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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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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.
 

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1997 Grumman Olson 12 ft step van, NA 6.5 diesel (RPO L57), 4L80E transmission
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34 Posts
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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You really should use additive to your diesel fuel. It is not just to keep the combustion chamber clean. Altho it does help with that.
Diesel additives add lubricity. ULSD is a very dry fuel. Without additive the IP and injectors do not get enough lubrication from the fuel. This can cause wear and premature failure. Because the fuel system was designed to run on older higher sulfur diesel formulations that lubricated better.
I use Diesel Kleen in the grey bottle. It is economical, and provides satisfactory lubricity at recommended mixture.
It also adds more cetane which helps the fuel/air mix combust better.
That is a nice looking old van. Glad your problem is clearing up.
 

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1995 Chevrolet Silverado Z71 6.5 TD
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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.
What is the long way to work in mileage and speed?
 

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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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There is a special socket for them. I've read some people have use a regular socket on them with success but when I did mine I bought the socket. I don't know how easy it is to access yours in a van but when I did mine I pulled the inner fender and turbo on the passenger side. I see you are N/A so that helps. I had a hell of a time with the little plugs that go on 7&8 return lines. Don't plan on reusing the old return lines buy new ones. I also did one side at a time. When I got the passenger side done I started it and let it run a few minutes to get the lines and injectors primed back up on that side. The lines i just took loose and carefully moved them out of the way enough to get the socket on and injector out and back in. If
 

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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?
I would pop test those injectors. You can test them yourself and make a pop tester out of a bottle jack. there are a few "How to " videos on Youtube on making a pop tester out of a bottle jack.

Injectors are fairly straightforward to remove/replace. You won't have a turbo getting in your way but still can be a knuckle buster if you're not careful.
When reinstalling be sure to use new return lines. There are kits out there that use no hold down clamps that will make things a little easier
 

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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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Yes, grey/white smoke can be injectors. It can also be a cooling system issue or just a glow plug system issue.
If it was a cooling system issue, you would also see bubbles within the coolant, recovery tank, hard upper rad hose while the engine is running, signs of oil in coolant or coolant in the oil.
Glow plug issues would be hard starts, heavy smoke that clears up. WTS light that stays on longer than normal, etc

Injectors that leak can cause some bad issues for an engine.
Leaky injectors will leave unburned fuel to pool up in the cylinder and cause excessive EGT's, pistons can crack or melt and cook the heads. excessive smoke, poor performance.
If you do not know the history of the Injectors then I would just recommend that you replace them.
If you know the history then you can test them.
 

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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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Exactly what I needed to know. New injectors, it will be. Thanks for your help!
When replacing the injectors it is recommended that you only use the OEM Bosch Injectors
 

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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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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.
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......
 

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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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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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