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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #1 ·
My old step van sometimes blows light grey smoke, but only under specific operating conditions. When driving at speeds from roughly 30 mph to 45 mph (not idling, but not highway speeds), if I encounter a gentle downgrade or hill, not steep enough to let me take my foot entirely off the throttle, I produce a light grey smoke. Some freeway off ramps have a decline that's just right to do this. I feel as if I'm just feathering the throttle to maintain my chosen speed.

Sometimes the smoke is sporadic. Not a steady smoke, but bursts.

Today, I think I felt small power surges coinciding with sporadic smoking at a speed of 40 mph, again, gentle downslope. At this speed, I only observed this in 4th gear. It doesn't do this at 40 mph if I first lock the torque converter by bringing the van up beyond 52 mph for a moment. The converter remains locked until slowing below 35 mph.

There are no operating issues with the motor. None at all. I track fuel consumption at every fueling, no changes there. No engine oil consumption. Smooth idle after easy starts, every time, hot, cold, or very cold. The high idle solenoid still works! The pitch of the combustion changes as the injection timing retards after the engine warms, just as it should do. It just runs great, all the time.

I think my usage may not be helping. I only live a couple miles from my work spot, so the engine doesn't get very hot sometimes before I park it. This may contribute to carbon deposit build up fouling an injector or two, but I am guessiing about that.

Today, I treated it to enough Seafoam to reach their recommended dose of 1oz per gallon. After work, I took it ten miles down the freeway, taking a long way home. The last four miles was 40 mph again, and it produced some grey smoke, but noticeably less than before I fed it the Seafoam.

i think I'm on the path to solving this, but I don't know what is causing it.

Wheel Tire Vehicle Truck Window
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #3 ·
I took the long way to work this morning with it. It was rainy, so the road spray was masking any smoke that may have been there. But, I saw no obvious smoke this morning. Not a very good test, but another good heat soak for the engine, at least.

Nothing to do for a while but wait to see if this step is effective.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #4 ·
The trend with the Seafoam treatment is definitely towards resolving the problem.

The loop I've been driving it twice a day is about ten miles. Half of it is freeway (60 mph), the other half is mostly old US highway 99, two way traffic (40 mph), with a mile or so of city street (30 mph). 60 is about all I like to do with the gearing the van has. It's a multi stop truck, purpose built for local stop and go usage. Grumman-Olson specced out the chassis they used very well for their intended use. Screaming down a freeway at 70 mph wasn't much expected, I think!

Sorry, I have no tachometer. The TCM certainly knows the engine speed, bit it doesn't tell me.

After only four days of taking the longer drives to work and back, the grey smoke production at feathered throttle seems to be gone. Yesterday, I couldn't force the smoking condition.

I usually fill my fuel tank when I've used a quarter tank. But this time, I'll wait to refuel until I've used must of the tank, to get the most cleaning from the fuel/Seafoam mixture before I dilute it with fresh fuel. And, I'll use this tankful up taking the long way to work, to get that sustained engine operating temperature. It seems to be doing the trick.

Maintenance in a can. Who would have thought?
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #5 ·
On further reflection, I can draw no conclusion at all from this. I've added the fuel additive (seafoam), but I've also changed my driving habit (long way to work). Which action is at work on the observed smoke reduction? I've confounded the variables.

What I suspect is the cleaner and drier components of the seafoam, along with my change in driving habits have dislodged some carbon, which was perhaps built up over time from lower engine temperatures caused by short runtimes.

I'm unconvinced that the need for these fuel additives should be chronic. I have observed with a borescope how effective this stuff is at removing carbon in a combustion chamber. It's dramatically obvious, even to an untrained observer. So, I think they have use cases that make sense to solve a problem. But, properly operating engines shouldn't need additives (lubricity restoral aside, obviously).

I think I caused the smoke I observed, by poor driving habits. It's only a mile and a half drive to work.

I think the long term solution to the problem may be to get that engine up to full operating temperatures and RPM for a few minutes to burn away carbon deposits. Ask it to so some work, may be a simpler way to say it. How frequently to do that? Daily? Weekly?

I suppose I'll just start somewhere and take the long way in to work every week after my break. It shouldn't take long for this symptom to reappear if that is not sufficient.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #6 ·
Maybe you just need to take it out for a nice long drive. Short trips are hard on a diesel engine. They like get fully warmed up and taken on a good haul.
Your injector nozzles may be carboned up and have bad spray pattern. If over 150K miles on the injectors. They are pretty much at the end of their service life. Should be rebuilt or replaced.
You should be using a diesel additive every fill up also. USLD is hard on older fuel systems.
I didn't read this carefully, because my eye caught the "150K miles" first, and I dismissed it, because I only have a third of that many miles.

But, I think you are right.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #9 ·
What is the long way to work in mileage and speed?
Here you go:

The trend with the Seafoam treatment is definitely towards resolving the problem.

The loop I've been driving it twice a day is about ten miles. Half of it is freeway (60 mph), the other half is mostly old US highway 99, two way traffic (40 mph), with a mile or so of city street (30 mph). 60 is about all I like to do with the gearing the van has. It's a multi stop truck, purpose built for local stop and go usage. Grumman-Olson specced out the chassis they used very well for their intended use. Screaming down a freeway at 70 mph wasn't much expected, I think!

Sorry, I have no tachometer. The TCM certainly knows the engine speed, bit it doesn't tell me.

After only four days of taking the longer drives to work and back, the grey smoke production at feathered throttle seems to be gone. Yesterday, I couldn't force the smoking condition.

I usually fill my fuel tank when I've used a quarter tank. But this time, I'll wait to refuel until I've used must of the tank, to get the most cleaning from the fuel/Seafoam mixture before I dilute it with fresh fuel. And, I'll use this tankful up taking the long way to work, to get that sustained engine operating temperature. It seems to be doing the trick.

Maintenance in a can. Who would have thought?
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #10 ·
Well, it turns out that seafoam does nothing detectable to solve the problem I have.

I think one of my injectors simply doesn't like low load, elevated RPM conditions. It's done this smoking thing since I've owned it (4 years), yet it starts, idles, cruises, accelerates perfectly, every time. No oil consumption, normal operating temperatures. But, that's only my first guess, and I have no experience with diesel engines.

It seems the only way to know for sure is to change out those injectors. Or, get them tested and cleaned/serviced, if that is done any more. Something new to learn about.

Are fuel injectors particularly difficult to remove and replace on the 6.5? Comparable to spark plugs in difficulty?
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #13 ·
Before I proceed with injectors, I'd like to ask a couple of questions.

First, am I correct that leaky injector(s) will cause the grey/white smoke like I am seeing? It seems to me the smoke is caused by fuel leaking into the combustion chamber from an injector that won't shut off completely. Do you agree with this cause for the symptom I see?

Secondly, if it is likely an injector, is it worth testing them, or simply replacing all eight? Being unsure what caused this possible injector malfunction, and since all of them lived the same life so far, if one is goofy, I'd think more were on the way to goofiness and should be replaced anyway.

Or, are these injectors rebuildable?
 

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Discussion Starter · #15 ·
Exactly what I needed to know. New injectors, it will be. Thanks for your help!
 

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Discussion Starter · #17 ·
Absolutely, I will.

The auto service shop from where I rent the spot for my business isn't a diesel shop, but I offered them the work to replace the injectors. I haven't reviewed the procedure or surveyed the engine compartment to assess the difficulty, but if they'll accept, I'll have them do it. The work will be warranted, parts and labor (as is the recent refresh they did to the front of the engine).

Otherwise, I'm a bit concerned about where to find a diesel shop that does this sort of work, especially on older equipment. Competently. Any clown with a set of tools can troubleshoot by substitution. I seek the guy that knows why. I'm sure there's someone near.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #19 ·
The easiest way to do this without any issues is to replace one bank of injectors and return lines then start and run the engine to work out the air.
Then replace the other bank with return lines then start and run it again to work out any remaining air in the system.
There is a great guide listed in the 6.5L FAQ page: Injector replacement for novice mechanics, or......
That information is like gold.

Thanks.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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Discussion Starter · #20 ·
When replacing the injectors it is recommended that you only use the OEM Bosch Injectors
That doesn't seem so simple.

May I ask what exactly are the differences between the injectors for the normally aspirated and the turbocharged models of the 6.5?

While reading our FAQ post on injector part numbers, there are two entries in the Bosch table for 6.5L NA engines. How do I know which to use?

Injector Numbers
BOSCH
New #-----------Body #----Reman----Tip-----Pressure---Application
0432217081....0430211051...NA50X...0SD248....126 bar......6.2L 1982
???????????.....0430211058...NA52X...0SD253....126 bar......6.2L Long body
0432217092....0430211054...NA51X...0SD253....126 bar......6.2L Short body
0432217229....0430211054....??????...0SD304....126 bar......6.5L N.A.
0432217251....0430211054....??????...0SD304....142 bar......6.5L Turbo
0432217255....0430211054....??????...0SD311....150 bar......6.5L TD Marine
0432217275....0430211097....??????...OSD304....126 bar......6.5L N.A.
0432217276....0430211097....NA56X...0SD304....142 bar......6.5L Turbo

"bar" is equal to 1 atmosphere - multiply 14.7psia by the number on each line to determine actual injection pressure

Delphi Injectors
6703803---6.5 T.D.
6703802---6.5 N.A.
6703801---6.2 "Van" Short fine thread
6704001---6.2 Long fine thread.

Standyne Injectors (New)
37818 10233973 6.5L T.D. same as 0432217276 6703803
38272 10233972 6.5L N.A. same as 0432217275 6703802

* Info has not been verified but is believed to be accurate till somebody proves otherwise.

Try get'n this info anywhere off the net.
I'm not seeing an abundance of injectors available for the normally aspirated 6.5 engines. What are the effects of using the model of injectors for the turbocharged 6.5 in my normally aspirated 6.5?

Regarding the Bosch preference, the other two manufacturers (Stanadyne and Delphi) are names known to me. Can you comment on your preference? I had a look on OReilly's web site, and they have AC Delco injectors. This decision may come down to what is available, but I'm curious about the differences.

Lots of questions, new things to learn. Everyone wants to make good decisions. Thanks for your help.
 

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Discussion Starter · #23 ·
Thanks, but I wouldn't know the right nozzle if it was in front of me.

I sure would like to know what Bosch part number to get for the L57 engine. There are two listed, and have different part numbers.
 

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Discussion Starter · #25 ·
Scheduled it for service in a week to replace the injectors and glow plugs. The smoking is getting worse. Starts aren't as smooth as they were, but still as quick. On some cold starts, there's a brief puff of that grey smoke and a stumble in the cadence of the running engine that quickly smooths.

I don't think there are any failed glow plugs, but they seem to be another wear item that we may as well replace while we're working there.

I expect I'll have a happy engine next week. I'll be back with the results.
 

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Discussion Starter · #26 ·
Hoo, boy! My engine is complaining some mornings now that it's a little colder. I've had a few very rough (though quick) starts, with rough running for a few moments, accompanied by that white/grey smoke. This indicates a glow plug or two not functioning also, I think.

Replacing those too, while they're in there working on my van.

My mechanic indexes the components when he removes them, so I'll be able to do some failure analysis when it's done. I'm pretty confident this work will solve the problem, and am very curious to see what failed and maybe learn why.
 

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Discussion Starter · #28 ·
This may be one of those, "If it ain't broke, don't fix it" moments. Might try to mess around with injectors and strip something or break something and end up wishing that you'd left it alone. Teenage trucks and ppl are similar, they tend to smoke sometimes.
This is my business' service van. It makes no sense to wait for an ill timed failure. Better to schedule preventive work on my off days.

A certainty is these symptoms won't fix themselves, and the symptoms are rapidly becoming more severe. it's cool, though. My clients in the last week just paid to do this work. My shop's van is a machine that pays to get itself fixed!
 

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Discussion Starter · #30 ·
After running Seafoam thru it with no better results. I think new Injectors and Glow plugs should fix your problem. Glow plugs wear out over time. as do injectors. As i said in previous post USLD is hard on injectors. After replacing yours. Be sure to run an additive to keep injectors and the injection pump lubed properly.
6.5s when running good, are a clean running engine. A little puff of grey smoke when first starting in the morning is normal. It should clear right up.
It should not smoke the way you describe. If my truck smoked like that. I would be on it fixing the problem.
With your business name on the side. A good clean running service van leaves a good impression with folks.
They have all of the glow plugs replaced, and half of the injectors (passenger side). Before quitting time, they got the return lines installed on that side, and we started it to check the work. No leaks on the new side!

It stumbled after starting, until the new injectors started delivering fuel to the starboard side of the engine. Then, it smoothed right out, and no smoke. We'll get the port side injectors done tomorrow! I'll have a little less cash reserves, but my van's engine will be tip top!

Lighting wasn't great for photography. There are visible carbon deposits on the faces of the injectors. Much more carbon than I would have expected to see. I expected to see blackening, but not depositing. But, what the hell do I know what I'm seeing? I'll get the rest of them tomorrow, and get some detailed photos posted as soon as I can.

I'm confident this is the solution. The proof will be tomorrow.
 

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Discussion Starter · #31 ·
No joy.

Although, I do have the original injectors and glow plugs indexed to their installed positions, and I'll get those pictures up as soon as I can take them. I assume a 1-3-5-7 (left bank) and 2-4-6-8 (right bank) cylinder numbering scheme with cylinder 1 at front left of the engine.

Cylinders 7 and 8 injectors show the least carbon deposition, while cylinders 3 through 6 injectors have the heaviest carbon buildup.

The fantastic simplicity of a mechanically injected diesel engine seems to lead to one component, since the injectors and glow plugs are no longer suspect. All glow plugs have under one ohm resistance, so none were burned open.

It seems I need a new DB2 injection pump. Sloppy timing chain may be a problem, I suppose. I don't even know if this engine has timing chains or gears.

How on earth do you test this stuff? How do you sense the fuel pulses to the cylinders to measure timing?

Wow! If I bring the rpms up to 1500 or so (estimated), I can blow that blue white smoke like crazy. Whatever is failing, isn't the fuel injectors

My next call is already in to a diesel specialist to consult on the problem.
 

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Discussion Starter · #32 ·
Can any of you work me back from what the symptom of grey/white smoke production means? What causes the smoking? What's happening inside the combustion chambers?

I'm just guessing, but isn't that smoke actually unburnt fuel? I am assuming the injectors won't inject at all, unless a high enough pressure fueling event occurs. I can't figure out how fuel can even exist in the combustion chamber except when it's supposed to be injected.

Something else that's confusing is, I thought overfueling caused black, not gray/white smoke.

I still don't have my mind around what conditions can cause this symptom. Troubleshooting by substitution hasn't been effective so far.

I was wondering if fuel starvation is causing this. A thing that makes me think not is that under full load, full throttle acceleration, it produces no smoke. It gets to work and drives up the hill, engine temperature peaking at 195 degrees, just like it should. Low load, above idle rpms a bit, and it smokes. Fuel starvation would behave worse at full throttle, I'd think, when fuel flow is supposed to be higher.

At this point, the injector pump seems the likely problem. I can't figure how that pump could cause the symptoms I see, though. Again, I have no experience with failed injector pumps. I have no idea how the engine behaves when the injector pump begins to fail, or how many ways it can fail, for that matter.
 

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Discussion Starter · #33 ·
So far, the only actual evidence I have is carbon deposition on 25 year old injectors. Until today.

To prepare to replace the injector pump, I had the doghouse off of the engine to survey the work. Aside from the need to remove the left front fender liner to get to the injectors on that side, the forward control step van chassis makes it fairly easy to work on the engine. And, the L57 normally aspirated engine layout makes the job mostly accessible right from the cab. My biggest concern is rigging a shield to prevent dropping the three driven gear bolts.

While I was surveying the work, I had the air cleaner off, exposing the fuel filter manager. Since I keep a spare filter, I thought it might be foolish to begin the job to replace the injector pump before having a look at that fuel filter.

The amount of brown crud in the bottom of the fuel filter manager was shocking. I don't know the age of that buildup, but the filter was visibly loaded with it. It took me quite some time to clean it all out of the fuel filter manager, before installing the new Wix 33976 filter, and taking it for a test drive. What appears to be a place to attach a piece of hosing to bleed the filter, is nothing but a knob to nowhere. The Wix filter bleed just leaks fuel out all over the top of the filter cap when the air is gone. You want a rag to catch that fuel.

I suspect flow through that heavily clogged fuel filter was pretty restricted.

The smoking was really getting heavy sometimes, to the point where I was avoiding some roads with speed limits that caused it to smoke. It was visibly smoking in normal driving conditions, now. Why the rapid onset? What can change so dramatically, so quickly?

I think the answer is it was me.

With a fresh fuel filter, the stumbling starts that were increasing stopped. The smoke on start stopped. I took it for a test ride and had difficulty making it smoke. Though, the engine had returned to the light, occasional smoking that I described in my first post. Until I let loose a couple cans of Seafoam into my fuel tank. I think I clogged my fuel filter.

I think that Seafoam did what it says it will do, and flushed all sorts of crap from the fuel tank, crap that had been there for 25 years, and was now clogging my fuel filter.

I'll replace the fuel filter again in a week, and we'll see what needs to happen next. I have to have a perfect fuel system before I go for that injection pump.

On the ride back from our test ride, I seemed to lose a cylinder, with a loss of power, rough running, and a hell of a clatter from that cylinder. It smoothed out while I was seeking a safe place to pull over, and returned to running normally. As if an injector were momentarily blocked.

The crud in the fuel filter manager and the visibly clogged filter are solid evidence, and I think could cause fuel starvation. I wonder if what I felt and thought were power bumps were actually dropouts from fuel starvation. I don't know exactly what that feels like or sounds like, either.

Finally, the tone of the engine has returned to how I remember it sounding, particularly on startup. Before replacing the fuel filter, it had a much sharper diesel clatter, noticeably quieter again now.
 
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