NOTHING coming out of the exhaust manifold

[pdecker]

After solving ignition and fuel system problems, I'm getting the boat ready to go for this wonderful July 4th weekend. I started the engine, and no water is coming out of the exhaust, even after several minutes. I changed the impeller since I haven't done it in two years, and still no water out the back.

Craftily, I isolated each system. I confirmed that water comes up from the sea when I take the hose off the water pump input. I confirmed that the water pump is gushing water by taking off the hose from the water pump output. I took off the thermostat input hose, and ran a rod through and found some sludge that I cleared out. After reassembly, still no water out the back. I took off the hose after the thermostat, and verified plenty of gushing water. However, there is nothing, zip, nada coming out of the exhaust manifold when I take off the hose at the outlet. It was running fine the last time I ran the engine two weeks ago.

The engine is raw water cooled, and has never been flushed with muriatic acid that I now know I should have been doing. I think it is too late to try to flush the exhaust manifold while the manifold is still on the engine. I think my options now are to remove the manifold and have it professionally cleaned, or to install a new one from MMI for four boat dollars, plus.

I'm trying to get over the fact that my July 4th weekend plans are effed, but I'm glad I caught it at the dock and not the high seas. I've read the archived posts on this topic, but still have some questions:

- If I take the manifold off to be professionally cleaned, who does this stuff? I think I read about "a radiator shop." What type of business should I look for, really?

- Can I take it off, knock the nasties off by hand, and reinstall it in time to salvage my holiday weekend? Do I need a special gasket?

- For the price, is it simply more efficient to get a new MMI manifold?

As always, thank you for your advice.

Phil
S/V Catmandu
1982 Catalina 27
A4 Late model, RWC

[Marty Levenson]

water flow

When you removed the impellor were are the blades still in the pump chamber? Sounds possible one got pushed downstream?

It is not hard to take off the exhaust manifold (three nuts). You will possibly need a new gasket to reinstall, but that one goes on dry so may be reusable. Then you can just poke around with coat hangers, screwdrivers, compressed air and clean it out yourself. Totally doable unless it is toast.

Maybe replace in the fall depending on condition?

[hanleyclifford]

Not until you have made an attempt to clear the manifold coolant chamber. If you remove the two brass plugs it will be easy. Don't worry if you ruin the landings for the plugs - it's easy to tap the holes with 3/4" NPT tap and just use pipe plugs to close up.

[JOHN COOKSON]

If there is a 90* barb or elbow at the manifold water outlet end then this is the #1 suspect for the area of the blockage.
Remove whatever barb you have at the manifold water outlet and try reaming the water passage in the manifold with a wire and see if you can bust the blockage loose. You can do this with the manifold on the engine. I've heard of folks sucking KRAP out of the manifold with a shop vac - never have tried it myself.
After the 90* barb on my manifold water outlet plugged up the second time I went to a straight barb. No problems since.

TRUE GRIT

[Al Schober]

pd,
I've been into manifolds trying to clean them out. If they're clogged, they're clogged - even with the core plugs removed. I suspect you're going to find the manifold filled with something like limestone. You can go at it mechanically with assorted tools, or chemically with various acids. Perhaps you'll have better luck that I've had. Give it a shot - perhaps you'll get lucky! At least the effort will justify buying a new manifold - that will be good for another 40 years (longer if you go glycol cooling...).

[joe_db]

Try reverse flow - put a garden hose on the aft fitting and push the crap out the front.

[Mark Millbauer]

I had the same problem a number of years ago on a Catalina 27. With the engine and manifold intact, I attached a container to the boom and ran a hose from the container to the manifold and another hose out the exit of the manifold to a bucket. I poured muratuc acid (probably no more than a pint) into the container and let it sit. 15 minutes later it started working its way through the manifold and into the bucket. Once the container was emptied I poured another batch of acid into the container and it went straight through the manifold. Then ran some fresh water in for a rinse. The acid with the assistance of gravity worked great.
I had to move the boat that day and had no time and no gaskets. . if I had had more time I would not have attempted this method. If you do it this way take extreme caution.

Mark

[pdecker]

Fixed! Aft elbow clogged.

Thank you Captains Clifford and Cookson for saving my weekend! I removed the 90 degree elbows from the manifold. The aft one was blocked. I cleaned up both and then ran a wire into the holes as deep as I could. I reassembled, started the engine, and I got cooling water flow right away. I had a nice hour cruise yesterday and three hour cruise today.

While diagnosing the problem, I noticed the hose from the water pump to the engine was rotten on the pump end. I had enough spare hose to replace it, but I cannot remove the hose from the fitting on the starboard side of the engine. There is no hose clamp there, and there is a metal ring beyond the end of the hose next to the fitting. How do I get that hose off? I pulled hard and it would not budge. I had to cut off the rotten end and add a piece of new hose with a connector to connect the water pump.

[JOHN COOKSON]

There is no hose clamp there, and there is a metal ring beyond the end of the hose next to the fitting. How do I get that hose off? I pulled hard and it would not budge.

Don't pussy food around. Cut it away with a hack saw or dremel then get a proper barb in there.
The hose was probably rotten because nobody could figure out how to replace it.

TRUE GRIT

[tenders]

A box cutter works well to cut off old hoses.

The wire you're looking at may be the vestiges of an old "wire hose clamp," which is not what you want there:

http://image.made-in-china.com/43f34j00SjsEyFYIkQom/Single-Wire-Hose-Clamp-GR-SC922-.jpg

They're designed to be removed by pinching the parts that stick up with a pair of pliers, loosening the clamp - perhaps the "arms" of the one you have are twisted out of sight, or reach. They have no place on a boat - and really don't belong on lawnmowers, either.