Verifying Water Supply-New to I/O

[Sunken Ship]

Just got this boat (2000 Larson 186) about a week ago, which needs a lot of work! Where to start...

Engine: 4.3GL 2000
I/O: Penta 3868893 SX-M 1.79

Hoping to try and crank it over in the next few days. Will grab some dual feed water muffs tomorrow.

Before I do though, I need to get water flowing. I can see there are two boots going to the outdrive, one upper and one lower. The lower boot is small in diameter and dry rotted quite badly. Is this smaller hose the intake or output for engine water? Is it correct that water goes in the series of holes where the muffs go on each side of the lower unit's case and then is supposed to come out the propeller?

Appreciate any info.

Happy boating. I hope to rejoin everyone later this season. I will be the guy sitting on a milk crate.

 

[spoilsofwar]

Look in your engine compartment, on the starboard side of the engine you may or may not see a hose running vertical, capped off with a blue hose fitting. If you have this, it is the engine flush port, and you attach a hose to the blue fitting and can run the engine off this without messing with muffs.

First, I would pull the impeller from the front of the engine and see if it's even worth trying to run on it or if it should just be replaced right off the bat.

 

[Sunken Ship]

Thanks for the suggestion...no flush port. I looked carefully, but I didn't see anything similar.

 

[skydiveD30571]

A 2000 model engine won't have the flush port as mentioned. That started around 2003.

The lower boot is the exhaust bellows. That's where water, after running through the engine block and exhaust system, exits the boat. The water will come out of the propeller and a couple other places including that boot (it is designed with holes in it to drain). The upper boot is the u-joint bellows, and obviously houses the drive shaft from the engine to the sx drive. It should remain dry. You'll see the water inlet tube on the port side running vertical next to both bellows.

Have you pulled the drive and inspected the drive and bellows? Do you have the owner's manual or service manuals?

 

[spoilsofwar]

Thanks for the suggestion...no flush port. I looked carefully, but I didn't see anything similar.

Yeah, I'm not sure when VP started putting the flush port on... No biggie, you'll just use muffs then. I would still pull the pump impeller and check it out first; easier to replace it outright then it is to try to flush broken fins back out of your cooling system.

I'm not sure if the two "boots" you're referencing are actually the driveshaft bellows and the exhaust bellows or something else. But yes, basically, water flows in those two inlets on the Outdrives lower where the muffs attach, up thru the drive and gimbal housing, and to the engine mounted raw water pump. You should see water exiting the drive via the exhaust (thru prop) and also underneath the drive at the relief port. I'm not tremendously familiar with the sx-m, having an sx-a myself, which is somewhat different.

 

[Maclin]

Regarding the bellows out back, the lower one is where the exhaust from the engine is routed. It is not "airtight" but has drain holes along the bottom, has nothing to do with cooling water getting up to the engine. It can be pretty ratty looking but sill be ok to run.

The upper bellows is the driveshaft and has to be sealed and intact to first keep water out of the boat and second to keep u-joints dry and tertiarily keep water out of the drive.

There is a smaller hose, like 3/4" ID, that routes from the middle of the drive on up thru the transom, you may be able to catch a glimpse of it. That feeds the raw water pump which on Volvos is up on the front of the engine, the impeller is easily serviced. On Mercs and others it is in the lower unit, not as easily serviced like yours.

Your boat engine cooling system has two pumps. The Raw Water pump which draws lake water in from the drive and makes it available to the Cooling system. The second is the engine's water circulating pump. In conjunction with the thermostat and water routing design it moves new cooling water made available by the Raw Water pump thru the engine at a specific rate needed to cool the engine. The Raw Water pump will always be (if in good condition) supplying a higher volume of cooling water than the engine can use. The "extra" plumbing on a Marine cooling system allows the excess water to bypass the engine and go on out the exhaust. The spent cooling water from the engine is mixed in as well and all goes out the exhaust. There are rubber connections from the Exhaust Manifold/Risers to the metal exhaust tube. Water has to be mixed in with the exhaust or those burn up in short order. That metal exhaust tube runs out thru the bottom of the transom thru the drive's exhaust.

The exhaust manifolds have two passages, the hot engine exhaust gases passage and the cooling water passage. On the top is a Riser, that is where the gases and spent cooling water and any bypassed water gets mixed and exists on out thru the exhaust.

The Riser joints should be quite a ways above the waterline in the boat to keep water from swooshing in from wave action. Don't worry about that now as not much you can do that the boat designer didn't already do, but it is good to keep in mind how all these components and systems work together to more or less keep the boat from sinking.

 

[Sunken Ship]

Thanks a ton for the education everyone! I guess it wouldn't hurt to test run with the lower boot being rotted in the driveway. Upper boot has some dry-rotting, but I did not observe tears. Will look for the 3/4 line next time I am out there. Have not pulled to drive yet.

I didn't get any manuals with the boat. I sure need to come up with some diagrams and parts lists though. Really need to get a grasp on everything I am working with. I did get a manual from Larson's website. Unfortunately, it is a rather generic "one size fits all" type.

Change in Plan:
- Engine is locked-up so plan has changed as far as cranking it. When I pulled the plugs water came flooding out of no.4 and oil came gushing out of No.5. Need to get engine out and torn down first. Where to find an A-frame....

 

[Sunken Ship]

I don't understand the cooling system on I/O boats as my title to this thread suggests. Wondering if there was something wrong with the cooling system that allowed no. 4 (only) to fill with water. On the opposite side no. 5 was full of engine oil. Confused? Can anyone explain probable cause for this? How could water seal inside 4 without running into the crankcase? The oil dipstick does not show anything is currently inside the engine.

 

[Maclin]

A cylinder is sealed with piston rings. It would take a long time for water to get past them into the crankcase.

Water gets into "the top of the engine", i.e. Cylinders, thru open valves. Water can show up at the valves when one of the exhaust manifolds water passages has cracked due to improper draining before a cold spell (usually about 2 months before the For Sale sign shows up in the window). The cooling water that goes out the exhaust when it is running stops moving when the engine shuts off. If water can breach from the cooling passage into the exhaust passage in the exhaust manifold then it will run into any cylinders on that side that the exhaust valve is open. Which one or ones just depends on what cam lobes are lifting the valves.

When a cylinder gets enough water in it while shut down then the engine will hydrolock and act like it is siezed. Water does not want to be compressed and the cylinder cannot move up towards the head on the next compression stroke.

Engine oil in the cylinder, well, that is bad, unless someone before you tried pouring some mystery oil thru the spark plug hole trying to Un-sieze it or something and left it in there and put the plug back in when that did not work.

When was the last time it was run? Has there been a freeze since then? Do you know any history on that honn-yock?

 

[Sunken Ship]

Thanks Maclin. Not sure how water could not leak down past the rings though over time. I could speculate with what I have learned on the history of the vessel, but it would not be much more than that. I would bet-not much though- it has a cracked manifold on the SB side. I would guess it has been sitting around two years approximately. Maybe even longer. I think the water has been in the cylinder for some time and has likely frozen several times since. But, the water got in there someway...like a busted manifold as suggested.

 

[Maclin]

I began to realize later after reading more of your posts that you did not expect much from the engine! It definitely had nobody that knew how to take care of it. From the other posts it appears you are on a good path now. Continued good luck to you