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New to me Mustang 940E - Some issues...

6t6cuda

Member
Joined
Feb 13, 2013
Messages
5
Location
Ohio
Hello,

I just bought a 1996 Mustang 940E (Yanmar 4TN82E-S engine). it is in good shape, and tight.

Sorry for the long post but I want to put everything out rather tan going back and forth with "what have you done", "did you try" questions....

It has one problem I am sure is going to bite me big: it smokes A LOT out of the vent tube coming out of the valve cover.

It starts fine, appears to run fine - have not had the chance to do any real work with it yet...

I did a "tune up" this weekend:
1. Replaced the engine oil/filter, added "restore" to see if it would help with rings
2. Replaced the hydro filter
3. Replaced the fuel filter
4. Replaced the air filter - very, very dirty - filter check was popped.

It smokes a bit at start-up (white) out the exhaust but after a short warm up it is clear - but it always smokes (white) out the engine vent tube - this did not change with the "tune up"

Things I know or observed:
1. It has 1300 hours but the meter does not appear to be running now
2. I got it from someone who did not take the best care of equipment - price reflected that (somewhat)
3. Has been and was running real rough when I got it because the low pressure fuel feed (between the feed and the injection pump) was leaking - ran erratically - so the thing was "randomly" fueled for who knows how long.
4. There was a LOT of oil and dirt in the bottom of the engine compartment
5. The vent tube is leaking oil
6. the vent tube smoke is not water - did the mirror test
7. There is substantial pressure on the vent tube
8. It appears to have decent power, but I have not worked it and did not know what it should feel like "new"
9. When I replaced the fuel filter it did have some water in the bottom, about 1/3 full. Also had dirt in the bowl (it is a removable bowl clear filter on this engine).

From my research everything points to rings; but I want to make sure before I tear the engine apart - could it be anything else (simpler)

Few things I do not understand and would like to know:
1. If it was rings would you expect smoke to come out of the breather and the muffler? - it is only coming out of the breather after warmup
2. I know gas engines, but how do you remove the injectors and do a compression / leak down test? - do I need to replace a seal after I pull them? - I don't want to damage them as they are expensive and harder to find than spark plugs... - is there an adapter that I will need to hook up the tester?
3. How do you do an engine RPM drop test on a Diesel? - can you unscrew the injector? - how do you measure RPM w/o a spark signal?

This will be a limited use homeowner machine so it needs to work, but will not be worked all that often and that hard - if I could limp it along for 200-300 hrs that would serve me well...

Thanks to all in advance!
 

apetad

Senior Member
Joined
Jul 24, 2012
Messages
385
Location
Leander, Texas
Occupation
Compact Construction Equipment Sales
You are absolutely bypassing compression gasses past the rings, That's the only way crankcase pressure can be present, MOST of the time when we see these they are also leaking compression into the water jacket, does NOT necessarily go "Both Ways" Open Radiator cap and look for exhaust bubbles / exhaust coming out of radiator. IF SO don't waste anymore time guessing, She needs rebuilt.

Mustang has the adapters to pull the injectors with a slide hammer / or an optional threaded puller, RPM is measured by an electronic diesel rpm sensing tool attached to an unpainted spot on #1 injection line / injectors have both a nozzle "protector" and nozzle "Seal" sometimes stay inside injector bore after injector removed.

SEE if the smoke gets less after running with that "Restore" whatever that is / Sometimes "Lucas oil treatment" reduces the smoke, doesn't fix it though / just helps a little.

Dirty air filters will "Dust" an engine like this in as little as 6 to 8 hours.
 

NCPIPELINE

Senior Member
Joined
Mar 8, 2012
Messages
444
Location
Raleigh, NC
Occupation
The Fixer
:iagree Had a piece of equipment do something similar not to cause horror stories but mine was from a glow plug tip coming dislodged and burning a tiny hole in top of piston.
 

apetad

Senior Member
Joined
Jul 24, 2012
Messages
385
Location
Leander, Texas
Occupation
Compact Construction Equipment Sales
This engine uses a grid heater in the intake manifold, Could be an injector nozzle did the same thing
 
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