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Discussion Starter #1
Just wondering - does a 7.3L diesel need a tune-up like any other truck or car? If so, what needs to be done? My husband has been having some problems, usually after filling up with fuel. His truck runs rough for awhile and then seems to be ok. Thanks for any help!
 
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Hey...welcome to the site.

There aren't points and/or plugs that he has to worry about. However...these diesels really run good on clean, fresh oil. When was the last time he changed the oil?

Also...give the fuel filter a check. Make sure that it appears clean. If its a dark black or a dark grey...it might need to be changed as well.

Have him start there. If he still has problems...let us know and we'll get it figured out.

Dave
 

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Welcome to the site. And there's no such thing as a stupid question.
 

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Discussion Starter #4
I'm just the wife who has the job of finding out all this stuff. :shrug: Sometimes to me, it sounds like a stupid question, but I just gotta ask anyway. Thanks for your help!
 

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:welcome2:

While there is no Scheduled tune up interval, many older engines with higher miles (150,000 plus) can benefit from having their injectors re-shimmed. This is similar to adjusting the valves (which these engines do NOT need), but is done to the injeectors while they are in the vehicle.

Due to difficulty in obtaining new shims, this is a dealer-only service at this time. It is also only suggested if the engine starts hard, or misfires when COLD, but gets better as the engine warms for a few minutes. Previously, you just replaced all the injectors.

We don't know where you are, but fuel quality can have an impact on how well any modern diesel runs. Could his problem be related to a praticular station or brand of fuel?
 

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John the shimming is just a hack patch for a bad set of injectors we are finding it doesnt help much more than delay the new injector purchase more than a few months

In fact the warrenty rep for Laidlaw school bus company has left explicit instructions to never shim injectors on a laidlaw bus under warrenty just put new ones in

Doc
 

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Docluv2577 said:
John the shimming is just a hack patch for a bad set of injectors we are finding it doesnt help much more than delay the new injector purchase more than a few months
Doc
Doc,

Apparenty there is some confusion about what the "rebuilders" actually do with the core injectors.

Do you know?

- Inspect the coils, reuse if they pass an ohms check
- Clean the nozzle and pintle
- Re-shim the injector

Now, if a diagnostic for the injectors is sone improperly, and the problem is NOT completely related to cold start-up misfires, then yes, you are chasing your tail by shimming them.

If, on the other hand, that IS the situation you have, you are dumping thousands of dollars for NOTHING with a set of new injectors, and risking damaging the HP oil seals on every new injeector you install.
 

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of the 20 or sets of injectors we have reshimmed for a cold startup misfire the reshim cured the problem when completed .. then 3-4 months later the bus is back again same prolblem.. and even Navistars engine reliablity group has stated that they are seeing most of the reshimmed injectors fail again in a few months time

Doc
 

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A local dealer has been shimming injectors for years, they have done more sets that I can count, and the customers could not be happier with the results.

You are correct however, that shimming is NOT a "cure all" for a misfiring injector. If it has internal problems, or the ECM needs updating, shimming is nothing more than a band-aid.
 
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