MerCruiser 5.0L - Maintenance & Issues

[MercruiserMan]

Hello,

I am just looking for a little general maintenance tips and performance tuning. I know most of you will tell me to replace the engine if I want more performance, however, I am just talking getting the most with what I have...

I have a 2005 Glaston 195 SX with the MerCruiser 5.0L 305, carb, Alpha
Serial: 0m682205
Family: 3M9XM05.02VC
FEL: 15.3 g/kw-hr
D.O.M: Oct 2003
DISP 5.0L
Conforms to 2003 California standards

I have a 4 Blade 21P and has 528 hours on the engine.

I have replaced the Distributor Cap (OEM), Distributor Rotor (OEM), PCV valve (OEM), Air Filter (K&N), Spark Plug wires (ThunderVolt 50), Spark Plugs (NGK Iridium IX – TR6IX / 3689)(NGK also recommended the standard plug BPR6EFS).

Other info: Fuel Filter/Separator (OEM), Oil Filter (Royal Purple - long filter #30-1218), Engine Oil (Royal Purple Marine full synthetic 10W-40, I’ve also once used 20W-50), Power Steering Fluid (Royal Purple Marine), and Stern Drive Fluid (Royal Purple Marine 80W90)
Does everything I’ve done sound okay? Anyone have any suggestions, different plugs or should I replace any other part just in case?

When I replaced the plugs 50 hours ago, one side of the engine, the spark plugs were slightly lean, the others side plugs were slightly rich. I can’t seem to find a reason why… as best as I can tell, there is not an intake leak… maybe there is. The engine runs well, however, there seems to be a slight tick / slightly rough idle issue. However it seems to smooth out as the RPMs rise. The tick sounds like a lifter or valve that is off… maybe; I think the issue comes from a single cylinder. However, I am unsure. Regardless of both issues, I don’t really want to take apart the entire engine, rebuilding it from the ground up. Does anyone have any thoughts on my issues? My motor has the EGR on one side of the engine only… could that cause the slightly rich / slightly lean condition? Can I just get some caps/plugs and remove that EGR tube? I also just had a starter issue starting today, however, I think it is just a solenoid, so I don’t think I need any help on that one.

Any comments or suggestions would be appreciated.

Thanks all,
MercruiserMan

 

[kghost]

Although I am not familiar with California standards as we don't have them in the rest of the country......




What I do know is, the 305 is a 305 cubic inch and what you see is all you get for performance especially with a carb. EFI may have more potential but you don't have that.

The only way to improve performance of a 305 is to do a couple of things.

1. Bigger cam and intake and carb...

2. get a 350 or 383 motor, intake and 4 barrel carb as all the peripheral components will bolt on.

As far as your choice of oils........royal purple is good stuff no doubt.....But it may be over kill based on the price. I know it is very expensive stuff.

I use Mobile one 15/50 I purchase from Walmart for ~$25.00 for 5 qrt jug. Napa gold oil filter, and I only use mercruiser high performance gear lube.

Not sure you need the iridium plugs...........kinda snake oil if you ask me........Standard plugs AC or NGK will work just fine and always have.

Not sure about your ticking issue but I would think you have what is called a TKS carburetor. Turn Key Start...
I would try to find a stethoscope and listen to/for the ticking to try to identify exactly where it is coming from. If it is a lifter you may be able to adjust it by removing the valve cover and tightening the rocker arm a bit. It could be the TKS carb??? could be the PCV valve clicking???

No way to tell from here.

Your lean condition could be simply one side is running hotter than the other or the carb is not working properly.

So in summary, there is not much more one can get from a 305.........it is what it is without modifying it or replacing it.
This is a very common issue for many who have this size motor.