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1977 Mercedes 450 SEL Radiator

Started by joel45077, 19 April 2020, 07:50 PM

joel45077

Hello everybody,

I have a 1977 Mercedes 450 SEL base sedan (4.5 v8) which has been sitting for about 18 years. Before replacing the fuel system components, I would like to flush out the coolant system. Upon inspection, i noticed the coolant reservoir has orange sludge sitting towards the bottom of the tank. I also noticed that all the hoses from the radiator feel "crunchy" as if the coolant dried up in there.. Before replacing the hoses for the cooling system, I would like the flush out the system, but i noticed that the radiator does not have a cap. the Haynes Repair Manual says to remove the drain plug, expansion reservoir, and the plugs on the side of the engine and to place a garden hose in the filler neck of the radiator but it does not have one.... I was wondering if anyone has any suggestions on where i should flush the radiator tank from? the coolant reservoir? the hose on the top of the radiator? If anyone could give me any suggestions that would be greatly appreciated as i cannot find any information about the cooling system. Thank you in advance.

joel45077

pic of the engine bay

daantjie

#2
Welcome to the forum ;D!

Personally I would just flush from the top of the rad by sticking in a hose at the top end and let it flush out the bottom.  You can also disconnect the hose that comes from the overflow tank at the rad side, and flush the tank itself by of course just sticking a hose in the spot where the cap goes.  Only buy genuine MB (Reutter) for rad cap.  They are super cheap. 

I would also replace both top and bottom rad hoses, as well as the feed hose from the overflow tank for starters.  Do not be tempted to use URO parts, they are utter garbage quality, genuine Benz hoses only, they are still available and cheap.

I would also personally stay away from trying to remove freeze plugs from the block, or the bottom plug from the radiator.  These things are hella tight and will likely strip or worse (as happened to me) tear out of the bottom tank, resulting in me having to drop big coin on a refurbed rad.

I would also change out the thermostat while you're at it.

To fill, use Zerex G-05 coolant (Valvoline) and dilute 50/50 with distilled water. 

That is what I would do for openers.  I am sure other members will chime in too but the above is what I would do as a bare minimum to see where you stand with regards adequate cooling.

If you see the "milkshake caramel colour of death" in your old coolant, then it might point to head gasket issues or similar, but let't not fret just yet, start with the simple things first ;)
Daniel
1977 450 SEL 6.9 - Astralsilber

daantjie

Oh and also, use that Haynes manual for kindling :D  Get a good used W116 workshop manual, they are readily available on ebay, or use the library section on the Forum here.
Daniel
1977 450 SEL 6.9 - Astralsilber

joel45077

THANK YOU
daantjie

For the quick reply and the great idea! thank you very much i will try this let you know how it works out and i will post some pictures, thank you very much !!!!!! :)

Randys01

I'm with Daniel......leave those drains in the block alone for openers. Once you get the thing flushed about 5 times and run it up, don't forget to open the heater taps.

Another trick is to tape the garden hose into the bottom radiator outlet  [inlet? ]  and back flush it with the top hose removed of course.

TJ 450

The radiator drain plug is "usually" not a problem for me and have been fortunate enough to not have an issue with the block drain plugs, although the amount of luck will likely depend on the climate where you are.

The good thing is that once you crack them open you can maintain them every few years without trouble and help remove silt out of the block that would otherwise be trapped.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

joel45077

Quote from: Randys01 on 19 April 2020, 10:24 PM
I'm with Daniel......leave those drains in the block alone for openers. Once you get the thing flushed about 5 times and run it up, don't forget to open the heater taps.

Another trick is to tape the garden hose into the bottom radiator outlet  [inlet? ]  and back flush it with the top hose removed of course.
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As of right now the car only turns over, i started it once and got it to idle for about 5-10 minutes then it died out. I have acquired almost all the parts for the rear end fuel system and i am currently buying all the hoses for the cooling system and i am going to change it all at once. But thank you for your input, i will probably leave the drains in the block. Do you know about where the heater taps are located?? thank you in advance.

rumb

Citric acid flush is a good way to clean the system.

Don't try stating the car until your fuel system is clean. You should remove gas tank and clean inside as well as replace filter in bottom of tank. Don't be surprised if after sitting that long that the fd will need rebuilt.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

joel45077

Quote from: rumb on 24 April 2020, 08:07 AM
Citric acid flush is a good way to clean the system.

Don't try stating the car until your fuel system is clean. You should remove gas tank and clean inside as well as replace filter in bottom of tank. Don't be surprised if after sitting that long that the fd will need rebuilt.
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Hello, any suggestions on what products i can use to clean my gas tank or what kind of shop i can take it to?
would a gas tank from a 1977 450SL or SLC fit into my 450SEL?
has anyone had any luck with aftermarket gas tanks or a fuel tank from a different car?
Thanks everyone in advance.

daantjie

#10
First you need to drain the tank and remove the screen at the bottom, then you can always take a borescope to see if the tank is really bad.  I would not jump to replacing the tank yet unless you know for sure it's nasty inside.  You can also inspect the tank from the top by removing the fuel sender gauge unit after you remove the rear bench and back rest.  Of course be very careful, keep a fire extinguisher handy and do this in the open with good ventilation, also use a ventilator type face covering as those fumes can be really bad for you.
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

If you can still find an old fashion radiator shop they should be able to clean it out.

Lots of homemade recipes for cleaning gas tanks. muriatic acid, vinegar to name a few.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

ptashek

If I recall the procedure from WIS correctly, the system flush steps went something like this:

- water
- <5% sodium hydroxide (lye) solution to de-grease
- water
- <5% citric acid solution to de-scale and de-rust (low concentration acids won't attack grease, hence the lye first)
- water
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE