'69 Mercedes, Engine dies when put in gear(auto) - PeachParts Mercedes-Benz Forum

Ruman999 · #1 09-04-2008, 08:05 PM

Any ideas? If I put it in reverse, w/ the brake held down, I hear a quick screetch and it dies. If I put it in drive it dies as well.

Torque converter?

I do not want to progress any further with the car until I figure this out. Also, if you think it's the torque converter, any price ballparks?

Ruman999 · #2 09-07-2008, 12:42 PM

Bump. Any thoughts?

JMela · #3 09-07-2008, 11:31 PM

What model?

Ruman999 · #4 09-18-2008, 09:15 AM

It is a W114. I just rebuilt the Zenith carbs, thinking it would run. It runs, but won't move! Not sure the best way to troubleshoot a transmission issue.... It just dies when put into gear.

79Mercy · #5 09-18-2008, 10:12 AM

what is the idle speed in park?

230/8 · #6 09-18-2008, 11:04 AM

It sounds like you have not set-up the idle speed properly and completed all the needed adjustments.

You should confirm that you have good points, correct ignition timing and have properly balanced the carbs with the idle speed set to about 850-900 RPM in neutral. Once that is done, you need to set the idle speed dashpot. This item helps prevent stalling when you put the car in gear. The dashpot is located on the font carb and acts by pushing on the linkage that is on the rear carb. It raises idle speed as idle loads change, like when you turn on the AC or put the car in gear.

Set the dashpot by measuring and setting the clearance to .004" between the dashpot plunger head and the linkage on the rear carb. The plunger should not touch the carb linkage when in neutral. Once you have done this you cross check the idle speed by placing the car in gear and observing the idle speed...it should be abut 650 RPM because (as the engine vacuum drops) the plunger extends and pushes on the linkage; this gives the engine a bit more throttle to prevent stalling. If the idle speed is lower than 650, you adjust the tension spring on the dashpot to allow the plunger more travel, reset the clearance mentioned above (car in neutral) and then recheck the in-gear speed. It is a trial an error process. Try to get close to the magic 650 in gear, some cars make it, others only get close, but once the dashpot is set it should run fine.

Search this forum for many posts on dealing with old Zeniths.

230/8

Ruman999 · #7 09-18-2008, 10:08 PM

I do not believe it is a carb issue. When putting the car in reverse, the tires actually squeal, then the car dies. When put in drive, it just dies. Both times the engine is at an appropriate RPM, and it just suddenly dies. It doesn't sound bogged down, then die, it's pretty quick.

My dad believes it is a torque converter issue. I am going to play around with it a little more this weekend and see if I can find out anything else.

The car idles perfect for a couple of minutes, and then seems to die. But when running into this issue we stopped to try and figure out the transmission problem. There is no guarantee that the transmission is good. The guy that bought the car prior to me bought it as a parts car.

If it were a torque converter issue, any ideas on the cost of getting another one or a rebuild? If it's too much I may have to pass on this project and try to sell her.

230/8 · #8 09-19-2008, 10:50 AM

The transmissions in these cars are usually very trouble-free, all they require is fresh clean ATF and correct adjustment of the pressure linkage to last almost forever...the Zenith carburetors are not trouble-free. They are a constant source of complaint due to improper tinkering by mechanics who do not understand their nature and the need for precise adjustments.

230/8

Ruman999 · #9 09-19-2008, 07:43 PM

Ok well I will play around with the carbs more this weekend. I just went out and tweaked some more things, so that it idles perfect now. I have no way of checking the exact rpms, and they yet need balanced perfectly. I would hope that it would still go into gear at all, especially when giving it a little bit of gas, but it just screeches the tires when it's put in reverse, then abruptly dies, and when put in drive, it just abruptly dies.

My dad has been the one doing the carb work, and that is actually his trade from school and he did it for quite awhile. He now is a computer programmer instead.

I was able to contact the previous owner that had purchased it for a parts car. He said the owner before him told him it was parked for 6-8 years but the tranny was rebuilt not long before that.

Thanks.

ja17 · #10 09-19-2008, 11:53 PM

Hello,

I agree with 230/8, it sounds like a carb set-up issue. The car should idle around 650 to 700 rpm. Turning the idle mixture screws on either carb should make a noticable difference in rpms or you may still have something plugged up. There are a lot of little subtle things on these carbs that make a big difference. Did you also check the gaskets on the plastic insulators under the carbs between the intake manifold and the carbs (they shrink or loosen and leak air)?

One other thing, we are assuming the engine is in good health. You may want to do a compression check before going much further.

Ruman999 · #11 09-20-2008, 11:03 AM

It idles pretty good now, but as I said I have no way of telling the RPMs at the moment. I don't believe it's leaking air down there, it has all new gaskets on each side of the plastic insulators. New gaskets throughout, entire carb was soaked in carb cleaner, completely disassembled, and all parts replaced that were in carb rebuild kits and reassembled.

If it's a matter of the car not getting enough power, why would the tires screech when the car is put in reverse? It doesn't move, but I do have my foot on the brakes. I believe the brakes are rusted a bit so I would have to replace those to make it street-worthy, but it's just odd that it screeches in reverse. Even if pushed up to probably 1k+ rpms and put into gear it does the exact same thing, and dies the exact same way and equally as quick, it just might screech a little more.

I will be looking at it more today and we'll see. It did this same thing with another set of carbs in it. I had purchased another set of carbs to use as a guide to make sure everything was correct in my carbs. I also put those on instead, it didn't idle perfect with those carbs, it idled high, but I tried putting it in gear with those carbs, and the exact same thing happened, screeched in reverse then died, and just died in drive.

ja17 · #12 09-20-2008, 03:13 PM

Hello,

Stalling when the car is put into gear is typical when the carbs are not set up right. In addition the high rpms does put more power to the rear wheels through the automatic. Your idle rpms must not be too high, otherwise your carbs are idling from the main jets instead of from the idle jets! You'll never get it right unless you check to make sure the engine compression is decent in all six cylinders and the idle rpms are low enough to allow the idle circuit in the carbs to function properly.

Ruman999 · #13 09-20-2008, 10:36 PM

OK well it does make a little more sense now. The calipers were basically rusted tot he rotors on both sides. That is why the car wouldn't move. I jacked up the rear of the car, took off the tires and put some PB Blaster on em and started the car, put it in reverse, and it idles, and the "wheels"(rotors) moved. Put it in drive, worked great too. Revved it up and got it to 50 mph, at idle they moved slowly. But when I apply the brake, the car dies, no matter D / R. So that is probably balancing the carbs. Knowing that the brakes were stuck that bad does make more sense as to at least why the car wouldn't move when in gear, I figured it would at least move some then die.

I will balance the carbs next weekend and hopefully my brake supplies will be there by then too. My next question is whether to buy the seal kit for the calipers or just all new calipers.

Have to spend tomorrow on a '90 Jetta diesel that my dad stripped, removed all the rust and we're painting tomorrow. Fun fun.

Thanks!