Wot

[ASD]

How do you know when you have achived WOT?

 

[illiad]

Re: Wot

the throttle lever is all the way foreward = WOT.
Appropriate RPM's for your engine will depend on the engine.

 

[bigdaddypt]

Re: Wot

the throttle lever is all the way foreward = WOT.
Appropriate RPM's for your engine will depend on the engine.

as well as the prop you have

 

[ASD]

Re: Wot

THANK YOU!!
I have a 4.3 merc, would you know the RPMS? 4500 -4800?

 

[cooter2506]

Re: Wot

what year ?

 

[ASD]

Re: Wot

if there might be anything else I could try to fix the back fire on cylinder #6 or could this problem be something else

1994 BAYLINER 2252

4.3 175 HP MERCURY CRUISER 6 CYLINDER

In the fall and early spring no problems. My mechanic informed me that the starboard side manifold needed to be replaced(original and it should be replaced 5-7 years) which I did and once it was replaced, I have been having a popping noise (back fire )from cylinder #6only.Performed pressure test with good results. I can run boat with out the wire on the cylinder and it will not back fire. I have already replaced wires and cap in hopes it might be that.
When running boat in gear at 2800 -3000 rpms popping will happen sporadically. sometimes it stops for about 30 -45 seconds. I have not pushed engine in fear of blowing rod.

Mechanic stated that he believes the rod has rust on it and it is sticking.I have also added two pints of marvel mystery oil to gas tank in hopes it will smooth out rod preformance.


Could this be true? any further info would be great.

Thank you in advance for your help.

 

[45Auto]

Re: Wot

Mechanic stated that he believes the rod has rust on it and it is sticking.

Anyone who tells you something like the above is trying to tell you that you need new mechanic .....

You need to do a compression and leak-down test on the motor. Make sure you don't have any bad or burnt valves.

 

[carcraze]

Re: Wot

Hey there ASD

In your last thread
http://forums.iboats.com/showthread.php?t=404666

The discussion ended with asking you to verify the firing order was correct as well as replacing #6 plug or swapping it to see if it followed the plug.
How did those tests turn out?

It really needs a leak down test as stated above after that I might be inclined to pull a valve cover and make sure you have proper lift on #6 valves and that a cam lobe did not wear out.

 

[ASD]

Re: Wot

What is a leak down test?

 

[carcraze]

Re: Wot

An engine compression test tests only the fact that the engine develops compression while cranking it over and can miss a lot.
A leak down is where they put the engine cylinder on TDC on compression stroke and pressurize the combustion area and allow it to hold and look for a pressure drop. It finds a lot more and is a much better test, you can even sometimes pin point an area of leak by listening to the intake, exhaust, so forth.
I have even heard the test can be done at mis travel to somewhat indicate if the cylinder bores are worn.