96 7.3 low boost issue

[chuckwagon009]

Hello all its my 1st post!

Bought my psd about 3 months ago. Ran pretty darn good when I took it for a test drive, got a great deal on it so i went for it. 2 weeks ago I installed a boost gauge on it and noticed I was only able to get to 8psi. Turbo sounds a little weak <not bad but not like most psd`s I hear>. Took off the air intake hose and all the compressor fins look perfect, hardly no shaft play, and even at idel she spins fast. Ran throught the parking lot with the intake hose off and a conical filter just on the end of the turbo with no gain. It has already had a replaced exhaust on it, so I am kind of assuming its not the kat or muffler. I can hear the ebpv in the cold mornings and notice a decent increase when it opens so I am assuming it is not stuck shut.

Engine seems to be a little louder in the knock region then most the other psd`s I hear too. Did the 10k mod, no difference in feel, went to 22k and noticed a bit of an increase. Cannot get a single puff of black smoke out of her, and it feels the same at 1/4 throttle as 3/4 to full throttle.

I have a egt gauge, I just need some time to install it. Hopefully that will give me a little clue as to what is going on! I get no cel`s, and scanning shows not a single code stored.

I am a mechanic for uhaul, and have quite a bit of experience with the 7.3 idi, but never messed with a psd so I am kinda in the blue. Did a lot of reading and research before posting but never came up with anything conclusive from others yet.

Next step is to shim the fpr and put a gauge in there to see what my fuel pressure is, but before I get in the engine bay again, wondering if I should get a turbo to replace or not. Really don't have money to toss at that right now.

If someone is in columbus ohio or surrounding areas, and needs anything hitch related I can get it for them at cost. I am now the hitch professional, and do goosenecks and 5th wheels, brake controls, air suspensions, sway controls, trailer brakes, hubs and spring, rewires, breakaway boxes, trailer hydraulics, etc... Baisicly anything truck or trailer related I can do it. Send me an email at ovco@tmail.com or call 4786617 and ask for charlie. More than willing to help anyone out, especialy if they can help me!!!!!

Thanks for time and concideration.

[Diesel Monkey]

Do you know the repair history?
You may want to look at the airfilter side of the turbo. Are the blades all there and complete or are they bent and pitted? Stock turbo rebuild and balance is about $310 from an independent shop.

[chuckwagon009]

Repair history is quite unknown. The person I bought it from said it was an older gentalmen that sold it, and he babied it, and judging from the interior/exterior he did just that. Very very nice truck for its age. Actually get a lot of compliments on it, and ppl think its a 2000». I said in my first post the compressor side of the turbo looks great. No impeller distortion, looks practicly brand new, blades are in great shape. The exhaust side I have to look at yet. Waiting for some cash to do a set of stacks, and get the downpipe off and a larger one on.

Was kind of wondering if anyone knew if it could be something other than the turbo causing weak exhaust gas/pressure that would spool the turbo slow/ weak? Maby a couple weak valve springs that are causing a timing issue hence the extra detonation knock? Hpop not getting enough pressure to hit the injectors hence the no smoke at all/ and weak throttle position responce.

BTW.. Truck has 153k on it, which from what we get out of the idi`s is low milage before we have to start hard maintence.

[95dieselsmoke]

are you able to check this truck for codes? maybe something will pop up on the scanner code-wise and tell you if something is wrong

[chuckwagon009]

Already stated in my first post, I have no cel on. I have a snapon code scanner and it shows not a single error. just to be sure, I ran it at autozone and still nothing. If I got time here soon I am gong to take it to the dealer and se what the tech can come up with. Got me stumped.

[chuckwagon009]

Just got back from a 10hr trip, no problems at all on the road. No cel came on, sounded and felt strong. Still maxing out at 8psi at 3k rpms, at 65mph its turning 2k rpms and I might get 1 to 2psi!! Anyone yet?

[ludwigs32]

I am running a 7.3 psd and i average 19 - 22 lbs of boost @ 3000 rpm.
recently I had the turbo pedestal gasket replaced due to oil leakage.
when i got the truck back I could only get 5 - 8 lbs of boost no matter what I did. After sweating a possible turbo rebuild and several moths of educating myself this is what I came up with.
There is a spring tensioner on the turbo waste gate that when udjusted altmately controls the amount of boost pressure build up in the engine. However this is supposed to be a very touchy modification potentially resulting in catostrophic damage to the turbo and/or powerplant. This is also supposed to be preset at the factory, and not particularly adjustable (maybe someone who has more experience than me could brave this mod). Ultimately after months of trying to out think this problem of no boost pressure and smoke on acceleration I noticed that the dealer forgot to connect the waste gate control arm. I reattached and that solved the boost issue.
I hope this helps

[chuckwagon009]

Unfortunatly it doesn't help as I have a 96 (OBS) that does not have a wastegate.

I am going to take the turbo off and have a look at it next week. Through the intake side everything looks great. Spin it with my pinky and I get 4 or 5 turns before it stops, barely no shaft play. Took the split charge air pipe off and inspected the pipe, rubbers, and intake manifold and cannot visually see any leaks. Took my handy pencil propane torch and went by all seems on the top end at idle and got no change in idle. So here I am still scratching my head. Going to get a 3" downpipe and diy intake so at the same time I am just going to rebuild the turbo and do pedestal o-rings.

Still, if anyone has an easyer/cheaper solution.....let me know!!!!!

[Powersmokein]

gut and plug the pedestal maybe ?

[chuckwagon009]

I am a little wearey of plugging the pedestal. On the obs trucks, isn't the pedestal the only oil supply to the turbo? From what I see, it has no lines that run from, or to it, so running it without oil would be a BAD thing??? Correct me if I am wrong!