3.0 motor knockin',....

[Hene]

Hello, '89 OMC 3.0 130 is knocking after 2 hrs of driving. I think it is coming middle of the engine, around crankshaft or camshaft. Removing spark plug lead one by one, there is no difference in sound. Cold engine runs very smooth without any noises, but when idling about 1 minute after cold start, knocking starts. Here is a link for video and sound: https://youtu.be/xw4xiDKlM70

 

[Bondo]

Ayuh,..... Welcome Aboard,.... Pull the valve cover, 'n try adjustin' the valves,....

If it's the crank, a new or rebuilt long block is the way to go,...

 

[alldodge]

Hello, '89 OMC 3.0 130 is knocking after 2 hrs of driving. I think it is coming middle of the engine, around crankshaft or camshaft. Removing spark plug lead one by one, there is no difference in sound. Cold engine runs very smooth without any noises, but when idling about 1 minute after cold start, knocking starts. Here is a link for video and sound: https://youtu.be/xw4xiDKlM70

Howdy

Yep in my opinion that is a con rod knock. Time for a new long block

 

[Hene]

I bought this boat about 4 months ago and engine runs very very smooth. Previous owner did a rebuilt last year. He told me that he replaced bearing etc.. Maybe something went wrong. If i can't find problem from valve train, then i pull the engine out and rebuilt it again.

After buying the boat, I noticed that thermostat is missing, so engine runs quite cool in cold water. I installed a new one and temperature is ok all the time. Do you think this is why the knocking starts? First a little ticking and after 2hrs of ride the situation is getting worse.

What kind of sound water makes in the cylinder? Spark plugs are very clean. Oil color is in very good shape.

 

[alldodge]

Your not going to hear a noise from water in the cylinder other then a miss. If there is a bit to much water the engine stops from hydo lock. For this to happened soon after the rebuild my guess would be it was not rebuilt correctly, or it was bad-aided to get it sold. The thermostat would have caused no harm, and it might have been left out because it was done as cheap as possible to get it sold.

As always just my opinion and adjusting the vales may help as Bondo mentioned

 

[Hene]

I removed valve lifters, because adjusting with manual was impossible. Lifters are jammed. Need to heat and push really hard to get oil away from the lifter. After valve adjusting engine starts better, runs really good and smoother than earlier. I run it about 10 minutes, then take some revs and knocking is back.... Removed cyl 1 spark plug wire and knocking ends.

How stiff lifter usually is when engine is warm?

I opened oil filter and found small amount of metal from it... Bad thing,.

 

[AlphaJustin]

Not saying you did it but mine does/did the same thing on automotive 5w-30 (tried to go cheap once) went back to quicksilver 25w-40 and a quart of Lucas at my oil changes and it hasn't come back since that was 2 years ago. I only use the boat every couple weeks so Lucas coats everything while it's sitting. Of course I never had metal shavings so may not work for you but worth a shot while you shop for a new block?

 

[Hene]

I used 20w50, changed to 15w40 when knocking starts. I forgot to tell this: when we arrived from our last trip, engine runs smooth on idle. When i started it on the next day, it knocks. So knocking does not started during cruise.
I will take lifters again off and disassemble them and clean if there are some dirt inside, maybe they work properly when oil is really hot. If that not help, it is bearing for sure.

 

[alldodge]

opened oil filter and found small amount of metal from it... Bad thing,.

Lifters are not going to help in my opinion and the brand of viscocity of oil is not what did this, you have a spun con rod bearing

 

[Hene]

The engine is now disassembled and I found some major things.
- One piston had skirt cracked off (Maybe source of knocking sound)
- Camshaft worn badly (That was source of metal in filter)
- Exhaust manfold/riser is maybe a scrap. Rust/water stains in exhaust side.

All bearings are in good condition

 

[alldodge]

Oh well I missed a broken skirt, but sure sounds like a new long block

 

[Bondo]

Oh well I missed a broken skirt, but sure sounds like a new long block

Ayuh,..... Or a good used motor outa a rotten hull,....

 

[Hene]

Oh well I missed a broken skirt, but sure sounds like a new long block

I'm going to repair it. Much cheaper than buy a new?

 

[alldodge]

I'm going to repair it. Much cheaper than buy a new?

That's the best way, at least you know how it was rebuilt. Cost about 2K for a long block

 

[Hene]

No Title

Broken skirt is not only problem. I Found play on the wrist pins. Lubrication failure?

 

[alldodge]

The piston pins are press fitted on the con rod and from what I see there appears to be lack of lube. Sure looks like the long block is the way to go, unless your doing the rebuild, then it may be a break even

 

[Hene]

Engine is now repaired. Block cyl borings honed and head machined. Assembled with all new pistons, bearings, oil pump, cam+lifters, new manifold+riser.
20 minutes test run and everything OK. Oil pressure is much better now. Hopefully have many hours without problems. Thanks for help!