4.3 Liter V6 Mercruiser I/B O/B

[joedesigner]

Ok guys I need some expert advice. I have a 2005 Trophy 2052 WA Equipped with the Subjected Engine.

My delema is I've got a knock or pop or backfire or ??????? comming from inside the Engine cover. From the helm running from 3k to 4.5k it sounds like a gremlin in there bending a beer can back and forth pretty intermittant never at an idle or trolling speeds just running. Sorry for the anaology but that's what it sounds like to me. I've had this happen in 08 and took it in for service and was told that I just needed plugs so I had them changed out and everything has been good til this season. I started hearing the popping noise again figured oh crap I've heard that before so I took the boat into a local Mercruiser mechanic in Monroe Wa. came highly recommended by several freinds. Told him what was going on, and what I had done in the past, so he changed the plugs and when he did he noticed the back 2 plugs were very rusty he showed them to me and yeah they looked terrible rusty corroded not good at all. He said he performed a compression check and everything checked out. He also said he can't figure out for the life of him how water could be getting into those back 2 cylinders as the the Coolant is in a closed system. The boat does have cabin heat so it's equipped with the heat exchangers that run saltwater through them but he was convinced that the system on my boat was designed so that Saltwater could not get down in the motor. Any thoughts or advice will be much appreciated Thanks!!!!

 

[Bondo]

Re: 4.3 Liter V6 Mercruiser I/B O/B

Ayuh,... My 1st guess would be Rotten Risers, leakin' back down the exhaust passages...
The aft cylinders are lower than the forward, so the backwash collects there...

 

[joedesigner]

Re: 4.3 Liter V6 Mercruiser I/B O/B

Thanks Bondo-o!!!

You know I religiuosly flush my engine with the clam shells for 20+ minutes everytime I use my boat which 100% saltwater use.
Now with the closed cooling system is that over kill for the flush. I'm wondering if I'm doing something wrong there.

Thanks

Jeff

 

[Bondo]

Re: 4.3 Liter V6 Mercruiser I/B O/B

Thanks Bondo-o!!!

You know I religiuosly flush my engine with the clam shells for 20+ minutes everytime I use my boat which 100% saltwater use.
Now with the closed cooling system is that over kill for the flush. I'm wondering if I'm doing something wrong there.

Thanks

Jeff

Ayuh,... Even with flushing, cast iron is gonna rot in saltwater...
The risers live in a pretty nasty spot, with hot exhaust gases on 1 side, 'n saltwater spraying into at the end...
Ya got 6 Years,...
From what I hear, that's pretty remarkable...

 

[joedesigner]

Re: 4.3 Liter V6 Mercruiser I/B O/B

So not overkill on the flushing time?

Do you know if there are aftermarket risers that would have a longer life span, perhaps manufactured with a material with better tolerables to the conditions.

 

[Bondo]

Re: 4.3 Liter V6 Mercruiser I/B O/B

perhaps manufactured with a material with better tolerables to the conditions.

Ayuh,.... look into SSteel...

 

[Fishermark]

Re: 4.3 Liter V6 Mercruiser I/B O/B

Ayuh,.... look into SSteel...

Yeah - and be prepared to open your wallet!!

I have to ask - what is a "Subjected engine?" Is that a typo?

 

[joedesigner]

Re: 4.3 Liter V6 Mercruiser I/B O/B

4.3 liter V6 I/B Sterndrive...............I thought the Title of the thread would be the subject like on an e-mail..........I'm a rookie to these forums...... but I'm really liking all the good info and really quick responses thanks everybody especially Bondo-o!!!!

Jeff

 

[achris]

Re: 4.3 Liter V6 Mercruiser I/B O/B

4.3 liter V6 I/B Sterndrive...............I thought the Title of the thread would be the subject like on an e-mail..........

"4.3 litre V6 Sterndrive" has MANY variants. First appearing in 1983 to replace the much maligned 3.7 litre '470' family of engines and filling the gap between the in-line 4's and the SBC V8's, it has over the years, had 3 different engine blocks, 5 different carbs (that I know of), throttle body or mutli-point fuel injection, some have balance shafts, some don't. Breaker points, Thunderbolt IV or Thunderbolt V ignition system. Pressed tin timing cover or plastic, pressed tin sump or cast ali. 3" or 4" exhaust systems. It has been configured for outputs from 155hp to 220hp....

The easiest way around be asked 'What engine' is to either give the model (like 4.3LX or 4.3MPI), year and serial number at the beginning of each new thread, or do as many of us do, put all the details in your signature so they appear at the end of each post (like I have)....

As for exhaust elbows, Merc did a line of S/S for the big blocks in the 90's that were the same as the 4" V6 exhausts. I managed to get a pair for my previous engine. That's 17 years old now and they are still as good as the day I put them on (lucky for the new owner). Merc stopped doing them for obvious reasons (no spare parts sales!), and now all the elbows are cast iron with a ceramic coating. A few years ago a mob in Queensland tried fabricating a fully S/S manifold with integrated elbows. It was an unmitigated disaster. The combination of red hot exhaust gases on one side and cold seawater on the other had them cracking in fairly quick time. Along with the loss of quite a few engine due to water in the oil.

The genuine elbows have generally given me the longest life. I have seen Chinese made elbows and manifolds fold in as little as 18 months. They are half the price and use a quarter of the material! Stick with the genuine parts and chalk it up as being part of owning a boat....

Chris..........