Still new to this 124 thing so please excuse me I'm still feeling my way around it. Couple of questions:

The auto trans is leaking from the sump and some one has had a go with silicon sealer. I understand that they are prone to distortion. I can see a couple listed for the W124 here on Pelican, one for $73 and one for $150 ish but my E300D is not called up in the basic model selection, just calls up E320, 420, 500, are they all the same regardless of the W124 model

Second issue, a friend who has had a few old mercs (but not a 124) recommended replacing the rad by way of preventative maintenance as they are prone to failure due to sudden failure of the trans cooler which apparently lies within the Rad. Is that correct for E300D of 1994 vintage? And do they go suddenly or do you get plenty of warning before damaging the box seriously

The trans pan's aren't very susceptible to warping - actually, I've NEVER had one distorted. 15+ W124's owned, countless worked on (do it for a living), various other's with 722's and I've never come across a warped pan. Damaged yes, warped no. Unless there was an outside force destroying it, of course. If someone went at it with silicone, sure seems like they must've been too cheap to buy the $10 pan gasket. A filter/gasket combo goes for $20-ish, so make it a point to service it and clear out as much of that sillycone as you can. Should you want to buy a new one, the pan is the same on your car as any of the others. They all share the same sump.

As for the rad - they're far more likely to break at the hose neck in the top driver side. Old style don't have metal reinforced necks and they tend to break off when the clamps are overtightened. Any radiator can fail the way you described, very unlikely, albeit possible, on these cars. I've been witness to it happening once...on a Chevy.

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

i have just replaced mine preventatively.

Thanks for putting that to rest Allen. I'll leave the rad well alone and concentrate on changing the gasket and filter on the trans..

Transmission pans - the torque for the bolts is REALLY low, like 7 Nm, and exceeding that will indeed warp the pan. Check the dealer price as well - you may be pleasantly surprised.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

The pan gaskets dry out over time, then crack and leak. Unless the pan has been distorted by a road encounter, try replacing the gasket first.

Don't replace the radiator unless there's something wrong. Never have I heard of the trans cooler just exploding? Your friend must have not worked on these cars that much. Unless some kind of maintenance was deterred, or something else internally went wrong there's no way that will just go bad without warning. The pan isn't prone to distortion unless someone hit something in the road. Just like everyone else said, nothing to worry about. Replace the gasket and call it a day.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Welcome to the forum! I've attached a helpful guide to get you more familiar with the W124 platform. These DIY articles should greatly help with any maintenance or fixes that you may run into. Please let us know if you have any questions!

Mercedes-Benz E-Class W124 (1987-1995) Technical Articles - 300TE 24, 300CE 24, 300E 24, 300CE, 280E, 300E2.8, E280, 320TE, E320 - Pelican Parts

IIRC you need a transmission pan for a 722.4 transmission. The cars you listed use a 722.3 transmission. Try a pan for/from a 190D/E, 260E/300E 2.6 or 2.8, C-class through '96...

Sixto
83 300SD
98 E320 wagon

There was a stretch in the early 2000's where Mercedes was having a problem with leaky trans coolers on Valeo radiators. The old Behr radiators can go for decades without trouble, as long as the coolant is changed from time to time.