Hello All!

I have a 1997 HD 7.3. Been a real good truck. Went to Virginia from Indiana last weekend to bring home small tractor. Cruising through the hills of SouthEast Kentucky and suddenly noticed a new sound coming from engine bay.

Yes, I was working the truck a little hard. My truck doesn't normally produce high amounts of unburned fuel out the exhaust during high acceleration or high load, however she was definitely pouring out the black smoke during one of the steady hill climbs. My guess is that EGT was beginning to get pretty warm. I don't have an EGT gauge, but I am running stock everything except for a 3.5 inch exhaust and a K&N filter.

Anyway - the new sound reminds me of exhaust leak or valve train tapping on my old Chevy 350. I experience no loss of power, fuel economy remains about same, and everything else seems normal. I only hear the sound during acceleration loaded or unloaded. Idling or revving engine in park does not make sound. Only when truck is in gear and moving (during a powerbrake, I can also get sound).

I have observed no new leaks. I cannot isolate the sound with the hood up since it only appears under load.

I am seeking some ideas of what to check and how to check it. No CEL, no nothing is giving me clues. Also, the sound is the same when truck is cold or hot....

Any help is greatly apprecieated. Sorry so long post......

 

Check for clearance on down pipe, is it the 3" replacement? Sounds like it is rubbing on the firewall or transmission under load or when power braking.

 

10-4 Hussler - I'll check it out after work today!

 

EGTs shouldn't be an issue with a stock truck. Sounds like you could possibly have an injector hammering, or have lost some compression on one cylinder. Also check the exhaust manifolds. Make sure all the bolts are in them and they are not leaking.

 

It is standard or auto? . And get rid that K&N filter ASAP.

 

Maybe the turbo isn't spooling up causing the black smoke.

 

Whats the issue with the K&N Filter? Just wondering..Hadn't heard that they were bad..

 

I think Turbo is fine. Normal power and fuel economy. I can still stomp on the accelerator and she'll get right with it with little to no black smoke.

 

It sounds to me like the added heat and pressure of towing heavy may have helped you blow a seal out of the stock up-pipes. That would explain the smoke since a significant boost leak can cause the turbo not to spool. Look carefully at the up-pipes for soot at the connections.

I also agree with Bill that it could be an injector that is hanging. These engines can make some really weird sounds when the injectors aren't happy!

 

They are known as a dusting turbo/engine. Im searching for a good write up about the bad things of the K&N Filters, but I cant find it. Seems that the searching tool is not working as it should, I put 6637 and came a lot of links, but none mention de 6637 Is just me or what?, anybody else?

 

More about K&N:
The K&N element should probably be avoided in turbo-charged applications. The initial filtration efficiency is not high enough to protect the compressor impeller.
K&N The problem is the thickness of the stacked gauze media will not allow for a high pleat count and severely restricts the available surface area. A typical RD-1460 that is used in a FIPK system only has about 44 pleats. The Donaldson is not only a larger filter overall, but the thinner media allows for 202 pleats, leaving us over 5 times the surface area to pull from. This is why it can outflow and out filter a re-usable element as long as minimum radial clearance is maintained.
Here are some comparison tests:
ISO 5011 Duramax Air Filter Test Report
More to read:
K&N Air Filter or ?? [Archive] - Ford Truck Fanatics

But in reallity the link Im trying to find, has a very good info. IIRC the title was: Different or best alternative to damage your engine with a K&N, or something like that. Im pretty sure that somebody will chime in here with the correct link.