Trojan Boat Forum

Started the motors yesterday and the port engine was making a popping noise. I pulled off the valve covers and found a broken push rod. One of the intake valves was rusted shut. Disconnected all the cables, wires and hoses so I can pull the motor tomorrow. If I can strip everything off by Tuesday I can have the heads rebuilt by the weekend. While I am waiting I will check the manifold, risers, etc. I will also clean the bilge under the motor. If anyone can think of other things to look at while the motor is hanging from the stand please let me know.

You should probably take a really good look at the fuel tank on that, if so equipped and the exhaust system,

Two more to add to the list, thanks.

Why pull the engine ? Thats a easy in boat job .

prowlersfish wrote:Why pull the engine ? Thats a easy in boat job .

x2

Rusty manifold bolts. Also, my yacht club has everything needed to pull the motor with ease, crane, work shop, motor stand, etc. All the bolts and cables came out/off easy. It's all disconnected and the engine should be out tomorrow and back in by early next week. I was not in the water yet anyway so I didn't have to haul the boat. I also want to check a possible leaking rear main seal. In the shop I can use an impact wrench and torches to remove the exhaust manifold. I know it seems like overkill, but with all the help available it will actually save time. With the condition of the exhaust bolts I would have spent days removing them, particularly the outboard bolts by the fuel tank. I plan on reusing the manifolds if they test OK.

Rusty valves sound like water in the fuel = bad. Did you have a fuel-water separator? Did you injest water at the end of the year?

Might consider upgrading to hardened stainless valves ... working great in my old 350 Corvette that was designed for lead (lubricates valves), but you'll also need heads with hardened valve seats.

I have separators and the fuel is clean. I won't be able to see what caused it to stick till I get the heads off this afternoon. Some quick internet research makes me think this is a common problem with big block GM's.

Sometimes it is not a bad idea to pull the valve covers and tap the rockers over the valves with a plastic mallet just to pop the valves that are closed ,especially if the engine has been sitting long and you are not sure if fogging oil was used---- curious why not just stick a new pushrod in if valve is loose now and not bent--I guess most of this advice is a bit late now--- if you are going to do the rear main--- have a look at the bearings,they are cheap and easy at this point---- oh and have a look at the cam lobe of the pushrod that bent or broke just to check for galling --- Mike

Mike thanks for the info. I tapped the stuck valve with a brass drift pin before doing anything and it was still frozen. I fogged the motor myself last year, as I have done for many years with no problems. Engine is out now and doesn't look like the rear main seal is leaking. I will check the cam when I remove the heads. I will also see if I can tell where the water came from. It looks like the riser was leaking down on to the exhaust manifold, but I don't think that would lead to a stuck intake valve. Total time for engine removal was about 3 hours including disconnecting everything. Cost was $50 to the club for the crane. I am not sure working on it in the boat would have been quicker, but my back will thank me later. I will remove the heads tomorrow and the shop said they should be back by the weekend.

Oh yeah, I have been taking pictures and will post them for everyone to comment on when I get a chance.

Okay, heads are off and at the machine shop. Water was in the middle two cylinders on one side and the middle cylinder closest to the rear on the other. What I noticed was there wasn't a metal block-off plate between the exhaust manifold and the riser, just one gasket. The gasket that was there had a metallic feel to it, but was saturated. Should there be a metal plate or is this something that's not needed anymore?

I don't know anything about these marine exhaust manifolds ,but hopefully the machine shop will pressure test the heads----- how can you tell if the water was there or could it be a result of pulling the heads off--- is there any pitting or rusting in the cylinders---- this info would help me as well to understand about the manifolds--- Mike

Sorry I meant signs of water, rust, pitting, dried salt built up in the exhaust manifold ports. They are going to magnaflux the heads to check for cracks. My engines are fresh water cooled, so the only way salt water could get in is thru the risers. The engine and the exhaust manifolds are cooled with anti-freeze. Here are some pictures of our yard equipment in action as well as some from the engine disassembly.







Here you can see that the joint between the manifold and the riser was leaking on the outside.

Yup now I see---- not hard to understand what happened when you see the pics---- must be nice to have access to the equipment to get that job done and done quickly---- good luck with it all,seems like you have a good handle on it---- Mike