I've searched but can't get any definite answers to my problem. I have a 95 3500 6.5tb with the 97 cooling upgrades. My problem is the truck gets terrible mileage (About 10mpg on a good day) and if I have any load on it it will barely do 55 up any grade, usually 45. I have replaced the fuel filter twice but no change. I cut the exhaust off from the end of the downpipe so now it has no cat or muffler. Just straight balls out! It is still a diesel sucking turd!(No change) It does not smoke at all unless I put my foot to the floor, then it will blow some black smoke. (But not that excessive from what I read) It starts fine in hot or cold and seems to run great other than the fact that I could use my fuel gauge as a speedo! (It moves faster) I thought maybe timing or plugged injectors and I have access to a scan tool reader. If it is timing is there any guide to timing these engines? I don't want to go "pay some diesel expert" as if I had the money to pay for a diesel mechanic I would have bought a D-Max. Plus if you give a man a fish you feed him for a day, teach him to fish, feed him for life. I don't want to keep taking my rig to anybody each time something goes wrong, thats why i'm here!:ro)
The only other diesels in my price range are old Fords and that is not a option. (Rather push my Chevy)

How much load up a grade? How much grade.

I'm getting about 11 mpg with mine, (but it's a bus with a 4.10 rear & pushes A LOT of air...)

May want to check out FAQ's... several listings about turbos can be found there.

For a complete check out of your engine, check out the diagnostic checklist sticky at the top of the forum page. Most times when you've reached the bottom of the list, you've check most of the common failure points. If not, post back the information, and we can point you where to go from there.

Also, is your service engine light on?

Click below for the three most popular "newbie" threads. Welcome to forum a must for new readers/posters. Do you have a tach? If so, what is your rpm's at 55 or 65? Just checking to see if your TCC is locking up as it should.

Put some guages on it and see what the boost and EGT are actually doing. Guages are something that every diesel truck should have anyways.

Put some guages on it and see what the boost and EGT are actually doing. Guages are something that every diesel truck should have anyways.

Sorry,Forgot to mention I do have gauges. The boost is around 7psi. The 10mpg I get with absolutely nothing on the rig. When it is loaded up it gets even worse but I'm not sure how bad as I don't l want to know! I don't tow anything with it right now because of this and at 10mpg (Or less) unloaded, I don't want to drive it at all unfortunately I have to get to work and back.:(

How much load up a grade? How much grade.


3500 lbs for load. Grade= anything that is not flat.


I'm getting about 11 mpg with mine, (but it's a bus with a 4.10 rear & pushes A LOT of air...)

Wanna trade? Gets better mileage and more room!


Also, is your service engine light on?


Nope!

At idle, do you have a lot of air coming out of your oil fill?

At idle, do you have a lot of air coming out of your oil fill?

I'm not sure if it is a lot. (Used to gassers) If I pull the dipstick there is some blowing out but at the fill it is not as noticeable although there is some blow by. I know diesels have some blow by but not sure what is considered excessive. If I check the compression what should it be range wize? (Good---Bad)

If your CDR is working properly, there should really not be anything coming out of your oil fill (the big unscrewy thing, not the stick ;) ) May want to read up on CDR link in FAQ's. Even if the CDR is working properly, if the blow by is too great, it won't be able to injest the amount of air that is blowing by.

Compression should be around 400 psi on all clyinders, and all clyinders close in reading too.

If your CDR is working properly, there should really not be anything coming out of your oil fill (the big unscrewy thing, not the stick ;) ) May want to read up on CDR link in FAQ's. Even if the CDR is working properly, if the blow by is too great, it won't be able to injest the amount of air that is blowing by.

Compression should be around 400 psi on all clyinders, and all clyinders close in reading too.

Thank you! I will check the compression as there is some that comes out the dipstick. The truck actually had chrome breathers on the fill and where the CDR was. I replaced this back to stock but did drive it for a little with the breathers, still was a fuel sucking turd! I will check the FAQ's. If it is low compression are these engines easy to just re-ring?(Drop pan, re-ring?) Or is it a pull job?

How much boost do you run empty at a given speed, what is your egt at that speed. Mine with 4.10's runs around 2-2.5lbs of boost and about 400-425F EGT at 55(about 1900 RPM's) on a 90F day. Check your trans and make sure you torque converter is locking up and holding. Check for blowby by pulling the CDR outlet out at the turbo intake(lot of blow-by at idle is really bad, small steady puffs seams to be normal). Pull the air intake tube off at the turbo and see how much oil is in the turbo intake. Sounds like you old engine may be getting tired, or you have really bad injectors. The trans is a good place to check as well.

How much boost do you run empty at a given speed, what is your egt at that speed. Mine with 4.10's runs around 2-2.5lbs of boost and about 400-425F EGT at 55(about 1900 RPM's) on a 90F day. Check your trans and make sure you torque converter is locking up and holding. Check for blowby by pulling the CDR outlet out at the turbo intake(lot of blow-by at idle is really bad, small steady puffs seams to be normal). Pull the air intake tube off at the turbo and see how much oil is in the turbo intake. Sounds like you old engine may be getting tired, or you have really bad injectors. The trans is a good place to check as well.

I don't know what the gearing is but mine runs about the same as yours if I remember correct. 2-3lb at 55 (about 1800 rpm?) and about 400F (? if I remember) on absolutely flat ground. If I go up a hill everything goes up. It will maintain 65 on a 4-5% grade empty but that is floored with 7-8 lbs of boost and I think about 900f EGT (Post turbo) Can't remember rpm's. If I load it with my 3000 lb camper and if it is a steep grade like say 5% (Actually anything over 3%) I would be lucky to do 40mph (More like 30mph) and the temps go up. (No more than 1100f if I remember correct)
One thing though the engine temp when loaded has gotten up to 230f once or twice scareing me. Each time the fan did not seem to kick in until I pulled over. Then I could hear it roar and I would bring the RPMs up and the engine would cool to about 195. Take off driving and the process would repeat. I believe I need a lower engaging fan clutch and this is not related to my mileage/power. (Although it may be?)
Other than the crappy mileage and low power it seems to run fine!
Oh and there is not to much oil in the turbo inlet. Just a little. When I pull the CDR there is some puffs but not a lot. (Small puffs as you say)

*IF* your tach is accurate, and not had a replace alternator, then double check those RPM's. Sounds a little off. in a 1 ton, you should have 4.10 rear..... double check RPO codes.

Have you checked the supply pump and air filter?

Have you checked the supply pump and air filter?

And again, check your air filter, Tho I work in construction sites, I'm changing mine about every 3-4 weeks in the summer months, I would have never believed it, changing the air filter so often, I notice the lost in power every time cruising on the highway.

Air filter is a good point, but building 7# of boost, sounds like things are running along okay.

Just for kicks the other day, while working on my veggie project, I had the engine running and stuck my fist in the the intake hose of the air filter....boy of boy, does that ever give you an appreciation for just how much air this buggers use.

Your EGT's are a little higher than mine(I measure pre-turbo not post turbo), but your heating seems odd. I've towed some cars for people(total weight of trailer around 4,000lbs) and had no problem accelerating up hills at 55(yes steep grades just not very long though) EGT's will go up to around 1050F-1100F max(floored and loaded). I know my power was getting down some and my air filter was the culprit(13,000 miles on my K&N dusty conditions:o: ), but the boost dropped off to around 6-6.5 max. Not sure as to what to tell you next, possibly change out the turbo downpipe to a larger one. I know my truck was pretty gutless until I did the downpipe(night and day difference), really helped out EGT's and power. Also cooled off the engine temps. Make certain your supply pressure isn't dropping off under load. Your temps could be helped, the d-max fan that I got from ssdiesel kicks in around 200-205(a little to soon actually).

Have you checked the supply pump and air filter?

Yah it is brand new! I ordered a down pipe recently and have it in hand but need to put it in. The next thing is the D-max fan/clutch assy. I stated 1800rpm at 55mph earlier it is actually about 1900rpm now that I looked closely yesterday. The power is one thing I actually don't care as much as my lousy mileage running empty. I did notice some vacumm on the fuel cap and loosened it to see if any diff but there was none.

I know doing the xhaust on my suburban made a huge dirrerence, doesn't even drive like the same truck since doing it. I hope it helps out. Have you tryed running a good cleaner through the fuel system. Mine has benefited greatly from running LUCAS upper cylinder lubricant in every tank(14 up to 17-18 on milage). It is not that expensive and is available at ADVANCE and NAPA auto parts.

two things jump out at me as possible causes...

Injectors and timing chain.

Injectors DO wear out. They will stop atomizing fuel as well, causing power loss, and some extra smoke, but not really excessive.

Timing chain stretch will retard the valves and injection event. This will Kill power, and milage will go in the tank as well.

How many mile on the injectors and timing chain?

Tim

Good point cowracer. Injectors get weak with age, opening pressure drops, atomization goes to snot and mileage/overall performance suffers as well.

As far as the timing chain goes, advancing the pump will only restore your injection timing, you will still have late valve timing.
Myself and several others here have attested to the improved performance after replacing an old timing set.

The motor has 140,000 on it. As far as I know the injectors have not been replaced. I know that you can check the injectors with a ohmeter but can you check with a thermal gun (laser) on each exhaust port? If so would the exhaust be hotter or cooler on a bad one? (Cooler cuz it ain't burning or hotter cuz its burning out the exhaust and not cyclinder?)
I will plan on changing the timing chain just in case.

You check the glowplugs with an ohm meter):h

Yeah! You check injectors with a dipstick!:lol: :iamwithst

Tim

seriously, though...

the injectors are probably shot. No way to easily check them. Replacing them is easy, and figure about $35 a pop. I'd bet real money you will se a BIG difference with new injectors

Tim

Yeah! You check injectors with a dipstick!:lol: :iamwithst

Tim

You mean when you go "hey, how is my oil pan getting more full instead of burning a little oil?" ???????

You mean when you go "hey, how is my oil pan getting more full instead of burning a little oil?" ???????

Funny you say that as I notice that it does not ever seem to use oil even though I have some obvious drips? Might not be so funny in my case! Looks like i'll just plan on changing them also and be done with it. I'll check the compression first and go from there. If low, pull motor and go thru. If OK then replace injectors and timing chain. (Maybe put in gear set?)
Thanks you guys. You have helped out a lot. Glad I found this place.

If budget is tight, and you have some time...you can pull the injectors and have them tested at a fuel shop. Cheaper than whole new set... but if original, might not be a bad investment. In your case, just for kicks, you might want to have them tested before ruling out anything else, that may be more expensive.

If budget is tight, and you have some time...you can pull the injectors and have them tested at a fuel shop. Cheaper than whole new set... but if original, might not be a bad investment. In your case, just for kicks, you might want to have them tested before ruling out anything else, that may be more expensive.

Thanks! Unfortunately my budget is always tight!:( I seen a full set on ebay for $225 which is the cheapest i've seen yet. Is there any good/bad brand of injectors? I don't want to find out after I buy some that they are chinese pot metal or something like that and only last 3 months.

One other thing. I see that there are rebuilt injectors that you can buy, if so where can one get the rebuild kit? If someone is rebuilding them then there must be some parts somewhere.

One other thing. I see that there are rebuilt injectors that you can buy, if so where can one get the rebuild kit? If someone is rebuilding them then there must be some parts somewhere.

Rebuilding injectors is kinda like working on a T.V.

Its pretty straight forward, but you need $10,000 worth of test equipment to do it.

best leave it to the pros

Tim

Rebuilding injectors is kinda like working on a T.V.

Its pretty straight forward, but you need $10,000 worth of test equipment to do it.

best leave it to the pros

Tim

I usually work on my own TV also!:) Can't imagine it would take 10 grand of test equipment.(I guess if you want to thoroughly test it!) Replace o-rings, seals, whatever goes bad and put in truck. Unless there is some adjustment or calibration involved I don't see a need for testing. Replace bad parts with good and done! Test in truck! Anybody have a breakdown of a injector? Or better yet any pro's know what typically goes wrong with the injectors and/or what gets replaced in a rebuild process?
Diesels always seem to cost more for everything even though they are a much simpler motor than gassers. I find out when I dig more there is always a simpler (and cheaper) way than taking it to the pro's! No disrespect meant by the way!

Well, when rebuilding anything you need to know what is bad in order to repalce it. So in the case on an injector, you need a flow bench to know what the injector is flowing in the terms of the spray pattern and flow rate under pressure and you need precision measuring tools. Possibly an optical comparitor, which is $15,000.00, or other assorted micrometers, calipers, pin gauges, etc. Then, you need to know the proper tolerance in the injector for the most inportant part, the pintle valve which is very delicate and has to be perfect or the spray-mist will be ineffective for proper combustion.

There is more than just a "rebuild kit", unfortunatly. Also, the spring inside needs to be checked for proper tension and spring coefficient (The "K" value).

Well, when rebuilding anything you need to know what is bad in order to repalce it. So in the case on an injector, you need a flow bench to know what the injector is flowing in the terms of the spray pattern and flow rate under pressure and you need precision measuring tools. Possibly an optical comparitor, which is $15,000.00, or other assorted micrometers, calipers, pin gauges, etc. Then, you need to know the proper tolerance in the injector for the most inportant part, the pintle valve which is very delicate and has to be perfect or the spray-mist will be ineffective for proper combustion.

There is more than just a "rebuild kit", unfortunatly. Also, the spring inside needs to be checked for proper tension and spring coefficient (The "K" value).

So is it the pintle valve,spring or injector body itself that goes bad? These things have to be put together on a assembly line and I can't imagine they flow test each one (I could be wrong) but things like the spring tension should be a given if you replace that component with a new one. (that should be the right tension) If the injector body itself gets worn then I can see the need to "adjust" other parts to compensate and then would be the need for a flow test. I guess I'm wondering if on the assembly line they flow test each one or just assemble the new parts and send it down the line.(Maybe quick test to make sure)

I own a old Porsche with CIS injection. It had a bad fuel distributor. They sell rebuilt ones for $500 but no rebuild kit as I was told that it took a very expensive tester to set it up after rebuilding and it was a very delicate task to rebuild. After searching to no avail I tore into it (Carefully) and found certain o-rings,copper gaskets,springs and etc.. inside. I replaced everything I could. At first it leaked like a sieve (Did not keep it absolutely clean). I pulled it apart and tried again with success. Been running fine for years now.
Like I said I don't know jack but I would like to be enlightened. I guess I need to find a breakdown on a injector and study this more thoroughly, but I defintely would like to know the process of rebuilding.

As best I know, the tips wear out and the pintle springs can "relax". It is my understanding (never done, not a diesel injection tech!) that the pintle lift and opening pressure should be adjusted/verified prior to installation. This ensures that all injectors "pop" equally and results in a smoother running and possibly more powerful engine. That is kinda the point of replacing / rebuilding injectors, as well as "freshening" the spray pattern...:rolleyes:

As best I know, the tips wear out and the pintle springs can "relax". It is my understanding (never done, not a diesel injection tech!) that the pintle lift and opening pressure should be adjusted/verified prior to installation. This ensures that all injectors "pop" equally and results in a smoother running and possibly more powerful engine. That is kinda the point of replacing / rebuilding injectors, as well as "freshening" the spray pattern...:rolleyes:

So if the lift and opening should be adjusted/verified prior to installation, then do they do this with each new injector that they run off the line at the factory? I'm just curious if they just assemble them like a assembly line.(Just put the new parts together) or after this they adjust each one!
If not it seems like you could replace the pintle and spring (If the injector body is good) with new components and be done with it! It also seems if the springs are identical (New) then the lift & opening pressure should be the same, no need for adjustment?
Like I said before, I don't know jack about these but will learn fast. Everything else though that I have found out about diesels seem to go that way. They start complicated and end up being pretty straight forward
Anyone know a good parts breakdown pic on the injectors?

Unless you are doing this for the fun of experimentation or learning, you maybe money ahead just to either a) have the injectors checked or b) buy new ones. Fouling up an injector could end up washing fuel down into the clyinder and into crankcase under worst case conditions.

A bad fuel stream could cause high EGT in one cylinder and not know it. A poor performing injector or acidentally assembled wronf injector WILL lead to engine failure. When an injector sprays a stream instead of a mist of fuel, it will contact the piston in a highly concentrated spot and eat at the top of the piston, eventually wearing though and then KABOOM! No more new injectors needed, a whole new engine will then be in order.

I myself have taken mine apart but I did not change anything, just put them in a Sconic-cleaning tank which uses ultrasound freequencies to disrupt dirt and varnish and makes things VERY VERY Clean. Put gold in there and it comes out like it was just polished

Unless you are doing this for the fun of experimentation or learning, you maybe money ahead just to either a) have the injectors checked or b) buy new ones. Fouling up an injector could end up washing fuel down into the clyinder and into crankcase under worst case conditions.

I don't think i'll expirement with my own truck other than buying new but I will take my old ones apart (If I don't send them in for core) to better understand them!
On that second part of washing down the cylinders into the crankcase, I'm now not to sure if that isn't happening with mine right now.

Chicago TDP on the subject of fuel stream. I do understand the atomization of the fuel for ignition at least in oil burners as I am a boiler operator and the boilers I run use number #2 fuel oil (Diesel) or bunker C (Fun stuff). I also work on residential oil burners and have expiremented on running waste oils in these which require a either much higher pressure and/or temp to bring to a mist. I know diesel IP's put's out a much higher pressure but the principal is the same on atomization. If it ain't atomized right, it don't burn right!
I actually own a sonic cleaner so cleaning is not a problem. Wish there was a easy way to bench test them. Oil burners you just pull the nozzle and let spray in a bucket. That might not be so easy (Or safe) on a truck!

Might have to see if I can check out the process first hand. I do know of a local shop that rebuilds them (Or at least they sell rebuilt ones).
In the mean time it looks as if I should just go ahead and replace all mine since they have some miles on them. Don't like paying $225 but I guess its worth the peace of mind not having to worry about one less thing.

One other thing. In replacing the timing chain, do they sell gear drives instead like they do for smallblock? If so are they cheap or expensive? Are they worth the money if expensive?

They do and many people have them on this site but I see no reason to use one. I am also curious as to how the cam and crank take the pumishment because the gear to gear contact transmits more rotational shock. With a double roller chain, the chain takes most of the shock which is why after 100,000 miles it sags and becomes slack.