Chevy Astro and GMC Safari Forum banner

Mercedes 616/617 turbo diesel Astro build

42749 Views 237 Replies 30 Participants Last post by  tinworm
3
NOTE- This is an old thread where all the images were lost due to broken links to photobucket in 2017. I have attempted to go through and upload images again, but some images may not necessarily apply to posts due to lack of availability years later


I been talking about this project, and after finally finding a "decent condition" Astro, time to start working on it!

The plan is to rip the OM616 65hp MB diesel out of my old Mercedes, adapt it to a NV3500 5-speed tranny, and put it in the astro van. The engine is also being mildly turbo charged. Its not built for it heat wise, but I should be able to get away with it, and a little extra oomph on hills would be much appreciated. Searching around, I discovered that the generation 2 passenger astro is only 600 lbs heavier than the 123 chassis MB I was previously using this engine in. I figure the generation 1 astro in the cargo version is closer to the 2 ton mark. The MB is around 3700 lbs.

Ultimately, for a fun swap project i am trying to build decent MPG manual tranny diesel work van. This engine was capable of 35 mpg in the MB with a .8 overdrive, the NV3500 I think is a .78, and I have to find a GM rear end that is close to 3.46, which was the MB rear end I had ready for my car. Stock, the 240 MB came with a 3.69, but with the turbo, a 3.46 would be better. Im not sure what the 1994 Astro has for a rear end, any ideas? If its not close, I will be grabbing another rear end from somewhere, or changing the gears.

Images of what the donor sedan looks like from wikipedia, the 207D that also was fitted with these motors (about the size of a express van), and a 1989 shorty recipient van-

Attachments

See less See more
  • Like
Reactions: 1
141 - 160 of 238 Posts
3
Steel leaf springs and 97 diff installed!

here is the fiberglass monoleaf compared to the steel- The monoleaf has these rubber blocks glued to it sort of 1/3rd the way through. Curious what their function is, if it has something to do with vibration, noise? interesting concept



Driver side monoleaf front hangar was a bit rusty-



the 4.56 installed! Still have to hook up and fix the brakes and wire wheel a lot of it and refinish it. Ironically the shoes on this yard diff were in better shape than the ones i had on the 3.23, so Im sort of take the best of both to remake my rear brakes

See less See more
tinworm said:
Steel leaf springs and 97 diff installed!

here is the fiberglass monoleaf compared to the steel- The monoleaf has these rubber blocks glued to it sort of 1/3rd the way through. Curious what their function is, if it has something to do with vibration, noise? interesting concept
I am not going to try it. But they sure look like they are Jack Lift points to me.
chevymaher said:
I am not going to try it. But they sure look like they are Jack Lift points to me.
Maybe during assembly at GM ? I thought the same thing but figured there were 2 per spring as if some kinda jig could grip it.
4.56 did the trick! 1st sluggishness gone, can pull overdrive with good cruising note on highway, most importantly can do hill starts in 1st now. Very steep little hill near work, previously had to floor in 1st and nearly stall out on the top, now can pull 2nd up same hill and downshift into first at the top, closer to the 240. Gonna try long steep hill elswhere with stop sign at the top and see how it compares to my DD 240 sedan, which can pull second up that hill

Tradeoff is van is slightly slower, 1st gear is almost a granny gear now. Very pleased though, now can dial in and tweak the power output. Gonna test towing performance next week. The difference in highway note and feel is amazing, engine seems overall way more comfortable in all gears, theres less of a valley between gears if you catch my meaning, you don't have to wind it out in first to catch 2nd at a pullable rpm in other words

Another issue is now with this diff, the popping the clutch stalling method of shutting it off does not work in 1st. The torque multiplication makes that super violent, like throw you forward violent. Time to get that shutoff valve working properly
See less See more
2
chevymaher said:
tinworm said:
Steel leaf springs and 97 diff installed!

here is the fiberglass monoleaf compared to the steel- The monoleaf has these rubber blocks glued to it sort of 1/3rd the way through. Curious what their function is, if it has something to do with vibration, noise? interesting concept
I am not going to try it. But they sure look like they are Jack Lift points to me.
doyoulikeithere said:
Maybe during assembly at GM ? I thought the same thing but figured there were 2 per spring as if some kinda jig could grip it.
Im thinking some kind of resonance purpose, or vibration? to keep the spring from cracking due to harmonic vibration maybe?



Hard material, could be a metal block coated in rubber, and its suspended via a membrane off the spring, and the upper side does not touch the spring itself, so it can't be a lift point im thinking
Here is one that was broken-



My springs both look in good shape despite damage from rust on the front hangars, even after 200k of hard use and 20 years. Im wondering if the fiberglass springs that fracture first lose these rubber coated (metal?) blocks off the spring surface. The rubber mounting was definitely deteriorating on some of mine, and one was hanging by only one side. Checking for these blocks is not something I would normally do, even if they fall out the mount looks the same pretty much from the side
See less See more
today was a big test of tow performance. I rented a 5 x 8 trailer and picked up two pallets of material and supplies from a shipping terminal about 20 miles from me. Each pallet was approx 400lbs.

trailer unloaded-



did pretty well, was definitely sluggish, but I was able to maintain highway speeds with the load and even travel up grades without too much difficulty, and get up to speed without too much disgrace. This was a fairly light load, I imagine including the trailer, it was probably 1200 to 1500 lbs total. Good news for me is that most of my work type trailer loads are not going to be that much different from this range of weight.

Its underpowered, but not incapable so far. Haven't done a good fuel economy test with the new diff, but if I can get decent economy combined with reasonably capability from the underpowered plant, I will consider it a good tradeoff.
See less See more
ok, it finally shuts off without popping the clutch. (which was getting very very old)

Using the boost overload valve from a 300D application to direct vacuum from the mechanical pump and draw closed the mechanical shutoff diaphram on the injection pump. Working well so far!



Now I need to concentrate on making a new transmission mount for this thing
See less See more
wow looks good, for what you build this van to do, i would say its preforming amazingly. just remember, that little engine isnt just pulling around a little trailer, its dragging a whole lot of van around with it!
I still think a big Benz hood ornament would fit right in.
:thumbup:
7
took care of a couple rattles and potential rattles

Since I spaced the subframe, I had this going on with the transmission mount-



I had it hacked together for a while with a couple 3.5 inch pallet jack wheels as spacers, but this was perpetually getting loose, and was really just a temporary solution-



replaced the drop mount with a piece of 2 inch pipe instead-




Next issue was I needed to support the downpipe. The flex joint I had put in was a bit small, and instead of taking up some of the flex, was just transmitting vibration up to the bolt flange where the downpipe connects to the turbo flange. Either the downpipe was going to crack at the flange, or the turbo housing was going to be damaged, so I wanted to make a beefy support



See less See more
C11MAN said:
wow looks good, for what you build this van to do, i would say its preforming amazingly. just remember, that little engine isnt just pulling around a little trailer, its dragging a whole lot of van around with it!
Thanks! yeah, it getting heavier and heavier. This swap actually made the van heavier amazingly, and of course, I still have to lay down my plywood floor. :mrgreen:

doyoulikeithere said:
I still think a big Benz hood ornament would fit right in.
:thumbup:
The fiance is working on something for me. Turns out she can pinstripe, so she might paint something on the van for me. I hate those giant benz stars, but something a bit smaller or understated might be in order. :think:
anyone recommend some gauges they have gotten good service from?

Im familiar with Isspro at the high end, installed a bunch of those and was heading that route, except for the $$$$$ price tag on Isspro gauges making it a long time before I can afford to buy all these below- Also, my opinion on Isspro is its a high quality product, but some of their gauges are WAY too complex for what they need to do.
Anyone have opinions on autometer?

what I need-
1-Speedo -Electronic self calibrating-
2- EGT -250-1650F-
3- Boost -0-15psi-
4- Oil Pressure -0-100psi-
5- Voltage
6- Fuel Level 0-90 ohms (I think for the 89, please correct if wrong)
7- Engine Temp- 100-250F

and im going to need an aftermarket dimmer switch as well

I priced it out buying all VDO gauges, and keeping the three crappy sunpro gauges I have installed for oil pressure, voltage, and temp, and im looking at about 500 bucks in gauges to do all VDO. The most expensive ones are EGT and the electronic speedo (with included digital odometer).

Also, has anyone installed one of these interesting self calibrating electronic speedos? How reliable are they? Sounds like an ideal solution, all I have to do is wire up the gauge to the hall effect sensor in the transmission, drive an exact measured 2 miles for calibration, and it will compensate for tire size, rear end, ect and work properly according to the sales literature
See less See more
You do nice work man. Most folks would have tacked together that exhaust bracket and called it good... Little things like a bit of paint on something g small like that speak to your craftsmanship....

That is a really cool van you have put together there. I appreciate your earlier video. Of it running early on, maybe you can post another one with the dog house on?

Trying to imagine the sound / feel of driving it... Pretty cool.
Sailing_Faith said:
You so nice work man. Most folks would have tacked together that exhaust bracket and called it good... Little things like a bit of paint on something g small like that speak to your craftsmanship....

That is a really cool van you have put together there. I appreciate your earlier video. Of it running early on, maybe you can post another one with the dog house on?

Trying to imagine the sound / feel of driving it... Pretty cool.
thanks!

just for you ive shot an incredibly long and probably horrendously boring video of driving around! :mrgreen:
it turned out to be 19 minutes long, if you skip to half way though, there is some highway driving finally. Things are a bit louder than the video demonstrates, but not by much.

also my restart issue is demonstrated here pretty well, still working on that related to the vacuum shutoff retaining too much vac to allow the engine to start

http://www.youtube.com/watch?v=ALuo4-5o ... e=youtu.be
coming up on 5k miles on the conversion.

Still don't have any gauges, but I have made a decision as far as drivetrain. I managed to source a 5 cyl 617 turbo diesel earlier this year, and next year will swap the 4 banger out, and put in the twice the HP 5 banger.

This is because while this motor is great for around town and short highway drives, it really has trouble with grades, especially loaded up. As soon as I built this thing for my around town needs, I suddenly had several job needs more than 150 miles away through hill country. :mrgreen:
I haven't messed with the injection pump yet, but I will probably be making the 4 banger a NA motor until im ready to do the engine swap.

the 616 motor once removed will be stored as a spare for my DD 83 sedan using the same plant, and ill move the turbo setup to that car as well, and over the winter before the swap, ill roll in a new timing chain and other renewal parts for the replacement 617 motor before it gets installed.

The fuel economy has been great, but the power could stand to be better, and ive been at war with myself on really pushing the 4cyl motor beyond what it can do, as far as optimizing the turbo arrangement. The difference in design between the 617 and 616 is better oiling with oil jets under the pistons, heavier duty pistons and connecting rods, bigger oil pump with better flow and higher HP, sodium filled valves, ect ect. Actually all the parts from the turbo motor can be installed in a 616 engine, so That might be a good project at some point as well. However, I could really use twice the HP in stock configuration. With the same gearing, this thing would be a heck of a tractor and would tow anything and power up anything.

the economy has been working out, despite diesel being more expensive, ive saved a few bucks on fuel over 5k miles already. By a few, I mean only a few hundred bucks or so, but that will only expand if I can keep the mileage up. Diesel prices locally are not that much higher than gas

5k miles
Diesel- 178 gallons (28 mpg average), 4 bucks a gallon- $712 dollars
Gasoline- 250 gallons (20 mpg average), 3.50 a gallon- $875 dollars

savings so far- $163 dollars.

I usually put about 20k miles on a work vehicle a year, some more, some less, and I estimate I have about 5-6 thousand into doing this swap what with all the new parts I threw at the van in the midst of it.
Using todays fuel prices, that looks like a fuel savings of just over 600 bucks a year, and I would estimate it would take just under 9 years to pay off the swap investment if I drive about 20k.
However, with the bigger engine, the fuel economy estimate would change to the lower.
See less See more
To spend thousands of dollars to build something that is only marginally useful to save $163 per 5,000 miles seems the perfect definition of pointless to me BUT, thank goodness in at the 49 states we can still build whatever we want and the hell with whatever somebody we don't even know on a forum thinks. I enjoyed your build thread and all the solutions you were able to make during it but wondered about it the whole time... Stan
DRZ said:
To spend thousands of dollars to build something that is only marginally useful to save $163 per 5,000 miles seems the perfect definition of pointless to me BUT, thank goodness in at the 49 states we can still build whatever we want and the hell with whatever somebody we don't even know on a forum thinks. I enjoyed your build thread and all the solutions you were able to make during it but wondered about it the whole time... Stan
lol, point taken, however I wouldn't say marginally useful, id say slow on steep hills and stop there. A condition I could change if I were to boost pump output and make some other performance changes. Otherwise its been in service nearly daily as a company vehicle. My decision to swap motors is really about not killing this engine before its time honestly.

To be fair on the cost analysis, you have to include a complete refurbishing of the suspension for the van as part of my costs, front and rear. Everything but some of the steering bars and steering box I replaced as it was rusted or worn out.

I have a table here somewhere, but the most expensive parts of this conversion have been-
1. suspension bits added up front and rear
2. getting my hands on and figuring out and rebuilding the 5-speed (paid a transmission shop to build it for me, and later realized how easy it was personally to do, so lesson learned. Also had to buy a whole nother van and deal with a clueless guy on shipping the gearbox, story there, but it was incredibly expensive to get my hands on a blown transmission at the end of the day. Actually, this may be number 1)
and 3. the adapter plate at 900 bucks.

A better way to describe it would be as I converted the van, I spend 5-6k in conversion costs and related costs on improvements to the vehicle. I need to separate the costs between direct conversion, and money spent on the van anyway since I was there. When i do that, ill post results of that as well. To swap to the larger motor is a lot more time than cost. All the changes ive made for the small motor work on the large motor, so it should be a fun weekend project.

Plus, dont forget. Biofuels are on the list! :mrgreen:
This is a hobby enterprise though. If I wanted a diesel van for 5k, I would have just bought a 6.5 diesel express, but wheres the fun in that? this has been an entertaining project for me
See less See more
Entertaining for you, and for the rest of us! Thank you for taking the time and effort not only to do this but to take pictures and post it. I know that is a pita especially when working with limited time.

FWIW, I think you would be fine dialing up the 616 a little. You know their reputation, and while you will likely still opt to swap in the 617 (my favorite MB motor ever) it should serve you well until you do the swap.

You have a van that does what you want it to do, and in a way no other does... My hat is off to you!
All I can say is that I want a turbo diesel Astro... You've given me something to ponder on. Thanks for taking the time to post this! You've done a great job!

Kurt
141 - 160 of 238 Posts
Top