Mercruiser 3.0 135hp. Crank and rods

[Bow4game]

Okay so my luck sucks I guess. I bought a used motor and it had been overheated and cooked. But I’m still running it. Only 90psi on all cylinders and it’s been pulling great. Some how. But it’s worn out. So I bought a new 2019 3.0 for cheap no warranty. Well prime luck I have it started making noise within 2 hours. Took it apart it had started eating a rod bearing. I found the problem the factory where the block was made never drilled out the number one oil hole all the way that runs to the main bearing and to rod bearing number 1. So took crank to machine shop had it polished new bearings and it ate them again. I think I’m gonna get a new crank but I can’t find one for this new of engine. Anyone know if an older one piece swap crank will work. Also I have the narrow rod bearings. If I get an older crank do I go to the wide rod bearings?

 

[alldodge]

The crank and rods are NLA, and I would not try to put an old crank/rods in a newer block

Unless you know what caused the second set of bearings to get eaten, I would look for the cause first before going further

Do you know?

 

[Bow4game]

The crank and rods are NLA, and I would not try to put an old crank/rods in a newer block

Unless you know what caused the second set of bearings to get eaten, I would look for the cause first before going further

Do you know?

I have a hint. So I had the journals polished by the machine shop. But there is still a grove in the crank. He said that it will be okay and will just fill with oil. Idk why he wouldn’t just turn it and I run oversized bearings. My rod turned blue from the heat but he said it was not out of shape. But I’m starting to wonder about this guys professionalism.

 

[Bow4game]

You can catch this grove with your fingernail also. To me this seems like a huge no no. But the machine shop said good to go. Opinions? I gauged bearings before installing everything and used assembly lube. I also primed oil pump about 20 min and rotated motor and primed again.

 

[alldodge]

You need a real machine shop, that guy just has a sign up

If its not to far gone, find a machine shop that will turn it. Also have block cleaned to make sure there are no filings in the channels. Also look at the oil pump, may need replacing

 

[Bow4game]

You need a real machine shop, that guy just has a sign up

If its not to far gone, find a machine shop that will turn it. Also have block cleaned to make sure there are no filings in the channels. Also look at the oil pump, may need replacing

I pulled all the plugs and made sure all the oil passages was clear. Also ran brushes down them all to make double sure. The oil pump was still showing 50psi. But no problem to replace it. I just thought when I bought this motor it should last me a good 10 years fishing haha.

 

[alldodge]

Once its fixed it should last you a long time
Some times cheap its really cheap

 

[Bow4game]

Well my old boat motor has two bad detonated pistons and two pistons with broke. Skirts. Still pulling skies lol. Pretty good motors in these light boats. So better idea to have the current crank turned? It’s a scat crank.

 

[Scott06]

Yes turn the crank - but find a competent machine shop first and have them go through it- check the crank and rods. Nothing you can cath your nail on will work .

When you say it was a new 2019 3.0 - new GM marine base engine or a remanufactured by some knucklehead?

 

[Scott Danforth]

you need new rod if it was blue and a new crank

 

[Bow4game]

Yes turn the crank - but find a competent machine shop first and have them go through it- check the crank and rods. Nothing you can cath your nail on will work .

When you say it was a new 2019 3.0 - new GM marine base engine or a remanufactured by some knucklehead?

It was not a gm. It’s an aftermarket 3.0. It has a scat crank in it. Not sure on the manufacture.

 

[Bow4game]

Here is crank groove.

 

[alldodge]

Find a good machine shop and let them inspect the crank and rods. They will be able to advise

 

[Bow4game]

Find a good machine shop and let them inspect the crank and rods. They will be able to advise

Also maybe you may know. Why the narrow rod bearings? The rods are the same size. Just narrow bearings. Also this mother r is 10.5 to 1. I’m thinking about rebuilding it with flat top pistons. It has domed pistons right now. Maybe harder on the rod bearings also? It ran well until it brought it to 3500rpm it lasted about 3 min. And I could hear something was not right.

 

[Rick Stephens]

It was not a gm. It’s an aftermarket 3.0. It has a scat crank in it. Not sure on the manufacture.

I heard there was a korean outfit making 3.0L motors. This one of those?

 

[alldodge]

The older rods are part number 3817T, the newer are 8164T
Tells me there is something different

 

[Bow4game]

I heard there was a korean outfit making 3.0L motors. This one of those?

Not sure the factory this came out of it is from Dallas I believe.

 

[Bow4game]

Not sure the factory this came out of it is from Dallas I believe.

Any ideas why all my rod bearings look like this? Other than one is fried. To high of compression? I checked compression with my gauge and I got 220-225psi....... it does diesel for awhile when shut off with 91 and timing retarded. Cant win for loosing.

 

[alldodge]

Any ideas why all my rod bearings look like this? Other than one is fried. To high of compression? I checked compression with my gauge and I got 220-225psi....... it does diesel for awhile when shut off with 91 and timing retarded. Cant win for loosing.

With compression that high there is liquid in the cylinder. Head is warped so gasket is not sealing or cylinder is cracked and water is leaking in.

When the motor diesels, that's when motor runs in reverse just before it dies and sucks in water. The water can bend rods and break things

The bearing journals are not parallel and flat. Your machine shop stuck it to you pretty good

Right now I would suggest find a shop to do a total rebuild which can be verified it can do the job, or buy a reman from a place like Michigan motors

 

[Scott Danforth]

Here is crank groove.

your crank needs to be reground or replaced.