Debris in Manifolds

[C_Litt]

Hey guys, I'm new here and hoping someone can give me a little advice. I have a 1992 SN w/ PCM 351. I pulled the plugs on the stern ends of the manifolds, finding quite a bit of debris. I used a stiff wire to work it a bit then stuck my garden hose in the inlet side of the manifold to flush it out... I did this a handful of times on both manifolds and thought it was cleared out. While out on the water yesterday I removed the plugs again, only to find more of the same type of debris, it seems to be never ending. I did find a small chunk of what seemed to be rubber from the RWP impeller (which I have replaced). Most of the debris seems to be metal flakes, most of which is no larger than the diameter of a pencil eraser and up to 1/4" thick maybe.

What should I do next? Remove the risers? Replace the manifolds and/or risers? Or do I just continue doing what I've been doing until it runs clear out the manifolds?

Any help would be greatly appreciated!

Thanks!

[RideButter]

Those iron manifolds are going to shed a lot of metal flakes from heating and cooling, getting wet and drying off. It's not uncommon to find some old impeller piece bouncing around in one either. Unless they are leaking, I would leave them alone. Every winterization I pull the plugs and use a piece of wire to make sure the metal flakes are not blocking a drain and thats about it.

[C_Litt]

Ok great, that's what I was hoping to hear! Thanks for the quick response. So unless I'm having cooling problems... just leave it be?

[RideButter]

Yes, everything in your manifold is on the way out anyways so you shouldn't have any problems.

[C_Litt]

Great. Unless I have any issues, I'll leave it at that. Thanks for the advice!

[AirTool]

I've never seen the insides/compartments of these manifolds, is putting a water hose even to the inlet safe? ...I'm thinking you could back flush water/gunk into the cylinders.

[TRBenj]

I've never seen the insides/compartments of these manifolds, is putting a water hose even to the inlet safe? ...I'm thinking you could back flush water/gunk into the cylinders.

Think about that for a moment.

More advice: http://correctcraftfan.com/forum/for...s-in-manifolds

[C_Litt]

I was flushing it from the same end that the water enters the manifold from the t-stat housing... so I imagine that if it can enter from the hose while running, that flushing it with a garden hose would be no different... Hope so anyways.

[81nautique]

I've never seen the insides/compartments of these manifolds, is putting a water hose even to the inlet safe? ...I'm thinking you could back flush water/gunk into the cylinders.

Here you go.

[DanielC]

It is normal. The exhaust manifolds are the last place the water goes before it exits the engine, so you can probably get some rust flakes from the block also. The heavy rust flakes tend to work their way to the back lower end of the exhaust manifold, instead of going out the exhaust, with the cooling water.

If you are worried about water back flushing into the cylinders, remove the spark plugs after flushing the manifolds, crank the engine. Then put the plugs back in, and start the engine briefly.

If you remove the raw water pump belt, you can run the engine without having to supply water to it, for less than 30 seconds.

[AirTool]

[ATTACH=CONFIG]17397[/ATTACH]

Here you go.

That's a great pic. So the water meets the exhaust after the elbow as it enters the downward hose. I guess low chance of the hose overflowing the riser as long as the hose and outlet aren't blocked with a birds nest or a duct taped flapper. Or no crack or hole in the innards that would normally not allow flow with the engine running.

PS to all. Treated drinking water (e.g. "city water") has enough chlorine in it to promote corrosion and chloride problems. I worked on a pipeline project one time where the operator refused to use city water to flush and fill an oil pipeline for storage prior to operation due to chloride corrosion/cracking. They drilled a well to get untreated water. Now that anal.

I'm with the posts above or on CCfan, If it is not getting hot, don't mess with it.

[81nautique]

That's a great pic. So the water meets the exhaust after the elbow as it enters the downward hose. I guess low chance of the hose overflowing the riser as long as the hose and outlet aren't blocked with a birds nest or a duct taped flapper. Or no crack or hole in the innards that would normally not allow flow with the engine running.

PS to all. Treated drinking water (e.g. "city water") has enough chlorine in it to promote corrosion and chloride problems. I worked on a pipeline project one time where the operator refused to use city water to flush and fill an oil pipeline for storage prior to operation due to chloride corrosion/cracking. They drilled a well to get untreated water. Now that anal.

I'm with the posts above or on CCfan, If it is not getting hot, don't mess with it.

yes I think there would have to be a blockage of some sort for water to come back up the riser into the exhaust so flushing should not be a problem. That picture came from CCfan member waterdog during a good discussion on flow characteristics of different style exhaust manifolds. He had just replaced his with new and spent a good deal of time sawing the old one in half for us all.