Volvo Penta Exhaust Manifolds Clogged!

[@Luigi-pk8mk]

I have the same exhaust on my OMC Cobra 4.3 V6, couple of suggestions: each bolt or fitting you put into the exhaust, coat the threads with OMC/Evinrude gasket sealer because it will keep the bolts/fittings from seizing in the cast iron. When removing fittings from the old exhaust elbows, heat the cast iron around it to get it to expand just enough to break the grip of the corrosion on the threads. When re-installing manifolds always use new gaskets, and take an exhaust manifold bolt to the hardware store. Buy 2 longer bolts, same thread pitch. Cut the heads off, and cut a slot into the stub for a screwdriver. Now you install these 2 in the block, with the side with the slot facing out, and next slide the gasket on. Then slide the manifold on. Now install the rest of the bolts. Last remove those 2 headless bolts using a screwdriver in the slot you made. Then install the last 2 bolts. This saves you having to juggle the gaskets and the heavy manifold. Same trick works on the exhaust elbow bolts. Just buy 2 longer ones, cut the heads off, cut a slot to remove them, helps keep the gasket and elbow lined up. Save the headless bolts for the next time you have to change them.

[@ShadetreeMechanic]

Great tip. I'll definitely use that in the future.

[@marcokemal]

Can you also share the cleaning process?

[@ShadetreeMechanic]

I used wd40, small wire brushes and compressed air to clean out the debris.

[@xDS420Gang]

Your not supposed to clean them!!!!! That isn’t good you can mess your motor up that way.

[@carlalm6100]

The useful service life of the manifolds can be further extended by sanding the sealing surfaces flat, giving new wider surfaces. The process is described on the left side of the manual/instruction that you showed in the video. The workshop manifold says to use 80 grit aluminum oxide paper or to mill the surface. I mounted abrasive paper onto a piece of glass and sanded manually. Where I live we have brackish water so my manifolds were not as corroded as the ones you got though.

[@ShadetreeMechanic]

What great information. Thank you for the comment!

[@Bushsniper308]

Interesting the instructions say not to use gasket sealer on the riser. I’m putting new manifolds and risers on mine at the moment and the instructions say explicitly to use sealant and even give example products and part numbers.

[@jticottage]

Can you do a video on winterizing process please? (That is if you live where you need to winterize)

[@ShadetreeMechanic]

I do live in area where I need to winterize. This fall I'll make a video.

[@badpete3497]

You did not show how you got the new/old engine side gasket on. Curious how it fit on. I just bought a 2004 boat with a 3 L penta. I'm going to pull the riser and inspect it before I decide I need a new one. No indications it's a problem yet!

[@ShadetreeMechanic]

I ended up reusing the old gasket. I used the bolts to help align it and high temp gasket maker as a precaution.

[@Luigi-pk8mk]

What I do is take the new bolts for the manifold to the head and elbow to the manifold to the hardware store & buy longer bolts same thread pitch 2 for each. Cut off the heads & cut a slot for a screwdriver in the stub. Thread 2 in the head, slide on gasket. Then slide on Ex manifold, install rest of the bolts. Remove the 2 longer ones using a screwdriver in the slot you cut. Install last 2 bolts then do the same for the elbow. This keeps everything aligned and you don’t have to to juggle the heavy manifold while trying to line up bolts & gaskets etc.

[@eagle5720]

Seems like you don't flush after you ran your boat in salt water.

[@ShadetreeMechanic]

For the first few years we owed it, we trailered it. I used to flush it after every use. Last three years, it's lived all summer at a marina in saltwater. I think that was definitely a contributing factor.

[@eagle5720]

@Shadetree Mechanic I just bought a set from summit racing for my new v8 that I'm putting together

[@drnandrean2767]

Hello Sir. How did the boat run with the manifolds after cleaning them inside? Did you had any leackages? The gasket was original ones? Also do you think i need to buy the new elbows and plugs? thanks a lot for your video!

[@ShadetreeMechanic]

The boat ran great for the vacation. I ordered new manifolds and they were delivered before I got home, so they old ones were only on for a week. I had new gaskets and it did not leak. I don't think you need new plugs, but definitely new elbows. Glad you found it helpful.

[@fabianoslack4269]

What you used to unclog that pipe that was carbonized?

[@ShadetreeMechanic]

Drill bit

[@RoronoaZoro-hd8rm]

hello can you really see through the pipes at the bottom part?

[@flexflow180]

Hi did you had to replace exhaust manifold Gaskets also?

[@ShadetreeMechanic]

I reused the engine side gaskets, but used new ones for the risers

[@flexflow180]

@@ShadetreeMechanic thanks im planning on doing the same.

[@ShadetreeMechanic]

@@flexflow180 good luck

[@raulgalvez2674]

I am in the same boat. What is the status of the repair?

[@ShadetreeMechanic]

All new parts were installed last year. No issues this year so far. Good luck.

[@rockerbigjoe5711]

Where did you buy them and how much were they?

[@ShadetreeMechanic]

Volvopentastore.com I think. They were $350 a peice.

[@walterhammond290]

Has that boat been used in saltwater?

[@ShadetreeMechanic]

Primarily in Salt water

[@roadjokers1119]

My boat driver side plug holes are filling with water gasket is fine everyone saying it’s a manifold?

[@ShadetreeMechanic]

Yes. The water jacket breaks down and you start getting water into the pistons. Not good!

[@roadjokers1119]

@@ShadetreeMechanic so how can i get all the water out ? I’m geting a new manifold tomorrow thank you for the reply man

[@ShadetreeMechanic]

@@roadjokers1119 pull all the spark plugs and turn the engine over. That should shoot out any water in there. Spray fogging oil into every cylinder Change the oil. New manifolds, gaskets and proably risers. Good luck!

[@gdebrango]

My mercruiser manual says to pull them apart and clean them with muriatic acid

[@codyhuffman4864]

Was the boat overheating before you changed everything?

[@ShadetreeMechanic]

The gauge was reading good, but the temperature sensors in the exhaust risers were going off at 3/4 throttle and up.

[@codyhuffman4864]

@@ShadetreeMechanic mine isn’t showing anything on the gauge so I hook up another one temporarily and it shows nothing I have a temp gun it shows it’s getting up to 200 I’ve replaced impeller recirculation pump and thermostat and it’s still showing its to hot. Could the manifolds be my problem?

[@rockerbigjoe5711]

Are you running your boat in saltwater?

[@ShadetreeMechanic]

Yes. It's docked at a marina in the Salt water all summer

[@xDS420Gang]

At least on 3208 elbows your not supposed to