Hydrolocked Engine
- Thread starter mcarrigan
- Start date
Many moons ago I bought a '95 Bayliner with a Merc 4.3L that had water in it. Got it very cheap because everyone assumed it would need to be re-powered. (Water had been in the engine for several months and the oil looked like a milkshake.)
I pulled the plugs and turned it over long enough to get the water out, then hosed the cylinders down with sea foam, changed the engine oil and installed new plugs. She fired right up and I ran it hard for 2 years before I had to rebuild it. (Valve seat cracked, but I was already losing compression due to stuck rings at that point.)
I got lucky because I knew where the water was coming from and the seller didn't. He thought the block was cracked and/or head gasket was bad. I found the crack in the breather cover that was letting rainwater from the leaking boat cover drip right into the throat of the carb.
I agree with others that dieseling will cause water ingestion. However, so long as you didn't bash anything in the head while it was hydrolocked and the head gasket is still good, you may well be able to run that engine for several years more. The 4.3 is basically the 5.7 with 2 cylinders lopped off. And it's a tough engine.
Good luck!
Adam
I pulled the plugs and turned it over long enough to get the water out, then hosed the cylinders down with sea foam, changed the engine oil and installed new plugs. She fired right up and I ran it hard for 2 years before I had to rebuild it. (Valve seat cracked, but I was already losing compression due to stuck rings at that point.)
I got lucky because I knew where the water was coming from and the seller didn't. He thought the block was cracked and/or head gasket was bad. I found the crack in the breather cover that was letting rainwater from the leaking boat cover drip right into the throat of the carb.
I agree with others that dieseling will cause water ingestion. However, so long as you didn't bash anything in the head while it was hydrolocked and the head gasket is still good, you may well be able to run that engine for several years more. The 4.3 is basically the 5.7 with 2 cylinders lopped off. And it's a tough engine.
Good luck!
Adam
Carburetor looked clean but one thing I noticed that is different between the engines when I took off the flame arrestor. The flap at the top of the carburetor will fully close when I manually close it with my fingers (engine not running) on the problem engine. The flap only moves about 30 degrees on the other engine and will not come close to closing. Which is correct?
Charlie's suggestion was not meant to clean the carb. It was mean to help dislodge carbon deposits in the cylinders and on the heads. You wouldn't be able to see any of this build-up if it was present. Also, this needs to be done while the engine is running and up to normal operating temperature.
Regarding your question about the carb "flap", I'm assuming you are referring to the choke plate that covers the two primary bowls (the two forward ones)? If so, then when the engine is cold it should close almost completely. But once the thermostatic spring that it's connected to warms up, it should start to open up on it's own. In either case, you should be able to move it with your finger freely from the full open position to the nearly closed position. (Nearly closed will only have a small gap at the forward edge.) If one of your choke plates will only close 30%, it is not adjusted correctly. This may not be an issue if you never try to start that engine in very cold weather, however.
Adam
Regarding your question about the carb "flap", I'm assuming you are referring to the choke plate that covers the two primary bowls (the two forward ones)? If so, then when the engine is cold it should close almost completely. But once the thermostatic spring that it's connected to warms up, it should start to open up on it's own. In either case, you should be able to move it with your finger freely from the full open position to the nearly closed position. (Nearly closed will only have a small gap at the forward edge.) If one of your choke plates will only close 30%, it is not adjusted correctly. This may not be an issue if you never try to start that engine in very cold weather, however.
Adam
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Anytime you get water in an engine, esp enough that it hydrolocks or partially hydrolocks the engine I'd want to take the exhaust manifolds off and do some inspecting. Drain them first and remove the exhaust risers, and look down into the center exhaust gas passage. You want to see if there are rust trails running down from the top of the manifold sealing surface to the center exhaust gas passage. If so that is evidence that the joint between the riser and mani could have been leaking. Remove the manifolds and then they can be tested for leaks with acetone. Acetone will leak through a crack/tiny hole that water may not. Then if they are bad buy a new set. If not then have a machine shop re-surface the sealing surface of the manis and risers and re-assemble.
I had a similar issue with my old '88 OMC 4.3 last year. All of the sudden it started with rough running, not wanting to start, etc. It turned out to be a blown head gasket on both sides putting water in #2 cyl and a bit less in #1. I pickled the engine with a lot of fogging oil and that really helped. No rust in the cyl walls at all and this was salt water. I took it apart in the winter and an just finishing putting it back together. When I took off the old heads you could clearly see the blown HGs in that the sealing rings for the cyls were split. I took the heads to a machine shop and they felt I'd be better off with re-man heads. So put it back together with a pair of re-man heads and all new Fel Pro marine gaskets. Hopefully it will last a few more years......
Oh and it is possible to have close to normal comp test readings but still have a blown HG that can let water in the engine while its shut off. I tested this on mine rigging a way to see if there was combustion gas getting into the cooling water. Your more common HG blowing between cyls will give you a low reading on 2 adjacent cyls but this was a split along the sealing rings in several cyls. The engine would not hydro lock right away, it took a day or 2 of sitting with water still in the block.
I had a similar issue with my old '88 OMC 4.3 last year. All of the sudden it started with rough running, not wanting to start, etc. It turned out to be a blown head gasket on both sides putting water in #2 cyl and a bit less in #1. I pickled the engine with a lot of fogging oil and that really helped. No rust in the cyl walls at all and this was salt water. I took it apart in the winter and an just finishing putting it back together. When I took off the old heads you could clearly see the blown HGs in that the sealing rings for the cyls were split. I took the heads to a machine shop and they felt I'd be better off with re-man heads. So put it back together with a pair of re-man heads and all new Fel Pro marine gaskets. Hopefully it will last a few more years......
Oh and it is possible to have close to normal comp test readings but still have a blown HG that can let water in the engine while its shut off. I tested this on mine rigging a way to see if there was combustion gas getting into the cooling water. Your more common HG blowing between cyls will give you a low reading on 2 adjacent cyls but this was a split along the sealing rings in several cyls. The engine would not hydro lock right away, it took a day or 2 of sitting with water still in the block.