Coolant leak 1985 280SL M110.990

[MistyMerc]

Hi all,
Just joined club and hoping for advice on coolant leak which has just started on wife’s 1985 280SL with 110.990 twin ohc.
Car been laid up for few years, although have occasionally started and not had issues until last week when noticed no coolant in heater tank.
When adding coolant it is leaking somewhere under the inlet manifold near the front of the engine but there are so many hoses etc there I have not been able to spot where the leak originates ! Tried looking from above, underneath and from side but with no luck.
Local classic car mechanic suggested core plugs but has plates not plugs and I think they are on the exhaust side of the block.
I am hoping someone knows if there are any coolant pipes or hoses in that area ?
It might be the head gasket but seems surprising that gone from no leak with engine running to leaking when just topping up the coolant !
No other signs of head gasket related problems.
All thoughts and advice would be most welcome
Thanks

 

[grober]

WATER PUMP OR THERMOSTAT ARE USUAL SUSPECTS-TRY AN INTERNET SEARCH

 

[MistyMerc]

Hi Gober,
Thanks for prompt reply.
They were my first port of call but no sign around them and the leak appears to be down the right side as you look at the engine just underneath the inlet manifold.
Have tried internet search but with no luck so far.
Also got pdf of R107 SL280-560 Merc workshop manual but unfortunately does not cover 110.990 engine !
Cheers