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1988 300SE W126
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60 Posts
Discussion Starter #1
Hi,

When I bought my car the transmission worked well in all gears but there was always a grating sound when I was reversing. Recently I drove the car to work and tried to reverse it into a parking space. When I selected reverse there wasn't the usual "nudge" you get when the gear engages and the engine raced. I found that it was best to feather the throttle to get it to reverse rather than try to push it with higher revs. All forward gears worked as they should and I was able to drive home.

Sometimes I have to push the selector lever forward when in park position whilst turning the key to start the engine. Putting it into neutral also works so it seems the neutral safety switch is fine. From what I have read this would indicate that the selector lever bushes are worn.

Does anyone think that renewing the worn selector lever bushes might be all I need to do to get reverse gear to engage?

Could worn selector lever bushes cause reverse gear to not engage properly, thus causing the grating sound, then finaly not to engage at all? Or will a gear either engage properly or not engage at all?

I did a search and have read some posts from people who have had a similar problem. It seems that most people who replied suggested the transmission needs to be rebuilt. Would anyone like to reply with their opinion as to whether I am looking at rebuilding my transmission or not?

The car has a tow bar but I don't know how much towing it has done or what it was towing. There is around 280,000 Kms on the odometer so maybe it is time to rebuild the transmission anyway.

Thanks and regards, Neil

If I had a time machine I would go back to 1988 and buy my car brand new and bring it back to today. Just a fantacy, indulge me.
 

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Registered
1981 300 SD, 1994 C280, 1990 560 SEC
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618 Posts
Yes, symptoms indicate toasted transmission. Never hurts though to check the cheap fixes first and pray. Be sure your transmission fluid level is right. If it has been a good while since you changed fluid/filter you could try that. Doesn't sound like the shifter bushing since it goes into other gears fine. Easy to check though. Get under the car, disconnect the rod on it and move the selector arm around manually. If it is your bushing it will be obvious. Normal for tranny to die at those miles though. Good luck!
 

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Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
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7,029 Posts
Sounds like my $1,600 rebuild a few weeks ago, labor was extra. Good Luck :crybaby2:
 

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Registered
1988 300SE W126
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60 Posts
Discussion Starter #4
Hi liammarsh, thanks for your input.

I checked the fluid level after warming the car up before I drove home that night and it was up to the top level on the dipstick. I don't know when the transmission was last serviced and the fluid and filter changed. The fluid looked clean and didn't smell.

I agree, it doesn't sound like worn shifter bushings would cause the no reverse gear problem. I'm almost certain they are worn however given that I have to push the shifter forward or put it into neutral to start the engine.

My plan is to take the car to an indy MB workshop and get them to have a look at it as I don't know enough about them to try to fix it myself. I will ask them to rule out any easy fixes first but from what I have read on this forum it would certainly seem my transmission is toast.

Cheers mate, Neil
 

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1988 300SE W126
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60 Posts
Discussion Starter #5
Hi 281lmx,

Nice, shiny new transmission you have there. Lets hope mine looks just as shiny when it's done. I've been quoted from AU$3000 to AU$3500 to have mine taken out, rebuilt and refitted by an indy MB workshop not far from home.

You paid US$1600 plus labor, how much was the labor?

Parts can be much cheaper in the US than here in Austalia. I paid AU$77 for an antenna mast and then found one for around US$32 on eBay. Even with postage its still cheaper. The antenna repair kit, gears etc., is priced at AU$140 here but I found one on eBay for US$28. Go figure!

Cheers mate, Neil
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,526 Posts
Where are you in Qld ? I had exactly the same problem -$2600 on the Gold Coast.That wasn't a full reno though.
 

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Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
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7,029 Posts
Hi 281lmx,

Nice, shiny new transmission you have there. Lets hope mine looks just as shiny when it's done. I've been quoted from AU$3000 to AU$3500 to have mine taken out, rebuilt and refitted by an indy MB workshop not far from home.

You paid US$1600 plus labor, how much was the labor?

Parts can be much cheaper in the US than here in Austalia. I paid AU$77 for an antenna mast and then found one for around US$32 on eBay. Even with postage its still cheaper. The antenna repair kit, gears etc., is priced at AU$140 here but I found one on eBay for US$28. Go figure!

Cheers mate, Neil
I cannot remember the labor just for the tranny, but it included all of the fluid gaskets etc. I also had the top end of the manifold rebuilt and all the vac lines, new cap rotor and too much to list. Total for the job, and it was alot of work done was about 6k and change. :eek: Plugs, new egr and icv, injector seals valve cover gaskets both fuel filters, plugs wires oil and filter change, radiator SLS brake flush etc, it goes on and on. I got about 1k worth of freebies too, cuz I sent another guy into the shop so....
 

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1988 300SE W126
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60 Posts
Discussion Starter #8
Hi Aussiemerc,

Thanks for your reply.

I live south of Brissie, north of the GC. I don't like being too specific about where I live, no offence intended, its just my policy.

The price I mentioned is for a rebuild. The mechanic said that it would cost from $2000 to $2500 just to fix the reverse gear. He told me most of the cost is in labor to remove and refit the transmission so he suggested that it would be better in the long run to rebuild it if I was going to keep the car, which I am.

I was hoping to get more replies with opinions on whether I need to do a rebuild or not given my problem. I can't wait too much longer so I'm inclined to book the car in for the rebuild at this stage.

A friend at work suggested getting a good used transmission but I'm not sure. Its a risk that just out of warranty I could be faced with similar problems and have to spend more money than if I just get mine rebuilt now.

I'm guessing from "not a full reno" you had just your reverse gear repaired and maybe some other worn parts replaced. At least now I have an idea that the cost is not excessive from what you told me you paid.

Cheers, Neil
 

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1988 300SE W126
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60 Posts
Discussion Starter #9
Hi 281lmx,

You and I seem to have the opinion that these cars are worth spending the money on to keep them on the road. I guess most members of this forum do too.

I paid $2250 to buy my car and have had the following work done on it. I spent about $2060 to get the front and rear suspension sorted out. Then $550 to have a new center muffler fitted. I paid about $370 to rebuild the rear brake callipers and new pads. It cost about $380 to replace the flexible link between the transmission and drive shaft. About $60 for a new mast and gear kit to fix the antenna. The only work I did was fix the antenna, the rest I paid a workshop to do.

Now I'm looking at a $3000 to $3500 cost to have the transmission rebuilt. I still have to fix the central locking but it may just need a new hose or rubber joiner or a new fuel filler door element. The cruise control doesn't work most of the time but I'm in no hurry to fix it because I don't use it much anyway.

Cheers, Neil
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,526 Posts
Partial reno

I'm guessing from "not a full reno" you had just your reverse gear repaired and maybe some other worn parts replaced. At least now I have an idea that the cost is not excessive from what you told me you paid.

Cheers, Neil
Yes. With hindsight I should have gone for a full overhaul, but it's been 5 years now.
I used Russell's - they are well known tranny people.
 

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'81 240D (Still truckin!) | '91 560 SEL (THE DARK KNIGHT)
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27 Posts
The grating sound you heard (was it a chik chik chik that varied with the speed of the car) is the reverse piston grating against 3rd gear. As the cars age the seals inside the transmission wear out and this piston starts to move too far when engaging reverse. Over time it gets worse and worse, and eventually the piston pops out, as do the 30-40 springs that it holds in place. There are doubtless more detailed explanations here; search for reverse basket and you'll get a bunch of hits. This is a known problem on several generations of the 722 transmission series.

If you catch it before it fails (like I did) you rebuild the reverse and transmission will usually be ok. If it fails the springs go all over the place and you'll probably need a rebuild as the metal floating around can chew up pieces of the tranny. 90% of the cost is the removal and re installation of the transmission; so it's not a crazy idea to do the rebuild now if you think you might need it later.

Once they pull the tranny and open it up you'll be able to see how bad it is. I was prepared to pay for a full rebuild but my guys said that the 2 drums they opened up were 'perfect' and there wasn't really any point in doing it now. I don't drive the car that much so I'm guessing I'll get a few years out of this particular repair.
 

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1988 300SE W126
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60 Posts
Discussion Starter #12
Hi jainla,

Thanks for your reply.

I'm guessing that the "30-40 springs" you refered to is what they are called rather than the number of springs there are.

I'm not sure I would say the grating sound was a "chik chik chik that varied with the speed of the car". It was more the sound you get when the teeth on a spinning metal gear grate against something stationary. Its hard to spell a sound so imagine the normal, slightly whiney, sound from a reverse gear and mix in a rapid, metalic grating as I described above.

My mechanic said that when the piston pushes to engage reverse gear the clutch has worn thin enough for (can't remember what) to rub against a pin. He said that if I didn't do anything about it eventualy (can't remember what) would catch, I'm thinking come to a sudden stop, on the pin and cause a "catastrophic failure". I formed a mental image of the internals of the transmission shattering into tiny pieces but instead all I got was reverse gear failing with a whimper. My guess is the piston popped out instead as you described.

So if what you suggest is the case then I'm thinking that the smart thing to do is get my transmission rebuilt now rather than just repairing reverse gear. I intend to keep my car on the road for as long as possible so spending $3000 to $3500 now instead of $2000 to $2500 the extra $1000 is buying piece of mind for the future not just a rebuilt transmission. My mechanic also said that most of the cost was labor to remove and refit the transmission so it makes economic sense too.

Cheers, Neil
 

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1988 300SE W126
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60 Posts
Discussion Starter #13
Hi,

Just in case someone is still checking in on this thread I thought I'd do an update for you.

I took the car into the workshop on Thursday 13th September to get the transmission rebuilt. Just my luck, the transmission specialist was on leave but due to return on Monday. However the man in charge said he would start work on removing the transmission and get it ready for the specialist to do the rebuild.

I don't know how long it should take to do a rebuild but I would imagine things could drag on for a while if one or more parts take their time to be delivered. I hope to have the car back by Friday 21st but I will just have to wait and see.

I will post again when I get the car back. Till then take care.

Cheers, Neil
 

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1988 300SE W126
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60 Posts
Discussion Starter #14
Hi,

Well I picked up the car from the workshop today and drove home without incident so all is good. What a relief to have the car back. I have a motorcycle which I have been using to get around but the fork seals are leaking so it needs to be put off the road till I can fund the repairs. The bike is my prefered mode of transport, it costs so much less to run and register, and use the car for when the weather is bad or I have passengers.

After the transmission was fitted the mechanic took it for a test drive. He ended up walking back to the workshop and caused a good deal of concern to the man in charge until he explained that the fuel pump seems to have failed. They did some tests, one using a bypass lead which I was told got very hot, to find that the pump was seized.

So now I have a new fuel pump and a rebuilt transmission.
Sorry, no pictures, but it isn't as shiny as the picture 281lxm posted of his rebuilt tranny. I guess some workshops make them shiny, some don't. Time could have been a factor as I was pushing for it to be done by Friday. Anyway, so far so good.

Cheers, Neil
 

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Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
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7,029 Posts
what a great feeling to have your ride back! Congrats!
 

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1988 300SE W126
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60 Posts
Discussion Starter #16
Hi,

That great feeling is starting to subside. The car sat for a while after getting home. Then I went out to do some shopping and saw a puddle of transmission fluid on the concrete under the car. Not a good sign. I will be contacting the workshop on Monday. You could say I'm somewhat dissapointed.

Cheers, Neil
 

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Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
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7,029 Posts
check the level of the warm engine while running. Maybe it was overdosed with fluid. Isolate where it is leaking from, it might be just an O ring that was twisted upon install and not seated. Think the best case scenario and call your credit card company to not pay the bill until you get this fixed.
 

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1988 300SE W126
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60 Posts
Discussion Starter #18
Hi,

I thought I'd post an update for anyone still watching this thread.

Today I will be taking my car back to the workshop that rebuilt my transmission. Transmission fluid has been leaking since I picked the car up on Friday 21st Sep. As I walked towards the car I saw some fluid on the ground which I pointed out to the manager. He put it up on the hoist and checked a few things. He told me that there were a couple of things that were a bit loose so he tightened them up. He said it should be ok now so I drove it home. I was home for about an hour before I went out to do some shopping and I noticed fluid under the car.

On Monday 24th Sep. I took the car back to the workshop and they put it up on the hoist. I was told it was leaking around the sump pan so the mechanic tweeked the bolts a bit tighter and said it should be ok now. I was told you have to be careful not to overtighten the sump pan bolts as you could bend and damage the pan so they tend to err on the side of caution. The next day there was fresh fluid under the car so I called the workshop. I was told to monitor it for a couple more days to see if it would settle in and stop leaking. I contacted them on Friday 28th to let them know it was still leaking. They said they were flat out till today so I agreed to bring the car to them today. They want to keep the car over night so I asked for a courtesy car which they agreed to.

There is something else I will be telling them about. On several random occasions, when the transmission is in D, I have noticed the engine race, like it is in neutral, then thump into gear. It never did this before the rebuild, the only problem was with reverse gear not working because the friction plates were worn too thin. The first time this happened I was stopped with my foot on the brake pedal for a minute. I went to slowly drive on and the engine raced for a second before the gear engaged with a thump.

The next time I was comming up to a roundabout under brakes to slow for the corner then as I went to accelerate gently through the roundabout the engine raced and thumped into gear.

Last night I was travelling at around 70kph on a level, straight stretch road when for a second the engine raced as the transmission dropped out and back into gear.

So over the past two weeks this has happened about four times under different circumstances. Last Sunday I made a round trip of about 350km on a mix of highway, suburban and hilly, country roads without a hickup.

Anyway, I didn't pay $3500 to have my transmission rebuilt only to have fluid leak on the ground everywhere I park. Nor did I expect to have one problem fixed, ie. no drive in reverse, only to have another problem show up, ie. dropping in and out of gear. A rebuilt transmission should be as good as a new one, right? So they will sort it out and it wont be at my expense.

I will post an update when I have news. Till then take care.

Neil
 

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Sorry to hear of your tribulations. I'm terrified of the day my transmission goes, (knock on wood.) Hopefully they can fix the problems without charging you any more and in a reasonable amount of time. Good luck.
 

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1986/1990 W126
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14,156 Posts
How incredibly annoying. I was really worried about this happening after raising enough money to get my trans rebuilt. The shop I used said they'd never had one come back, so that gave me confidence.

Yup, it should be good as new. I hope you manage to get it sorted, let us know how it goes.
 
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