Installing 1979 300D Motor in 1983 300D - PeachParts Mercedes-Benz Forum

wrenchmaniac · #1 01-17-2007, 10:59 PM

Hello to All:
I'm new to the Forum & have a question. I have a 300D motor & trans out of a 1979 116 chassis that I want to install in a 1983 123 chassis. What problems will I encounter with this swap? I am concerned with the vacuum connections & ignition switch shutoff. Could I use the ignition sw from the donor car? The 1983 is missing the ign sw. Or should I fix the motor in the 1983? It has a broken timing chain, broken cam & cam tower & most likely valve damage. All at 169,000 mi. Bought it like this & the body is real nice.
Any advice is welcome. Thanks

bgkast · #2 01-18-2007, 03:16 AM

Put on the W123 motor mount arms and it should bolt in. Fuel shutoff is the same. The '79 engine will have less emissions stuff to worry about. The '79 SD engine is a good one, turbo charged and no EGR!

Johnhef · #3 01-18-2007, 09:17 AM

the bolt patterns for the transmissions are different, but most of the holes will line up.

vstech · #4 01-18-2007, 11:02 AM

I believe the glow plug system is different also... and the 116 is an SD, right?
John

Johnhef · #5 01-18-2007, 11:11 AM

glow plugs are the same, timer is a bit longer but thats it.

SwampYankee · #6 01-18-2007, 11:23 AM

Whether it's an easy swap or not, I just figured I'd throw this out there. Since I'm assuming that you're going to need to get the '83 inspected and registered because you said you bought it that way, check with your DMV to see if there are any restrictions on engine swaps. In CT you can only replace an engine with one that is the same model year or newer. They check block #'s to confirm the date of manufacture. It doesn't make any sense on an emissions exempt vehicle, on a newer one I guess I can see their point. A lot of states don't care, but you may want to check before going through all of the work only to find out that they won't register it.

winmutt · #7 01-18-2007, 11:26 AM

Yall need to move down south where we burn tropical forests just for the fun of it! LOL. Seriously tho, GA has no inspections on diesels at all or on cars 25yrs or older.

MS Fowler · #8 01-18-2007, 12:18 PM

Quote:

Originally Posted by SwampYankee

Whether it's an easy swap or not, I just figured I'd throw this out there. Since I'm assuming that you're going to need to get the '83 inspected and registered because you said you bought it that way, check with your DMV to see if there are any restrictions on engine swaps. In CT you can only replace an engine with one that is the same model year or newer. They check block #'s to confirm the date of manufacture. It doesn't make any sense on an emissions exempt vehicle, on a newer one I guess I can see their point. A lot of states don't care, but you may want to check before going through all of the work only to find out that they won't register it.

I ran into a similar problem when I swapped engines in a Geo Metro. The junkyard said the replacement was exactly the saem, but it lacked the crankshaft position sensor( CPS). The only function for the function for the CPS was to tell the computer which cylinder was misfiring once a misfire had been detected; it had no bearing on the running of the engine. The problem was that becasue of the missing CPS and it s signal, the computer turned on the "check engine" light. No problem for the guy I did this for as he ignored all warning lights ( including "engine oil"). It would have been a problem at emmissions testings as they will not test if the check engine light is on. Removing the bulb won't work as they look to see that the light comes on beofre starting. I was actually working on a timing circut to turn the check engine light on for a number of seconds and then off just to fool them. But since this guy never did emmissions tests, it was not an issue.

Great quote!! When he was asking me why the engine died, he said, " It may be low on oil, it was making the same noise it always does when its low on oil".
I hope never to know what noises my cars make when they are usually low on oil....

Mustang_man298 · #9 01-18-2007, 01:00 PM

Quote:

Originally Posted by MS Fowler

the computer turned on the "check engine" light. It would have been a problem at emmissions testings as they will not test if the check engine light is on. Removing the bulb won't work as they look to see that the light comes on beofre starting. I was actually working on a timing circut to turn the check engine light on for a number of seconds and then off just to fool them.

I too had begun looking into doing exactly the same thing on a 90 Lincoln I had, got it for $500 with a bad trans, rebuilt the trans, but the computer kept having a prob saying it couldnt get overdrive to work (even though it was), made the chk eng. light come on, but emissions were fine. I ended up selling it to my brother in law when his car grenaded, he drove it on DMV one month red tag permits for a year (he knew some people) and the light finally fixed itself, he smogged it and good to go,lol.

bgkast · #10 01-18-2007, 05:00 PM

Quote:

Originally Posted by Johnhef

the bolt patterns for the transmissions are different, but most of the holes will line up.

You should be able to swap the rear plate for a total match.

Johnhef · #11 01-18-2007, 11:03 PM

yep. preferrably before its in the car...

wrenchmaniac · #12 01-19-2007, 12:11 AM

Thanks for the response:
I don't have to mess with any emissions or number inspections here in Mo. so that's good. The donor car just says 300D Turbo Diesel on the trunk. I planned on using the donor trans with the motor. What plate are you referring to changing? The donor car ign sw doesn't have vacuum shutoff lines to it & I wanted to use that sw in the 123. Will it fit? Also wondering about the vacuum sw on top of the 123 valve cover which the donor motor doesn't have. Can I just swap valve covers? Thanks

bgkast · #13 01-19-2007, 02:23 AM

There is a plate between the transmission and the rear of the engine. If you are swapping transmissions it should not be a problem. The new engine should have vacuum lines running to the rear of the Injection pump to shut off the engine. That is how all of these engines are shut down.

Johnhef · #14 01-19-2007, 07:58 AM

The 79 should have the 4 bolt trans attached to it... not quite a direct swap if you know what I mean.

Tonnum · #15 05-18-2007, 12:16 PM

Hello to All:

I'm new to the Forum & have a question. I have a 300D motor out of a 1979 116 chassis that I want to install in a 1983 123 chassis. What problems will I encounter with this swap?Also wondering about the vacuum sw on top of the 123 valve cover which the donor motor doesn't have. Can I just swap valve covers?

Any advice is welcome. Thanks