[300dweeb]

Hey all.
well, once again, I should saved up for a cummins (sorry)
the 93 N/A idi 7.3 pita has developed the 'thud' in the exhaust, with lots of smoke, lots of smoke on startup, and mild but constant smoking while idling.
Plenty of power.
Just did new injectors and return lines, fuel filter, and I tried cracking all the lines to determine where the fault was, it seemed the intake noise (chug? it correlated with the exhaust thud and vibrational miss) on #3 pass side lessened the sound, but had little impact on the running of the truck.

So, I've worked on this truck 20x more than I 've driven it, and I'm not doing the heads, I'll check the rocker arms, etc. soon, but as a general question:

I've seen several people on this forum have said they're driven like this for years, anyone still doing this (miss/smoking/etc.) if so, for how long, and if your motor failed: how long did it take from the onset?

I just need to get a few good trips out of this thing, not too much.

Thanks for all your help in the past guys.
Nick

 

[redpowerd]

stuck valve?

 

[300dweeb]

stuck valve?

thats a hunch for now, I pop tested all the new injectors and alll were good, I assume it's going to be a bad guide/worn seat, bad lifter even?

 

[cdnsarguy]

Have you watched this........

TheDieselStop.Com - www.thedieselstop.com

If it is a valve, if it drops and does NOT return on time......KABOOM.

What does the smoke smell like...... fuel, oil, coolant.

 

[300dweeb]

smoke smells like fuel, lotsa fuel.
Coolant is good, oil is good, I've smelled coolant coming out of OTHER peoples exhaust before, so I'm familiar with the aroma.

I'll have to start looking under the valve covers I guess?

Have you watched this........

TheDieselStop.Com - www.thedieselstop.com

If it is a valve, if it drops and does NOT return on time......KABOOM.

What does the smoke smell like...... fuel, oil, coolant.

 

[M.L.S.C.]

You said you put new injectors in - did you fish out all the copper washers from the bottom of the injector bores in the heads before you drop in the new ones? Reusing old copper gaskets is okay (or so I've been told), putting all new ones is better, but double-stacking new on top of a stray old one may cause compression leaks. Also, I've had my injectors loosen up on their own, when that happens I lose some compression at that cylinder and it behaves like a misfire - so far I've had #4, #5, #6 twice, and last weekend #2 and #7 do that, at different times of course, but still at this point that's the first thing I'd check if I get a bit of funky idle accompanied by some smoke.

 

[300dweeb]

Yes sir, I have retrieved all of the previous crush washers, and unfortunately it has the same symptoms as before I replaced the injectors.
Has a little more power, but same smoke, shake, miss.

You said you put new injectors in - did you fish out all the copper washers from the bottom of the injector bores in the heads before you drop in the new ones? Reusing old copper gaskets is okay (or so I've been told), putting all new ones is better, but double-stacking new on top of a stray old one may cause compression leaks. Also, I've had my injectors loosen up on their own, when that happens I lose some compression at that cylinder and it behaves like a misfire - so far I've had #4, #5, #6 twice, and last weekend #2 and #7 do that, at different times of course, but still at this point that's the first thing I'd check if I get a bit of funky idle accompanied by some smoke.

 

[M.L.S.C.]

Well then heck if I know - injection pump going bad?

 

[300dweeb]

well I can't fit this pig into the garage, and it aint going over 27f today, I'll post updates once it warms up in a week and I have a look under the valve covers, and maybe do a compression test.
thanks guys.

 

[goatwrangler]

any luck on your miss and finding yor problem ?? I have the same thing going on with my truck. ive just been lazy and havent checked it out yet.

 

[300dweeb]

half hearted update

any luck on your miss and finding yor problem ?? I have the same thing going on with my truck. ive just been lazy and havent checked it out yet.

I haven't been driving it due to being nervous about motor failure, but we got a decent amount of snow monday and I took it out, still smokes hard on startup with heavy constant miss, smokes light idling at operating temperature with occasional miss. miss seems to go away around 1200-1300 rpm.

I noticed cracking one of the injector lines on the pass side seemed to calm the miss a little, and I've since re-noticed a pronounced 'ticking' noise from that side that is telling me I need to start looking under that valve cover.

We will apparently achieved over 44 degrees F in the destitute state of MI over the next few days, and aside from a master cylinder on one car, a water pump on another, and what ever the wife throws at me, this is getting looked at.

Winter is a mean, motivation killing time.

 

[M.L.S.C.]

Injector!!! The one you cracked its line open and it calmed it down, bet that one is pissin fuel in like no tomorrow! One of the OB guys just went through that too, same darn thing - he replaced the injector with a new one and set it up to pop at the same pressure as the others, and life was peaches again.

 

[asauer]

But does a drooling injector issue like that clear up above idle?

 

[hotrod220257]

ok i stopped reading i bought the truck 100k ago and since then ive had rattles thuds knocks and hummms wow it really sounds mean though anyaway still runnig strong

 

[300dweeb]

not the injector(s) unfortunately

sorry if I conveyed that cracking a line made a big difference, it really didn't.
It seemed like the intake sound and exhaust popping was smoothed out a little when I cracked one of the lines, but it didn't take away the smoke or the miss.

I know the miss would still be there if there was a non-contributing cylinder,
and no fuel delivery but I'm thinking it may still smoke due to built up fuel in the cylinder from the valve not closing/opening fully.

The exhaust smells only of fuel, no oil, no coolant, fluids are good otherwise.

Weather is looking good boys, time to piss off the neighbors with my ass crack hanging out of the hood of this beast amidst a cloud of smoke, update will follow.

Btw, if I can't get this figured, anybody near Waterford MI could be paid in beer and favors if I can get a hand on diagnosis, or anybody who wants to donate a cummins 6bt would get a nice 7.3L boat anchor as compensation.

I kid, btw, I have a pop tester if anybody around here needs to use one.

Injector!!! The one you cracked its line open and it calmed it down, bet that one is pissin fuel in like no tomorrow! One of the OB guys just went through that too, same darn thing - he replaced the injector with a new one and set it up to pop at the same pressure as the others, and life was peaches again.

 

[300dweeb]

well, I took off one of the valve covers today, mostly (couldn't get it clean off due to the ac condensor box in the way) but all the valves are pretty tight, they don't move much, nothing looks bad under there.

I spoke to a technician today, who called a friend familiar with 7.3 and db2 pumps, he seems to think its the IP going out on me.

So... when I get the money together, I'll repost on my results with a new IP.

Cheers.