4.3 GL Penta Diagnostics - Water on Spark plugs

[Swift_Striker]

Hello Everyone,

I'm quite experienced in automotive engines and decided to take a step into marine engines to fix my father's Regal 1800 LSR with the Penta 4.3 GL.

The Background Information:
We have the boat stored at a marina for the winter and this time, before putting it away, they replaced the impeller claiming it was broken (The temperature gauge never hit the red zone when we were using it, though it ran a little warmer than usual). They ran a test on the engine and have no problems; great. Fast forward to this summer. The marina is getting our boat ready for us and give us some bad news. Supposedly the engine cranked over and would begin to run but it made an unsettling noise which led them to pull the spark plugs. They found water in 2 cylinders and decided to pull the heads. Upon pulling the heads they gave up, they had no ideas what could be wrong as the intake manifold, exhaust manifold, heads, and exhaust manifolds were all uncracked, undamaged, and not warped; According to them at least.

My Goal:
I aim to double check everything the marina checked and more. I think they missed something, or were too hasty to pull everything apart instead of running some diagnostic measures such as a compression test. I know I will soon have to put everything back together and run diagnostics but I don't want to waste gaskets so I'm learning what I can while the top end is apart.

What I've noticed so far:
Cylinder 5 definitely seems to have some sort of issue; the piston is cleaner than the other cylinders and looking at the intake port in the head for this cylinder I can see some foamy glycol (Maybe got in their when the marina took the engine apart or perhaps a crack in the intake/head. I'm not sure what the second cylinder with water in it could be, the rest don't seem to be an issue in terms of a visual inspection.

I spun the crankshaft and checked all the cylinder linings and did not find any cracks.

So much for no problems with the intake, found a bunch of rubber junk clogged up in one of the thermostat hose connections as shown in the picture (Does anybody know what this specific fitting's function is? it's on the exhaust side of the thermostat.

Hoping to check out the exhaust manifolds next... Does anybody have any leads I can work on? Any help would be greatly appreciated.

 

[Tail_Gunner]

The black debri are simply vanes broken off the water pump impeller, they can and will collect in all the choke points in the engine and exhaust system..nasty little bugger's they are...

 

[Tail_Gunner]

As to the water i would check the fuel supply for water..gas tank that is. Recently i had some water intrusion in my tank it took on almost 7 gallons luckily it seperates the water literally will lay on the bottom of the tank and your fuel pickup will suck pure water into the engine.

 

[callen369]

Just a shot in the dark....my father had multiple cylinders full of water after setting....his is a merc, but the issue I found was that the plastic cover for the carb/flame arrester had a few cracks from mechs overtightening it. His cover was worn, and allowing water to drip down inside, and found its way on top of it. The water seeped down the intake and eventually to the cylinders. When we tried to start it, it didn't even turn over. pulled a plug, and rusty water. Of course 7 more plugs later, no prob. Of course this didn't happen overnight, but after being stored for several months.

Otherwise, when were your exhaust manifolds replaced last? Those and the flaps will wear out and cause water ingestion.

 

[Swift_Striker]

Hmm some good starting points for some diagnostic work. Thank you al; I will keep this thread updated on what I find.

So far, I found this cooling schematic which indicates that the port that was blocked by the impeller bits is the water intake for the engine which is the first clear indicator of a starting failure point.

 

[Swift_Striker]

Well, I have checked over the exhaust manifolds visually and found no visible cracks so I will now take it to the next step of doing some pressurized testing.

I have developed a testing procedure which should be fairly comprehensive in testing for leaks. If anyone has any suggestions I'll incorporate them and return with the results.


- Buy flat aluminum for blocking coolant ports with silicone to create pressure and do leak tests.

Exhaust Manifold check
- Exhaust manifold rear plug
- Exhaust Manifold Block-off plate
- Bench test Exhaust Manifolds with compressor holding manifold in tub of water

Cylinder Check
- Install cylinder heads
- Leakdown test cylinders

Cylinder Heads Check
- Block Cylinder head coolant outlet port
- Buy fittings to connect garden hose to circulating pump with a shut-off valve
- Connect garden hose to engine
- Open valve and check for leaks at cylinder head

System Check
- Check Impeller
- Remove gas from fuel tank (may be water mixed in at pick-up).
- Get fresh fuel in tank
- Install intake manifold
- Install exhaust manifolds
- connect everything
- run water through engine with ear muffs and attempt a start.

I believe that this procedure should help me determine where/if any leak exists.