2002 5.0 V8 Mercruizer, knocking engine noise?

[BoatMyAssOff]

Help,

I have a 2002 Maxum 1900SR with an inboard 5.0L V8 Mercruizer motor that has approximately 150 hours on it. When its idling (low rpm), I hear this knocking sound, maybe valve rockers? I belief they are hydrolic, so is it due to the low oil pressure at idle? Should I have this looked at? Any idea of the costs involved?

Thanks.

 

[BoatMyAssOff]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

A knocking sound from your engine is NEVER a good thing. Have it looked at ASAP.

I belief they are hydrolic, so is it due to the low oil pressure at idle? When I increase the RPM it's quiet, or at least I think so?

 

[BoatMyAssOff]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

Ok, I have just enough knowledge about egnines to really mess things up, I will take it in and report back.

Thanks.

 

[abj87]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

Valve train noise is normally a ticking, not a definite knocking sound. Hydraulic lifters should make no noise, whats your oil pressure at idle?

 

[a70eliminator]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

Ticking sound= lifter
knocking= rod

Exessive rod bearing clearance will knock at idle then go away under accelleration or decelleration you can hear it when the engine is under no load condition, from an idle increase the rpm and listen close bring the rpm up and then level it off again at the higher rpm, knock still there only faster and less prominent? If so I would try some heavier oil like 40 or 50 Wt and see if that helps.

 

[BoatMyAssOff]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

Thanks for all the replies.

Took the boat in this morning. The noise is only present after the engine has warmed up and at low RPM (idle). If you increase the RPM it goes away. The mechanic did the following:

Removed each spark plug cable, in turn, from the rotor cap, and checked if the noise went away or changed. Result, no difference in the sound.

He concluded I had some minor play in one of my lifters and said its not a issue we need to be concerned about. Oil pressure was good, but I had them do the annual anyway so that we can ensure we are using the correct oil.

Thanks.

PS. Never tow the boat with a cover. I was lazy and didn't remove the cover, ripped it in two....aaghh!

 

[BoatMyAssOff]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

I don't what is more expensive, my flying hobby or boating....

Boat Cover - $247.00
Annual Service - $650.00
Trailer Wheel Service - $300.00
Gas Tow Vehicle - $800.00
Gas Boat - $600.00
Lake Fees - $300.00
Payments - $6000.00

So, taking the boat out 20 times per year costs $432.00 per outing. Go ahead and send me some money...

 

[KJSmitty]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

I don't what is more expensive, my flying hobby or boating....

..

I bet that would depend on whether or not you

"FlyYourAssOff"....




Cheers

 

[Mischief Managed]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

A failing water pump (circulating, not raw water) can knock menacingly without leaking a drop. That's what happened to my last boat's 5.0. I thought for sure it was a rod bearing and did exactly the same thing your mechanic did, with exactly the same result (except I never thought it was a lifter). I scratched me head a bit and eventually removed the serpentine belt, started the engine momentarily and the noise was gone. Wiggling each accessory pully revealed excessive play on the water pump. It sure is easy to check...

 

[BoatMyAssOff]

Re: 2002 5.0 V8 Mercruizer, knocking engine noise?

******** UPDATE **********

The service center just called...Besides the lifter making some noise, they said they found a bit of water on cylinder 5/7 sparkplug. They think the manifold needs to be replaced, and just the parts is $1900.00. Does this sound correct?

Keep in mind I only have 140 hours on this engine....

This thread is continued here:

http://forums.iboats.com/showthread.php?t=289947