First time threadstarter, newish reader, but i've read alot. I jumped head first into the diesel world when i purchased a used 95 k2500 4x4. Started nice, idled nice. I took it.

I Should of done a more thorough test drive because when i went to take people out the first night and show em 'the beast' I noticed black smoke pouring out the back end. :( I nearly cried thinking i just spent my saving on a dead truck. After much cursing I found myself cruising the net for good forums for the truck. this is my first gmc (i had 3 dodge dakotas and got fed up with them, but they are good) but i'm no stranger to working on vehicles. Diesel however was like buying a mac after using windows pc all my life. (i dont use a mac, but its a good analogy)

Ok so reading came to the conclusion that its the vacuum pump. Hmm, like 5 hg max when connected to just the pump. So i replaced that. bent the pulley a little getting it off (destroyed old pump too, if you have a pulley for sale let me know) but its not that bad. SO the turbo works now and i try doing some rippin hill climbs and still have a bit of smoke and a whole slew of codes all the time, and it would come on as i pushed the pedal down. So wtf was going on?

Well I assume that because i live in canada it should have a F engine. Too lazy to check vin and is pretty irrelivant because the engine has been rebuilt. (or swapped, i dunno, i have no history) But i have the EGR solenoids but no EGR. WTF? My fuel filter is not in the right spot nor is it the stock one. The EGR isnt in place and just has a brass screw. (who even knows whats under there, havent checked) and weirder yet it has the vacuum pipe that is SUPPPOSED to be connected to the EGR on a brass T valve from the IAT sensor???? omg wtf its hard enough to diagnose this stuff when its stock let alone everything being WRONG.

I tested for blowby because there is fumes coming out of the oil while runing so i cleaned my CDR with some kerosene. dont know if it worked but i sure got high. Didnt use the manometer before cleaning it but i know it checked out at 5" during 2000rpm after cleaning it. When i did that i also decided to check that stupid vacuum hose that is supposed to be connected to the egr. I plugged it and put a cap on T. !BAM! no codes anymore.

I have an EGT but no boost gauge. I dont know whats going on with boost when i stomp on it but its seriously weak. Probably fuel filter but i have yet to figure out that whole assembly, perhaps someone will recognize it from another truck.

other weird things about my truck:
1. When fueling up I cant pull the handle all the way or it will stop the pumping. Is there a vent or something that is blocked? It takes a long time to fill up :( It wooshes a tiny amount when opened like it should.

2. Havent checked my lift pump but i hear kind of like a clicking for a couple seconds after I shut the truck off. Is that the noise? I need to check that but i have no T valve. ( i think the bleed screw on this weird filter assembly would work for testing lift pump pressure) I was thinking i couldnt get the filter out to change it without a diesel bath but i suppose i could drain it from the bleeder screw too. Will have to get to that this weekend.

3. Wasnt happy when i first tried the 4x4 and found that it didnt work. But after some searching i found a posilock 4x4 handle under the dash I got it to work. BUT i guess someone swapped the rear gears and didnt do the front cuz they were broke a$$. Anyways i pulled ahead half a car length before i figured out what was going on, thankfully not hurting my drivetrain. The front wheels were trying to run away!

4. I can barely make it up steep short inclines, have to go real slow or else i see lots of white smoke (at night, not so sure about daytime as its always raining here and looks like smoke sometimes) but should really have more power. I'm thinking injectors are worn or fuel filter clogged. I dont have milky oil and havent really checked the coolant but it SEEMS to be dimminishing as when i start it in the cold lately it says low coolant but goes away as the truck warms up a few minute. I do not have a hard upper rad hose after start but also its not hard after a longer trip. Though my temp doesnt usually waver from 1/4 full (90 i think, i foget, its celcius). My oil pressure doesnt move much from center of the gauge. I

5. I tried checking the oil when i got it and it was way up the stick, but couldnt really read it. Changed oil, tried again. (15w40) and still couldnt get a proper reading, seemed like oil was up the stick, i dont know, i just assummed that because i added a little less than capacity with oil filter change it SHOULD be good. but it also has a oil relocation kit to mount the filter just under the drivers door (its pretty sweet actually) . So if anything i should be low. The pan isnt dented or anything either.

6. I piled up 1500# of scrap drywall in the back and took it to the recyclers. It was the first haul I had done and wasnt impressed with the lack of power. (i'm telling you something is up) The REALLY weird part was when i really tried givin'r or the freeway my egts dropped. it was like 3-400 post turbo. (clogged filter right? cant provide the fuel to match all the air it was getting? therby lowering egts?)

It would be good to get it running tip top. But for now i get a decent 13-15 mpg all city if i baby it a bit. Would be nice to have the power when I need it.

I'll post some pics maybe tonight or get some good ones tomorrow.

well, number 1, mine does the same thing, i think its just the newer pumps the stations are using. there like 10 gpm pumps witch are too fast for a little gas neck. the other problems, im stumped. i dont know a thing about the old 6.5's. i just know there notorious for problems after problems.

The obvious stuff first - is the air filter clean, is the fuel filter clogged? You mentioned you are getting codes, which ones? If your still OBD-1 you can use the paper clip trick, its listed in the 6.5 reference section.

Its sounds like that will be just the tip of the iceberg, but a good place to start. Oh, and S of F - we need to know!

got some pics!

http://www.dieselplace.com/forum/attachment.php?attachmentid=76892&stc=1&d=1229059946

http://www.dieselplace.com/forum/attachment.php?attachmentid=76893&stc=1&d=1229059946

Realized the Filter assembly is obviously a Racor 445. k got that figured out. Turns out its a nice little piece if you check this http://www.maesco.com/products/racor/r_spn_intro/r_spn_intro.html

or for the lazy here is a nice little pic. http://www.dieselplace.com/forum/attachment.php?attachmentid=76894&stc=1&d=1229060252

Looks like the next step is to take the intake off to see whats going on in there. Imagine the egr was wide open into the intake?! :eek:

My codes are clear now, well at least my check engine light doesnt come on while driving. I'll go check the codes again right now. When the egr vac light was plugged into the IAT 't' (how i bought it) it was throwing codes:

DTC 25 - Accelerator Pedal Position 2 Circuit High
DTC 32 - EGR Circuit Error
DTC 33 - EGR Control Pressure/Baro Sensor Circuit High
DTC 49 - Service Throttle Soon Lamp Circuit Fault
DTC 57 - PCM 5 Volt Shorted
DTC 62 - Turbo Boost Sensor Circuit Low

I'll go check them again right now, i havent checked it since they went away while driving when i plugged the egr vac line (and the t).

Man that thing looks all messed up. I dont see a boost pressure sensor and I cant tell what that thing is that in under the pliers, coming out of the brass T. It wasnt there from the factory i promose you that. Some people put a "T" there to hook up a boost gauge but i didnt and wouldnt do mine that way. I also dont recognize that braided line that is running thru the pic.

ok cleared the codes and took it for a run. only code now is 49 which is STS light which is no biggy.

You are correct, its all messed up. The boost sensor is there, its the black box behind the tip of the pliers. The 't' on the IAT i put a cap from a valve stem on there to plug it for now.

Its looks a little weird but that braided line is the oil line to the turbo i believe.

Since there are no codes now I guess there isnt much point to this post anymore, but I still wanted to show people the stuff that was done to my engine. obviously this racor fuel filter is a nice upgrade from stock so thats good. the egr though i'm worried about.

I would assume its an S engine, because it has all the solenoids for the EGR and its vac lines are all identical (except egr setup) to a S engine. But what about the brass screw thats plugging where the egr should be? If there was nothing there inside wouldnt the exhaust gas just pour back into the intake? I get a fair amount of smoke from my intake snorkel when i crack the filter box open. Could be just from hot oil on the turbo (theres a trail from the CDR) though the turbo spins freely and doesnt rub or wobble or anything.

Does sound like its an "S" engine. That UPPER intake is from an "F" engine tho. Hard telling what that little brass plug is for, perhaps that's where someone tapped it for a boost gauge in the past and then plugged it later on. The last owner may have switched the upper intake and not the lower intake. If they didn't switch the lower intake then yes it is probably dumping exhaust into the intake, that explains the smoke and lack of power. In fact id say the way the last person did things, that is probably the case. Put an "F" lower intake on it. It does not have the exhaust crossover in it so the exhaust never enters any part of the intake.

are you sure its an F upper? I would tend to say that that is a S upper, but with no EGR on it. That brass screw would be where the plunger would go through to the inside of the intake.

well, number 1, mine does the same thing, i think its just the newer pumps the stations are using. there like 10 gpm pumps witch are too fast for a little gas neck. the other problems, im stumped. i dont know a thing about the old 6.5's. i just know there notorious for problems after problems.


I love how you come in, admit you know nothing about the 6.5, then flame the motor.

Really classy.

:rolleyes:

are you sure its an F upper? I would tend to say that that is a S upper, but with no EGR on it. That brass screw would be where the plunger would go through to the inside of the intake.

Its flat. The S intake would have a flange on it and some bolt holes for the valve to mount on. Take a look at this. This is my engine. The hole for the boost gauge is one that I drilled and tapped. This is an "F" engine/intake. http://www.dieselplace.com/forum/showpost.php?p=2831114&postcount=18

I looked again and notice that it looks like they used some lug nuts as spacers for the center intake bolts. I suppose it could be an S intake if the EGR bolts to the intake using the center intake bolts. I wouldnt think it would bolt that way but i dont know, ive never had an S engine. I also dont see any outline of dirt or gasket material or anything that indicates something was sitting there before.

There are NOT pics of my truck but of some i found on this forum. Both are F engines but one has a slightly raised flange where the EGR would go, but no hole in the middle.

Is it only the 4 bolts to take the upper part off?

6 bolts, the two wiring connectors, and a little arm that bolts to both the turbo and the intake across the little rubber tube that connects the turbo and intake together. Loosen one side of that arm and remove the bolt from the other side and turn the arm out of the way. Intake should come off then. That 2nd pic is indeed an F engine and it doesnt have a hole for the EGR in it but it still has all that S engine webbing inside it. I dont know why they did it that way. Ive seen another one that way too. http://www.dieselplace.com/forum/showpost.php?p=3003336&postcount=26 See, this guy has that same intake too, no hole in it for the EGR but still had the webbing in it. He cleaned it out. I still think yours is the first style "F" intake, but you should pull it just to see. It kinda makes sense that they may have switched the S upper for an F upper but not the lower. That would probably cause your problems...that would be like having an EGR valve stuck open which we have run into on this board before. It causes smoke and lack of power.

It looks to me like you have a VIN F upper intake at least. The "S" intakes had a large opening, much larger than where you have the brass plug. So if I have read correctly, the motor may not be origonal with the truck? What is the 8th digit of your vin#?

There are NOT pics of my truck but of some i found on this forum. Both are F engines but one has a slightly raised flange where the EGR would go, but no hole in the middle.

Is it only the 4 bolts to take the upper part off?
The hose that runs fron the T handle is not connected at both ends. It is so you can drain water from the filter bowl if you need to do that.

Actually, you have a better fuel filter there. Most of us wants to put that filter there instead of the original filter.

Well, I didn't see anyone else say this yet, so here are my small suggestions: First, I would take out that 'T'. That sensor on the top of it is your IAT sensor. It is supposed to be protruding into the intake so that it is getting a good reading. Being in a 'T' that far up, it isn't going to get an accurate reading, and it is going to be lazy also. What is the other part of the 'T' connected to?
That brass plug that you have labeled as "where the EGR should go". If that is just a brass plug, then I would use hole to connect a boost gauge to.
Check the 8th digit of your vin. Easy to do and will tell if you have an S' or an 'F', or at least how it came from the factory. You say that it has the solinoids for the EGR, so it probably was an 'S' to start. If that is the case, you want to make sure that the egr port was either closed off or the bottom half of the intake was replaced as well as the top half.

I'm pretty sure his is an S engine, since its a 6 lug 2500. But i think its got an F intake on it, atleast the upper portion. Im still seriously wondering if they swapped the lower intake too or not. I also agree to get rid of that tee, that is why i drilled and tapped the intake for my boost gauge.

Is it possible to contact the person you bought it from? He may have the answers to alot of the things that don't look right. I would be taking it back to him anyway. Sounds like you have had problems from the start.

The hose that runs fron the T handle is not connected at both ends. It is so you can drain water from the filter bowl if you need to do that.

Hehe actually those werent pics of my truck, just some ones i found online with pics of the intake on it. I know what the T valve does :) (thats not my writing in that pic)

finally got around to pulling the intake off. It is indeed an F intake, both upper and lower. Lots of wet oil in there!

finally got around to pulling the intake off. It is indeed an F intake, both upper and lower. Lots of wet oil in there!

Pulled my intake around 90k and it was dry. Pulled again to install boost guage around 110k and it had lots of wet oil in there ais your does.

I was concerned and general sensus is that it is normal BTW. Since then I did replace the CDR, but have yet to remove the intakes since.

So... No worries.