Any ideas

[DavidP]

Hi
I have twin mercruisers 4.3 ltr petrols, they run fine ,preform well and touch wood have had no problems with them to date, fully serviced last October, but since i have had this boat in September last year ,one engine runs with more engine noise than the other, the only difference with the noisey one is that it drives the power stering, it is noticable because the other one is so quiet .
Any ideas why ???
cheers , Dave.

 

[hlb]

But is it noisey when your not steering. And what sort of noise.
Is it brum brum type or clatter clatter bang, noise!!

No one can force me to come here-----------
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Haydn

 

[DavidP]

Hi
Not bearings or cam noises ,just louder ,
EG, the difference between a jag engine and say a escort engine, the jag just purs the escort is quiet but not like the jag.
Dave

 

[chippie]

In my experience it is often the hydraulic valve lifters that create that bit extra noise. I dont know if the mercs have them or not, but if they do, change the oil and filters and see if that helps. I have used a flushing agent on cars before the oilchange with some success.

 

[syd]

Hiya David,
I take it your not having any overheating probs with the noisy engine. Does the noisy one run hotter than the quieter one? I ask because I did some work on a 5.7 Merc that became noisy, as in exhaust noise, it turned out to be water flow, or lack of, through the exhaust riser. These risers are quite intricate inside and can get partially blocked from time to time thus misdirecting the water flow. Put your hand on each riser when the engines are up to temperature and see if there is a great deal of difference in the heat.
Cheers
Syd

 

[Guest]

Does one engine heat the calorifier and so have a slightly different exhaust layout?

In fact do both engines have identical exhaust layouts or is one a bit more twisty?

One of my exhaust outlets just constantly runs with water and the other squirts out a bucketfull about every 10 sec or so and I believe it's for this reason. Could effect the noise?

Bernie

 

[DavidP]

Hi,
No overheating problems ,i know my way around car engines ,but not marine adaptations, where are the risers ,
Dave

 

[DavidP]

Hi,
I dont think so ,i dont know what the calorifer is.
the engines run only them selves ,and charge the batteries.
Dave.

 

[syd]

Dave,
The risers are on top of your exhaust mainfolds, they stick up slightly, usually square in shape with four bolts on top connecting them to the exhaust manifold. I'll try and send you a diagram if I can get one scanned.
Good luck
Syd

 

[DavidP]

Cheers Syd
Dave.