with the open gasket that some of the water being pumped into the exhaust manifold would go out over the riser into the exhaust and not get recirculated.

 

[kwoolard]

Re: Another Riser/Cooling Question

As you said Bondo, I also feel that the number 8 gasket is what I need. My opinion, I feel like the engine would run a little cooler since it would not be recirculating hot water.

 

[yoced]

Re: Another Riser/Cooling Question

Your setup could be completely correct in that it may be copying the OEM design.<br /><br />Chances are you motor used to have a log-style manifold with a bleed-hole stainless plate between the riser and manifold, running a three-hose system - all raw water. The setup was to run water into the manifold, back to the thermostat, then into the riser from the thermostat. The idea, i have been told, was to pre-warm the engine water.<br /><br />Whoever changed the system to a center riser design was trying to mimic the original (right or wrong) for ease of design - same hoses, same thermostat, etc.<br /><br />I would recommend calling Osco before you change gastkets, as you will also be changing your hose system and thermostat setup.

 

[Bondo]

Re: Another Riser/Cooling Question

Something is Not Right........<br />Water is picked up at the outdrive, by the Impeller,+ pumped into the engine........<br />Where does it Leave Your engine ???????<br />Either it's got to go through the manifold, up into the riser, to escape......<br />Or, There's Another hose going to the Risers.....<br />Your motor Must be different than the 1 I've got here, as it moves the water into the manifolds,+ up out thru the Risers........<br /><br />BTW,<br /> "I feel like the engine would run a little cooler since it would not be recirculating hot water. " <br />That's the Job of the T-stat.... You Have to be able to recurculate, Some........

 

[kwoolard]

Re: Another Riser/Cooling Question

The 888 Mercruisers originally had log style manifolds, according to my shop manual. Apparantly the previous owner switched over to the newer center rise style. <br /><br />The water flow on my system from the thermostat housing is as follows:<br /><br />water out of thermostat housing into the exhaust manifold, out the exhaust manifold into the thermostat housing, out the thermostat housing to the riser, out the riser - out the boat.<br /><br />That may be why there is a block off gasket between the riser and manifold. I didn't think to check back at the old design. Apparantly, as was stated earlier, he was trying to mimic the water flow from the log style to center riser style. Makes sense now. So I guess that I will need to stay with the block off gasket????

 

[yoced]

Re: Another Riser/Cooling Question

You can change the gasket, but you will need to buy a new (or rig the old) thermostat housing and re-route your hoses.<br /><br />I am sure you will run much cooler once you do that. It is only a matter of how much time and money you want to put into it.

 

[kwoolard]

Re: Another Riser/Cooling Question

If it will help me run cooler I would like to change over to the newer style. Where can I find a thermostat housing for a Ford 302 for the center riser style cooling??

 

[Bondo]

Re: Another Riser/Cooling Question

If it will help me run cooler

You haven't stated How Hot, you're running Now.......<br />Colder is Not Always Better........<br />Mercruiser Never ran center-riser manifolds on a Ford....<br />As Stated, You could probably Reroute the system you have Now,<br />But, If there's No Real Problem, Leave it Alone......

 

[yoced]

Re: Another Riser/Cooling Question

Roger That.

 

[kwoolard]

Re: Another Riser/Cooling Question

I haven't noticed a problem of it running hot...therefore I will take the advice of leaving it alone and just use the block off gasket. Do you guys recommend using a stainless steel plate between the riser and the manifold along with gaskets? I feel that will give the gasket support where water will be trying to push through the openings between the manifold and riser.<br /><br />Also, when I took the risers off I noticed a lot of rust collected in the riser. I was wondering what is the best solvent to use to clean the rust off? Acid...?

 

[Bondo]

Re: Another Riser/Cooling Question

using a stainless steel plate between the riser and the manifold along with gaskets

Was there 1 Before ?????<br />You Said, It ran Fine for 3 years......<br />

I noticed a lot of rust collected in the riser.

All that Rust,<br /> USED to be Cast Iron..........<br />That means they're getting Thin.......<br />Are you running in Saltwater ???????<br />Your Risers are in the Twilight of their Lives.....

 

[Ryoken]

Re: Another Riser/Cooling Question

muriatic acid... it'll knock another 6 months life off em.. if they're loaded up, just replace em... not worth losing a motor over...

 

[kwoolard]

Re: Another Riser/Cooling Question

No, the s/s plates were not one their before. Just thought about taking some precautionary measures. <br /><br />As for the corrosion, I know the manifolds will need replacing...I can peel layers of iron off from the exterior side and there may be enough corrosion on the inside which may be what is collecting in the risers.<br /><br />The risers look decent, a little rust dust but no sign of corrosion. Should I say the heck with it and replace the entire set?

 

[kwoolard]

Re: Another Riser/Cooling Question

A little grammar error! ......there before......

 

[yoced]

Re: Another Riser/Cooling Question

Don't worry about the stainless plates. <br /><br />If you check the risers and decide to change them as well as the manifolds you might try finding another style of manifold altogether. The CRR risers tend to clog up easily, which makes for a maintenance problem. Just something to think about for the future.

 

[kwoolard]

Re: Another Riser/Cooling Question

You mean other than center rise style all together? Is it just the OSCO brand style you say clog up or center riser styles in general? <br /><br />What recommendations do you have for manifolds...style, brand, etc?

 

[yoced]

Re: Another Riser/Cooling Question

I was talking specifically about the Osco brand CRR-1 and CRR-3 because that is what you have, but the comment can be made of many older (and the CRR risers among the oldest) center rise designs - especially in the 3" sizes: <br /> They are made with stainless steel tubes in the business end of the riser, and not much room between these tubes and the iron that the exhaust hose sits on. While they have plenty of flow as designed, any junk that enters the system has trouble leaving - think impellers, or, more appropriately to this conversation, the rust flakes like those you are seeing now.<br /><br />They can be cleaned out all right by removing the stainless sleeve, then pop-riveting a new one inside, but it is a bit of hassle.<br /> <br />Most of the newer designs, including most of the 4" risers out there, have a wider flow area, and junk has an easier time getting overboard.<br /><br />Not a real issue in life, and often not one at all. Just that if you have to make a purchase, there may be better options than that particular FLCR818 with CRR riser. Even the sales folk at Osco will try to sell the other styles unless circumstances dictate otherwise.