4.3L V6 Alpha has been sitting for a while

[Caldacan]

So I picked up a 1999 Lund Tyee with a 4.3L EFI alpha One Gen II from a family member. The boat itself has likely been sitting for 4 years but possibly ran using ear muffs a few years ago. Overall the boat was rarely used and might have 60-70 hours on it total. Acknowledging that I was in for a bunch of work getting it ready and reliable again I have so far performed the following:

- replace exhaust and U-joint bellows - my first time working on a boat and it was quite the learning experience to say the least!
- checked engine alignment (dead on) while I was doing the bellows
- replaced impeller and chained drive oil
- drained gas tank
- replaced fuel filter

(I have new engine oil, filter, and plugs but plan to fire the engine up before changing those)

A couple of issues I ran into:

- upon pulling the drive I found rubber in the exhaust, which I immediately identified as an exhaust shutter. Upon pulling the rubber boots around the shutter in the Y-pipe I found that BOTH sides had failed and what was left was burnt to a crisp. This made me a bit concerned as I also noticed that a few hydraulic lines that were crossing the exhaust manifold had also partially melted to the manifolds (both sides). At first I figured impreller, so I went ahead and replaced that. New exhaust flappers will be here tomorrow.

- Just tonight I pulled all plugs and noticed that the port side middle plug had a bit of rust around the edge indicating that there could have been some moisture in the cylinder. Reading up on the exhaust flappers I discovered that I have the lovely Batwing exhaust manifolds that Mercruiser discontinued due to their **** poor design failing resulting in boats hydrolocking from water entering the cylinder (quality control issue on water jacket thickness). After reading about the issues with Batwings I immediately ordered the 2 piece conversion kit from MP. Unfortunately the new manifolds arn't going to be here until the 6th, and like everyone else, I'd sure like to have the boat for the weekend

Any thoughts on what my risks might be firing this thing up and maybe using it for the weekend? I have yet to fire up the boat, but as an initial precaution I squirted some 10w30 into each cylinder and will let it sit overnight and then spin the engine w/o plugs. Then reinstall the plugs, hook up some ears, and lite the match.

Could I get by with the Batwings for the weekend given my findings (I am not sure if the slight rust and remnants of hot manifolds are related to a failed manifold)? I am assuming they are still good with the low hours, but heck if I know. Boat is mint.

 

[Caldacan]

I did find Don's neat trick to use Acetone to check manifold leaks:
http://forums.iboats.com/forum/engi...-testing-exhaust-manifolds-for-leaks?t=288629

If I pull the manifolds, can I use regular Chevy 4.3 exhaust gaskets from the autoparts store?

 

[Bondo]

I did find Don's neat trick to use Acetone to check manifold leaks:
http://forums.iboats.com/forum/engin...leaks?t=288629

If I pull the manifolds, can I use regular Chevy 4.3 exhaust gaskets from the autoparts store?

Ayuh,.... Welcome Aboard,....Ya need a long one piece gasket,...
Most automotive are individual gaskets for each cylinder,....

As for runnin' the manifolds,.... It's Yer boat,... Roll the dice,....

 

[NHGuy]

Welcome to the forum!

I don't think you can expect to trust it this weekend til you have run it in the yard on muffs, changed the oil, and then taken a test ride.
Since it got so hot some of the bits melted, there's a chance that the inside of the drive could have other issues related to cooling water pumping. When you did the impeller did you find distortion in the impeller housing or the area below it? That part of the pump needs it"s shape to be correct or the pump won't pick up your water correctly. Also In the upper drive the water pocket cover can get distorted by heat too. So start it on muffs and see how it cools.

Heres' a tip for the exhaust install next week. If your manifolds are a hard reach or if you aren't super strong this can help. Or if you just want to do the job with less effort this way is good.
Get some long bolts the same thread pitch as the mani bolts and grind off their heads. Put two into the head, slide on the exhaust manifold gasket and then slide on the mani. Put in some real bolts partway, then remove the headless bolts and replace em with real ones.
You can remove the manifolds this way too, it avoids broken spark plugs and mashed fingers and toes.
You can use one piece Chevy exhaust manifold gaskets.
If there was only one plug with corrosion it could be from the valve on that cylinder being open during the layup. So there's a possibility the engine didn't get water in the exhaust. Testing the batwings will tell you more.

 

[Caldacan]

When I changed the impreller I didn't notice anything unusual in the housing. The impeller itself looked OK, but did have some cracking evident if you bent the fins as well as the slight imprints on the tips caused by the intake. It seemed to me like like the impeller would have cooled sufficiently.

I thought about changing the thermostat, but my understanding is that the water coming in can bypass the engine pump and the thermostat, which makes sense given the need to cool the manifolds prior to the engine heating up. I think that I'll pull the thermostat housing and see if it is clogged.

Thanks for the tip on the exhaust. I did see this elsewhere as well, and given the weight of these manifolds I can't imagine not using the guide bolts. Any idea if the manifold bolts are the same as the two piece riser bolts (3/8"-16)?

 

[NHGuy]

Maybe someone already fixed up what happened in the drive when it got hot, but didn't do the flappers. So give it a try.

 

[Caldacan]

I just finished up a compression test. How would you guys interpret the results?

Port side (bow to stern) 175, 93, 158
Starboard side (bow to stern) 180, 130, 176

Afterwards I shot some more oil into the 93 cylinder and it bumped up to 105
This was the cylinder where I saw some minor rusting on the spark plug.

Would this happen to be Cylinder #4? My apologies, I am not sure how the cylinders are number on this engine.
I seem to recall reading that the Batwings may fail in the middle first.

The engine is clearly not toast, but 93 was much lower than I had hoped....

 

[Rick Stephens]

Not as good numbers as one would hope. Probably best way to know exactly what happened is to do a pressure check with air and chase the leak down whether it is exhaust, intake or crankcase.

Mercury has a Service Bulletin on specifications for compression checks - http://www.boatfix.com/merc/Bullet/97/97_25.pdf

 

[flipbro]

You more then likely have a exhaust valve rusted and not seating properly.

 

[Volphin]

Best thing to do is to get that engine oil changed and fire her up. Run her for a couple of hours or three on the water and inspect from there.

 

[Caldacan]

Thanks for the help everyone!

Best thing to do is to get that engine oil changed and fire her up. Run her for a couple of hours or three on the water and inspect from there.

would you change the oil prior to firing it up? Looking at the oil it appears to be brand new so I'm guessing my relative changed the oil before putting it away. Maybe it was ran one or twice in ears but there is no discoloration at all. I was thinking about firing it up to get it warm and then change the oil.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... Why throw away fresh oil to replace it with fresh oil,..??

Get it goin', 'n see if that cylinder will come up,.....