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Discussion Starter #1
I have see postings that question injectors that are over 160,000 miles. Mine have 175,000 and this is my question.
How do you determine if the injection pump is just getting weak or if a new set of injectors is warranted? Both my injectors and injectoin pump are original. There is no indication of lose of power, once running, when towing but cold starting is getting harder. Today at 15 degrees it was clear that only one cylinder was firing while the starter was turning this went on for close to 30 seconds of cranking before the others got into the act. Glow plugs were changed less that 5,000 mile just before wenter set in.
Warm starting is fine.
 

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Not quite as simple as this but: Injector pumps often quit completely and injectors die a slow painfull death.
 

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Keep up whatever you are doing! The injection pump will not wear out as fast as the injectors will. The 6.5 pumps are much better than the 6.2 except for the electronics. The 6.2 pumps wear out in the advance piston area. The 6.5 pumps have a steel sleeve. The injectors will erode over time and the fuel coming out will deteriorate from a fine mist when they are new to more of a course stringy spray when they are old. The course fuel is harder to burn and therefore giving you more smoke (unburned fuel) when cold. When you get some temperature in the engine it will light. Just like a camp fire you start with small sticks and once it is going you can throw in logs. The injectors wear out so slowly that you don’t hardly notice it until they are really bad.
 

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Discussion Starter #4
I am familiar with the injuction pump failing because of the FSD dying having replaced 3 of them in this period, Beyond that what are the characteristics of aging rather than failure? Is there a high pressure while cranking test that can be done? Once the pump is spinning at engine speeds I assume it's output pressure would be higher than while cranking if there was any degree of wear.
 

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I agree on the injectors - pull them and have them tested - they can burn holes in your pistons.

Leave the IP, as long as you're not uneasy about it - if you are, pull it and have it tested

I'd also pull the glow plugs and test them, one at a time, particularly if they're not 60G's

If you don't have the DSG gearset, it's high time for a timing chainset, at 175kmi - that will recover power and driveability that you do not realize that you've lost.
 

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I bought one of those ebay pop testers made in India copies of a Bosch tester, for self testing wasn't too much money, works like the Bosch one a member here uses in his shop he demoed to me when I visited him, a little propane torch & pop tester fun for the afternoon (I'm a professional don't try this at home moment) :eek: :eek: look at all that fire :eek: ,

It is probably not suitable for revenue generating work for that if i was in the business I'd want a real Bosh tester, but for determining if I needed a set of injectors or just cleaning, it works well for no more than I use it.
 

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HowieE;1598123; said:
Is there a high pressure while cranking test that can be done? Once the pump is spinning at engine speeds I assume it's output pressure would be higher than while cranking if there was any degree of wear.
The pump does not vary the output PSI with RPM. The pump’s job is to make enough pressure to overcome the injector spring. The biggest problems with these pumps are electrical or seal failure. If it is working don’t mess with it. As mentioned above the injectors can be removed and taken to your local injection shop for testing. You should be able to watch. Keep an eye on the spray pattern and the opening pressure. You also want to hear a crisp pop when the injector fires.
 

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Yep - it's usually the OS, sometimes the Fuel Solenoid that fails - we've had a rash of those, lately.

The OS can be replaced in-frame, the FS needs some tlc from yer local Stanadyne shop.

The TSM freezes, occasionally, also.
 

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gmctd;1598185; said:
The OS can be replaced in-frame, the FS needs some tlc from yer local Stanadyne shop.
I would say both need to be performed by a Syanadyne shop. The optical sensor is fastened to the cam ring. The hold down screw is in an adjustable slot and is adjusted to the proper fuel delivery. If it was changed in the truck you would have to be careful to get the new one installed in the same spot. Not a simple change out.
 

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Prepare yourself for a shock, my friend - do a search here on optical sensor, also the OS 'bump'.

Make sure you're sitting comfortably and relaxed, and - no caffiene ;)
 

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Discussion Starter #11
gmctd

Your last comment is addressed to whom? My original post did not mention the OS or any function of it
 

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Posts 7, 8, 9, and 10 address the three electrical failures that usually result in Stanadyne DS4 Inj Pump replacement - two can be repaired on the engine, one cannot.

Huck is a long-term member, but doesn't often post, here - a search may offer him a different perspective.


Quid pro quo, HowieE............
 

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I'm in the same boat as you are Howie, 180000 miles, all original, no loss of fuel milage, no power loss and truck has never had the exhaust burn so clean since the new downpipe and low restriction air induction. I have a bit of a injection cluck on the pasangers side if I forget to use stantadine fuel treatment. I asked my Standadine injection shop about the cluck and the miles on the injection system. He said the cure for the cluck is the fuel treatment not to worry and keep running the truck till there is some sign of a injection problem like smoke or fuel milage, cold start not firing. Going back to my days at pre employed Heavy Equip mech. trade school, IIRC there wasn't big concern about engine damge from poor injectors on indirect injection engines like there was on direct injection engines. The indirect engines are much more forgiving.
 

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Tracy;1598872; said:
Going back to my days at pre employed Heavy Equip mech. trade school, IIRC there wasn't big concern about engine damge from poor injectors on indirect injection engines like there was on direct injection engines. The indirect engines are much more forgiving.
I have to sort of argue the point about engine damage, guys...

I've had about a dozen people tell me horror stories about how they let their injectors get so bad that they 'leaked' or 'dribbled' after shut-down, and how the rings subsequently 'grabbed a wall' and scored a cylinder badly. Result? New engine (which might not be so bad, considering the new AMG builds).

I talked with a couple GM techs I trust and got confirmation of this. One of them quoted the recommended interval of 100K miles, and said this was for a reason. He also talked about what happens to the pistons if the injector 'freezes' and 'pees' a stream (rather than a mist) of fuel onto the piston while running. Didn't sound pretty.

Long story short - I just ordered new injectors. Mine are 'way overdue, and they're a lot cheaper than a new engine.

Like the FRAM commercial ... pay me now, or pay me later.
 

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If you figure the cost of these injectors at discount parts prices and the fuel savings you have by changing them at 100k the cost is almost nothing doing the work yourself.

Consider 150,000 miles your 50,000 miles over.

A conservative mileage decrease of 1 mpg at average of 16 to 17 mpg.

Average to 6% loss.

50,000 miles at 16.5 mpg is roughly 3000 gallons at 6% or 180 gallons of fuel wasted.
 

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gmctd;1598745; said:
Prepare yourself for a shock, my friend
I did not say it was impossible, just that it is not as simple as unbolting and installing a new one. The ingenuity of people here is a great thing. That is why I keep coming back. Go ahead and do whatever you want. If you mess it up an exchange pump is the same price either way. :thumb:
 

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My OS swap worked out great.

I will say that it's a good idea to compare timing before and after to see if it's off a bit. If it's off a little in the right direction, well some people are doing that on purpose.
 

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jifaire;1598896; said:
I have to sort of argue the point about engine damage, guys...

I've had about a dozen people tell me horror stories about how they let their injectors get so bad that they 'leaked' or 'dribbled' after shut-down, and how the rings subsequently 'grabbed a wall' and scored a cylinder badly. Result? New engine (which might not be so bad, considering the new AMG builds).

I talked with a couple GM techs I trust and got confirmation of this. One of them quoted the recommended interval of 100K miles, and said this was for a reason. He also talked about what happens to the pistons if the injector 'freezes' and 'pees' a stream (rather than a mist) of fuel onto the piston while running. Didn't sound pretty.

Long story short - I just ordered new injectors. Mine are 'way overdue, and they're a lot cheaper than a new engine.

Like the FRAM commercial ... pay me now, or pay me later.

I think the key is "they let thier injectors get so bad". There were symtoms of worn out injetors that they ignored. Poor cold starts with mis firing, more smoke, reduced fuel milage so on.

Scoring a cylinder is again more prevalent on direct injection engines were the the spray pattern can wash the cylinder and burn any oil on the cylinder walls. Also it can be industry/operator related, as in generator or power plant engines that may need to go 0 to 100% load, the govenors on these engines give little or no feed back to the operator and there is no real feel for the load on the engine so if there is a bad injector it may run for days weeks before it is noticed, sometimes to late. Not saying it can't happen or hasn't happened to a 6.5 but most likely caused by the operator ignorance.
 

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Tracy;1599174; said:
I think the key is "they let thier injectors get so bad". There were symtoms of worn out injetors that they ignored. Poor cold starts with mis firing, more smoke, reduced fuel milage so on.

...

Not saying it can't happen or hasn't happened to a 6.5 but most likely caused by the operator ignorance.
Yep, you said it, Tracy ... the one guy that I KNOW this happened to is the chapest basta** in the world ... he didn't change 'em just because they cost too much, and figured they were still doing OK. At about 300,000 km, one of them suddenly stuck ... didn't shut properly (I assume this means a crappy spray pattern). He was on the job at the time, and so he drove it for 2 days in the boonies so he could get to the weekend. Didn't make it. In less than a week, no engine.

I figure I'm gonna change mine before that happens.
 

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Acutally, I decided to pull mine out this afternoon on the passenger side, I have the inner fender out to put the pyro in, then figured I should replace the heater hoses while I was there, then I figured I really should replace the original water pump, and of course If I'm doing that I should put in the dual T stats, and if I'm that close really should replace harmonic balancer and maybe the timing chain. The wastegate bushings are worn on the turbo so while that is off never a better time to change the injectors or at least have them tested. Its hard to know were to stop on an old truck. LOL
 
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