Running with no intake, white smoke troubleshooting

[Dsilverline]

Hey guys,

This is my first post but I've been reading for a while. Been troubleshooting white smoke on my CUCV since freaking August!

In August she totally crapped out on me, lost all power and it wouldn't stay running.

Things I did after that:

electric fuel pump add
fuel filter
clear return line to IP to look for bubbles
new injector return lines
new injection pump
new injectors

After all that stuff she'd stay running with mild white smoke out of *both* exhausts at idle, when i rev it quick and hard it'll belch a ton of smoke, smells more like unburnt diesel to me but my sense of smell sucks. If I rev it up slowly the smoke actually goes away somewhat.

I then suspected it could be a bad head gasket/cracked block (seemed unlikely since it was on both sides and exhaust smelled more like fuel) and did the radiator exhaust gas test twice which showed negative for exhaust gases in the coolant system. Then I did a compression check on all cylinders and my readings were 350-400 across the board.

Then decided it could be a worn out timing set, took it all apart and put on a new timing chain (the old one *was* pretty loose), replaced the water pump and radiator while I was at it. Rotating the IP either way made very little difference.

Its doing exactly the same thing now- but I will say the throttle response is amazingly improved! I'm starting to think maybe a cracked block or indeed head gaskets that aren't showing up on the tests. I've been doing all my smoke testing with the manifold off as you can run it that way and less work if I need to pull the heads. At one point I thought maybe the manifold has to be on to avoid smoke issues (don't see why it would make a difference, but just to be sure I slapped it on temp style and it didn't make a difference)

I didn't technically put the manifold back on with the gaskets and torque everything properly though. Is the situation you can technically run the motor with the manifold off but it needs to be on completely to run properly? I know the manifold blocks the two exhaust ports but don't see why that would matter.

Thanks for reading guys, just trying to get some info before I blindly decide to pull the heads (also I don't really want to haha)

Daver

 

[tourus]

well I just went trough a white smoke issue then was told to take the valve covers off and look for a bent or broken push rod or broken rocker arm .. I would try that first you already have the intake off. only the injector lines left . what the heck take a look . you may also have bad injectors bleeding by. just and other thought. if you are not using or blowing coolant then I would try other things before head gaskets. I was also told that the nylon buttons that hold the rocker arm in place could have broke and the rockers would move around and can cause white smoke like that. mine when I check had broken push rods on one side and the lifter pushed up out of the cam hole and was still running like you said lots of smoke at idle and goes away after a few minutes or driving but returns when stopped.. just throwing things out to you.

 

[Dsilverline]

Thanks for the reply! ahhh- valve train, hadn't thought of looking in there. Makes sense. Found some more stuff out yesterday as well -

threw the gaskets and manifold on and just tightened down the studs near the little exhaust ports for testing- it *does* run a little different, I guess the design is the exhaust ports heat up the intake manifold and incoming air.

after that more testing - very slight white smoke at idle (same as before), if I hold constant revs (any rpm) there is *no* smoke, if a quick rev then a billow of med/dark gray smoke. It seemed good enough to drive so i took it around a bit, to my surprise in 2nd (stick) up a slight hill full throttle I was rollin coal! It had surprising power (for a 6.2 lol). If I hold constant revs while driving partial throttle then, again, no smoke or almost none.

The new IP I put in is a "baby moose" pump from Conestoga diesel which are slightly modified along with fuel turned up. New injectors all around as well also... I'm starting to think by yesterdays tests that maybe I just need to dial it in? Turn down the fuel till its not blowing black on full throttle and dial in the advance. A used Tach N Time showed up in eBay (hope it works), so I ordered that. By the absence of smoke during constant revs and the black smoke on full throttle it's making me think its more just setup and less so head/mech issues, the *slight* white smoke seems to only be at idle...

Does my logic make sense? I probably should look under the valve covers either way....I could have something a little out of whack there as well along with my suspected tune issues....

 

[rsh4364]

Dsilverline I see you are new here,Welcome,if you scroll down a bit you can read similar posts.Lots of good info. there.Notice you said stick shift,4 or 5 speed?

 

[panzerwillie]

Advance the IP a little to the drivers side...

 

[Dsilverline]

the stick is a 4 speed ,its really more a crawling gear (L) plus 3 street-able gears. Great for off-roading and not sucking up the minimal power of the 6.2!

Today I experimented with backing off the fuel and advancing the timing. Advanced the timing a couple mm and backed off the fuel screw 1/8 turn. Still had black smoke on hard accel (a little less) and almost no gray smoke at idle. Backed off the fuel screw another 1/8 for 1/4 total and still had black on accel but a little less again. It definitely seems improved at least. I know its unburnt fuel but I don't want to back the fuel screw off any more until I can verify the timing with the Tach N Time when it arrives(assuming it works). It also seems weird I'd have to back off the fuel that much with a quality rebuilt pump (unless they really messed up the setting somehow?) Installing some gauges along with EGT as well.

Yeah, gut feeling is it needs some more advance, I'm just a little concerned I'm starting to adjust fuel/timing to the limits without knowing the actual numbers....
Has anyone got a rebuilt pump and had to turn the fuel down more that a 1/4 turn to get ride of black smoke on accel?

 

[nyoffroad]

To me it sounds like a fuel/timing problem, you seem to be on the right track. One thing that I've noticed is that you can still quite a bit of smoke after a timing/fuel change but in reality it takes a little time to blow the soot out of the pipes.
So in a nut shell go out and get on it a few times!

 

[Dsilverline]

Much better today! I noticed it was running a bit weird with the fuel screw a 1/4 back so I went 1/8 to the right and bumped the timing a little more advanced (maybe 3/16 to the right total?). No more white smoke at idle! Then the tach n time showed up in the mail and actually worked! Its giving me 7.5 btdc with the pulse clamp at 1400 rpm. Searched a bunch and couldn't find any *legit* data on what this should be, mostly just found stuff for the lumi probe. Anybody have some solid data on that?

Drove it around a bit and its got plenty of power, still black smoke on hard accel. Something I realized is I live at 4700 ft- could this be coming into play?, would make sense why I'd have to dial the fuel back a bit I think...

As soon as I install the egt gauge I'll be getting on it plenty haha