3.0 4 CYl Mercruiser Engine Rattle at High RPMS

[peacekeeper6]

Boat runs great no problems, starts up right away, i notice that at above 3/4 thrott;le it rattles as if a nut is bouncing around inside the valve train. I thought it might be the belt on the front of the eninge but that doesnt make sense. If i reduce the engine to 3/4 throttle the clanking/rattling goes away slowly to barely anything at all. Sometimes it takes half throttle to get it to stop. But my hole hsot is great and the boat runs great at high RPMs other than the clanking. I tightened the belt up to no avail. any ideas? Give me a list to check tomm when i get back to the lake. Also notice when i shut it off after this trip it dieseled for a second then shut off.

 

[Bondo]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Ayuh,... It's going Lean,+ consuming itself with Detonation...
It could be as simple as dirty fuel filters...
Or, it might be the Carb...
But,.. Fix it before you run it...

 

[Don S]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Another possibility, What is your idle timing and advance timing? Are they to spec?

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

I will rent a timing light frmo autozone tomm, also i will purge the fuel system tomm and see if that helps. Will post with further information tomm.

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

i am looking through my clymer for the procedure to set the timing and check it but cant seem to find it. does anyone have the procedure??

 

[fishrdan]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

i am looking through my clymer

Go up to the adults section and down load the OEM Mercruiser manual for your engine. I think there is a ignition specific manual too that covers all ignitions, well, at least I have one downloaded and I think I got it here.

 

[180shabah]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Then burn the Clymer, if it is even any good for that.

One more possibility, yourt 3.0 probably doean't have a water seperating fuel filter, you need one.

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Then burn the Clymer, if it is even any good for that.

One more possibility, yourt 3.0 probably doean't have a water seperating fuel filter, you need one.

i do have one. the adults section? i believe i am missin a bad joke here...

 

[ENSIGN]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Don'use CHEAP gas!!!

 

[fishinpa]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

i do have one. the adults section? i believe i am missin a bad joke here...

No there not pulling your leg

look up here
http://forums.iboats.com/showthread.php?t=288430

manuals and information !


fish

 

[achris]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

... i believe i am missing a bad joke here...

The only bad joke is that clymer you're using.... As 180shabah said, if you can get it alight, burn the damn thing!

Chris......

 

[Bondo]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

The only bad joke is that clymer you're using.... As 180shabah said, if you can get it alight, burn the damn thing!

Naw,... No reason to waste a perfectly good Knee-pad...
It'll save ya from gettin' those stone divets in your knees...
Clymers is as thick as the Seloc ain't it,..??

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

thanks guys!

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Spot on with the timing. The 2 and 4 cyclinder was firing when it was supposed to be the 1 and 3. Timing was 90 or so degrees out if i am thinking correctly. Removed the distributor and moved it to the #1 cylinder at 0 degrees then retarded it to 8 BTDC and runs like a charm. Thanks guys.

 

[achris]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Spot on with the timing. The 2 and 4 cyclinder was firing when it was supposed to be the 1 and 3. Timing was 90 or so degrees out if i am thinking correctly. Removed the distributor and moved it to the #1 cylinder at 0 degrees then retarded it to 8 BTDC and runs like a charm. Thanks guys.

With the timing 90 degrees out!!! How did it even run at all????

Good catch.... But who did that!

Chris.......

 

[glennwolf]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

have had the same issue and it was a carb problem. It went away the longer I ran it. It was getting lean due to dirty/water in fuel.

 

[fishinpa]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

Spot on with the timing. The 2 and 4 cyclinder was firing when it was supposed to be the 1 and 3. Timing was 90 or so degrees out if i am thinking correctly. Removed the distributor and moved it to the #1 cylinder at 0 degrees then retarded it to 8 BTDC and runs like a charm. Thanks guys.

O K we'll buy the timing was off , but 90 deg

im thinking your calculation is just a tad off here !


well glad to hear its better !

fish

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

i have no idea who did it, i just know that when it was supposed to be TDC it was pointed at the #2 cylinder instead of 1 or 3. SO it was off alot, thanks for all the help.

 

[bigskiohio]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

uh... i dont think so but as long as you ended up right.
You probably weren't on compression stroke on one.

 

[peacekeeper6]

Re: 3.0 4 CYl Mercruiser Engine Rattle at High RPMS

everything is awsome just took the boat out yesterday for the whole day. runs like a top now just need to get new guages.