Mercruiser 4.3 Knocking noise when idle

[Evinrude Boater]

Re: Mercruiser 4.3 Knocking noise when idle

Did you check the compression? No sense trying to repair a 15 year old engine that needs a full rebuild.

 

[adam125]

Re: Mercruiser 4.3 Knocking noise when idle

no I am still awaiting pressure gauge. I don't think it's that bad I hope not anyway as the boat is running well I am still using it. surly the play on this balance shaft shouldn't be there? even if its not causing the noise? I see a lot of people remove theses shafts totally from the engine ?

 

[Evinrude Boater]

Re: Mercruiser 4.3 Knocking noise when idle

My 87 engine with unknown hours had a slight knock only audible at an idle. It had one cylinder with no compression, others with low compression and a piece broken off one piston skirt. It ran well otherwise and I didn't know it had bad compression until tested it. I ran it that way for two years.

 

[slothman]

Re: Mercruiser 4.3 Knocking noise when idle

My 87 engine with unknown hours had a slight knock only audible at an idle. It had one cylinder with no compression, others with low compression and a piece broken off one piston skirt. It ran well otherwise and I didn't know it had bad compression until tested it. I ran it that way for two years.

LOL the boat probably ran 20 MPH.

 

[Evinrude Boater]

Re: Mercruiser 4.3 Knocking noise when idle

LOL the boat probably ran 20 MPH.

Honestly the only difference is less blow by now with the new engine. It ran fine and towed tubes and wakeboarders without a problem.

 

[slothman]

Re: Mercruiser 4.3 Knocking noise when idle

Honestly the only difference is less blow by now with the new engine. It ran fine and towed tubes and wakeboarders without a problem.

wow talk about the little engine that could lol. normally low compression makes a motor run like junk with little to no power.

 

[adam125]

Re: Mercruiser 4.3 Knocking noise when idle

Hi guys so sorry for the late reply! a quick update ... winter is now here so the boat is it out of the water! the engine lasted the season still with that dam knock! its now time to take the engine out and get it sorted once an for all over the winter months! Thanks again for every ones help on here! next questions are any one have good tips on removing the engine or any step by step guides? you could send my way would be much appreciated!
thanks again
Adam

 

[antikbuff]

Re: Mercruiser 4.3 Knocking noise when idle

Hi guys checked the harmonic balancer seems to be all good there! if I have a bad lifter is it possible to replace theses without removing the head? I am taking the rocker covers off tonight! hopefully to find something that isn't to much of a big deal to fix!

Adam

Mind if I join the conversation ?

I had the same problem. Found out it was the flywheel. Some of the engines require a shiv behind the flywheel to prevent the knocking you hear.
Found out after checking everything. Other possibility of noise is the tag piece of aluminum on the flywheel.
Some engines require the shiv some don't. Don't know why this is. Maybe something to do with the crank tolerances when they're turned.

 

[Bondo]

Re: Mercruiser 4.3 Knocking noise when idle

Mind if I join the conversation ?

I had the same problem. Found out it was the flywheel. Some of the engines require a shiv behind the flywheel to prevent the knocking you hear.
Found out after checking everything. Other possibility of noise is the tag piece of aluminum on the flywheel.
Some engines require the shiv some don't. Don't know why this is. Maybe something to do with the crank tolerances when they're turned.

Ayuh,.... Welcome Aboard,... You can join in, but the OP hasn't been to iboats since Oct. last year,...

Did ya read the Big Red banner that was on the lower part of the page, Before ya posted,..??

 

[antikbuff]

Re: Mercruiser 4.3 Knocking noise when idle

What big red banner are you referring to ? I don't see it.

 

[achris]

Re: Mercruiser 4.3 Knocking noise when idle

What big red banner are you referring to ? I don't see it.

That one right there.....

Forum rule #12

12. Please do not post to threads that have been inactive for more than 3 months UN-LESS you are the original poster. We have very active forums and any thread that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old thread. This is considered a hijack. Please start a new thread of your own.

For all of the rules and guidelines you agreed to when you signed up, FORUM RULES

 

[adam125]

Re: Mercruiser 4.3 Knocking noise when idle

Hi guys i'm still here had a busy winter but this week I am just about to pull the engine, I have recently got a lifting frame in place, ahh thank you for that advise so you would advise fitting a shiv first before pulling the engine to bits? when you say shiv ? Im not 100% sure what you mean by a shiv? any pictures would be very helpful. Thank you so much for you advice much appreciated

Got to get cracking with this project summer is coming

 

[Clarko1988]

Re: Mercruiser 4.3 Knocking noise when idle

Hi guys i'm still here had a busy winter but this week I am just about to pull the engine, I have recently got a lifting frame in place, ahh thank you for that advise so you would advise fitting a shiv first before pulling the engine to bits? when you say shiv ? Im not 100% sure what you mean by a shiv? any pictures would be very helpful. Thank you so much for you advice much appreciated

Got to get cracking with this project summer is coming

What was ur problem

 

[Sealine123]

Re: Mercruiser 4.3 Knocking noise when idle

Hi guys so sorry for the late reply! a quick update ... winter is now here so the boat is it out of the water! the engine lasted the season still with that dam knock! its now time to take the engine out and get it sorted once an for all over the winter months! Thanks again for every ones help on here! next questions are any one have good tips on removing the engine or any step by step guides? you could send my way would be much appreciated!
thanks again
Adam

Hi mate did you find the fault with the engine with the knock ? .