1976 280C 110 motor. What are these plugs, why are they leaking, how do I fix? Thanks

[Tomas7]

Is there an O-ring that needs replacing, can these be removed and the leak fixed without repercussions?

Thanks in advance.

[Mike D]

Coolant passages. You can remove and reseal them. They are basically just pipe plugs. Have you done a recent coolant flush or other coolant work?

They will collect water if you have driving in heavy rain or go through deep puddles.

It is unusual for them to begin leaking without any reason.

Is it oil or coolant puddling in the cavities?

[Tomas7]

It is oil...so that means that I have another issue...possibly a leak somewhere up the motor.
Thanks for your reply.

[Frank Reiner]

The oil leak is from the joint between the cam box and the cylinder head and/or the cam cover gasket.

[kraakevik]

My '74 280 M110 had oil seeping through the seam between the cam tower and the cylinder head on the exhaust side.

I re-torqued the cylinder head bolts and carefully re-torqued all the smaller fasteners securing the cam tower to the head. That stopped the leak. I suspect the extreme heat from the reactor-style exhaust might have distorted the cam/head join enough over time to allow oil to seep out.

Best of luck



Tim Kraakevik
kraakevik@voyager.net

[Tomas7]

Originally Posted by kraakevik

My '74 280 M110 had oil seeping through the seam between the cam tower and the cylinder head on the exhaust side.

I re-torqued the cylinder head bolts and carefully re-torqued all the smaller fasteners securing the cam tower to the head. That stopped the leak. I suspect the extreme heat from the reactor-style exhaust might have distorted the cam/head join enough over time to allow oil to seep out.

Best of luck



Tim Kraakevik
kraakevik@voyager.net

When you say re-torque, do you mean loosen and then torque to specs or just tighten the bolt(s) a tad more?

[kraakevik]

I loosen the bolts perhaps 180-270 degrees, half or three-quarters of a turn--then re-tighten to specification.

Make sure the allen-head recesses in the smaller bolts are absolutely clear and clean--they're prone to stripping if the bit isn't inserted full-depth into the bolt head




Tim Kraakevik
kraakevik@voyager.net

[Tomas7]

Thank you all for your replies, help and input.

[meltedpanda]

identify the oil leak before you mess with those, as mentioned not usually the issue

[Tomas7]

Originally Posted by kraakevik

My '74 280 M110 had oil seeping through the seam between the cam tower and the cylinder head on the exhaust side.

I re-torqued the cylinder head bolts and carefully re-torqued all the smaller fasteners securing the cam tower to the head. That stopped the leak. I suspect the extreme heat from the reactor-style exhaust might have distorted the cam/head join enough over time to allow oil to seep out.

Best of luck



Tim Kraakevik
kraakevik@voyager.net

By the way, If by "reactor style" you mean the huge obnoxious catalytic; it's been long gone. I have the three into two into one exhaust with no cat.

[kraakevik]

Even with the catalytic converter and other emissions-related exhaust components removed--those later engines run lean and hot--they could use sheet-metal shields to cut down on heat transfer by radiation under the hood



Tim Kraakevik
kraakevik@voyager.net

[Idle]

You will find these plugs on all Mercedes engines. If they are not used in some market for a water passage they are just plugged and plugged good. It is very rare for one of them to leak.

Some of these ports are just to clean out the sand that was left from the casting process. But they are then sealed up forever as they are not meant to functions as freeze plugs.

Go to a car wash and clean that part of the engine. Then drive home. The leak will be quite apparent when the engine is clean as the only part covered with fluid is the part where the leak is.