Water in 318 starter motor

"1974 318 has been backfiring

"1974 318 has been backfiring at high revs under load. No backfire in neutral, even at high revs or under load below 1500 rpm.

Changed the gas, fuel filters, rebuilt the carburetor, adjusted the timing, no improvement.

NOW, the engine won't start. Removed starter motor and found the motor end full of water and rusty muck. Put on a working starter motor and engine cranks but won't turn over.

There is no sign of water in the crankcase oil, and random spark plugs that were checked, were dry. No sign of leaking at the frost plugs that are visible.

Does anybody know what's going on here? How can there be water in the starter, but not the crankcase? Does anyone have a diagram of the block configuration? Any suggestions would be appreciated. Thanks."

I once had a 318 starter get t

I once had a 318 starter get to that exact condition. It was outside on its skid (brand new engine!) and covered with a tarp. Apparently rainwater dripped on it and found its way into the housing.

Thanks. I guess the first thi

Thanks. I guess the first thing I'll look for after we rebuild the starter is water access to the engine compartment from above.

..."Put on a working start

..."Put on a working starter motor and engine cranks but won't turn over."

Confusing. Does it crank (meaning it's "turning over") or does it crank but not start?

Jeff

"The starter motor is trying t

"The starter motor is trying to turn it, but can't get things moving. So the starter 'cranks' but not the engine. We're thinking now that maybe something else got wet besides the original starter motor and is seized inside.

Others have suggested 'hydraulicing' so we're pulling out all plugs today and checking if the crankshaft will move with the plugs out and if any water comes out of the cylinders through the plug holes.

We're mostly just winging it, with very basic (and limited) mechanical aptitude, and advice from friends. I've seen a lot of expertise in the discussions here so we thought maybe somebody would know what was happening, or had some idea on what else to check. Thanks for any and all suggestions
Jayne"

"If The engine turns over afte

"If The engine turns over after removing the plugs, and warer shoots out, you have bad manifolds and risers. Spray transmission oil or wd 40 into the cylinders and turn the motor over to coat the walls and get any rust out. Before cranking it though, remove the coil wire, the arcing from the plug boots could cause any gas spraying out of the plug holes to ignite, (seen it happen). What probably happened was after the last time you shut down, water leaked into the cylinders through rotted out manifolds, and hydro locked the motor. If this is the case, replace manifolds and elbows and risers all at once. Hopefully not too much time has passed to cause any damage to the rings or cylinder walls. good luck."

Could a vacuum leak through ro

Could a vacuum leak through rotted manifolds account for the backfiring we were getting originally?

"There is no vacuum source on

"There is no vacuum source on the manifolds, the backfiring could have been a slight bit of water getting sucked into the cylinder(s) and causing the backfire. Then when you shut down, all the water in the manifolds leaked down into the motor. Did you check all the plugs? there should be some sign of rust on a couple of them. Best to remove them all and see if the motor turns over and if water shoots out. If it does then thats your problem. You would then have to remove the manifolds and risers. Look into the exhaust ports on the manifolds, if they have rust or actual water in them, they are shot. Even if one looks good, replace them all, they are probably the same age , and ready to go also. Goes for the risers also, they most likely are all plugged up and rotted out as well. Better to do it all at once than have to take everything apart all over because a riser failed."

"Thanks. We'll be checkin

"Thanks. We'll be checking all this out ASAP.

Looks like our boating season is over, and our winter project has been decided."

"If it is the manifolds and ri

"If it is the manifolds and risers, its not a big deal to replace, just some nuts and bolts and gaskets. It would take a couple of hours and you're back in buisiness. I just had the same problem, water in the cylinders. Thankfully it was just sitting a few days before I caught the problem. I got all the parts I needed from a site called boatfix.com, I looked all around, and these guys were the cheapest. Hope all goes well and you can get the rest of the season out of it."

"When we pulled the plugs and

"When we pulled the plugs and turned the engine over we had substantial amounts of water coming out of all 8 cylinders. Is it possible that both manifolds failed so catastrophically, simultaneously? Could water from the exhaust have been drawn backwards and distributed into cylinders through the exhaust ports? Are we looking at a different fix if that happened?

This is our third season with this boat, so we know that riser heights are OK and we always idle for a few minutes before shutdown.

Does this still sound like bad manifolds? We really hate to pull them off if it won't fix the problem. Many thanks for any thoughts."

"RE:"Could water from the

"RE:"Could water from the exhaust have been drawn backwards and distributed into cylinders through the exhaust ports? "
Yes, if the elbows/risers failed... Same fix, unless manifolds are in MINT condition, replace elbows/risers and manifolds.

Assuming this is a straight inboard installation and ifso, that the exhaust ports at the transom are above the water line????

Unless bolts retaining manifolds are rusted, removing manifolds not a tough job."

"Jayne:

If you chose to rep

"Jayne:

If you chose to replace the manifolds, get back to me FIRST. I can save you a bunch of expensive misery.

Jeff"

"If you have water in cylinder

"If you have water in cylinders on both sides, you have bad manifolds and or risers on both sides. If the old ones were installed at the same time, then its not uncommon for them to fail together since they are corroding at the same pace. Same thing happened to me, I replaced each side with all new parts, and I'm back in buisness."