Longevity of a Lehman 4D61

[davidfarrington]

Can anyone tell me about the longevity (In hours) of a Ford Lehman 4D61? Thank you.

[Dennis.G]

Well maintained diesel, maybe 15,000 hours between rebuilds. Can rebuild several times if done right. Poorly maintained, can turn to junk 1st year.

[Dockhead]

How long is a piece of string? It depends entirely on how the engine has been used and stored, maintenance, mishaps, etc., etc., etc. From 20 hours (literally) to 20 000 hours or more -- it all depends.

[leftbrainstuff]

The factors affecting the longevity include:
1) Ratio of starts to hours. Lots of short runs at low load with the engine cold will cut useful life by up to 90%
2) Quality of oil. The oil will become black as it picks up carbon as a natural by product of combustion blowby. Left too long those byproducts become abrasive scoring bearings and bores.

Good tests for determining the condition of an engine with no provenance include:

1) oil particulate and chemical composition test. Any heavy mech maintainer can organize this for a few hundred dollars. Back to back tests over time are most useful but a single data point before an oil change is useful.
2) compression leakdown test. Any issues with scoring, damaged pistons, valve seats etc will be obvious.

I also look for the general cleanliness, filter changes and spares onboard. This will give you a first indication of how well maintained the powertrain is.

Does it start, run and not blow too much smoke when warm?

[davidfarrington]

Thank you all. How do I remove a post?

[Sailmonkey]

Originally Posted by davidfarrington

Thank you all. How do I remove a post?

You don't, it is maintained in perpetuity for sake of a knowledge base.