Heavy smoke at cold start up, light smoke when warm

[mpascino]

I'm not sure what to make of this anymore. My motor now has about 14K since being completely overhauled. Compression checked out at about 370ish every cylinder a month ago. When starting cold, the truck fires right up, no stumbling or excessive clacking. However it smokes like a pig. The only way to get it to stop is to bring the rpms up a little. I do not have the Cold advance hooked up, but I didn't think that would cause a problem as such. It hasn't been hooked up for 5 years and never acted like this. Keep in mind it's still "warm out" right now, only getting down to 50 at night. Could the initally excessive smoke be from the cold advance not wired in? I have to park away from the house when I start the truck in the morning....

The thing that bothers me more is the fact that just idleing, cold or warm, there is light smoke from the exhaust. Now I know the truck burns oil, but I have always attributed it to the high oil pressure and the turbo. Is this something I should be worried about? There is a fairly consistant stream of smoke from the breather cap once the truck is hot. Not too excessive, and even when the truck was ""newer"" it did the same thing 10 years ago.

The truck is basically in complete form now. TE06h, set at 10 psi, basically running as much fuel as I can without constant black smoke and egts too high. The truck runs excellent and pulls hard. I can actually kick the back end out by punching the throttle around a corner. I think thats fairly impressive for a 7400 lbs suburban. I never let the EGT's get higher than 1000 degrees. Do you think this is basically normal symptoms for a motor pretty much maxed out? I just got back from a 1300 mile trip with no engine related problems(parts america rebuilt alt. fell apart. The truck ran superb and loved the highway. Am I being paranoid and just flipping out since there isn't much left to work on or is it time to sell the truck and buy a 12 valve? Any input is appricated,
Thanks,
Mike

[20050420|7|006071|000022|69.19.2.78]

Hello mike,

when the engine was overhauled, thid they the timing chain also, or put they the old one back on the engine?

[mpascino]

The chain was replaced. Thx- Mike

[john8662]

First off, you really should connect the HPCA system, this aides in starting and keeping the engine running smoothly while it's cold and cylinder temps are down.

Could you describe excessive smoke when cold for me? Is this smoke like a big cloud of white smoke (or what color smoke), or just enough to notice? If at all possible, a picture is worth 1k words...

When the engine was overhauled, what was replaced and what machining was done? Were the cylinders bored, or was this a re-ring and new bearings rebuild?

And finally, another thing that it could be is timing, has this engine's timing ever been set with a meter to see where you're at?

[mpascino]

I've discovered the smoke at start up is pretty minimal if I hold the glow plugs on for about 10 seconds. I would think this would be excessive, but I guess it's not a big deal. The smoke at idle once warm is light, as in hard to tell if it is white or blue or black. If I am at a light and look to the passanger side of the truck I can see a light haze. Standing outside the truck you see a translucent cloud that disipates to about 2-3 ft before you can't really see it much.

The rebuild entailed of:
Heads-checked for straightness, not surfaced just polished up. I did not want to remove any more material than needed. The heads were dipped, fluxed, recieved a valve job, and fitted new valve seals. No excessive guide wear was found. Turbo pre-cups were used.


The block was cleaned, checked and honed for the moly rings, not bored. New cam bearings were installed. Clevelite pistons were used and the old pistons were showing signs of cracking from a bad head gasket and leaky injectors. The original cam was reused. The timing chain was replaced. New oil pump obviously, pressure is typically 40-60 psi hot, off the guage when cold. All felpro gaskets were used. The injection pump was rebuilt. The injectors were sent out and check good. About 9-10K after the rebuild the # 6 piston cracked right in the middle. I later found out the injector for that cylinder was not holding pressure. I then purchased a set of 6.5 injectors and installed them, obviously with a new piston. There were no unusally signs noted when the motor was apart the second time. Although I consider it a somewhat rough measurement, I figured the compression ratio to be 19.6. I didn't think a set of clevete pistons, new gaskets and T-precups would make that big of a difference, but I can't complain. I am running a dual plane non egr intake with a TEO6H turbo. The air filter is the K&N that comes with the banks kit. It could use a cleaning, but it's not bad enough to choke the motor by any means. The exhaust is the 3" mandrel setup from banks.

Is this a condition that could be simply from the idle being on the low side? I have noticed the idle is a little choppy. I was going to look for air getting into the fuel system somewhere as time permits. The timing has not been set with a meter, just by ear and pretty close to line to line. Once on the road the truck doesn't smoke that I can tell. It obivously does from a stop and when I flog the throttle with little boost. I am confident this is strictly because of the overfueling before the turbo spools up. I metered the fuel back for a while to see if it would change anything, it didn't seem to have a huge effect.

The turbo was inspected and given a clean bill of health. I guess with the high oil pressure it could be blowing oil into the exhaust, causing the smoke. Has anyone had a problem with this? The more I think of it, I don't believe I had this problem, at least to this extent, until I swapped this turbo on. That still doesn't explain the "blow by" though. Any Ideas?
Thanks.
Mike

[garysleeman]

When I got my motor with 26K miles (supposedly) it would only run with the HPCA activated all the time. At start ups it would send out a cloud of smoke. After a year it wouldn't run even with the HPCA activated. I had the IP rebuilt and added a geared timing set-up. Now there is no smoke at start up or normal driving.

[john8662]

Sounds like the smoke is a white variety that's not that thick, but could be considered normal on a cold start.

Here is a qusetion for you, when you mention that you see smoke in the rear view, is this at night or in the day? I can see smoke in my rear view mirror while sitting at a stop light in the headlights of the guy behind me. When the timing was right on my 86 pickup, I didn't see any smoke, it's hard to get them to that point though...

You mentioned in your message that you think that the idle is on the low side, this could contribute to the smoke, but not that much. You could turn the idle up using the set screw on the driver's side of the injection pump, it will be a larger screw that will be somewhat hidden by the fast idle solenoid.

Again, timing is key here. Since the engine has been overhauled and the timing cover has been removed, the line for aligning the injection pump is now void. This line can still be used as a baseline to get the timing in the ballpark, but not near as close as before the cover was removed. When the cover is removed, everything gets moved just slightly, thats why the mark will be off. I still recommend contacting some diesel shops in your aread and see if any of them have a timing meter that works on the 6.2.

I'm curious how you came to the figure of 19.6 compression ratio. The stock c/r is 21.5 to 1.

Obviously you have power with your engine, so it's running pretty good, just want to get it fine tuned...

I don't know the answer to your turbo question, but how oily does it get in the intake? And how much oil do you see on the output of the compressor of the turbo? Thats really the only way I know to tell if the turbo is feeding the engine oil.

But, the blow-by is going to be the usual, compression getting by the rings.

On the rebuild, how many miles were on the engine prior to the rebuild? Usually if the engine has over 100k miles on it there will be enough cylinder bore wear to justify a bore. On my engine that had 150k on it and it was in between needing it and not, so I bored it so that I would have the cylinder bore clearances just right. Otherwise you could potentially have an engine with pistons that are still too loose in the bores and this will lead to the rings wearing pre-maturely. This is because they cannot extend beyond a certain point and the ring gap on the ends of the rings will increase, which is a source for compression to bleed.

[arveetek]

I had the same symptoms with my engine before I rebuilt it. I had a huge cloud of white smoke upon startup, and a little smoke all the time after warmed up. It ran great, though. When I tore it apart, I found tapered cylinders, and one broken compression ring.

If your cylinders have any taper at all, this causes the rings to expand and contract as they move up and down with the piston. This eventually weakens the rings, and could cause one to break.

It's just an idea.

You do need to get the HPCA working....even my new engine will smoke and stumble without it on a cold startup. With my 19.75:1 CR and working glow plugs and HPCA, I see very, very little smoke at startup, and none at warm idle.

Casey

[mpascino]

All very valid points. I guess my next step is to either get a timing meter or find someone who wants to bother with it. As for the cylinder wear, looking back at it now, I should have bored it for piece of mind. The shop I brought the block to for cleaning and inspection told me not to bother. I was tied up with work and took their word for it rather than take the time to measure everything up myself. Again, one of those things I wouldn't let happen again. I guess either way, the truck runs strong and hasn't gotten any worse over time. I'm sure I am just nit-picking more than anything.

As for the compression ratio, it was a rough measurement. I took a piece of lexan and placed it on both the head and the cylinder. Keep in mind I did my best to measure up the thickness of a used head gasket. Either way, this is all with the craplite pistons and the turbo precups. The volume of the 6.2 vs 6.5 T pre cupps is indeed different.

Ultimately, time will tell. I'm not worried at this point. The rest of the truck will fall apart before the motor dies again....
Thanks again,
Mike