Author Topic: Steps Tips for flushing and filling radiator  (Read 18287 times)

aomastu

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Steps Tips for flushing and filling radiator
« on: January 13, 2007, 12:29:56 »
Hello all,
I recently picked up a 280SL with 1988 license plates.  The car passed TX vehicle inspection.  

I thought a radiator flush and fill would be a good first step to taking care of this car.  With your help, I got the hood off.  This site is great.  Now for the work.

I am used to American cars with radiator caps on the radiators.  I read the strings on flushing and filling, but they mentioned many places to unscrew and unplug to get fluid and air out.

Does anyone have a nice step by step directions for a great way to flush and refill my cooling system?  Many strings have great photos, but I couldn't find one for this task.

Sincerely,

Stuart Bailey
Austin, TX
280SL

'69 280sl
P.O. Box 150128
Austin, TX  78715

hands_aus

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Re: Steps Tips for flushing and filling radiator
« Reply #1 on: January 14, 2007, 04:37:38 »
Here is a document I copied to my PC some years ago.... worth a read at least

How to back flush a w113’s coolant system.

A back flush causes reverse water flow through the entire cooling system.  Normally, cooling water goes up through the block, pushed by the water pump and convection, up through the thermostat (when open), then down through the radiator and back to the suction of the water pump. The heater takes hot water from the rear upper head, through the heater valve and core, and back to the suction of the water pump. Normally, a back flush is done by disconnecting the heater side, then connecting water to the head and removing the radiator cap. The remote tank makes it a little different, but this should work.  Here are the first few steps.  After step 4, there is some commentary on what just happened, and then the process continues in steps 5 through 15.
1.   First place the car on pavement or a well-drained surface.  This will be messy.
2.   Place the heater valve lever (red lower lever) to the left, full open position.
3.   With a cold engine, remove the drain plug (18mm wrench), drain all coolant and disconnect the top radiator hose at the thermostat. This will be an outlet so point the hose end toward the ground.  Re-install the drain plug and hand tighten (you will remove this plug again at step 5 below)
4.   Disconnect the left (driver’s side) heater inlet hose from the firewall inlet.
A.   Connect a length of hose to the entry point (mine is brass) to the firewall just disconnected at step 4. This will be an outlet, so point it down.  A hose of 4 feet in length or more will allow it to clear the side of the car.
B.   Connect a garden hose to the existing heater hose just disconnected at step 4.  I bought a flush kit from the local parts store that included a 3/8 to ½ “T” connector with a garden hose connection point.  I plugged one end of the “T” and inserted the other end of the “T” into the existing heater hose.   This is the hose that takes water into the upper head.  I then screwed the garden hose on (need a female adapter for your garden hose as the “T” connector is male).  Turn the garden hose on.  This will send water down through the head and block.  This will also be the entry point for the new antifreeze once you get to step 11.
Commentary on Steps 1-4
Step 4a above should result in sending water down through the head and block, down through the water pump (since the thermostat will be closed) then up through the radiator and out the upper radiator hose. Water will also flow up the water pump’s heater return line on the right, through the heater core and out the left hose you've attached. If you don't get much flow through the heater core, restrict the flow out the upper radiator hose, by pinching it partially closed.  Since these engines incorporate a full bypass type thermostat, which allows circulation of the coolant through the block while warming up, some water will bypass the lower block.  Use sufficient flow to get a good stream of water out the openings.

5.   After the water runs clear, with no rust particles, remove the radiator cap on the remote expansion tank to flush it's connecting lines.  This may reduce or even stop the flow through the heater core, due to an easier exit.  Open the lower radiator drain plug again (see step 2) and run it until clear.
6.   Shut off water and fully drain system.  If you have an air compressor, disconnect the water hose from the house, insert an air gun into the hose end previously connected to the house and blow out any remaining water.
7.   Close the lower radiator drain plug opened at step 5.  But first, examine copper crush washer and if old, replace to ensure a good seal.
8.   Remove the drain hose attached to the brass entry point on the firewall (see step 4a)
9.   Disconnect the garden hose from the heater inlet hose.  Place a funnel into the heater inlet hose that was previously connected to the garden hose.  This will be the entry point for the new anti freeze.
10.   Pre-mix anti-freeze (50/50 mix of water and anti freeze if you used air to blow out all water, or because some water will remain in the block if not blown out by compressed air, suggest an initial stronger mixture of about 60% antifreeze, then check it.)
11.   Pour pre mixed anti freeze into the funnel attached to the hose to which the garden hose was previously attached.  Add 10 liters of the 50/50 mix.  Suggest the MB anti freeze.  See http://www.imcool.com/articles/anitfreeze-coolant/G05-Glysantin.htm.
12.   Re-install the top radiator hose at the thermostat.
13.   Disconnect the top hose on the cold start vale of the FI pump.  Continue filling with the 50/50 mix of anti freeze until water emerges from the top hose of the cold start valve and from the brass entry point on the firewall.  This should clear all air from the system.  Note:  Total capacity 10.7 liters.
14.   Reconnect the hose disconnected at steps 4 and step 13, replace cap on over flow bottle. You are done.


Questions:

1.   Doesn't coolant run to the top of the injection pump to make a thermal sensor or valve or something work? Will this process flush that pathway out?
2.   I have heard that it's easy to get air trapped in this car's coolant system. How do you minimize that? I suppose parking on a slope or disconnecting a particular hose when filling with fluid? Can you elaborate?


The cold start Valve on the Governor housing would be back flushed also, however there's not much flow in this circuit, so it wouldn't hurt to disconnect the top hose during this process. After you've checked it, push it back on, but don't tighten the clamp (see next).

The M-B engines from the fifties-sixties can easily form air pockets inside the cooling system after the coolant has been drained from them.

You're right; the cooling system is difficult to bleed out all of the air.  I've found that the top hose on the cold start vale is the highest point in the cooling system. After topping off the tank, slide this hose off carefully, until antifreeze solution comes out. Same with the heater inlet hose on the firewall. Heater Temp valve wide open.

Another useful practice is to park the car uphill (or raise the front end) while the engine runs and continuously fills water as needed. When the thermostat opens, the air will come out nicely from the system.

I'd install a new thermostat. Not expensive at all, but not carried by most automotive stores. It's a full flow type, which circulates water through the block when cold. Most American built cars didn't have this feature until years later. It looks much different than most common flat plate type of thermostat in that it has an additional lower plate. As the thermostat opens to the radiator, this lower plate closes off the bypass line (smaller hose running from the bottom of the thermostat housing to the water pump inlet). This insures even warm-up, among other advantages and is used on truck and industrial engines.

Also, You might want to consider having the radiator professionally cleaned, I.e.: vatted and rodded out. This made an impressive change to my car. I'm able to run in southern Oklahoma on 100+ days with the air-conditioning system on.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

JPMOSE

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Re: Steps Tips for flushing and filling radiator
« Reply #2 on: January 14, 2007, 06:32:13 »
Bob..what a great write-up!  I am getting ready to flush my 250SL and 560SL.  I will print and follow your directions (you make it sound pretty easy!).

Best Regards,

J. P. Mose
1968 250SL
1987 560SL
Best Regards,

J. P. Mose
1968 250SL
1970 280SE 3.5 Cabriolet
1987 560SL

Patrick

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Re: Steps Tips for flushing and filling radiator
« Reply #3 on: January 14, 2007, 07:36:41 »
Bob, a great contribution, have already printed off and filed for future. Had my mechanic flush the rad this year. Next time I will do it myself. Thanks again,

Patrick
'68 250SL

graphic66

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Re: Steps Tips for flushing and filling radiator
« Reply #4 on: January 14, 2007, 12:01:40 »
I have always added water pump lube and anti rust additive to all my systems. Ever since starting I have not had a single water pump failure. I have also used flushing chemicals with good results.

aomastu

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Re: Steps Tips for flushing and filling radiator
« Reply #5 on: January 14, 2007, 12:15:01 »
Bob,

Wow - This is great.  Just what I needed.  Thank you.

I will send a note to the webmaster to see if it can be added to the technical articles.

Many of the posts involve areas I will most likely not be going (transmission rebuild?), but this type of maintenance is what many of us need.  imho



'69 280sl
P.O. Box 150128
Austin, TX  78715

aomastu

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Re: Steps Tips for flushing and filling radiator
« Reply #6 on: January 14, 2007, 17:17:48 »
The part of the fuel injector called the "cold start valve" - -

13. Disconnect the top hose on the cold start valve of the FI pump.


Is this the same as the "warm running device" coolant lines in this diagram?



'69 280sl
P.O. Box 150128
Austin, TX  78715

hands_aus

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Re: Steps Tips for flushing and filling radiator
« Reply #7 on: January 15, 2007, 04:27:08 »
I found the article very helpful when I flushed my system. I forget where I copied it from... maybe the old Yahoo w113 site?

aomastu,
The WRD and Inj pump CSV are the same thing.

Keep adding coolant until it runs out the top pipe and then re-connect the hose. You can do the same to the LHS heater hose too.
I then topped off the overflow tank and capped it.

I have a rubber hose attached to the small overflow pipe which drains below the frame of the car and definitely not on the internal frame of the engine bay.

I started the engine and let it warm up to normal operating temperature. When the thermostat opens any air and excess fluid is blown out the overflow and the correct fluid level is established.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

rwmastel

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Re: Steps Tips for flushing and filling radiator
« Reply #8 on: January 15, 2007, 07:58:48 »
quote:
Originally posted by hands_aus

3.   With a cold engine, remove the drain plug (18mm wrench), drain all coolant .....
My only advice is to be careful with the drain plug.  Some owners damage (ruin) the radiator because their drain plug is seized into the radiator.  If yours does not remove easily, an option is to remove the lower rubber hose at the bottom of the radiator.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420
Rodd

Did you search the forum before asking?
2017 C43 AMG
2006 Wrangler Rubicon
1966 230SL auto "Italian"

aomastu

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Re: Steps Tips for flushing and filling radiator
« Reply #9 on: January 15, 2007, 09:11:33 »
Bob and Rodd,

Thank you for the posts.  

I was going to take pics of the job, but the descriptions did the job.  Any interest?



'69 280sl
P.O. Box 150128
Austin, TX  78715

Abbas

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Re: Steps Tips for flushing and filling radiator
« Reply #10 on: January 15, 2007, 09:46:48 »
Right in time - after reading about how old coolant becomes acidic and ruins the engine cylinder I decided to change my coolant. I bought the extended life one from CALTEX here in Dubai.

Now Bob, do you have a picture that can relate the hoses to the steps you mention. I am talking about a real engine picture indicating where the various parts are located - like the thermostat, heater hoses ... by the way I read that there is a hex plug on the cylinder head that needs to be unscrewed to drain the fluids from inside the engine - does any one know where is this located.

Stuart, I guess if you can take pictures of what you did will be a great help for us and can demostrate Bob's procedure visually.

Thanks.
Abbas

280SL W113 1969 Ivory
E280 W124 1995 Silver
« Last Edit: January 15, 2007, 09:52:10 by Abbas »

aomastu

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Re: Steps Tips for flushing and filling radiator
« Reply #11 on: January 15, 2007, 13:31:53 »
I'll do it and mention it here when the job's done.  I have some parts on order and will start when I get them it.

'69 280sl
P.O. Box 150128
Austin, TX  78715

Raymond

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Re: Steps Tips for flushing and filling radiator
« Reply #12 on: January 19, 2007, 19:22:53 »
Aomatsu,
  Be aware of the terminology of the Cold Start Valve (CSV).  It is NOT the same thing as the Warm Running Device (WRD).  

The CSV is shown in this parts diagram as "Intake Starting Valve".  Nearly everyone who works on these engines refers to that "Intake Starting Valve" as the Cold Start Valve because it squirts an extra bit of gas into the throttle body to aid in starting the engine when cold.  The Warm Running Device is warmed by water to change the fuel mixture as the engine warms up.

But understanding the procedure, you'll still get to the right hoses.

Ray
'68 280SL 4-spd Coupe
Ray
'68 280SL 5-spd "California" Coupe

aomastu

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Re: Steps Tips for flushing and filling radiator
« Reply #13 on: January 20, 2007, 16:35:10 »
Ray,
Thanks for your tip.  Now, though, I would like to be clear.

On the diagram, there are two hoses on the WRD coolant lines.  I should disconnect the top hose when emptying the coolant.  Then, reconnect the hose.   Then, after flushing the system, carefully unconnect the hose to ensure fluid gets back into the WRD.  

I am still waiting for the hoses and thermostat and Blizzard 2007 to be over.

Stuart in Austin, TX
'68 4-spd 280sl

Abbas

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Re: Steps Tips for flushing and filling radiator
« Reply #14 on: January 21, 2007, 02:53:24 »
Hello All,
  Yesterday I took my car to the mechanic and flushed the coolant in the radiator and replaced it with an extended life (5-year) 50/50 coolant from CALTEX/TEXECO as suggested here by one of the contributors.
The mechanic did the job the old fashioned way and it worked fine. Here were the steps:

 1- Open the heater valve lever so that the coolant stuck in the heater pipes circulates/drains.

 2- Open the coolant reservoir cap and then open the drain plug to let the coolant out.

 3- When the coolant is drained start the car and let it run for 4 seconds - this will eject all remaining coolant inside the cylinder head.

 4- Insert a hose connected to the water supply into the reservoir and let the water run into the radiator for a minute or two.

 5 - Close the drain plug and fill in the radiator with water and turn the car on for 10 minutes until the thermostat opens and the water circulates in the engine and heater hoses (they become hot)

 6- Open the drain plug on the radiator again and let the water completly drain.

 7- Repeat steps 3,4,5,6 for one more time. This will makes sure that all old coolant is drained from inside the engine and the heater hoses etc. You will notice that the water becomes clearer and clearer on the second cycle..

 8- Close the drain plug on the bottom of the radiator.

 9- Open the top hose outlet that returns excess coolant from the radiator to the reservoir as in the picture.Download Attachment: Step 9 - Return outlet.gif 31.83 KB

 10- Start filling the engine coolant through the reservoir. After filling in half the quantity turn the car on and keep it running while pouring in the remaining coolant.  

 11- As the coolant starts to fill in the radiator all air will start to escape from the small hose outlet at the top of the radiator returning to the reservoir - which was opened in step 9.

 12- When the coolant starts to pour out of that small outlet close it with the hose - since all air has already escaped.

 13- Fill in the reservoir to the top and close the cap.

 14- Take a round with the car for 10 minutes and check the reservoir again and add some coolant if needed.

Using this method very few hoses or plugs are opened and much is done by circulating fresh water in the system - by repeatedly draining then filling with water then running the car then draining again.
 
Abbas

280SL W113 1969 Ivory
E280 W124 1995 Silver
« Last Edit: January 21, 2007, 11:14:14 by Abbas »

JPMOSE

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Coolant Level In Expansion Tank
« Reply #15 on: May 20, 2012, 22:21:32 »
Question:

What is the proper level of coolant in the Expansion Tank  when cold?   1/2, 3/4 or number of inches from the top???
« Last Edit: May 21, 2012, 23:07:21 by JPMOSE »
Best Regards,

J. P. Mose
1968 250SL
1970 280SE 3.5 Cabriolet
1987 560SL

jacovdw

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Re: Steps Tips for flushing and filling radiator
« Reply #16 on: May 22, 2012, 08:17:39 »
The level should be 40mm (or about 1½ inches) below the filler neck of the expansion tank when cold.

JPMOSE

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Re: Steps Tips for flushing and filling radiator
« Reply #17 on: May 22, 2012, 12:53:57 »
Thanks!!!
Best Regards,

J. P. Mose
1968 250SL
1970 280SE 3.5 Cabriolet
1987 560SL