E7 engine ruined after 9hrs rebuild - trying to understand why

[Okiki Olufokunbi]

On ‎6‎/‎10‎/‎2017 at 3:30 AM, Hobert62 said:

Just a idea ..... But if this is the first they seen coated bearings is it possibles they put it together without assembly lube?    That could maybe explain all the bearings looking like this???  Maybe something this simple??  

Thanks for the feedback. They used lube oil, and not any specialized assembly lube.

[Okiki Olufokunbi]

18 hours ago, GreenGiant2 said:

Could the new block had the oil galleys full of crap and got pumped to bearings?

It is very possible. I was not onsite, and cannot vouch for how clean the replacement block was. I was told it was cleaned, but as one of the other poster's mentioned, clean is relative, depending on which part of the world one is. Not as excuse though, it could have been the problem

 

[Okiki Olufokunbi]

I appreciate everyone's input. I do have an update.

After the techs saw the scarring on the main journal that fed oil to the #2 rod journal,  they decided to have the oil pump checked out at another shop. As of now, the rebuilt motor has non coated bearings in it, a serviced oil pump system and a replacement crankshaft. The oil pressure on cold start of the rebuilt engine is now 30 psig instead of 60 psig, which to me is really strange . This can suggest an oil flow restriction issue, or a bearing journal size mismatch ( I don't know if this mismatch can really happen though). But the engine has gone through three 3 hour run on idle operations ( 9 hrs total) , and no reported problems.

It is rather frustrating that no main failure cause could be determined for this engine failure;  but it seems to be more oil supply related,  or an installation problem, rather than a material of construction issue. But I do feel that the coated bearing will be more prone to initial distress than the non coated ones, for the same amount of oil starvation, because I feel the PTFE based coating may be more prone to cold flow and  initially and flake off at a lower temperature than none coated ones. But regardless, oil starvation is bad, period.

  Does anyone know if there is an online version of the mack E7 PLN manual available, and where to obtain one? The paper manual one I have is with the Truck in Africa, and I need to really understand the manufacturer designs and specs on these engines, as there are more E7 PLNs added to the fleet.

 

Thank you all, and I will provide additional updates if there are any,