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Discussion Starter · #1 ·
Considering a couple different rigs (step vans):

At the moment:
2002 Freightliner M-Line Cargo Van (24 valve cummins)
2003 Workhorse P42

Seems like there are pluses and minuses to both. Cummins seems recommended by a lot of people but sounds like the 12 valve is better. One person told me that the 2003 6.5 in the p42 is the worst diesel ever made. 506 block he said was bad and prone to cracking. Some people that worked in the post office said it was a good truck.

I read the 6.5 is an IDI and veg oil runs better in IDI vs. DI which is the 24 valve. I also read lots of pumps fail in 6.2 and 6.5 especially in the years: 1982-2000.

So does that mean the pump would be better in the 2003 p42?

Both of these were used by the post office and I am looking to get one. The more widespread one seems to be the 6.5l.

Some different kids of diesel step van engines but in order (roughly) from most common to least.
  1. (6.5)
  2. (24 valve)
  3. (Mercedes 4 cylinder diesel)
  4. (12 valve)
  5. (6.2)
  6. (4bt)
In terms of numbers it seems like there are more p42's available with the 6.5 than any other engine.

Planning on running them with veg oil or blend so ideally would like to find the best one.
 

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Welcome to DieselPlace

Running WVO is going to be a little harsh on the fuel system no matter what you drive. Filtration is the key to longevity
You can look through our alternative fuels section to get some ideas Bio-Diesel/Alternative Fuels and Supplements
(y)
 

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Discussion Starter · #3 ·
Considering a couple different rigs (step vans):

At the moment:
2002 Freightliner M-Line Cargo Van (24 valve cummins)
2003 Workhorse P42

Seems like there are pluses and minuses to both. Cummins seems recommended by a lot of people but sounds like the 12 valve is better. One person told me that the 2003 6.5 in the p42 is the worst diesel ever made. 506 block he said was bad and prone to cracking. Some people that worked in the post office said it was a good truck.

I read the 6.5 is an IDI and veg oil runs better in IDI vs. DI which is the 24 valve. I also read lots of pumps fail in 6.2 and 6.5 especially in the years: 1982-2000.

So does that mean the pump would be better in the 2003 p42?

Both of these were used by the post office and I am looking to get one. The more widespread one seems to be the 6.5l.

Some different kids of diesel step van engines but in order (roughly) from most common to least.
  1. (6.5)
  2. (24 valve)
  3. (Mercedes 4 cylinder diesel)
  4. (12 valve)
  5. (6.2)
  6. (4bt)
In terms of numbers it seems like there are more p42's available with the 6.5 than any other engine.

Planning on running them with veg oil or blend so ideally would like to find the best one.
Which is the more reliable engine?
 

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Discussion Starter · #4 ·
Welcome to DieselPlace

Running WVO is going to be a little harsh on the fuel system no matter what you drive. Filtration is the key to longevity
You can look through our alternative fuels section to get some ideas Bio-Diesel/Alternative Fuels and Supplements
(y)
Thanks. That's how I originally found this forum was for searching for info on veg oil and 6.2's and 6.5's.
 

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Mercedes the best. Uses similar injectors to the 6.5, easy to access the injectors for cleaning if veg oil causes issues. Also notoriously well liked and well tested by thousands of individuals for use with alternative fuels which opens an absolule tsunami of relevant information to your platform.

Second best I would say is 24 or 12 or 4bt with the Bosch P-pump injection pump. The truck I rode in with the veg kit had a heated tank and the fella could pump right from the waste bins into a reservoir But the system wouldn't even begin to allow run off of it unless the oil was 120 degrees plus so it would push through the filters and run similarly to diesel temp/viscosity/atomization for the DI injectors. I don't know if it was just a 'special' system or if they are really that sensitive. No optic sensor, generally better engines than 6.5 but generally much more expensive to buy by a long shot.

Any 6.5 platform using the DS4 injection pump is subject to the optic sensor. Cloudiness or burnt/dark fuel is going to stop it or make it hesitate, shut down, or derate. Any older 6.2/6.5 platform with the DB2 injection pump is going to be excellent for alternative fuels. However, adding a turbo makes it significantly more difficult to service the passenger side injector bank. I've been on a lookout for a 1993 turbo truck or maybe a 6.2 truck for waste motor oil burning for years. Haven't been able to seal the deal yet.

I've poured all manner of **** into my tank with my DS4 and this truck will eat a lot of stuff you would barely expect it to, BUT IT NEEDS TO BE TRANSPARENT. The truck begins to see a fuel economy and performance hit that is just not even worth the effort to pour it in the tank, no matter how expensive regular fuel is. Easier to acheive "normal" performance levels with veggie oil versus waste motor oil, yes. But still emulsified water and other things can cause cloudiness and problems as well unless you expect to burn it at a high level of refinement all the time to eliminate that as a possibility.
 

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Discussion Starter · #6 ·
Mercedes the best. Uses similar injectors to the 6.5, easy to access the injectors for cleaning if veg oil causes issues. Also notoriously well liked and well tested by thousands of individuals for use with alternative fuels which opens an absolule tsunami of relevant information to your platform.

Second best I would say is 24 or 12 or 4bt with the Bosch P-pump injection pump. The truck I rode in with the veg kit had a heated tank and the fella could pump right from the waste bins into a reservoir But the system wouldn't even begin to allow run off of it unless the oil was 120 degrees plus so it would push through the filters and run similarly to diesel temp/viscosity/atomization for the DI injectors. I don't know if it was just a 'special' system or if they are really that sensitive. No optic sensor, generally better engines than 6.5 but generally much more expensive to buy by a long shot.

I've poured all manner of **** into my tank with my DS4 and this truck will eat a lot of stuff you would barely expect it to, BUT IT NEEDS TO BE TRANSPARENT. The truck begins to see a fuel economy and performance hit that is just not even worth the effort to pour it in the tank, no matter how expensive regular fuel is. Easier to acheive "normal" performance levels with veggie oil versus waste motor oil, yes. But still emulsified water and other things can cause cloudiness and problems as well unless you expect to burn it at a high level of refinement all the time to eliminate that as a possibility.
Thanks. The MT45 with the mercedes engine is not common. Think the postal trucks that had them were 2004 models so those aren't old mercedes. 1 guy who works on fleet vans was saying they are pricey to repair and get parts for.

The DS4 is in the workhorse p42? What do you mean by transparent? Said you poured all kinds of stuff into your tank so this seems contradictory. Don't get it.

So whether the engine is IDI or DI doesn't matter to you?
 

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MT45: Only know about alt fuel viability of the OM606 etc... No idea bout this other engine.

IF the truck has an electronic injection pump it will be a DS4 (very, very likely on a 2003). It has an optical sensor. Anything besides clean diesel (aka black fuel or red dyed fuel, air bubbles from cavitation or suction side leaks, cloudiness from water or additives clashes etc) will obscure the trucks ability to see the timing. You run the risk of performance knock back and economy loss, if the fuel quality is bad enough, it will even leave residue on the sensor or wheel and cause extended periods of derate. This is way less forgiving than a non optic sensor pump of any kind. IE... Why I would put a Cummins above it.

IDI is more forgiving as far as combustion etc is concerned, I am not aware of the concessions that must be made to successfully run alt fuels in an DI engine, but I'd rather deal with that rather that the pain of the optic sensor.

I've heard of people putting lots of miles of Veggie powered DS4 equipped 6.5's but they are running this fuel with a 2 tank system, tank heaters, auxiliary filters etc. I did not have the money for those things and attempted to process the fuels and putting them in the primary tank.
 

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Discussion Starter · #8 ·
MT45: Only know about alt fuel viability of the OM606 etc... No idea bout this other engine.

IF the truck has an electronic injection pump it will be a DS4 (very, very likely on a 2003). It has an optical sensor. Anything besides clean diesel (aka black fuel or red dyed fuel, air bubbles from cavitation or suction side leaks, cloudiness from water or additives clashes etc) will obscure the trucks ability to see the timing. You run the risk of performance knock back and economy loss, if the fuel quality is bad enough, it will even leave residue on the sensor or wheel and cause extended periods of derate. This is way less forgiving than a non optic sensor pump of any kind. IE... Why I would put a Cummins above it.

IDI is more forgiving as far as combustion etc is concerned, I am not aware of the concessions that must be made to successfully run alt fuels in an DI engine, but I'd rather deal with that rather that the pain of the optic sensor.
IDK I tried searching whether or not it was electric without luck perhsp I'll ask in another forum. Is it possible to change it to a mechanical pump? You're saying that's better? ALso isn't the cummins 24 valve have some electronic parts? Thought I saw a video that talked about some of the problems and the lift pump not being so good like the 12 valve cummins.
 

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Commercial spec stuff may be different maybe? But its almost 100% sure that it is a DS4.

Mechanical pumps are more forgiving for low quality fuels. Yes its possible to change it, but it requires a pretty extensive list of mods. All bolt in and very doable, but adds to the complexity. Many people do it to get rid of the 6.5 PMD module failures alone.

The GM lift pumps suck too. I have an aftermarket FASS pump instead of the "bumper" style pump on my 6.5 due to multiple lift pump failures. With any alt fuel system you are going to want an upgraded lift system, anyway.
 

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Re cracked block and 2002 Cummins. I would make sure the engine is not a 53 Brazil block. If so stay away. They were made from 1998- 2002. They are notorious for cracking. Any other block number is OK.
.Then you have the Vp44 electronic IP. It has some issues. A lift pump failure will usually kill it. I would not run WVO oil thru it. It wont last long. You can buy conversion kits.
I would take a 6.5 over a 53 block Cummins

2003 6.5 block should have all the upgrades and is most likely a Navistar bloc. They are stronger and less prone to cracking than earlier GM cast blocks. You can run Veggi oil in 6.5s. My truck ran the first 1/2 of its life on Bio Diesel with no problems.

You can run WVO in older P7100 mechanical IP Cummins 12 valve 1994-1998. They do not like to start when cold on WVO. But that issue can be addressed. They are a stout pump.
12V Cummins is a very durable engine. In 1998 Cummins went electric IP so 1998.5 to 2002 may be the VP44 IP. But not sure in the Postal Vans.
 
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Discussion Starter · #11 ·
Re cracked block and 2002 Cummins. I would make sure the engine is not a 53 Brazil block. If so stay away. They were made from 1998- 2002. They are notorious for cracking. Any other block number is OK.
.Then you have the Vp44 electronic IP. It has some issues. A lift pump failure will usually kill it. I would not run WVO oil thru it. It wont last long. You can buy conversion kits.
I would take a 6.5 over a 53 block Cummins

2003 6.5 block should have all the upgrades and is most likely a Navistar bloc. They are stronger and less prone to cracking than earlier GM cast blocks. You can run Veggi oil in 6.5s. My truck ran the first 1/2 of its life on Bio Diesel with no problems.

You can run WVO in older P7100 mechanical IP Cummins 12 valve 1994-1998. They do not like to start when cold on WVO. But that issue can be addressed. They are a stout pump.
12V Cummins is a very durable engine. In 1998 Cummins went electric IP so 1998.5 to 2002 may be the VP44 IP. But not sure in the Postal Vans.
Great thanks. It is a 2002 24 valve so may be that one. Someone in the reddit forum said the 6.5 was a 506 block so I am not sure.
 

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Yes It should be a 506 block. But in 2000 GM sold the 6.5 engine design to GEP. They still use the 6.5 engine in HUMVEES. More metal was added to the block casting to make it stronger, and they used a better metal alloy. Navistar was contracted to do the casting. The engine name was changed to Optimizer. They are stronger casting than 2000 and earlier castings.
 

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Discussion Starter · #13 ·
Yes It should be a 506 block. But in 2000 GM sold the 6.5 engine design to GEP. They still use the 6.5 engine in HUMVEES. More metal was added to the block casting to make it stronger, and they used a better metal alloy. Navistar was contracted to do the casting. The engine name was changed to Optimizer. They are stronger casting than 2000 and earlier castings.
Okay good to know so you are saying the later 6.5's with the 506 block after 2000 were better?
 

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Yes. Below is more info.
 
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Discussion Starter · #15 ·
Yes. Below is more info.
Thanks for sharing that. That clarifies it I think. Unless the USPS and Workhorse got a bunch of old pre 2000 engines to put in 2003 models then I guess that means those 506 blocks are better.
 

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1995 Chevrolet Silverado Z71 6.5 TD
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Great thanks. It is a 2002 24 valve so may be that one. Someone in the reddit forum said the 6.5 was a 506 block so I am not sure.
I think 2000 was the last year the 6.5 was in a GM/Chevy truck. Humvees still used them though.
 

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Discussion Starter · #17 ·
I think 2000 was the last year the 6.5 was in a GM/Chevy truck. Humvees still used them though.
I am not exactly sure what engine it is, but of all them say GM 6.5 and those models were made in 2003 0r 2004.

Search:
2003 p42 workhorse

Or:

Says:
GM 8 Cylinder 6.5L Diesel Engine,
 

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GM manufactured the 6.5L until 2000 then Navistar briefly took over production then it went to GEP for Military order production
 

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That 2003 van has the 6.5 N/A mechanically injected "Y" L57 diesel engine.
The vans could have a number of different engines.
GM sold the GMT-400 3500's at least thru 2002 with the 6.5td.
 
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I am not exactly sure what engine it is, but of all them say GM 6.5 and those models were made in 2003 0r 2004.

Search:
2003 p42 workhorse

Or:

Says:
Yes they were in cargo vans still I missed that in your post.
 
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