1992 400E 3rd gear fails to engage
 

Dear members,

I am considering buying a 400E MY1992. It looks solid and close to original state to me though I haven't got chance to actually drive it yet. The one thing that concerns me is that, as told by the current owner, its AT's 3rd gear fails to engage. That started to happen recently after the car was changed with new clutch disc.

Some mechanics tell me that AT is difficult to repair given expertise available in Vietnam (hopefully you know where Vietnam is) The problem may be resolved somehow but it will likely return. The best solution is to have a new gearbox.

So, I have 2 questions:

1. Are all W124's AT interchangeable, meaning I can swap 400E AT to any W124 AT?

2. Could this problem come from what's so called gear start relay K29/1. The relay is responsible for rapid heating of the catalyst.

I'm sorry if a thread like this already exists and looking forward to hearing response from you.

Well first of all, AT's have no clutch disk to replace.

I would assume that it needs a transmission overhaul and go from there.

I have the following questions:

-When was the trans last serviced?
-Is the fluid at the correct level?
-Does the trans have the correct fluid in it ?

Sometimes it can be as simple as the above.

3rd gear fails to engage. Does it double-shift right from 2nd to 4th, or simply flare/rev after 2nd, or shift 1-2 and stay in 2nd?

Check fluid level, if that's okay then you might have a clogged filter creating a low control pressure, $50 for fluid and a filter to find out.

The AT was serviced just about 2 weeks ago. I didn't look at the fluid level but the owner says that after he replaced sort of clutch of the AT system the problem arose.

I drove it for about 10 miles and felt quite good about the engine. It picked up real fast but just stayed at 2nd gear. When the engine was heated it started running intermittently and the owner said it is probably due to the fuel pump. I could see the odd sound of the running pump to.

I read the manual it says KAT version 400Es have their transmission shift point retard relay (K29) for heating the catalytic converter so that it reaches its operating temp more rapidly. Should K29 be the suspect for the failure of 3rd gear 2?

Sounds lots of problem, doesn't it? I am in negotiation of the owner about the price. I believe those problems are solvable. This beast is quite rare in here so I want to grab it though I already have a 300E.

Thanks for your response, I will do as suggested once it's mine.

Yeah, it just stays at gear 2 and revs and revs when you step the gas pedal.

Questions for my 300E
 

What should be the right operating temperature for M103? My 300E runs at less than 80 degrees celsius on the highway. The fan seems to be always in the same speed with the crankshaft though I can hold the fan without it running with the crankshaft. The book says the fan only engages when the coolant temperature reaches 82.

So, the question is is 80 too cold for M103 and what's wrong with the fan?

Possibly low pressure, change the fluid and filter, I've had this happen.

Thanks all. The car has not been mine yet. The owner is still considering my offer.

Then get a quote from a transmission shop for a replacement or rebuild, the NADA for the car minus any other flaws, subtract the transmission, you've got your offer. If it has clogged the filter to that point the transmission is likely pretty much gone anyway.

Thanks for yr advice. Things are quite different here. Parts for this kind of Merc are expensive and hard to find. I often go to Malaysia and Malaysia for parts. Anyway, I am in good bargain position. The car is not fashionable to most people here but me.