Lifter Issue??

[SeaRay]

I have a 5.0L EFI Mercruiser engine that seems to run just fine.

However, when I run it at high rpm for 10-15 minutes I will get a slight tapping sound from the engine. If I let it sit for a minute then take back off at a lower RPM it goes away??

We typically run at 20 - 25 mph and I haven't ever noticed it before. But twice in the last few times I took off for a high speed run across the lake I have heard it.

I think it is a mechanical noise and not an exhaust leak but I am not positive. It sounds like a sewing machine.

Any ideas?

I was considering trying some Sea Foam in the crankcase before I change the oil for winter?

Thanks

 

[skibum]

Your best bet is to get a mechanic's stethoscope and start listening to different parts of the engine to determine where the noise is coming from... I am not necessarily recommending this particular vendor or item, it is just an example I found with a quick Google search. It had a decent picture. Any auto parts store should be able to hook you up with one.

Michael

 

[dtoerper]

I had that same problem with my 5.7 mpi due to the engine running too cold from a stuck open thermostat which in turn causes the engine to run too rich deluting the engine oil with gasoline. A simple oil change using mercruiser 25w40 stopped the ticking.

Note: when coolant temp is low, the ecu thinks that the engine is at start up thus injecting more fuel like a choke on a carb stuck on.

 

[BonBini]

I've seen sea foam clean up lifter noise in the past. Before doing anything else I would pull the filter and see whats inside. Lets hope your not making metal. ...Ron

 

[Lazy Daze]

What kind of oil do you have in there and what is it's condition? Also, is the oil level "full"?

 

[SeaRay]

I have actually used a long screwdriver in the past to find noises in motorcycle engines. I am almost positive it is a lifter, on the starboard side.

The oil that is in there now is Rotella T W15-40. It is made by Shell. This oil was recommended by an engine rebuilder (and a fellow boater). He said that this oil has a higher level of zinc additives which have been removed from many other oils.

It came highly recommended - I am not usually one to stray from the stuff the engine manufacturer would recommend. One would assume that they know what is best. But he really liked this stuff.

Oil level is good. But it is the end of the season and there are maybe 80 hours on it?? (don't remember for sure what is was at the beginning of the year) so I am sure it is getting a little worn. It is still brown (dark brown), not black, on the dipstick.

I just picked up some Mercruiser Synthetic Blend W25-40, a filter and a bottle of Sea Foam. I may take it out to the lake, pour in some Sea Foam, drive around for a 1/2 hour or so, drain the oil, change the filter and pour in the new oil and see how it does.

Then just be done with the oil change for the season. Any harm in this?

My goal would be to determine if I really need to give it more attention during the winter or if it will be OK. If I need to do anything I would much rather work on it over the winter then in the spring.

 

[SR Tech]

15w-40 eh?

I bet when you do your oil change to 25w-40 the noise will magically disappear...depending on how long you've been running like this

 

[tdappleman]

15w-40 eh?

I bet when you do your oil change to 25w-40 the noise will magically disappear...depending on how long you've been running like this

Why? The problem is showing up when the engine is running hard at higher RPM's. So - the 40 weight characteristic of the oil remains the same. Rotella is a quality oil - may not be FC-W certified and may not have the corrosion inhibitors but it's a quality oil.

 

[SR Tech]

Nothing against rotella at all, its the cold viscosity hes using.

I had a similar problem with my car, was at 5w-30, went to 10w-30 and it went away.

 

[tdappleman]

I guess that's my confusion - once the engine has warmed up the cold viscosity rating wouldn't apply - only the 40weight. I've seen engine noises appear on cold starts and even sometimes at idle with higher cold viscosity ratings. It's certainly easy enough to change out and it's that time of year anyway to change to fresh oil for the winter.