95 Mercruiser 4.3 water in oil

[Lou C]

What's interesting in your pix is that the water passages in the cyl heads have LESS rust than the intake ports, and your intake ports are a lot more rusted than my old ones were. So I'm still suspicious that it came in through the carb.

 

[poconojoe]

It is run off the camshaft. GM found that even after adding an even fire (split journal) crankshaft to the naturally unbalanced 90* V6 there were still vibrations so the balance shaft removed the rest of those. I think they were added in ‘95. Vortec heads came in ‘96.
My old ‘88 doesn’t have it and there is a definite vib you feel and can see like a front to back shake but the soft engine mounts damp it out mostly. Some prefer the non balance shaft version because it takes some power to turn….

Very interesting. Thank you for the explanation!

 

[Lou C]

What GM did was an inexpensive way of creating a 90* V6 using existing V8 tooling. This was done due to the energy shortage in the '70s because all they had was the Buick V6 built a few years earlier and the old GM inline 250 cu in six. They did it with the Buick V6 creating the 231 cu in V6 (these were real shakers till they got the split journal crank) and the Chevy 3.8 and 4.3 V6s. A V6 engine should have a 60* included angle between the cyls to have even firing pulses between the cyls. So the 4.3 V6 is really 3/4ths of a 5.7 V8 with the same bore and stroke. The 3.8s were 3/4ths of a 305 cu in V8, same bore and stroke.

Now, interestingly enough, Mercruiser who created "all new" engines for sterndrives, has their 4.5 V6. Guess what, they are still using this ancient GM technology today. Cast iron 90* V6 with split journal crankshaft and a balance shaft. It all looks IDENTICAL to the old GM 4.3 except for some modifications to the cyl heads. They run better, smoother etc but that's also more modern fuel systems. Kinda makes me think they just bought all the old GM tooling when they stopped making cast iron 4.3s a few years ago.
If Merc really designed an all new V6 it would have had a 60* included angle and no balance shaft!

 

[Jerm8]

Here's pics of the carb. I poured the fuel it had into a bowl and noticed that there is some water in it. I don't know if that could be the source or not?

 

[Lou C]

I see a bit of rust on the throttle blades and the underside of the casting. Water in the fuel too? Might be the smoking gun
In any case I'd put the intake back on, spray fogging oil in the cyls, crank it over carefully and do a compression test. You might get lucky as it is only fresh water. With mine I had to valves starting to stick and it would run rough till it warmed up, then ran mostly normal, some roughness and warmer than normal temps due to combustion gas in the cooling water. But that is salt water that does not forgive. If you get lucky it might be fine or you might have to pull the heads and do a valve job. You COULD do that now, but might not really need to...when I had my valve covers off I could actually see that 2 valves weren't closing all the way. I got lucky in that it never hydrolocked and the valves didn't hit the top of any of the pistons. So I bolted on a set of reman heads because mine were cracked and basically at the end of their service life due to salt water cooling.

 

[Rick Stephens]

You have a real puzzler. And yeah, you have water everywhere isn't supposed to be. Clean everything up. Reassemble. Get it running soonest to get the last of the water cleaned out and everything moving freely. Pull the plugs when you shut it down to observe whether the manifolds leak back. Then Pressure test block. Make sure you do not have a cooling system leak, or you will be forever chasing your tail. Too easy to do. Don't buy anything until you diagnose the problem.

 

[Scott Danforth]

@poconojoe , @Lou C balance shafts started in 92.

 

[Jerm8]

Thanks for all of the input. I'll get working on cleaning it up/reassembling and will report back how it goes.

 

[poconojoe]

It is run off the camshaft. GM found that even after adding an even fire (split journal) crankshaft to the naturally unbalanced 90* V6 there were still vibrations so the balance shaft removed the rest of those. I think they were added in ‘95. Vortec heads came in ‘96.
My old ‘88 doesn’t have it and there is a definite vib you feel and can see like a front to back shake but the soft engine mounts damp it out mostly. Some prefer the non balance shaft version because it takes some power to turn….

Very interesting. Thank you for the explanation!

What GM did was an inexpensive way of creating a 90* V6 using existing V8 tooling. This was done due to the energy shortage in the '70s because all they had was the Buick V6 built a few years earlier and the old GM inline 250 cu in six. They did it with the Buick V6 creating the 231 cu in V6 (these were real shakers till they got the split journal crank) and the Chevy 3.8 and 4.3 V6s. A V6 engine should have a 60* included angle between the cyls to have even firing pulses between the cyls. So the 4.3 V6 is really 3/4ths of a 5.7 V8 with the same bore and stroke. The 3.8s were 3/4ths of a 305 cu in V8, same bore and stroke.

Now, interestingly enough, Mercruiser who created "all new" engines for sterndrives, has their 4.5 V6. Guess what, they are still using this ancient GM technology today. Cast iron 90* V6 with split journal crankshaft and a balance shaft. It all looks IDENTICAL to the old GM 4.3 except for some modifications to the cyl heads. They run better, smoother etc but that's also more modern fuel systems. Kinda makes me think they just bought all the old GM tooling when they stopped making cast iron 4.3s a few years ago.
If Merc really designed an all new V6 it would have had a 60* included angle and no balance shaft!

Thanks again!
I really appreciate the explanation and the history of it all.
I now know that my (2003) 4.3L has that balance shaft and why.

 

[Lou C]

Other uses of balance shafts included the Mitsubishi 2.6 inline 4, the Chrysler 2.5 inline 4 and the Porsche 944 inline 4. All of them were large 4 cyl engines that tend to vibrate & shake more than smaller displacement 4 cyl inline engines.
PS
For 6 cylinders an inline 6 is very smooth compared to the older odd fire 90* V6s. The old AMC Jeep/Chrysler 4 liter inline 6 is much smoother at idle and high rpm.

 

[Jerm8]

I promised a response so here goes. The short story is that I have it back together and running. It appears that everything is fine and that no water is entering in where it shouldn't be to get in the oil. Thanks again for the input.

Now for the rest of the story. This will get a little long. And let the circus music begin...

As I was cleaning up the intake manifold it became quite clear that the water came in thru the carb. There was a lot of rust under the carb so I took a lot of time to scrape and blow it out. Then on to the heads that were still on the block in the boat. As carefully as I could I scraped them clean with a towel tucked neatly over the top of the block to prevent anything from dropping down inside. When I got that finished and vacuumed up I just stretched the cockpit cover over it and snapped it over the back of the boat to protect it from the elements in case of inclimate weather. It hasn't rained all summer long since probably June and you can imagine where this is going.

We had a spectacular lightning storm that night and then came the rain. But everything was fine because the boat cover was on...right? As the storm went on I thought that I should maybe just check on it, only to find a large pool of water that had collected on the cover directly over the engine. Sunbrella material holds water doesn't it? Probably if I didn't have a seam running down the middle of it. I peaked under the edge to see if any water was leaking thru. It wasn't dripping....it was gushing exactly into the top of the engine....right thru the towel. Man what a pain! I took care of the pool of water to stop it and the storm quit. I went to bed to deal with it in the morning.

I woke up and headed out there, figuring that I had another quart of water in the fresh oil that I had in there. Pulling the dipstick showed that the oil was several inches above where it should be. I inserted my pump tube and started pumping out the water. I still had a half full container of the the old oil/water mixture from the last time so I pumped that the rest of the way full of straight water. The started on another gallon jug and filled that to the brim...again, nothing but water. I had close to 2 gallons of water this time!

This was the day that I had the new gasket and everything else that I needed so I got the water out, cleaned up everything and reinstalled the intake and everything else, this time making sure it was covered up well in case it rained again. The RTV needed a little time to cure and I had church and stuff on Sunday so Monday I was able to get it running again...thank goodness!

During the saga I had time to develop what in my mind is the only plausible way that the water could have made it in there over the winter while it was shrink-wrapped. When I winterized it last year, I recall that I didn't close off the engine cover all the way. There was a few inches directly above the middle part of the engine that was exposed. No big deal....it was shrink-wrapped! I always cut vent holes in the front and back so it can breath. Well, apparently I made them too big because our local feral cat saw it, and as you might imagine, decided to use my boat for its house for the winter and in forcing it's way thru the hole, it also tore off the cover to the vent hole which would allow some rain and snow to get thru the hole...which just happened to be positioned....yep, you guessed it....right over the engine area. And my plastic engine cover that fits over the air cleaner has a couple decent cracks in it so I can definitely see how water could pool on the cover and funnel right thru the cracks and into the carb.

Needless to say I learned a lot from the experience. It appears that everything is fine with the boat. I haven't been able to get it on the water yet but did run it quite a bit yesterday.

Is anyone on this forum good at feral cat hunting?

 

[alldodge]

Is anyone on this forum good at feral cat hunting?

A bullet if your in the country. When I lived in the city and had similar problem I got a live trap cage. Caught them and took them to local pound. Got 5 of them before I stopped seeing them

 

[Lou C]

Both Merc & VP have used plastic covers that fit over the flame arresters, might be worth it to try fitting one of these, I have heard they can keep water out. Might also want to add a gutter to keep water from running onto the back of the engine. As much as using the cockpit & bow covers is a nuisance I always keep mine covered when it’s out on the mooring and have not had any water in the engine via the carb issues. Even when it’s been out there in tropical storms!

 

[Baylinerchuck]

This is from my 1990 4.3.

 

[Scott06]

View attachment 369218View attachment 369218
This is from my 1990 4.3.

Yes these often get removed but are there to keep water out of the flame arrestor and off the distributor...

This would have likely helped if not prevented the issue. You can find them on ebay for $50-100

 

[alldodge]

Get a plastic try for $1 and drill a hole with rubber washer below

 

[poconojoe]

I double cover my boat.
The factory bow and cockpit covers with their 3 poles, plus a full trailerable aftermarket cover.

The factory covers help support the top cover to prevent pooling.

My boat is always dry.

 

[Lou C]

You don’t get mildew between the covers?

 

[poconojoe]

You don’t get mildew between the covers?

No mold/mildew.

I do this during the boating season when the boat is stored in my driveway. We use the boat on an average of once a week.

For winter storage, I do the same, but it's in my garage.

Both covers are waterproofed every other year. The mooring covers are the normal sunbrella material, whereas the top cover is more like a nylon fabric. The top cover is supposedly trailerable and has the two rear facing vents. Maybe they are providing enough circulation so no mold occurs?

Never any mold and the boat stays bone dry. I'm a fanatic when it comes to water anywhere in the boat. My bilge is bone dry.

If we have swimmers that get water in the boat or it rains on us, I always dry everything off, including the bilge if it rains real hard.

 

[Bondo]

Get a plastic try for $1 and drill a hole with rubber washer below

Ayuh,..... Without usin' a rubber washer, water will chase the stud, right down the intake,....
Even an ole o-ting will help,....

Jerm,.... Welcome Aboard,...... In yer 1st picture of the top of the motor, I Knew yer problem,.... Rust tells the tale,....
Glad ya figured it out,.....

Lotsa boats need the doghouse/ swim pads redesigned, with water flow in mind,....
'cause that gap seems to Always be right directly over the center of the carb,....