Phazar454Mag

I have been lurking on this great forum for some time, and now I have a problem and would like some help please! I have a Doral Phazar 23 with a 454 magnum Bravo 1 with silent choice (365 HP) from 1989. The engine has a standard cooling system and has been running on a freshwater lake in Canada until 1996. It was then exported to Denmark by the previous owner and it ran in saltwater but was flushed after every use until 2000 when I bought the boat. I use it in brakish water (mixture of fresh and salt) and keep it in a marina and I do not flush the boat after use. It has been properly winterised by the best Mercruiser mechanic in Denmark every year. Now to the problem. I was out boating Wednesday and the engine ran great. Wanted to go boating today but when I tried to start, the starter could not crank the engine. Tried once more same result. I then got concerned that the engine was hydrolocked so I checked the oil. The oil level was above full (and I know that I did not overfill) but no sign of water. I then removed the sparkplugs and all the starboard plugs were wet. Port plugs were perfect. Cranked the engine and a lot of water splashed out. No matter how much I cranked the engine, water was still pouring out big time. I then removed the cooling hoses to the exhaust manifold and the elbow and removed the drain plugs. Water was still pouring out even after extensive cranking. Finally I drained all water from the engine and removed the belt to the seawater pump. After having cranked some time the water finally stopped. Refitted the sparkplugs and started the engine. Kept it running for a short while in order not to overheat and then shut it down. During all this I called the dealer and he insisted that I started the engine to get the valves lubricated. Where is the water coming from ? First I thought it would be the elbow or exhaust manifold but why did the water then keep pouring out after I removed the cooling hoses and drained the water using the drain plugs ? If it is a cracked cylinder head, or gasket or the block would it then be all 4 cylinders taking in water ?
Other items to look out for ? Thanks for your help.
Regards Brian

Fast Forward

Brian, Your story sound to familiar! Other than you were lucky enough to be able to turn yours over. I had the same thing happen last weekend myself, went out one day no problems at all, shut her down, the next day a nasty noise and hydrolocked with no warning. I'm tearing mine down this weekend to se what happened. I'll let you know what I find on mine. It to is a 454 mag.

offthefront

iTrader: (1)

I would guess manifold and or Risers ....how long has it been since they have been checked ....

Phazar454Mag

I don't know to be honest when the elbows and manifolds have been checked. I have asked the mechanic for 2 years when doing the winterisation to check the elbows, but he said they were fine and there is no need for disassembly.
I have just returned from the marina and started the engine again and it ran fine (still without the seawaterpump connected) and poured some oil through the carb for additional protection. Hope there is no damage to the engine because of this leak.
First thing I will do when the weather allows is to check the elbow/manifold.
Thanks.

Fast Forward

Phazar454mag, Sounds like we have the same problem other than you were much more lucky than myself. Just talked with a guy and was told that more than likely it was the riser gaskets based on the starboard side haveing water. He stated the gaskets had a recall some time ago due to this problem. If the gaskets are blue change them out. Matter of fact you should be able to see where they were leaking I would think. I',m hoping to take my down tomorrow and see what I can find.

Phazar454Mag

Pulled the elbow yesterday and the gasket was blue! The elbow and manifold appeared to be in fine condition at a first glance. But after having removed the old gasket and tried sanding the mating surfaces of the elbow and exhaust manifold it became clear that the mating surfaces have corroded too much to make a leak free connection again. So I have just removed the manifold too, and I am now considering my options. I called the dealer and he wants app. 1170 USD +sales tax (which is 25 % in Denmark) for 1 Mercruiser mainfold and elbow! This is crazy. I am going to check out prices in Germany and Sweden to see if it is cheaper. I can't wait for parts to arrive from the US if I order via the internet. The worst part is I still don't know if my engine has sustained any other damage during the hydrolock, even though it ran fine at idle. I wonder if the cylinderhead gasket or valves have been damaged ? I guess a compression check could give an indication ?

Fast Forward

Well I went down to the shop for the bad nad good news on my hydrlock. Bad news was on the starboard side there was water in all cylinders. The rear had a fair amount equal to a coffe cup. The others about a shot glass full. The port side was fine, which leads me to believe the riser gasket went. Only damage was 1 bent rod. All other rods, pistons and cylinders were near perfect. Also due to the exhaust flappers being burned out I ordered a new set of tips with the new stainless flappers. If all goes well I should in the water by Saturday. Not sure on the cost yet but looks like $1200 to 1500 should cover it.

Phazar454Mag

Bad news. Replaced the exhaust elbow and manifold today and did 4 oil changes to get the water out. After one of the oil changes I removed the plugs and cranked the engine, no water! Good news. But after the 4'th oil change tried to start the engine and hydro locked again! Couldn't believe it. Pulled the plugs and water in one of the cylinders. So I went from a lot of water in all 4 cylinders before the the exhaust elbow and manifold change, to just a little bit of water in one cylinder. Strange that I could see no sign of water during our oil warm up runs, then on the final run where I went on a longer trip and pushed the engine harder: hydrolock in cylinder number 4 after the run. I guess I need to pull the cylinder head to find out whether it has a crack, or may be the block is cracked ? Could it be just a leaking cylinderhead gasket that could cause this (probably wishful thinking) ?

Panther

Pull off the exhaust elbo and look for signs of a leak around the elbo and manifold. Even though you have new parts, the gasket may have leaked after everything warmed up. I've also seen new manifolds and elbo's machined wrong.

did you do a compression check?

Fast Forward

Panthers on the right track. I would think a compression check should show if you have a cracked head or block.