Author Topic: Time for a head gasket (Read 8924 times)

76bayflite · « **on:** September 15, 2013, 08:09:34 PM »

Started to disassemble the ole mercruiser today and naturally I took pictures to remember what it's supposed to look like. Got the cooling hoses, exhaust manifolds, and carburetor off. Next will be all the wires and etc bolted to the intake so I can take that off.

wiliermdb · « **Reply #1 on:** September 16, 2013, 06:59:47 AM »

Camera is your best friend in these rebuilds. A long time can pass between tear down and reassembly and those photos are priceless to remember where everything goes.

fireman24mn · « **Reply #2 on:** September 16, 2013, 09:19:24 AM »

I would pull the Lh or Port side head first. That seemed to be the one that was getting water into it when we were messing with the plugs. The very rear cylinder on that side. When you get it going again change the oil a bunch of times in a very short period. If there was water in there you want to get it all flushed out and should do it sooner that later. If water sits on the bearings over the winter that would not be good.

Jason · « **Reply #3 on:** September 16, 2013, 09:57:32 AM »

I would also take the heads into a machine shop. Have them at least checked to make sure they are not warped or cracked. Wouldn't hurt to have them pressure tested too. Some Napa's have machine shops that can do this.

catchnedge · « **Reply #4 on:** September 16, 2013, 01:12:14 PM »

Quote from: 74GlasCarlSS on September 16, 2013, 09:57:32 AM

I would also take the heads into a machine shop. Have them at least checked to make sure they are not warped or cracked. Wouldn't hurt to have them pressure tested too. Some Napa's have machine shops that can do this.

Amen to that! I know first hand that is a good idea.

CVX Fever · « **Reply #5 on:** September 16, 2013, 03:53:42 PM »

Sean sorry to hear you didn't even get one season out of it before you had to fix the motor.

76bayflite · « **Reply #6 on:** September 16, 2013, 08:34:18 PM »

On the plus side I'm getting pretty good at working on mercruisers. Think I still prefer outboards.

CVX Fever · « **Reply #7 on:** September 16, 2013, 09:13:46 PM »

if you have ever worked on a small block chevy this will be a piece of cake.

76bayflite · « **Reply #8 on:** October 16, 2013, 08:44:29 PM »

Got the intake and port side head off tonight, everything looks in order except for all the milky oil. Tomorrow I'll pull the other head and hopefully see a bad gasket, could the intake gasket be the cause of all the water getting in?

Rich_V174SS · « **Reply #9 on:** October 16, 2013, 08:49:10 PM »

Definitely. If the head gasket is bad water could leak into the cylinders and/or into the oil return galley which drains down into the oil pan.

Glastronjohn18 · « **Reply #10 on:** October 16, 2013, 09:42:30 PM »

Make sure you keep your pushrods and lifters in the order and cylinder they came from.

76bayflite · « **Reply #11 on:** October 18, 2013, 11:06:11 AM »

So the starboard cylinders were all full of water but the head gasket looked ok, does that mean a cracked head? Does that rule out the intake gasket being the issue?

Jason · « **Reply #12 on:** October 18, 2013, 11:22:37 AM »

Seems to me it could either be head gasket, intake gasket, cracked head, or warped head. Best thing you can do is bring in the heads to a machine shop have them pressure tested, checked for flatness, cracks, ect.

Rich_V174SS · « **Reply #13 on:** October 18, 2013, 11:32:16 AM »

If the head gasket looked ok the problem could be in the exhaust manifold or elbow joint. I just did a job for someone that was getting water in 6 of his 8 cylinders and that's where the problem was. I replaced the manifolds and elbows.

76bayflite · « **Reply #14 on:** October 18, 2013, 11:41:33 AM »

Do you know of a good place to take them Jason? I suppose there is a chance it's the exaust too. Too many variables here.

Jason · « **Reply #15 on:** October 18, 2013, 12:04:29 PM »

I guess exhaust manifolds could do that too. Actually, now that I think about it, I know my dad had that problem with a 4.3 Volvo. Basically hydrolocked the motor. Maybe the check valves got hung up???

Just about any machine shop can do the tests on the head. Some Napa's have a machine shop. Otherwise my buddy down in Inver Grove Heights can do it. http://sampsonracingengines.com/

fireman24mn · « **Reply #16 on:** October 18, 2013, 12:56:18 PM »

I would have the heads checked out. If I remember right didnt you get it pretty hot at one point? Could have just warped one of the heads.

76bayflite · « **Reply #17 on:** October 26, 2013, 08:51:45 PM »

Almost like Christmas today. Only other theory is I don't have the flapper in my Y-pipe, could water get in the engine from there? If so is there a solution that doesn't involve pulling the engine?

Rich_V174SS · « **Reply #18 on:** October 26, 2013, 09:22:35 PM »

You shouldn't have to pull the engine to replace Y-pipe flappers. If you have old log style manifolds you'll probably only need to pull the elbows off, for center rise manifolds you pull the rear downward facing elbow pipes out.

CVX Fever · « **Reply #19 on:** October 26, 2013, 10:24:40 PM »

He has the old style log manifolds. That drive system ran fine for the 3 years I had it in my CVX18 so I am a little suspect about the flappers missing. I do wonder if the motor is sitting low enough below the waterline of the boat that water could be pushing up and into the motor. The motor that came out of it had centerise manifolds w/standard risers.

Rich would log manifolds be more suseptable to something like that than the centerise manifolds or no difference. Just a thought, I could be way off base.