Oh boy do I have a doozie this time. 1988 Merc 260 5.7

[DJ Jaws]

Alright fellers, This one kinda freaked me out. I've never seen anything like this before though. As I posted last week, I have a 1988 Merc 5.7 that I'm in the process of rebuilding. Had a timing issue, got it fixed last week with some help from you guys, so here I am again.

I've been running it in short bursts, no more than 10 seconds at a time because the water jacket wasn't finished. It's on a pallet, so no worries about the water pump. Anyway, I closed it up and pulled it outside, hooked up the garden hose. Went to start it, she cranked about a half turn and locked solid. And by solid, I mean to the point that it split the bendix drive right in half, ripped the starter casing in two, bent both starter mount bolts, and basically completely destroyed the starter. Made a few phone calls through my tears, and I ended up pulling the spark plugs out. Port bank was fine, for the most part. STBD bank all cylinders were full to the gills with water. It eventually loosened up the motor, and I got all the water out. I don't think there was any major damage to the bottom end, but I wont know until I get a new starter. I still can't turn it on the front bolt, but it turns pretty easily with a crow bar on the flywheel.

My next plan is to take the STBD exhaust off and put the water back on. My idea is that this will determine if this is a broken exhaust or a broken head. Basically by removing the exhaust completely, if the cylinders fill up with water again, it's obviously a break in the head. I had the heads tested and they were ok, but that dosen't mean a leak didn't open up somehow. My brain is leaning toward an exhaust failure, but I think this will make sure. Obviously the two aren't mutually exclusive, it could be both.

I guess what I'm asking the group is if there's anything I should be looking for along the way as far as possible damage. Basically any advice would be helpful. This kinda spooked me as this motor just about jumped off the pallet.

 

[tpenfield]

Damage on a hydro-lock can include connecting rods and crank shaft. I would think that since the engine barely got moving, these may not be probable, just possible.

I would run a compression test once you get things back in order just to see if there are any signs of trouble.

 

[LX Kid]

Pull all the plugs and see if it turns. If it turns put the #1 piston at the TDC, on the compression stroke, and see if the timing marks line up correctly. If it does that will rule out timing chain/gear problem. Pull distributor cap and ensure the rotor is pointing to the #1 plug wire. If not the distributor may be off a tooth or two. If you had replaced the cam gear or had the chain off are you sure the timing marks were lined up correctly.

 

[alldodge]

Alright fellers, This one kinda freaked me out. I've never seen anything like this before though. As I posted last week, I have a 1988 Merc 5.7 that I'm in the process of rebuilding. Had a timing issue, got it fixed last week with some help from you guys, so here I am again.

I've been running it in short bursts, no more than 10 seconds at a time because the water jacket wasn't finished. It's on a pallet, so no worries about the water pump. Anyway, I closed it up and pulled it outside, hooked up the garden hose. Went to start it, she cranked about a half turn and locked solid. And by solid, I mean to the point that it split the bendix drive right in half, ripped the starter casing in two, bent both starter mount bolts, and basically completely destroyed the starter. Made a few phone calls through my tears, and I ended up pulling the spark plugs out. Port bank was fine, for the most part. STBD bank all cylinders were full to the gills with water. It eventually loosened up the motor, and I got all the water out. I don't think there was any major damage to the bottom end, but I wont know until I get a new starter. I still can't turn it on the front bolt, but it turns pretty easily with a crow bar on the flywheel.

My next plan is to take the STBD exhaust off and put the water back on. My idea is that this will determine if this is a broken exhaust or a broken head. Basically by removing the exhaust completely, if the cylinders fill up with water again, it's obviously a break in the head. I had the heads tested and they were ok, but that dosen't mean a leak didn't open up somehow. My brain is leaning toward an exhaust failure, but I think this will make sure. Obviously the two aren't mutually exclusive, it could be both.

I guess what I'm asking the group is if there's anything I should be looking for along the way as far as possible damage. Basically any advice would be helpful. This kinda spooked me as this motor just about jumped off the pallet.

You have something that is leaking water into the cylinders big time. Start with checking out the exhaust manifolds and elbows. If they check out go to the engine. With the plugs out you should be able to crank the engine from the front bolt, if not do some more checking

 

[Bt Doctur]

To have all of them with water would beg the question "Did you use the correct torque pattern"? Is there a head gasket in place?

 

[Volphin]

Your starboard manifold is dumping water. Replace them both.

 

[DJ Jaws]

To have all of them with water would beg the question "Did you use the correct torque pattern"? Is there a head gasket in place?

Yes sir.

 

[81 Checkmate]

Check on what AllDodge said........

 

[NHGuy]

Some new boaters don't get a good seal between the exhaust manifold and the riser. It's critical to get it perfect. Any problems and water can get in the exhaust tract, from there into cylinder(s). You need new gaskets each time the risers and manifolds are assembled. So if you find good parts take a look at the riser to manifold gasket, you are looking for a water track going toward the center where the dry exhaust gasses are supposed to be.

 

[DJ Jaws]

SO I was down there yesterday, only had a little time to play. I pulled both exhaust manifolds off and turned the water back on. I sealed up as much as I could, and it seemed to hold pressure fine. For as full as the cylinders were, a bad head would have caused water to be pouring out the cylinders with no spark plugs. I think the core of the engine is in tact, but I'm going to run a few more tests. I ordered a new starter, which should be in this week. My next test is to attempt to run it with water on and no exhaust to see if there is any mechanical damage. It was running before, so if everything else is ok, it should still run with no exhaust. I guess I have to save up for a new exhaust system.

Is there a way to test each component of the exhaust, or should I spend the $$$ and replace the entire system?

 

[NHGuy]

There's a write up in the stickies at the top of the forum on how to test exhaust. But more importantly, get the spark plugs out and get the water out of the combustion chambers. you can do it by turning the motor over dry, or if you don't have a starter yet blow out each plug hole til dry then use wd40 a couple of times. you want to dry and oil it so there's no risk of rust.