4.3L V6 Mercruiser Hydrolocked

[joewithaboat]

Re: 4.3L V6 Mercruiser Hydrolocked

"Also, automotive 4.3s from the mid 90s are notorious for leaking coolant on the front left side from the area between the intake and head."

I would have to respectfully disagree with that. I am a licensed mechanic ... my entire career and apprenticeship was at a GM dealer starting in the 90's. I don't remember any probem like that on 4.3's.

First of all, 4.3's in the mid 90's were Vortec engines with one single large injector in the middle of the plastic air plenum that sat on top of the intake manifolds. Boats don't have this ... plus boat 4.3's have cast iron intakes. The 4.3's in the late 90's and 2000s have the same style but they have 6 sequentially located in a rectangular box in the middle of the air plenum with plastic lines leading to the intake manifolds (check valves at the end of the plastic lines).

These engines were famous for air plenum and fuel injector leaks / problems. Also the check valves at the end of the plastic tubes were so sensitive, they would simlpy not open below 55 PSI fuel pressure. I remember replacing a lot of plenums, plenum gaskets, fuel injectors and fuel pump. I remember very very few 4.3 mechanical problems.

Not sure where you worked or what you worked on...

Please see link for class action lawsuit covering among others 1995-2000 4.3 v6

As I stated earlier... i think if you look into it it was the coolant breaking down the gaskets that caused the leaks.

http://www.topclassactions.com/close/14-gm-dexcool-engine-coolant

 

[joewithaboat]

Re: 4.3L V6 Mercruiser Hydrolocked

Thanks for the great suggestions! This is going to seem like a REALLY dumb question to most of you so please forgive my ignorance. :redface:But, how do I get to the flywheel bolt to turn the engine with the housing and engine coupler installed? Do I need to remove those to get to it?

You can turn it by using the crank bolt in front.

 

[joewithaboat]

Re: 4.3L V6 Mercruiser Hydrolocked

littlebookworm makes some very good points.

Nothing wrong with that starter in the video. Would help to get us more videos like that.

Don't be duped into thinking that just because a starter will engage and free-wheel that it will operate under load. Ive fallen victim to this test before. It must be tested under a load.

Here is a pretty good explanation of things, its automotive oriented but most still applies.

http://www.misterfixit.com/starttst.htm

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

You can turn it by using the crank bolt in front.

Unfortunately I can't get to that bolt. The engine is should all the way back against the floor of the boat.

 

[joewithaboat]

Re: 4.3L V6 Mercruiser Hydrolocked

Unfortunately I can't get to that bolt. The engine is should all the way back against the floor of the boat.

Id take your starter out to be load tested if you can't figure out how to do so with the above link.

I would bet that is your problem or a bad connection somewhere. Have you disassembled cleaned and reassembled all of them + and - ??

Someone else suggested that it might be the u joints. It seems plausible, only takes a few minutes to remove the drive.

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

Someone else suggested that it might be the u joints. It seems plausible, only takes a few minutes to remove the drive.

The outdrive is brand new and just installed. The engine did run since it's been installed so I don't think that's the problem, but I'll probably still yank it to eliminate it from the equation.

 

[makonnen]

Re: 4.3L V6 Mercruiser Hydrolocked

While I respect your experience, I've fixed mine and 2 others. The problem seems to develop around 80K according to the massive amount of forums and Youtube videos dedicated to the subject. Maybe people can't afford to take a 16 year old vehicle to Mr Goodwrench? I was just trying to contribute....I'll leave now.

Point taken.

We usually only see a vehile within the first 3-8 years of its life.

Plus those Vortecs had aluminum intakes. A marine 4.3 would have a cast iron intake.

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

Y'all, I'm both elated and ashamed to say that I have found the problem.

Apparently, the individual who owned the boat before me had the trim limiting switches disconnected......

I'm sure y'all can finish the rest of the story. DOH!!!

 

[makonnen]

Re: 4.3L V6 Mercruiser Hydrolocked

How can trim switches cause this?

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

How can trim switches cause this?

I had the outdrive trimmed up too far which was binding the u-joints and locking the engine. Had the trim limit switches been functioning, they would have disabled the engine, thus telling me the outdrive was trimmed up too far.

 

[Struc]

Re: 4.3L V6 Mercruiser Hydrolocked

At least it forced you to look elsewhere and you found your manifold & riser issue.

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

At least it forced you to look elsewhere and you found your manifold & riser issue.

Amen to that. Now that it's all over, I wouldn't trade the experience and lessons learned for anything.

 

[makonnen]

Re: 4.3L V6 Mercruiser Hydrolocked

Its all good. I learned a lot too. I think I'll be re-reading the thread just because it has been that good of a read.

So bookworm dude called it!

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

Its all good. I learned a lot too. I think I'll be re-reading the thread just because it has been that good of a read.

So bookworm dude called it!

I'm glad you got some benefit from it.

And thanks to EVERYONE for your help!!!

I know it has to get old with all the noobies like me coming on here with silly questions, but it means more to us than you can possibly imagine. I wish I could buy y'all a beer or six!

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

Well it would appear as though I was a little premature with my certainty that I had figured the problem out. I finally got the new risers, manifolds and gaskets installed. Ensuring that the outdrive was trimmed town, I hooked up the water and tried to start her up. She turned over and started to roll. After starting and then cutting out (typical for being cold), it eventually locked up again. I pulled the plug from the #6 cylinder and about half a cup of water poured out. I left that plug out and tried to crank it.....no good.....still locked up. I pulled the rest of the plugs out one by one and the engine would not turn with a single plug in. Even after purging the the cylinders and not having the water running and the fuel pump unplugged, the engine was still locking up. I went ahead and purged the cylinders one more time, the put everything back together with the intention of just taking it to the mechanic. On a last prayer, I hit the starter and it fired right up. It was idling for a while but seemed to be missing at one cylinder. I went to the back to make sure all of the plug wires were pushed in all the way and the engine bogged down a little bit but continued to run for another 20 seconds before it finall died. All of this was without having the water hooked back up. After it died I tried to start it again and it the engine was locked back up. I'm really starting to hate this boat. I'm going to take a shot at replacing the starter to eliminate that from the equation. it doesn't make sense that the starter can't turn the motor over with no water in the system and only one plug installed. Any other suggestions?

 

[Struc]

Re: 4.3L V6 Mercruiser Hydrolocked

If water poured out of the cylinder, any cylinder, at any time it's just on the muffs, then you've got other problems. I'm not saying your starter isn't bad, but there is no reason you should have water in any cylinder.

 

[nola mike]

Re: 4.3L V6 Mercruiser Hydrolocked

1. Get your starter tested. Yes, it should turn the engine over with the plugs removed. Or with the plugs in place. If the wiring is good, you're left with the starter (unless your timing is WAAAY off).
2. Replace your impeller. If you've been running without water, you've probably fried it by now.

 

[rodgeml1]

Re: 4.3L V6 Mercruiser Hydrolocked

1. Get your starter tested. Yes, it should turn the engine over with the plugs removed. Or with the plugs in place. If the wiring is good, you're left with the starter (unless your timing is WAAAY off).
2. Replace your impeller. If you've been running without water, you've probably fried it by now.

My timing is not way off because I am able to start the motor up and let it run. I'm going to pull the starter today and have it tested. I'm thinking it needs to be replaces regardless of the other issue.

With the exhaust manifolds, risers, and gaskets all being brand new, what are the other ways the water will be getting into my cylinder? Are the only other possibilities the head gaskets or heads?

 

[nola mike]

Re: 4.3L V6 Mercruiser Hydrolocked

Have you done a pressure test on the coolant system?
I assume that the mating surface on the head was in good shape before you replaced the manis/risers?
Is water getting into both cylinder banks?
Maybe could try hooking up the hose directly to the coolant circuit (after the leg) and let it run with the engine off to see if you still get water intrusion.
Others can chime in, but I wouldn't think a HG leak should cause intrusion into the cylinders. The combustion pressure should force everything the other way.

 

[Struc]

Re: 4.3L V6 Mercruiser Hydrolocked

With the exhaust manifolds, risers, and gaskets all being brand new, what are the other ways the water will be getting into my cylinder? Are the only other possibilities the head gaskets or heads?

Most common would be head gasket, cracked head, cracked block. Absolutely time for a pressure test on the coolant system to see what's happening.