New A4 owner needs some cooling system help

[breweraz]

Yesterday I launched my boat and was doing the in water engine checkouts before heading down to the mooring fields (previously,while on the hard, I replaced the oil, sparl plugs, impeller, points and etc.) She started right up and ran great. I ran her for about 2 hours to charge the batteries at a fast idle. Everything ran great with good water flow and cooling.

Returned today and she started right up but with very little water circulation and she started heating up. (I did leave the sea cock open overnight.)

I turned her off and check the all the valves and everything was good. I open the fresh water strainer it is full of black gunk like carbon pieces. (There is a hose that connects into the T just past the seacock that feeds into the intake line before the strainer.

I emptied the strainer. pulled the water pump and checked the impeller. All checked out. restarted the motor and same thing, Very little water flow and she started heating up in about 2 minutes. I check the strainer again and it had about 1 inch of balck carbon pieces in that short run.


Can someone please help as to what to do next.

Thanks

Tim

[hanleyclifford]

You didn't say whether you have fresh or raw water cooling, but in either case you have a blockage in a critical spot. The fact that you are getting gunk in the strainer indicates the engine is trying to clean itself and the bad stuff is moving. Keep doing what you are doing as long as you continue to get junk in the strainer.

[ndutton]

Originally Posted by breweraz

I turned her off and check the all the valves and everything was good. I open the fresh water strainer it is full of black gunk like carbon pieces. (There is a hose that connects into the T just past the seacock that feeds into the intake line before the strainer.

Confusing. Fresh water strainer? What does the other hose on the T connect to?

Clearly the black gunk is coming in ahead of the strainer. Deteriorated hose? Something in the water? Something to do with the other hose on the T? You might want to disconnect that other hose and cap off the T for testing. If the problem goes away, you found it.

I once had a brand new head that all of a sudden failed to draw water. It was my practice back then to leave the thru-hull open (bad practice I should add). I looked and looked for the problem. Finally I pulled the intake hose off the thru-hull with the seacock still open. No flow but there was the head of a fish stuck in there. Guess he tried to make it his new home.

[SeaFever]

Tim,

When you say you are getting black stuff in the water strainer, you mean the water strainer that is filtering the water coming from below the boat and going to the engine's water pump, correct? If yes, here are a couple of suggestions.

1. First, and in this I agree with Niel, block of the 'T' so the water is only coming from below the boat and nowhere else.
2. Close the thru' hull for the raw water intake and remove the hose from the thru' hull that goes to the strainer (here I am making an assumption on your hose connections in the raw water intake circuit).
3. Remove the hose from the water pump that is coming from the strainer
4. Now using a garden hose connected to the water at the dock, flush the complete section. Put the hose you disconnected from the thru' hull in a bucket and somehow attach the garden hose to the hose you dis-connectd tom the input of the water pump. What you are doing here is flushing that section in the reverse direction.
5. Again check and clean the water pump
6. Connect the garden hose to the thru' hull from where you disconnected the hose going the the strainer. Turn on the water in the hose SLOWLY and open the thru' hull (being alert to close the thru' hull if there is water coming in or leaking from the temporary joint into the boat). Here basically what you are doing is flushing the thru' hull and whatever items such as the scoop you have to take water IN for cooling.
By doing these steps you would have cleaned up the complete raw water input section
7. Now take a bucket and put the garden hose in there and fill it up say about half. Next reconnect the hose going from the strainer to the raw water pump. Now take the hose going from the strainer to the thru' hull and put the thru' hull end in the bucket of water. If it does not reach you may have to use another longer spare hose. By doing this you will be 'sucking' water from the bucket for cooling rather than the water below the boat. Note that when you start the engine you will have to turn on the water in the garden hose and regulate the flow so that there is sufficient amount of water all the time in the bucket. If flow is too less the bucket will empty and water pump/engine will run dry. If flow of water in the garden hose is more than that needed by the engine, water will overflow from the bucket in your boat...:-)
8. Turn on the engine making sure you regulate the flow of water in the bucket to keep it at a steady level. See if your engine works properly and no overheating occurs. If it overheats, you have a problem other than in the raw water input circuit. If it does not and engine runs fine, you had a problem in that circuit. Turn off the engine
9. If you determine there is a problem elsewhere, follow that lead
10. If engine runs fine, reconnect the hose from the strainer to the thru' hull and run the engine to check if it runs fine.

Sorry for the lengthy description and the steps. Hopefully it is clear and helps. Let me know if you have any questions.

[thatch]

Tim,
It would help tremendously if we had an accurate description of your cooling system type. Is it a one pump system or a two pump system?, ie. RWC or FWC. If you have a FWC type with a strainer on the engine side of the system it is possible that the new impeller created enough agitation to stir up some scale which has been sitting in the bottom of the block. This scale which does look like chunks of carbon could either be lodged in the "T" in the engine side plate or in the thermastat area. Since the thermastat housing is far easier to remove than the side plate that would be the first "major" piece I would remove. Back flushing, as describbed in the previous post, is normally the most effective way to clear out debree from cooling systems. The object is to clean the passages without removing the water jacket side plate if at all possible, (which can quickly turn into a major project). Acid flushing is also an option which might be in the cards.
Tom

[breweraz]

Thank you for all of the responses. She seems to be upluggedand and working.

Not being sure if it was on the intake side ofthe exit side I decided to start in the middle by removing the crossover U on the top front of the motor. I started the motor. The water pumped out of the block side. It was black and full of crud. I let the motor run until the water was clear. That told me the intake to that point was clear.

I then undid the hoses leading out of the by pass T and ran water from the hose back through the T and it exited the manifold side of the U with the same black crud. I let it run until it was clear.

I then ran water through the hose leading to the exhaust until clear water came out of the exhast at the transom.

I detached the hose from the water pump and ran water backward through the strainer out the seacock.

Al lot of crud came out of each area.

I attached everything and she has run good. I let her run for about 1 hour at varying the RPMs. There was some initial steam off the block but that cleared. There is still a little steam comining out the exhaust but I attribute that to 45 degree water and a 50 degree day.

Tomorrow it is off down the Penobscott river to the mooring field in Stockton Harbor. I will let you know how she runs.

Thanks again.

Tim

[thatch]

Breweraz,
Thank's for the update on your A4. Keep us informed about her condition.
Tom
P.S. I think we may have frieghtened her back to civility.