My 87 300SDL is leaking oil from the plug in the attached pic. I was thinking it may have something to do with the timing chain tensioner, so I haven't messed with it yet.

Is this something that has a seal or can I just take a socket and tighten it?

It is dripping about 6-8 drops on the garage floor each night.

Thanks!

__________________
Lance Allison
Lance@LanceAllison.com

Current:
11 MB S550 4Matic, 55k miles, Designo Black/Black
14 Ford F150 XLT Lariat Crew, 73k miles, 5.0
Coyote V8 4x4. Black/tan.
09 GMC Envoy Denali, 5.3 V8, 4x4 SWB. 38k miles,
Jewel Red/Med Gray.

Gone:
87 MB 300SDL, 320k miles, Astral Silver/Blue.
98 VW Jetta TDI, 488k miles, Classic Green/Gray.
85 Olds 98 Brougham FWD, 4.3 DIESEL V6, 80k
miles, 3x Gray.

MBCA Member, Chicago Region

That is the chain tensioner, and probably the o-ring seal is shot. I don't know how to replace this one, I'm not sure if it is a ratcheting type or not. Some of the "real" techs can help.

Should be a simple R&R.

Makes me think I need to check mine -- too much oil on the engine last oil change, all from that area.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

The simplist fix would be replace the tensioner and seal. (603's of certian era's had t-chain issues as well)



Joe

__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

The chain and tensioner are about 70k old. What would be the easiest way of changing this tensioner? Any tips...how about special tools?

__________________
Lance Allison
Lance@LanceAllison.com

Current:
11 MB S550 4Matic, 55k miles, Designo Black/Black
14 Ford F150 XLT Lariat Crew, 73k miles, 5.0
Coyote V8 4x4. Black/tan.
09 GMC Envoy Denali, 5.3 V8, 4x4 SWB. 38k miles,
Jewel Red/Med Gray.

Gone:
87 MB 300SDL, 320k miles, Astral Silver/Blue.
98 VW Jetta TDI, 488k miles, Classic Green/Gray.
85 Olds 98 Brougham FWD, 4.3 DIESEL V6, 80k
miles, 3x Gray.

MBCA Member, Chicago Region

No need to replace the tensioner Lance. Replacing the seals will fix the leak. By the way, they're not o-rings. They're aluminum and various sizes of this type seal can be found elsewhere on the vehicle ( transmission cooler lines, torque converter drain plug ). I believe there is even an old service bulletin pertaining to this problem. Good luck

A new tensioner is less than $45 from FastLane and I believe it comes with new seals -- aluminum crush seals as ILUVMILS stated. I don't know if you just pop it in or if you have to prime it in SAE 10W oil as it says in the manual.

I don't see the seals listed in FastLane so give Phil a call.

Sixto
91 300SE
87 300SDL
83 300SD

Have a leak in the same area on my 380SL. Thought it was coming from my oil temp. sender next to the tensioner[that's dry] because the ceramic end was loose. I replaced it, but oil still comes from the same area. Neither the old or the new one had a gasket. Is this the way it should be?
Thanks.Don

Come to think of it there are two sealing rings; one between the tensioner and the cylinder head and one between the sealing plug and the body of the tensioner (between the small hex and the big hex).

If the leak at the head interface, then replace that seal. You'll have to prime the tensioner as described in the shop manual before it goes back in the head.

If the leak is between the small hex and big hex, the tensioner will have to come apart. I wouldn't do it in-situ because there are spring loaded parts waiting to get lost behind the sealing plug. The manual says nothing about taking the tensioner apart other than that one of the internal components was upgraded in late 87.

Sixto
91 300SE
87 300SDL
83 300SD