Fan to radiator clearance on 280SL

[Mechudo62]

After setting up the proper factory adjustments to engine and cooling system, my 1970 280SL still tends to run hot driving on steep grades and in city traffic. A friend from the  Club Mexico suggested me to check the distance between the fan and the radiator, stating that he read on some Mercedes manual that the distance should be 1.8-2.0 centimeters or about 3/4 of an inch. This distance can be achieved by loosening the 4 side screws that attach the radiator to the frame, which have an adjustment eyelet to move radiator to precisely this distance. Is this so? Can anyone suggest a manual that states the proper distance to minimize overheating problems? Thanks for your help in advance!

Fernando Mangino

[WRe]

Hi,
I couldn't find an answer to your question in the workshop manual for a 280SL (1968) but in the old one for a 230SL (1959). It says 20mm+2mm.
...WRe

[wayne R]

Fernando, thought i would let you know, my 1965 230SL is exactly
1 inch--25mm clearancefront of fan to radiator, and radiator still has  about another
3/8 inch that it could go forward further with the adjustment bolts.
My car never over heats even in 35 degress 95f in slow or traffic jambs,temp needle
never goes above 190,---1/16inch above half all the time.
Another thing to check is the actual radiator core inside for flow, can get build up with hard
calcium,and can restrick flow, --radiator shop can check this, or with a Pagoda you can drain
about 2 or 3  pints coolant ,and lean over with strong light and see if the cores are clear and clean looking.
this may help as  its abit of a job to remove radiator etc to check. regards.

[WRe]

Hi,
You can find here a lot of stuff dealing with overheating and more reasons because it happens but distance between radiator and fan is of minor importance in my opinion.
- https://www.sl113.org/forums/index.php?topic=27735.msg199515#msg199515
- https://www.sl113.org/forums/index.php?topic=27865.msg200610#msg200610
...WRe

[MikeSimon]

There is a fan shroud available for the W113 that will improve air flow.

[Mechudo62]

Thanks for the advice!  I put a brand new radiator from the Classic Center with original MB coolant. I also installed a fan shroud and the MB factory TSB recommended hose to drain hot coolant from the engine head.  Remember 280 engines are bored 230’s/250’s for increased cylinder volume that reduced the coolant tanks in its block. That is why MB put an oil radiator on all 280’s. 230/250 seldom have cooling problems, but in contrast, rhe 280’s cooling system needs to be perfect. I will try to adjust my radiator to fan distance to 2 centimeters , making sure there is enough space for the fan blades and see what happens.

[Benz Dr.]

Try a bottle of water wetter. Stuff really does help.

[wayne R]

Fernado, like benz Dr says , in most cases there are better solutions and results from other manufactures.
Example will living in US, alot of buick club members with  37-38-39-40 straight eights, used a coolant called
Evans high performance waterless engine coolant, especially when members fitted A/C to there Buick eight.
There cars never overheated,lasts the life of the car,will not vaporize,boil over,and not after boil,
two of my best friends there still use this today.Incase you dont know Straight eight Buicks especially the large,
320ci engine in Roadmaster were prone to over heat slow in traffic ,etc.
There is one big problem Evans is very expensive,   for memory around $100,----regards Wayne.

[MikeSimon]

Thanks for the advice!  I put a brand new radiator from the Classic Center with original MB coolant. I also installed a fan shroud and the MB factory TSB recommended hose to drain hot coolant from the engine head.  Remember 280 engines are bored 230’s/250’s for increased cylinder volume that reduced the coolant tanks in its block. That is why MB put an oil radiator on all 280’s. 230/250 seldom have cooling problems, but in contrast, rhe 280’s cooling system needs to be perfect. I will try to adjust my radiator to fan distance to 2 centimeters , making sure there is enough space for the fan blades and see what happens.

I dare to disagree with the statement that 280 engines are merely bored 230/250s. The M130 is a completely different animal.
Mercedes Benz also changed the later 280s water jackets and heads for improved cooling

[Benz Dr.]

I dare to disagree with the statement that 280 engines are merely bored 230/250s. The M130 is a completely different animal.
Mercedes Benz also changed the later 280s water jackets and heads for improved cooling

Yes and sort of no. Each engine is a further modification of the previous edition which can all be traced back to the 220SE. Go and measure the basic size of the block and you will find the dimensions to be the same - bore and stroke are different of course.

Later 280 engines run hot ( in fact most 280's do ) and the USA versions run even hotter. Most of this has to do with running ignition timing ADTC at idle - a sure way to induce over heating. They made modifications but it improved little in real terms.

[MikeSimon]

  Each...  is a further modification of the previous edition which can all be traced back to 

Sure. That's even true for all cars. They can all be traced back to the "Benz Motorwagen" of 1886...

[hauser]

I also had a bit of a hot engine problem.  After the rebuild we added a shroud by Buds Benz a re cored radiator with extra row of cooling tubes SLTech along with a multi blade fan Buds Benz.