Engine over heating

[KenBourque]

I've been told in the mid '70's that 280SL engine rebuilds at that time or simply a new head could sometimes result in over heating.  The reason suggested was that the new head gasket did not have the water holes in exactly the right place(s) and thus caused restricted water flow.  I have not followed that discussion for years and don't know of any results or conclusions but now after a remanufactured engine from Metric Motors, my new motor runs much hotter than the original one.  I spoke to them and they said that they do a internal cleaning as best as they can and offered no other solution except to say that this is not a too uncommon problem.   I also heard that there were many versions of these head gaskets with respect to hole location.
Does anyone have any further information on this possible gasket dilemma?

[Cees Klumper]

Is it possible something else is responsible, such as air trapped in the system?

[wisnia07]

There were two types of head gaskets in 280SL. An early 'square' type (up to engine numbers M130.983-10 -5301 and M130.983-12 -8784) and later 'oval' type. They are not interchangeable and I think it's almost impossible that someone mixes them up. The problem must be somewhere else - have you checked the ignition timing?

[stickandrudderman]

It’s possible that your old engine was underperforming such that it did not generate as much heat and the new engine has exposed some previously undetected fault with the cooling system.
You need someone to check temps with a laser thermometer.

[ja17]

Yes, as suggested, be sure to check the ignition timing, it can make a big difference in engine temperature if it is not right. Make sure your thermostat is in place. Leaving it out will cause the engine to run hotter.

[Benz Dr.]

It’s possible that your old engine was underperforming such that it did not generate as much heat and the new engine has exposed some previously undetected fault with the cooling system.
You need someone to check temps with a laser thermometer.

I agree. This is something that most people wouldn't consider but a fresh engine produces more power and power has a way of creating heat. I generally use a 79C thermostat which is the coolest one available and I add a bottle of water wetter. If you have AC don't use it in very hot weather or stop and go traffic. Late US style 280SL and AC do not mix well to due timing retard used on those engines. 

[KenBourque]

Thanks for all of your comments.  I did indeed check the temperature with a laser temp unit and it matches the temp gauge.  The timing is right on - 32° BTDC at 3000RPM and 2° ATDC at idle.  The radiator has since been re-cored and no improvement.  I truly believed that the internal passages of the engine are gunked up.  I'll just open the heater valve in hot weather and with the top down, I shouldn't feel the real heat only the emotional heat!

[mbzse]

.../... I truly believed that the internal passages of the engine are gunked up.../...

This is not entirely uncommon. See some comments about corrosion and scale inside engine block in this Forum thread:
https://www.sl113.org/forums/index.php?topic=26194.msg187715#msg187715

[Benz Dr.]

This is not entirely uncommon. See some comments about corrosion and scale inside engine block in this Forum thread:
https://www.sl113.org/forums/index.php?topic=26194.msg187715#msg187715

Try 38 degrees full advance and see if that helps. Engine shouldn't ping but if it does set it back 2 or 3 degrees.

[jeffc280sl]

Ken,

I suggest you purchase two T fittings and a piece of heater hose.  Basically bypass the heater core so it is not necessary to open the heater core to cool the engine.  This will avoid bringing heat into the cockpit.  This solution has worked very well for me.  Search on "heater core bypass"  for more info.