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Exhaust Manifolds and Risers Recommendations
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Author:  MCLKS [ Mon Sep 22, 2008 7:38 pm ]
Post subject:  Exhaust Manifolds and Risers Recommendations

Question: I currently have stock Volvo Penta's set-ups and now looking to replace my exhaust manifolds and risers. For those that have done this as part of a preventative maintenance program - which brand did you select and why (factory replacements, third party)?

Thanks!

Author:  aquamak [ Wed Sep 24, 2008 2:14 pm ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Replaced my manifolds and risers this past Spring on my 2000 268 Vista with the VP 5.7Gsi. I shopped around and was trying to get OEM Volvo Penta parts but the prices were too high. There are some OEM risers and manifolds on eBay but you have to be careful because you do not know what you are getting. Volvo has changed the part #'s so many times as they are trying to standardize all the manifolds and risers (according to my parts guy). Therfore, the current parts have all of the bells and whistles (sensor ports, etc.) and you pay for this whether your boat needs them or not. I did some research on the Internet and narrowed it down to 2 aftermarket brands, Osco and Barr (both made in USA-Lifetime Warranty). I read too many bad things about GLM (made in China-cheaper price). I went with Barr through Michigan Motorz as they had the best price on the entire kit (manifolds, risers, bolts & gaskets). I was going to get Osco (talk on the web claims they are better than Barr) but they did not have a specific port tapped out in the riser that I needed and they come un-painted. I called the factory about the port and they said it was not tapped on the riser. I asked them if I could have it tapped out on my own and they said I guess you could but it woulf void the warranty. Didn't want to chance it and I needed the port for one of the small coolant lines coming off my fuel pump. The Barr's have all the necessary ports and are painted (although after this season, I notice some rusty areas and probably should have repainted them with hi-temp engine paint. Something now for me to do during winter lay-up). Anyway, I replaced the risers and manifolds myself and it wasn't too bad. I got some good pointers off the web. If you are going to do them yourself, let me know and I will pass on the pointers. I can tell you that if my boat was newer and I could afford the VP parts, I would have used them. After 8 years (I've had the boat for 3), the risers and manifolds were in suprisingly good shape. The experst say that in saltwater after 5 years you are pushing it. A far as preventative maintanance, I have the factory installed flush kit and flush the engine after each use for the past 3 years. Good luck1

Author:  MCLKS [ Fri Sep 26, 2008 8:00 am ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Minnow,

Thanks!

Author:  Cap'n Morgan [ Fri Sep 26, 2008 8:25 am ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Good info to know aquamak. Thanks for the detailed info.

Who is minnow?

Author:  Guinnydog [ Sun Oct 05, 2008 5:29 pm ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

I just picked up a set of Osco manifolds for my 99 Sundowner w/5.7 and plan to install in the next couple of weeks. At this point, it looks fairly straight forward to do. They have all the ports and new brass fittings I need, but I did have to paint them. I have had the boat for the past 3 years and do run in salt water with FWC.

Aquamak, I am eager to hear about the pointers you aquired off the web.

One thing I have noticed is the factory manifolds are installed with bolts and the Osco's came with studs and nuts for the install.

Any info. would be greatly appreciated.

Rod

Author:  aquamak [ Sun Oct 05, 2008 8:30 pm ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Guinnydog:

I'm glad the Osco's worked out for you. Just curious, do you have the small coolant line coming from the fuel pump to the riser and if so was it tapped out from Osco? Anyway, the pointers I got off the web that worked for me are:

1. If you don't have one already, pick up a copy (buy or check your local library) of the SELOC manual for your year engine/drive. It has a good write-up on the removal and installation of the risers/manifolds as well as the torque specs.

1. Check your riser to manifold bolts and manifold to block bolts and see if you can get a turn on them to loosen them. If you can, half the battle is over. If they are corroded, soak them with PB Blaster or similiar and don't attempt anything until you can break the bolts free. If you snap off a bolt in the block, you have problems.

2. Obviously change the risers and manifolds when the boat is out off the water and drain the risers and manifolds from the brass drain plug on the back of each manifold.

3. In your case with the Osco's, the threaded studs with the bolts are designed to help with the installation (I'll explain later). You will use these to position the new manifolds on the block as the manifolds are heavy (I think something like 70 lbs. each). I would still pick up some threaded rod the same diameter/thread as the studs in order to aid in the manifold removal. Cut the rod 1-2 inches longer that the new studs. You'll need 2 of these along with 2 nuts.

4. I believe the Osco's are primed and ready for paint. I would touch up any bare areas with primer and then spray both the risers and manifolds with a good high-temperature engine paint (available at auto parts stores). Get the highest temperature paint available. Be sure the mating surfaces (riser to manifold and manifold to engine) on the new parts are FREE from paint and primer. If there was any primer on these surfaces, I would use acetone to remove it and the mask it off when painting. DO not use a razor blade to remaove any paint on these surfaces as it can nick the casting. Let the paint cure for a couple of days.

5. Once you are painted up and you know all your bolts are able to be removed, you can tackle the replacement. Give yourself a full day and take your time. Disconnect the round exhaust hoses on the backs of the risers (they are tough sometimes to break free. Try a little soapy water and be careful with using a screwdriver as you can puncture the rubber). Remove all of the coolant lines and anything else attached to the risers and manifolds.

6. Unbolt the risers and remove from the manifolds. Note the orientation of the existing gasket as you want to put the new one back the same way. Now unbolt the manifolds from the block. Replace the 2 end bolts with with the 2 threaded rods and put on the 2 nuts. This will hold the manifold in place as you remove the other bolts. Once you get all the bolts off, you may have to tap or gently pry the manifold off the block. Be careful not to damage the block/manifold mating surface. Once you have it free, remove the temporary nuts and slide the maniflod away from the block.

7. Thoroughly clean the old gasket off the block. Gasket remover and a gasket scraper from an auto parts store will help if it doesn't come off easily. Be very careful not to get anything into the exhaust ports when cleaning the gasket off!

8. Repeat for the other side. Once the manifolds are off, some recommend to replace the spark plugs as you know have easy access. Your call.

9. Hopefully the Osco's came with installation instructions which should recommend if any sealants are needed on the gaskets. There is alot of opinion out there. I used a gasket tack on the manifold to block gasket and a little smear of Permatex on the riser to manifold gasket. I also used Permatex on the brass fitting threads into the manifolds and risers. Any way, it looks like you can use the Osco studs to help position the manifold on the block and the tighten up the nuts. Get a good torque wrench and tighten the manifold to block nuts starting in the middle and working out to the ends. Once tight, now install the riser on the manifold. Gasket positioning is critical. Once the riser is on, tighten the bolts with a torque wrench. Reconnect everything back together the way it was. If you can, put the boat back in the water to test for leaks or run it out of the water with muffs. With the engine running, check for leaks. Run it until it is up to temperature and continue to check for leaks.

10. After you have run it to temperature and you have no leaks, check the torque on all of the bolts. You would be surprised that you may get 1/4 to 1/2 turn out of them. If you are going to use the boat, check the torque again after a couple of run cycles. If you are going to lay-up the boat for the winter, check the torque again in the spring. Even if you find a leak, usualy re-torquing will stop it and even if it doesn't, it is not the end of the world as it can usually be trace to a bad gasket.

Good luck!

Author:  Guinnydog [ Mon Oct 06, 2008 6:39 pm ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Aquamak, thanks for the list of pointers.

1. I already have the SELCO manual. I agree, good information on this and other procedures.
1. My biggest fear is getting the manifold bolts out without a problem. Snapped bolts "bad!".
4. I have already painted the manifolds.
8. I like your idea of changing out the spark plugs at this time. It will be done.
9. Supplied instructions state to clean all paint from gasket surfaces with lacquer thinner and to install gaskets "dry", no gasket sealer, silicone, or other compounds. Also says to avoid using thread sealant tapes or compounds which contain Teflon on brass fittings. To prevent studs from loosening, use red locking compound on threads that will seat in the casting.

I will also be doing the impeller.

Again, thanks for the tips,
Rod

Author:  woodnkerr [ Fri Mar 27, 2009 3:22 pm ]
Post subject:  Re: Exhaust Manifolds and Risers Recommendations

Aquamak, can you post the link you mentioned for replacing the exhaust manifolds?
Thanks

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