Injectors rebuilt, still smokes!

[240ZD]

Well, I finally got my injectors rebuilt, over at AG diesel in Portland. They said they were all popping at about 1800 lbs but were spraying erratically. They set them at 2000 lbs pop pressure with new nozzles. I reinstalled them, torquing the injector flange bolts down to about 20 ft/lbs since I couldn't find the real spec.

The engine runs a lot better, but it's still having some problems:

I had to advance the IP a few degrees to get the car to run somewhat normally after installing the new injectors, and reduce smoke to a barely tolerable level. The car still spews out a steady stream of whitish-greyish smoke though, somewhat less after warmup. If I advance the IP timing any more, then the loud diesel cackle gets really bad, and it still smokes the same. Retarding the timing makes the car run like crap and billow white smoke.

The whole engine is louder now, even though it runs smoothly and very well. Power is good.

The other thing is that it has a hard time starting if it sits for more than like a minute after running. It cranks over a lot and finally roars to life with a burst of blackish smoke.

I think the valves need to be adjusted BAD. It could be my smoke/hard start problem, maybe? The thing has been across the country and back enduring pretty extreme driving. Heeeeellllp!!!!!! <;[

[rlaggren]

Whitish gray may mean something besides diesel is getting into the cylinder(s).

You using a lot of oil?
- This is turbo'd right? Is the turbo dumping oil into the intake? Might take things apart and look in the intake?
- Is the sump grossly over-filled so you get a lot of churn and splash on the cylinder walls, overloading the oil rings?
- Maybe "high oil" results from the turbo draining large amounts of airated oil scum into the sump and raising the level way above what it'd be w/the oil all fluid; just a guess - don't know anything about this beyond the fact the bubbles do strange things to fluid. Can't right off think of a way to "see" what's going on in the sump, but maybe if the turbo bearings or seals are gone, the volume fluff and spume draining back into the sump has gotten way to high... Again, just a guess. I don't know beans about turbos first hand.

How about coolant? (I know, fear and loathing...)
- Pressurize the cooling system and see if it holds. Do it cold and then (carefully) do it hot. (Tooling is needed.)

I've alway heard that timing a diesel by ear is dicey for those of us not endowed with years of love and dedication in the service of engines - like DaveHoos. IOW, your timing might be way off and that can't help anything.

Valves. Well, the FSM has a pretty good instructions on setting the valves and that only takes a crows foot and some feeler gauges.

Compression test. Be sensible to do it first but it's a PITA and you can run through the above fairly easily. You might want to do it after the valves anyway.

Best luck.

Rufus

[asavage]

Generally, white or whitish smoke is unburned fuel, esp. if accompanied by a fuel smell (as opposed to the smell of diesel smoke).

Air in the injector lines can retard the effective timing and lead to white smoke, but the LD28 is usually self-purging in this regard. You might check for an air leak on the intake side of the fuel system (rubber lines to the fuel tank, to the fuel filter, to the IP).

Low compression (your valve lash adjustment that you alluded to) can also cause misfire and unburned fuel to make whitish smoke.

I can't think of anything else right now.

[diesel-man]

First off, everything Al said.

Sounds as if your timing is too far ahead. Was the injection belt changed at all in this process? Not a good idea to change a bunch of things at one time...harder to diagnose. Does the temp get up to halfway on the gauge?(thermostat) Has the car been run alot but not driven? I bought a car that was run alot but not driven much and it took 50 miles to get it to stop smoking (rings gunked up).

Take the valve cover off and adjust the valves, see if there is "like chocolate pudding" on the head...oil not changed enough.

Bleed air at fuel filter. It bleeds itself if there is no problem, but I had a fuel filter housing go bad once...diaphram? had pinhole and let air into the injection pump.

Hate to think about antifreeze and head gaskets. Any white-ish oil under oil filler cap? Is this white smoke visable only a few feet away from the car or 30 feet away? Does it have a sweetish smell or fuel smell?

With a crazy problem, I'm ususally looking for a crazy answer.

[240ZD]

Thanks for the thoughts, fellas.

Well, the engine sat around for about two months after being driven a lot. It was smoking like this before I got the injectors rebuilt, only WAY worse.

The whiteish smoke smells like unburned diesel fuel (though my friend says it smells like something else). The coolant is clean and is still sitting at the same level since the radiator was out a year ago. It is hard to start when warm (8 seconds of cranking time), unless i give it about 4 seconds of glow plug first, then is fires right up. When I start it cold, it stalls immediately if I don't give it a lil' bit O' gas.

Well, if I manually open the cold start advance, the startup smoke goes away almost completely, and it is generally running a little bit better as I drive it around. It idles quite slowly and easily when warmed up - it can't be more than like 600 rpm.

It actually seems to be a little lacking in power, even though it runs very smoothly. ANYWAY....

The turbo isn't leaking any oil into the intake or exhaust, but the sump is likely overfilled....it is filled to about the level of the turbo drain/alternator pump oil return nipple. The head/cam area is very clean and the oil is nice and thin. It does not use any oil. The valves do need adjusting...I can't find my feeler gauges anywhere! :[ I'm sure it's part of the problem, along with timing.

It is highly likely that some air is getting into the fuel lines, because the hoses by the tank are all super brittle. I'm embarrassed to say that one of them is even the original Z braided hose. Yes, it's true: a turbo can go on before replacing old hoses. Ridiculous! Right? Ahh, the manifold incongruencies of the automotive experimentalist.

[240ZD]

Also, the IP belt was not changed, but the timing was slightly advanced to make it reduce the billowing smoke. The smoke is easily visible from 30 feet away until it is completely warmed up. Then the smoke is minimal, but steady. The thermostat gets up to halfway and then holds steady.

[plenzen]

With it running better with the CSD pulled and lacking power when running with it pushed in then it sounds like the timing is retarded. Hard start at hot sounds like valves too tight. ( if compression is good ) . Also, late timing will make it hard to start as well. You are alredy dealing with the possible air leak

Paul

[asavage]

It is hard to start when warm (8 seconds of cranking time), unless i give it about 4 seconds of glow plug first, then is fires right up.

Well, this sounds completely typical of this engine in a Maxima. Warm starts were never good on mine, for 14 years. Because mine was an AT model, I could use the manual afterglow method and get some GP time on a warm start, independent of the GPC.

The turbo isn't leaking any oil into the intake or exhaust, but the sump is likely overfilled....it is filled to about the level of the turbo drain/alternator pump oil return nipple.

That's a Bad Thing.
The turbo's bearing aerates the oil into a whipped-cream-like consistency, which will NOT drain to the sump if the drain point is below the fill level.

If your smoking was only in hot conditions, I could make a case for that being a serious contributor to your smoke. In any event, you'll want to either move your turbo drain point higher or lower your oil level as soon as practical.

[240ZD]

UPDATE:

The valves were all adjusted to proper specs, and it made a huge difference. The engine stars much easier, there is less smoke, it is markedly smoother at all rpm ranges, as is the torque. The turbo spools up quicker and louder as well, and holds it's spool better between shifts! Most of the valves were way too tight.

Secondly, the fuel lines by the tank have been taken care of, so if there was an air leak it should be gone.

Third, I advanced the IP timing by about 1 mm. It sounds a bit more like a "diesel" but it definitely runs better and has more power.

Finally, I took the advice of my diesel guru friend and turned the smoke screw, about 1/8 of a turn. Amazingly, this reduced the weird whitish smoke to zero, and when I revved the engine up there was a small, quick and unmistakable poof of black smoke, which I haven't seen since installing the new IP more than a year ago. This made the engine way more "turboey." Second gear is now like a slingshot, and the ride is seriously neck-bending under even half-throttle acceleration. I was unable to get out of third gear before going way too fast, holding at 14 psi. During all of this there was no noticeable black smoke at all.

I'm gonna turn the little Nissan safety wire from the smoke screw into a neck pendant! Also, a few months ago I hooked up the IP altitude compensator to the intake plenum a'la TurboMage, to fool the pump into curving the fuel volume in relation to boost pressure. This also gave the turbocharger system a healthy dose of "act right."

The whole thing is really starting to come together. I really appreciate this forum and all you characters, with your advice and stories, without which this ridiculous project would have been seriously stunted.

[rlaggren]

Thanks for reporting back. And always nice to hear good news! <g>

Rufus

[windsock]

Always good to read of positive results after fix jobs.

Love the thought of "seriously neck-bending " acceleration