starting my diesel swap, 4cyl MB diesel engine into 89 Astro

[tinworm]

hi, first post on this forum! glad to be here. I have a few running threads on this topic on other forums, and seeing as how this forum has a diesel specific page, I figured it was appropriate to put up a thread.

Im in the midst of a slightly different diesel swap. I am going down in size and power in order to increase efficiency and fuel economy for a delivery van I use a lot around town and shuttling back and forth between two locations about 50 miles apart. I also use the van a lot for property maintenance and other visits to job locations, so I am attempting to lower the costs of these types of visits over the long term.

The donor engine is a 1980 Mercedes 616 out of a 240D, and has a whopping 67hp from the factory. I am working on ways to improve this a little as well, my end goal is somewhere around 90 hp, which should be more than adequate for the use of the van.

My recipient van is a 1989 chevy astro, it has a 205k 4.3 that smokes a bit on startup, a much abused transmission, and has been extremely reliable and durable, selling me on these particular vans big time. Tow rating, turning radius, visibility; all excellent. Took about a week for me to become an astro/safari fanatic.

Additionally, I jettisoning the automatic and using a 5-speed manual T5 tranny mated to the diesel. Im also adapting a turbocharger to the diesel, so the end goal is a approximately 90hp, 5-speed, turbo diesel work mini van.

I am a pretty decent way along, so Ill be posting a bunch of pics of where I am so far shortly. Any questions or comments much appreciated!

[Smiliesafari]

Welcome to the site, Tw. Sounds like a great project. Lots of pics.

[tinworm]

so here is the van targeted for this swap-



Amazingly, based on about 50 dump run weigh ins, this stripped down passenger version is a mere 200lbs heavier than the 240D that the diesel came out of. Also, the diesel rear end ratio is close to the stock astro rear end ratio. The Mercedes stock diff for the 616 motor is a 3.69 ratio, while my van has a 3.73 rear end. Im not sure it will be able to pull 5th, but there are enough ratio options available that will fit this van that I am thinking I will be able to nail down a nice compromise long term if I don't find the 3.73 to work well with overdrive.

Since the van was in daily service, I grabbed a parts van and removed the subframe to adapt it to the diesel, The #1 principle difference between the 4.3 and the 616 is the location of the oil sumps. The 616 oil sump is large, and in the front. This presents problems with steering I have not yet worked out, but here are a few pics showing the difference between the two drivetrains-

This is the 4.3 and auto out of the parts van compared to the 4cyl 616 and manual-




here is the initial fitting on the refinished subframe. I was fortunately stopped by a mercedes forum member from making motor mounts with the engine that high, as he pointed out that the 616 will require 15k valve adjustments, and will I be able to get the valve cover off? Thank god he said this, as those valve adjustments done regularly make a difference between good power and zero power.
Here is how it initially looked-




I had to drop it, which required taking a big fat bite out of the subframe-



because this made the subframe uselessly weak, before I did the above cut, I clamped it in position using the tops of the control arm bolts, and beefed it up on the back side-





Its not going anywhere now, though it still needs a little trimming for final fitment.

To adapt the mercedes diesel to the T5 I purchased a kit made for this purpose in adapting GM transmissions to the larger 617 turbo diesels. (The transmission is an actual astro T5 I got off a guy in the midwest, excepting the fact that the gearbox was completely destroyed. Its been rebuilt using the guts from a same year S10 for the same ratios as the 1990 AstroRS source vehicle.) Bits I got with buying the gearbox were the unobtanium stuff I still have to install, like a clutch pedal, and some other bits.

Here is the gearbox all ready to install-



Here is the adapter kit- (comes with a custom flywheel and pilot bearing adapter)



Here is the clutch fitted, and below a comparison between the mercedes clutch and a typical chevy clutch.





flywheels MB on the right-

[tinworm]

Welcome to the site, Tw. Sounds like a great project. Lots of pics.

you may get more than you want! thanks
you are the man I have to talk to about steering eventually I have seen, ill post up whats been done to that point, but steering will be an interesting problem to solve as subsequent pics will show

I may have more pics on any particular subject than I post, in case anybody wants a specific clarification of how ive decided to destroy my perfectly useful van.

[tinworm]

returning to the adapter plate, this is a product made specifically for the 617 motor. These mercedes use an absolutely great toploader huge oil filter, but as you can see in these two pics, that component is quite a bit different in location between the 616 4cyl and 617 5cyl variants. On the 5cyl, its completely in front of the end of the motor, but on the 4cyl, its spaced back to hang over the transmission a little. The plate absolutely will not work with that excellent oil filter unfortunately




close up to show what kind of room I have with the plate fully bolted. It will have to be a remote oil filter instead. Im making a 1/4 inch plate with JIC fittings welded to it to attach to a nice moroso head. Those two lines in the foreground are the oil cooler lines, another issue to work out, though I have some tentative plans for that.



after getting to the above point, I stopped to wait out an EPA and state restriction on repowering where I am. (Rhode Island). Last week the van got the last inspection sticker which is good for two years, at which it will never have to pass an emissions inspection again locally, meaning that since its a diesel and will fail the gas emissions will make no difference on registration as long as safety inspections are passed. I may be able to actually retitle it as a diesel, but that will be a bridge crossed in a while from now.

within 48 hours of getting that last sticker, I ripped out the engine.

Here are a few pics of that-

I thought this van was good on rust, but look how the driver side hangs down. Never noticed until now, but both front subframe mounts are wiped out-



FR mount= nasty



Engine ready to come down, still debating between a Mercedes radiator or the astro radiator that I had replaced less than 20k ago. Will have to compare the two. Locally there is an excellent custom radiator shop, so I might have something whipped up with huge cooling capacity possibly.




(I also took out the seats to be replaced, and marked things like the steering-)



A lot of rusted out fastners had to be cut. I ran the van dry before dropping the motor, and opened the tank, but I wasnt able to remove the fuel line fastners, too rusty. same with some brake fittings. The stock fuel filter location makes for an excellent oil filter placement I think though



engine finally dropped-




once it was down, this subframe too had numerous rust issues, though not as bad as the donor subframe from the parts van, its still pretty nasty, mostly mount locations though-





Motor down and out-




looking up into the engine bay-

[tinworm]

as a note, make sure the chain the body or have someone hanging onto it if you use a lift to drop the subframe.

Im sure you can guess what almost happened.

[LiftedAWDAstro]

Awesome swap thread! Definitely keep the pics coming. Nice thing for you is your 89 Astro is in really great shape! Around here it would be rotted out.

[tinworm]

so now that I had the stock motor out but still mounted, I constructed a jig to give me an approximate height and angle for the mercedes motor. This was specifically so that my stick handle will come up in the right place and be the right length.



Then removing the motor, I could work on placement and angle to build motor mounts-




A couple test fits show the interference with the steering on the horizon-

stock-


diesel-



I then set up my refurbished subframe, and using the jig, arrived at what I think will be a good ride height for the diesel-



Here is where it will sit-




Ill be using GM stock motormounts as they are about 1000% easier to deal with then the hellish MB mounts, though I will be modifying the bracketry a bit on the driver side in order to incorporate and engine vibration shock that is stock on the diesels. Here is how the mounts line up. Passenger side seems almost made for it, but drivers will take a little work-

passenger side-



driver side-



thats where im at right now. Working on building motor mounts, and my remote oil filter plate. In the meantime since ill have it all apart, I ordered new springs, shocks, and control arm bushings for this van. waiting on on those before I move parts over to the new subframe. I also will be cleaning up and painting the control arms, especially the upper one, which is pretty rusty (though still strong)

I will be using a ford V10 starter, which seems to fit quite well without interfering with the subframe. Im especially pleased by its access underneath, meaning it will be straightforward to replace down the line in service if i have problems.

[tinworm]

Awesome swap thread! Definitely keep the pics coming. Nice thing for you is your 89 Astro is in really great shape! Around here it would be rotted out.

thanks!

This van is actually out of New Haven CT ironically. It was owned by a florist who sold it to me when all but the driver door broke and he couldn't open it.

Otherwise, its surprisingly unrusted for a new england vehicle that has been on the CT coast its entire life. The guy definitely washed it all the time though.

There are some rust issues not pictured, the driver side rocker is gone, and there are some issues further back. The passenger side rocker is bashed in, and there is rust I will have to repair before putting the subframe back up-



Once its done, I will take the van down for some undercoating service before the surface rust underneath gets really bad. there is a place locally which will sandblast the rust under your car, and apply thick undercoating afterwords I might look at

[markmitchinnh]

Great project, I just have to ask: are you aware that the smaller engine will require you to push the pedal more to get to speed which will in turn use more fuel? That's why a lot of guys do the V8 swap which usually get better mileage then the stock V6.

[Coyote X]

When I patched my frame I found out the holes in the 4.3 flexplate were the same size as the stock frame bushing holes. So I cut up the flexplate and used it to patch the rusted areas on my frame.

Also would it be possible to bend up the oil pan or reshape it somehow a bit to get clearance for the steering and save a lot of trouble?

[mdmead]

Cool swap! You have my attention! =D>

[tinworm]

Great project, I just have to ask: are you aware that the smaller engine will require you to push the pedal more to get to speed which will in turn use more fuel? That's why a lot of guys do the V8 swap which usually get better mileage then the stock V6.

Im hoping for high 20s, possibly 30 in mpg. Even though this is a smaller, lower power engine than the stock powerplant, its way more efficient than the 4.3. I think the difference between this 616 and a 4.3 is much larger than the difference between the 4.3 and a V8, but everything below is pretty much speculation, so im going to love to get some real numbers once its road worthy. A 2nd driving reason is I can run it on alt fuels, which im already doing on my DD car, so id love to do it on the van as well. Even if it gets 18mpg, its still a win for me since I can run it on other options, not just unleaded.

Here is my reasoning looking for increased fuel economy-

The 616 NA diesel was standard in most of the Mercedes TN/T1 van chassis. (the precursor to the sprinter) The T1s are about the same size as a full size van.
The body options for that model were-

207D- just over 2.75 ton to just over 3 ton
307D- 3 and a half ton to nearly 4 ton
and the 407D-, which is an over 5 ton option.

This van below, a typical T1, is a heck of a block shape, similar to the astro, and im thinking even less aerodynamic than a gen1 shorty-

207D pic-



Additionally, all the T1 models had 1.1 final ratios (if that) and low gearing as you would imagine using a small powerplant to move a big vehicle. A base 207D would have a 4-speed manual with a 1.1 final ratio.
I found some fuel economy numbers on a 307D (3.5-4ton chassis) in England, that i converted from imperial gallon over to US, and the owner was talking about 20-25mpg (US) on a much heavier vehicle about the same shape (though larger), and without an overdrive option.

Taking his info, im hoping that my lighter van, with the engine mildly turbo's with a .78 overdrive final gear would yield me better economy if he was doing the same economy as a stock 4.3 in a much bigger and heavier vehicle with the diesel.

Another reason is I pulled this 616 engine out of a 240D I was running with a modified overdrive transmission at .8 overdrive, and in that body, it was capable of 35mpg at reasonable speeds, like 65 or so. It would typically run over 30mpg with average driving, and not hypermiling at all. That body being close to the same weight and close to the same ratios posting those numbers points me towards believing that the biggest difference would be one of wind drag between getting 35 in the car, and what I might get in this van, which is where I arrive at the high 20s to 30mpg being my ultimate goal.

Sorry for the long winded post.

[tinworm]

When I patched my frame I found out the holes in the 4.3 flexplate were the same size as the stock frame bushing holes. So I cut up the flexplate and used it to patch the rusted areas on my frame.

Also would it be possible to bend up the oil pan or reshape it somehow a bit to get clearance for the steering and save a lot of trouble?

This is great, thanks!
I already patched the holes in the refurbished subframe, but since they were all rotten, some of the openings are estimates from when it was done. I might use the flexplate as a template if I can't trim to fit when the bushings finally arrive.

Im definitely thinking of cutting the oil pan. Im going to drop the pan once I finish the mounts and see where the oil pickup is.

I am hoping to join you with a diesel astro ASAP.

[tinworm]

Here are some pics of where im going with turbo charging this motor. Preemptively, MB specifically forbids turbos on the 616, stating that its not built for it like the 617.

However, ive been in correspondence with some guys who did it, and they all say its great, and they haven't noticed any long term issues at all. On top of that, MB sold the 616 design to India, and the Indians have turbocharged the motor to move their people carriers, so it seems to me its definitely possible.

The big thing one guy was telling me was keeping the pressure low, and having both a boot gauge and an EGT gauge, and keeping an eye on them. With those items, he's said he abused his car daily without any discernible negative result with something like 50-80k on the conversion, so i figured the potential advantages outweigh the potential disadvantages if I do it.

its not put together completely yet, but my plan is to the use the stock 617 turbocharger which is approximately 10psi max. Since the 616 and 617 motors are nearly identical, the 5cyl manifold fits on the 4cyl motor, and all I had to do was lop off that final cylinder on both the exhaust and intake to be in business.

some pics-
this is the 5cyl turbo setup sitting on the 4cyl-



this is where I approximately had to cut to make myself a 4cyl turbo intake manifold, however, the intake holds the stock air cleaner, and a bunch of other ports and brackets, which I wanted to keep, so I made a complex cut and had an aluminum welder patch it back up for me. Now I have a shorter manifold that still has all the nice bits from the longer motor.

My criteria with this swap has been trying to preserve stock systems as completely as I can for future maintenance. I want to combine all custom mods into single or a few parts per each system, so that it makes it easier to use as a fleet vehicle. For instance, if every mod for fitting the engine is done on the subframe, I can order replacement parts for the engine just using the donor car. Same on the turbo, if the turbo is basically stock to a 300D apart from the manifolds, replacement parts can easily be ordered from that donor vehicle as well. Its still going to be a list, but ive already learned to my cost what a car with a million custom bits means when its used by a company in daily service. Id rather keep it to half a million if possible.

pics-

where the length would be decent on the intake-



cut and welded-





on the exhaust, same deal, nipped off the last cylinder-

They helped a little by dividing the manifold-



fitted on the motor-



I mailed it off to a guy who super professionally brazed shut the hole, and cooled it properly to keep the cast iron from getting brittle at the brazing. Guy did an amazing job, has some serious old school talent, and im thinking it will react nicely in service with this treatment-



how they both look on the motor, ready to bold a stock turbo from 617 motor-