1981 300sd motor and tranny into 1985 300sd body - PeachParts Mercedes-Benz Forum

bjenterprises · #1 01-25-2007, 07:42 AM

I have 2 300sd's the 1981 has a new rebuilt Motor From Mercedes and it has so much power you can't tell it's a diesel. Only problem is the body is falling apart. It has several water leaks when it rains and the sunroof no longer works, the power windows have stopped working and other problems. My 1985 300sd is in excellent condition except for the fact that I was passed the other day by an old lady with a walker. I took the 85 to our local shop and he did what he could to make it faster. Now i must say i might tie an old lady with a walker. Its still a dog he Said i just need to let it warm up. Even when its warm my 81 cold has tons more power.
The reason for this is i asked if i could swap the tranny and engine from the 81 into the 85? The mechanic said they would bolt in but he was not sure the wiring would work. Does anyone here know how to get this swap done??
A couple years ago i read a thread on here about how to make an 81 turbo fit an 85 but i searched and cant find that thread. I would rather have the whole Motor and tranny swapped.
Thanks,

bjenterprises · #2 01-25-2007, 07:43 AM

I have searched and couldnt find the answer

vstech · #3 01-25-2007, 09:24 AM

I can think of nothing electrical that would be different. move all sensors, and manifolds over.
but if your 85 starts, has good compression and a good air filter, it should be almost as powerfull as the new motor, IF the alda line/overboost protection circuit is working perfect.
search banjobolt. tons of info there.
John

ConnClark · #4 01-25-2007, 11:21 AM

The only thing that will be different (assuming its federal emissions) is the compressor housing on turbo which has an ARV and the computer and vacuum amplifier to control it.

Icefire · #5 01-25-2007, 12:03 PM

Lots and lots of differances, but non that are difficult to overcome.

The 85 engine has alot of extra wireing, for the IP, EGR, TACH,
Overall the 85 has a more complicated vacuum system.

It will bolt in and work just fine, however there are definitly some wireing issues.

The problem I see, is you will be paying a mechanic by the hour to figure out what needs to be changed over,

Since you describe taking the benz to the shop, I assume you are not a DIYer
This is a time consuming process, so labor will be an issue, however it is definily worth it,

vstech · #6 01-25-2007, 12:11 PM

I wanna know why the 85's motor is running just strong enough to keep up with the walker.
seriously,
if it starts, doesn't smoke, and will drive, either you have no turbo, or the alda is not enriching the fuel with the boost.
or you have throttle linkage issues, but I assume a mechanic would have checked that...
I guess the wastegate could be stuck open, or the egr dumping straight exaust into the system all the time...
who knows, but if you swap bad components onto the new motor, it will not run well either.
John

bjenterprises · #7 01-26-2007, 01:59 AM

thanks for all the input. As far as being a do it yourself guy well I put the motor into the 85. My 2 day job tuned into 7 Months and my wife said she would rather have me pay someone this time.
No smoke at all, high compression, no power. It really is bad enough that if I park on a hill I can't go up it until the car warms up. It feels like the turbo doesn't kick in early enough. I want to change everything from the 81 to the 85 as far as the engine is concerned

vstech · #8 01-26-2007, 08:54 AM

Quote:

Originally Posted by bjenterprises

thanks for all the input. As far as being a do it yourself guy well I put the motor into the 85. My 2 day job tuned into 7 Months and my wife said she would rather have me pay someone this time.
No smoke at all, high compression, no power. It really is bad enough that if I park on a hill I can't go up it until the car warms up. It feels like the turbo doesn't kick in early enough. I want to change everything from the 81 to the 85 as far as the engine is concerned

High compression? well that tears it, DO NOT PUT THE MOTOR IN.
get the alda and banjo bolt issue fixed. the turbo's are nigh indestructable... unless you had the dreaded football still in your exaust system... anyway, mostlikely it's a simple fuel problem. a tank screen issue, plugged fuel line. something simple.
try disconnecting the two fuel lines that go into the firewall, and dropping them into a gallon jug of fuel and see how it drives.
if that doesn't help, check the other issues with the turbo. keep that 81 motor as a spare for when the 85 motor DOES fail... about 500,000 miles or so...
John

bjenterprises · #9 01-27-2007, 09:53 PM

By a football in it do you mean the trap oxidizer? Well the 85
Still has it. I never Found anything to replace It with. Is there someone on here Who is Making a replacement?
I appreciate all the help.
The accelration problem did Feel like a linkage problem. I checked all that and thatS not it. I am no expert but it feels like the turbo does not kick in soon enough.
Does someone actually own an 85 300sd with some get up and go?

GRIESL · #10 01-27-2007, 10:13 PM

Quote:

Originally Posted by vstech

High compression? well that tears it, DO NOT PUT THE MOTOR IN.
get the alda and banjo bolt issue fixed. the turbo's are nigh indestructable... unless you had the dreaded football still in your exaust system... anyway, mostlikely it's a simple fuel problem. a tank screen issue, plugged fuel line. something simple.
try disconnecting the two fuel lines that go into the firewall, and dropping them into a gallon jug of fuel and see how it drives.
if that doesn't help, check the other issues with the turbo. keep that 81 motor as a spare for when the 85 motor DOES fail... about 500,000 miles or so...
John

First, I'm jealous you have a rebuilt motor; second, we've all been there with the wife; and third I have to agree with John. Don't switch motors. You'll find a cheaper and easier solution diagnosing the motor that's giving you fits, seems to me. I'd check fuel delivery (by the method described up top here). Adjust valves if not already checked. Can't remember if you said you did anything with checking/cleaning injectors. Check injector return lines for leaks.

Then find yourself a cream puff body with a bad engine and put the 85 motor in it. If you can convince the wife, of course. Good luck!

bjenterprises · #11 01-27-2007, 10:22 PM

By a football in it do you mean the trap oxidizer? Well the 85
Still has it. I never Found anything to replace It with. Is there someone on here Who is Making a replacement?
I appreciate all the help.
The accelration problem did Feel like a linkage problem. I checked all that and thatS not it. I am no expert but it feels like the turbo does not kick in soon enough.
Does someone actually own an 85 300sd with some get up and go?

MB-Owner-in-ind · #12 01-28-2007, 08:48 AM

I have an '85 and although it doesn't have the get up and go of my '83 I attribute that to the difference in weight. When I got the car it would slow down when going up a grade. I looked and found the line going from the intake manifold to the Alda was leaking. Fixed this and found my lost power.

bjenterprises · #13 01-28-2007, 11:29 AM

i didn't know they weighed any different. once the car is moving it is not as bad but i will not hesitate to pass in my 81. it will get up too 90 very fast. the 85 will get to 90 sometime. I thought the 85 has a different turbo and exaust with an extra bend. I also thught it has a lower first gear to compensate for the lack of powere. am i wrong?
The mechanic was going to charge me 1000.00 to do the swap.
Thanks again
sorry about the typo's I am on my phone

bjenterprises · #14 01-28-2007, 11:18 PM

I am no longer on my phone. I was at Disneyland with my family. Is there a way to get rid of this trap oxidizer? The one on the 85 was not replaced during the campaign so I am a little worried about it giving me problems. Both my cars only have 130k with new engines in both. The 81 body is just not holding up all that well.
I figured for 1000.00 I couldn't fix all the things wrong with the 81.
No rust on either car, (norther ca cars)

MB-Owner-in-ind · #15 01-29-2007, 10:53 AM

I have read that the dealer will replace the trap for free but no personal experience.

The SD is a larger body than the 300D thus more weight. Mine is slow off the line, (I think my '77 na 300D can beat it.) but has reasonable power once it is going. I haven't done much to this car but valves, purge and the alda line thing.