Thinking of buying a 1992 300D 2.5 turbo - PeachParts Mercedes-Benz Forum

MTUpower · #1 10-21-2018, 10:17 PM

Any advice on what to look for? Problem areas? things I should know? thanks!

sixto · #2 10-22-2018, 02:08 AM

How familiar are you with 124s in general?

Early 2.5s had accelerated wear of the timing chain and cam sprocket. Nothing replacement doesn’t fix.

There’s not a lot of guidance on sorting lack of boost. You might find a bargain car with no boost or it might hit during your ownership. IMHO you’re better off swapping the EDS controlled vacuum boost actuator for a simpler manifold pressure boost actuator.

Too many 2.5s suffer from failed head gaskets that leak oil into #1 and even #2 cylinders. Plan on a head gasket job at least once in it’s lifetime.

Mind the early style vacuum pump with exposed bearings. You want a new style vacuum pump with shielded bearings.

Sixto
98 E320s sedan and wagon
02 C320 wagon

MTUpower · #3 10-22-2018, 05:39 AM

Quote:

Originally Posted by sixto

How familiar are you with 124s in general?

Early 2.5s had accelerated wear of the timing chain and cam sprocket. Nothing replacement doesn’t fix.

There’s not a lot of guidance on sorting lack of boost. You might find a bargain car with no boost or it might hit during your ownership. IMHO you’re better off swapping the EDS controlled vacuum boost actuator for a simpler manifold pressure boost actuator.

Too many 2.5s suffer from failed head gaskets that leak oil into #1 and even #2 cylinders. Plan on a head gasket job at least once in it’s lifetime.

Mind the early style vacuum pump with exposed bearings. You want a new style vacuum pump with shielded bearings.

Sixto
98 E320s sedan and wagon
02 C320 wagon

I owned a 95 e320 wagon so a little. Is the 92 an early 2.5? $2100 in what looks like a nice example a fair price? thx

shertex · #4 10-22-2018, 06:08 AM

A 92 should be safe both from the timing chain issue (there was a VIN number run in 93 that had the issues) and the vacuum pump issue (cover over bearings at that point).

sloride · #5 10-22-2018, 09:27 AM

Degradable engine bay wiring harness, AC evaporator?

jay_bob · #6 10-22-2018, 10:19 AM

Biodegradeable wire was 95 to 97 from what I have read. However I would check the now 25-year old harness carefully in the high heat areas, as it might well be extra crispy by now even if it is normal wire.

Evaporator trouble is highly likely, any 124 up through the 210s has this problem.

Mxfrank · #7 10-22-2018, 01:02 PM

Lack of boost may be caused by one or more faulty vacuum transducers, but around here nobody diagnoses, they just rip out the plumbing and install a vacuum operated wastegate. Or it may be caused by a plugged Alda port, which is the most common problem in older turbo diesels, easily corrected.

Pinging or nailing is not ok in a 2.5, even when cold, even under heavy load. If it has any such sound stay away. Look for oil leaks around the base of the head.

I'd be most concerned about the HVAC systems: the usual "it only needs a freon recharge is the telltale symptom of a $2000 problem. Also the "sometimes slips a little going into 4th" is a hole in your pocket. If it's a wagon, the self leveling hydraulics are simpler than reputed, but parts are hugely expensive. And I'd be concerned with rust ("just a little around the jack points, like they all have"), which is the way these cars die.

MTUpower · #8 10-22-2018, 05:14 PM

https://lakeland.craigslist.org/cto/d/1992-mercedes-benz-300d/6714346454.html

I texted to the owner:
"Starts with no stumbles? AC works as designed? Has the head gasket ever been changed? thank you"
he replied:
"No ac don't know about the history Im a used car dealer runs and drives well glow plugs dont get up to temp until 2 min after running Thanks Jimmy"

I think I'll pass.

Quahog · #9 10-22-2018, 05:50 PM

looks clean in the ad

don’t know about rust underneath

did you drive it?

might be a diamond in the rough

got my 91 w/255k for cheap as a quasi-runnner, now after much time & $$ is 270k & running well
it still klacks on #1 @ idle, but is fun to drive fast, nice & smooth.

MTUpower · #10 10-22-2018, 06:05 PM

Quote:

Originally Posted by Quahog

looks clean in the ad

don’t know about rust underneath

did you drive it?

might be a diamond in the rough

got my 91 w/255k for cheap as a quasi-runnner, now after much time & $$ is 270k & running well
it still klacks on #1 @ idle, but is fun to drive fast, nice & smooth.

The ad does make it look nice. I thought it was priced right but I don't know the market for the 2.5's No AC and the guy says it takes time for the glow plugs to heat up means it stumbles for a bit until it's warm. That indicates trouble, yes? It's three hours from me and I haven't driven it.

Quahog · #11 10-22-2018, 06:19 PM

if he’s not giving it a glow cycle (or two) it won’t be happy untill it warms up.

might be coked up & just need to be driven hard for a bit

3 hours is a long way, only you can make that call....

as cheap insurance, i change all glowplugs when i get a new diesel.

its a weekend job for not a lot of dough

MTUpower · #12 10-23-2018, 06:10 AM

Quote:

Originally Posted by Quahog

if he’s not giving it a glow cycle (or two) it won’t be happy untill it warms up.

might be coked up & just need to be driven hard for a bit

3 hours is a long way, only you can make that call....

as cheap insurance, i change all glowplugs when i get a new diesel.

its a weekend job for not a lot of dough

Is that a good price if the car looks as advertised - knowing that the AC doesnt work? thx for the advice and heads up.

sixto · #13 10-24-2018, 01:46 AM

How important is AC to you? $500 would be too much for me if getting AC working isn’t a simple thing.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Bengoshi2000 · #14 10-24-2018, 08:48 AM

It irritates me to see an ad for a car that I'm interested in, then contact the owner to find out something major (like the AC doesn't work) was left out of the ad. But I digress...

I bought a one owner '91 300D a year ago that the owner described the AC as "weak". I found out that "weak" meant "no worky"... compressor wouldn't engage. No indication in the maintenance paperwork that any ac work had ever been done. I rolled the dice, bought the car and put in two cans of r12 (with oil and dye, no stop-leak). AC has worked well over the spring and summer and I haven't found any leaks. I know it needs a proper evac, purge and refill, but I didn't want to do all that to find out the evap core was compromised. I spent less than $100 for my EPA license + the r12.

I've driven further than 3 hours to walk away from cars that didn't look that nice in photos.

The fact he's evidently flipping the car worries me more than the AC. I'd want to see maintenance records. On my '91, I had the owner fax me all of the maintenance records.

w123fanman · #15 10-25-2018, 03:51 PM

Quote:

Originally Posted by Mxfrank

Lack of boost may be caused by one or more faulty vacuum transducers, but around here nobody diagnoses, they just rip out the plumbing and install a vacuum operated wastegate. Or it may be caused by a plugged Alda port, which is the most common problem in older turbo diesels, easily corrected.

Pinging or nailing is not ok in a 2.5, even when cold, even under heavy load. If it has any such sound stay away. Look for oil leaks around the base of the head.

I'd be most concerned about the HVAC systems: the usual "it only needs a freon recharge is the telltale symptom of a $2000 problem. Also the "sometimes slips a little going into 4th" is a hole in your pocket. If it's a wagon, the self leveling hydraulics are simpler than reputed, but parts are hugely expensive. And I'd be concerned with rust ("just a little around the jack points, like they all have"), which is the way these cars die.

Any advice on sourcing transducers/diaphragms? My parents bought a 90 300D 2.5 in great mechanical shape, turbo is nice and tight, it just doesn't build boost (I think it does start to spool though). We figure it's probably partially a clogged tank screen (had been sitting for a while so algae grew in the tank, we have another tank to put in) but vacuum transducers would make sense as well. That vacuum system is complex.