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Krob7

AMI 370

Question

Hi guys.

I have a 2005 Mack Granite roll-off truck that recently spun a rod bearing at 400,000 miles. It has a AMI 370, Serial # 5k0232. We tried to replace the rod bearings only and it lasted about 20 miles before it spun again (we think the same one #6).

Not sure we really want to attempt a full rebuild in our current shop (its not an engine shop... pretty dirty)

My question is, what is the best option, in your guys opinion to proceed. The truck is not in bad shape and I plan to keep it for a few more years at least. 

Long block reman? 

Used engine complete? Will any AMI engine work or does it need to be 370hp rated?

We are a small family owned business and I am trying to get some options before we proceed.

Thank you for any input 

 

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1 hour ago, Krob7 said:

Hi guys.

I have a 2005 Mack Granite roll-off truck that recently spun a rod bearing at 400,000 miles. It has a AMI 370, Serial # 5k0232. We tried to replace the rod bearings only and it lasted about 20 miles before it spun again (we think the same one #6).

Not sure we really want to attempt a full rebuild in our current shop (its not an engine shop... pretty dirty)

My question is, what is the best option, in your guys opinion to proceed. The truck is not in bad shape and I plan to keep it for a few more years at least. 

Long block reman? 

Used engine complete? Will any AMI engine work or does it need to be 370hp rated?

We are a small family owned business and I am trying to get some options before we proceed.

Thank you for any input 

 

When you "spin" a rod bearing it typically damages the crankshaft journal the bearing rotates around. Given your replacement bearing only lasted a very short time, this I'm afraid is the case here. The crankshaft will require removal and machine shop work require expensive equipment.

Your best and quickest route would be to replace the engine either complete, or long block, reutilizing many parts on your existing engine. You could install a short block also but that is going to take more time than a long block to dress up for reinstallation into your chassis.

You are looking at a pretty fair sum to get back operational regardless. If time is of the essence, I would look for a salvage engine which is the quickest route and there are good ones out there. I can't vouch for upping the horsepower rating as the platform is much too modern for my antiquated thought processes.

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Upping  or going down on power requires a reflash on the ECM to run well, stick with your rated power.

Edited by 41chevy

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If I had the time and a shop to work in I would put in a reman crank and proper sized bearings along with a new oil pump,flush all the oil ports to be sure they are free of trash. you can put in new rings if you want and save the trouble of doing it later. All so are you sure the bearing cap you changed went back on in the same position it came off, because of machining tolerances they can bind in the wrong position and wipe the bearing. It is a lot of work but like you said you are a small family  business ,and paying a shop 10 grand  for a used motor and install is a stiff nut to crack,when you can lay on your back and get dirty for a few days  . Don't know where you are  but look for a place like this for reman parts.

https://www.capitalremanexchange.com/parts/

https://www.ebay.com/itm/2006-Mack-AMI-Diesel-Engine-Serial-6B1958-Family-6MKXH11-9V65-11-9-400HP/323812564304?hash=item4b64bb9d50:g:Z0EAAOSwyAVc2bgM

Edited by gxbxc

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43 minutes ago, gxbxc said:

If I had the time and a shop to work in I would put in a reman crank and proper sized bearings along with a new oil pump,flush all the oil ports to be sure they are free of trash. you can put in new rings if you want and save the trouble of doing it later. All so are you sure the bearing cap you changed went back on in the same position it came off, because of machining tolerances they can bind in the wrong position and wipe the bearing. It is a lot of work but like you said you are a small family  business ,and paying a shop 10 grand  for a used motor and install is a stiff nut to crack,when you can lay on your back and get dirty for a few days  . Don't know where you are  but look for a place like this for reman parts.

https://www.capitalremanexchange.com/parts/

https://www.ebay.com/itm/2006-Mack-AMI-Diesel-Engine-Serial-6B1958-Family-6MKXH11-9V65-11-9-400HP/323812564304?hash=item4b64bb9d50:g:Z0EAAOSwyAVc2bgM

But if you don't install a reman or replacement connecting rod on that journal the problem very likely will reappear. Usually the rod journal is beat out of round with a spun bearing if allowed to run and knock.

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Search military surplus for a new motor. They are somewhat easy to find. Uncle Sam is dumping his supply. Try to stay away from 300 HP range, they have an older style smaller cooling pkg. you’ll have to do more conversions. 

Edited by Mack Technician
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