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autotech41 (Automotive) (OP)
1 Jul 10 15:11
we have a 4-53 diesel engine i am not much of a diesel person, but this thing has a miss/ low power it is in a log skidder, i was wondering how to test the injectors this is what the owner suspects.

MikeHalloran (Mechanical)
1 Jul 10 18:45
You got elected to do, what?
Agree with the owner that the injectors need testing?
Get on the phone and call a Diesel person?
Figure out some cheap way to avoid an expensive test?

 

Mike Halloran
Pembroke Pines, FL, USA

TrackRat (Automotive)
1 Jul 10 19:46
Some Diesel service shops have injector test rigs. Some Bosche service centers can do this also.
TheBlacksmith (Mechanical)
2 Jul 10 6:43
The injectors have to come out and be tested with the appropriate test rig.  Get a manual, the injectors aren't that hard to remove, but you can mess up the timing (which is essentially controlled by the "lash" between the injector and rocker arm) when you reinstall them.  Find a qualified shop to test them.
autotech41 (Automotive) (OP)
2 Jul 10 9:22
Thank everyone will save me some time owner has anextra blown engine we may just replace injectors with the good ones in blown engine.
TheBlacksmith (Mechanical)
2 Jul 10 9:34
How do you know if the injectors in the blown engine are good?  How do you know the injectors in the skidder are bad?  But it's your time, go on an "Easter egg hunt" if you want.
patdaly (Mechanical)
2 Jul 10 13:01
Autotech, how will you know that the Injector you pull from the blown engine is not the reason the engine blew?

Diesels are funny animals, do it right.
CH5OH (Petroleum)
2 Jul 10 14:19
autotech41,
I looked on the internet for a picture of the engine
It looks like a two stroke engine so here is your trouble:
first, leave the injectors in place, nothing wrong with them
what gives you less power output is lack of combustion temperature, caused by lack of air . Either there are some piston rings broke or the scavenging ports are fouled (from running long time on idle speed).you can check your piston rings two ways:
1.while running the engine, block the carter dearator pipe with your hand, if there is pressure build up, you have to pull the pistons to renew the piston rings.
2.on each cylinder somewhat in the middle of the height,you should find little covers, held in place by four screws.
behind it you find the scavenging box (air manifold)and the scavenging ports in the cylinder.check if they are clean and rotate the crankshaft to inspect the condition of the piston rings through the ports.
good luck
rmw (Mechanical)
5 Jul 10 18:24
CH50H,

You usually give some great advice on this site, but if you had to look on the Internet to find out that this is a 2 stroke engine, with all due respect, I question the advice you gave.

Based on the OP's description of the original problem, I think he/she has been given the correct advice to get the injectors to a qualified Diesel Injection shop which can test them and fix them if necessary.

Sorry, I have dealt with quite a few Detroit's in my life and I haven't met the carter deaerator pipe yet, or maybe if I did, I didn't know it by that name.  What are you referring to?  If the air box drains, they always have pressure on them since it is a blown engine (no pun intended based on the OP's subsequent post).

And Autotech41, when you have the injectors put back in the engine, get someone who knows how to "run the rack" on a Detroit to set the valve lash on the injectors and the exhaust valves and set the fuel racks on the injectors.  It is touchy and tedious.  If are as inexperienced as you state with diesels, it is no process for you to try to attempt.

I'll give one more piece of advice.  Change your fuel filters before making the final decision to remove the injectors and take them to a shop.  If it still misses and lacks power, then go for the injector check.  I think you will be pleased with the results.

rmw



 
CH5OH (Petroleum)
6 Jul 10 14:23
rmw,
since you question my advice here some explanation:
first of all, as a former chief engineer,I had lots of expierience with diesel engines and there related operating troubles, everything ranging from 10pk to 10000pk.everything between 100rpm and 1800rpm,2stroke,4stroke, different setups of turbo/blower charger,...
the detroits I have overhauled were V8 and V12 blocks
they were two strokes and charged with a roots blower.
the injectors were combined units (fuel pump and injector as a single component.Despite having worked so many hours on diesel engines,I can't say I know all ever manufactured diesels, therefore I looked for a picture.here are some typical values on component wear and there reflection
on engine performance:
injectors:wear on needles and seats,2000-4000hr,leaking injectors don't have to much impact on power output,improper combustion causes smoke and raised cylinder exhaust temperatures
fuel pumps:wear on helix and pump outlet ports,15000-25000hr,the helix on the plunjer and the outlet ports on the pump barrel defines the amount of fuel being injected.wear in the form of cavitation marks in this area causes the plunjer to seal off later, so the injection timing is retarded,this causes a drop in combustion pressure and decrease in engine power.
piston rings:they pass openings in the cylinder bore (air inlet ports) and sometimes brake.because its not a running time related failure, they need to be inspected on a regular base.since the OP mentioned the use of the diesel engine in a log skidder (I assume this is a machine to chop blocks of wood), before you hit the maintenance interval for pump plunjer/barrel (2 years continuous operation), you are a few years down the road.further,lack of power as a result of lack of compression is easier to detect without specialised equipment than as a result of fuel pump wear.(because of a bigger drop in engine performance)
see attachment for air box inspection covers
CH5OH (Petroleum)
6 Jul 10 14:30
sorry read fuel pump inlet ports
rmw (Mechanical)
6 Jul 10 20:52
CH5OH,

Thanks for the explanation; interesting.

Detroit's are bad about the oil rings sticking and causing them to blubber due to oil getting past the rings and into the air box.  This will cause a lot of smoke on load changes and especially after idling for a while when a lot of that oil is suddenly picked up and carried into the cylinders through the ports.  But it does tend to wash the air box and keep it clean.

Some people have tried capturing the oil dripping out of the air box drains and reusing it, but too much fine dirt gets through the air filters and contaminates it.  They paid a price for this foolish practice.  Detroit had to put a warning in the manual against the practice.  Leaking blower seals can contribute to the mess too.

Detroit's typically have a gear driven gear tooth fuel pump that is a transfer pump that merely feeds the rail that supplies the injectors.  It is relatively low pressure, with the injection pressure being raised by the plunger action alone.

The injectors do have an inlet screen that can become plugged if good fuel "hygiene" is not practiced.  I am suspicious of filter changes in the woods without getting some of the dust and sawdust into the filters and the screens.

Air box cover gaskets are notorious for leaking too, but then with all the places that a Detroit can find to leak, who would notice.

I could go look in the manual and check but I won't but the 6's and 8's that I am most familiar with were rated to use one gallon of oil every 10 hrs of operation and they did it religiously.

A skidder is a machine that drags trees through the woods either to a chipper or to a collection point where they can be put on trailers or otherwise removed from the woods.  It works near the saws and in dust and mud.  Not a clean environment at all.  Abuse of all sorts is this machines constant companion.

The Detroit is a rugged and reliable engine in spite of its foibles and oil leaks and drips horror stories.  The 4-53 was a popular pickup truck conversion engine some years ago and may still be.

You still didn't tell me what the carter deaerator tube was.  I would be interested in learning what that is.  Can you post a picture?

rmw
CH5OH (Petroleum)
7 Jul 10 13:08
carter dearator:
since the pistons in an engine compressing air and at combustion see some rather high pressure on top of them, they need some provision to prevent pressure build up in the carter,due to some leakage passing compression rings.on bigger marine engines, this is done with a vent pipe, connected to the carter.on car engines and the like, the pressure is vented through the cylinder head drain channels and via a hose from the cylinder head cover to the air filter.
TDIMeister (Automotive)
7 Jul 10 16:48
In the Diesel locomotive world I've worked in, I think the part CH5OH refers to is called in our circles a coalescer.
CH5OH (Petroleum)
7 Jul 10 17:24
de-airator, breather, vent,...
it might be not there on a detroit, since it's a two stroke.
coalescer is a filter device, no?

crankcase breather is the proper english term i guess
TDIMeister (Automotive)
7 Jul 10 17:42
Yes.  

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