Coolant Change Tips

[J. Huber]

Need them.

Over the last almost decade, I have learned a ton on this site and have saved many many dollars by doing some of my own maintenance (filters, points. plugs).
One of my goals this year is to try and change the coolant in my 230SL myself. I am hoping for some direction: no matter how much or how little so I can get this accomplished. My hope is others will also learn along the way.

So, in my case, the coolant is about 4 years old, and has been changed prior to that fairly regularly. Radiator is a H-E recore done in about 2004. Question one: given this, can I just drain and change the fluid -- or do I have to flush the system as well?

Question 2: In preparing for the job, I plan to use the MB Coolant discussed in previous threads. Anybody know exact P/N and how much I should purchase?

Question 3: My Overflow Coolant tank is currently off the car, having been boiled and repaired (broken bracket). It now must be repainted. Should I use hi-temp paint? metal primer? This is not a show car, so I am imagining something from a local hardware store.

Question 4: Where do I start?? 

Thanks all.
JH

[jameshoward]

James,

Edit - read the wiki first. There's a ton of stuff on changing the coolant that may well be at odds with what I've written.

Did mine a few weeks ago. I think that 4 years is as long as you'd want to wait to change the coolant. 3 - 4 years would be about right. It's a simple job to do, if a bit messy.

I prefer to remove the large hose at the bottom of the rad rather than attempt to undo the drain plug (to save anyone asking why, there's a post on the site somewhere from the last time I went to change my coolant by undoing the drain plug on the rad. It's been re-soldered now, and is in place where it will stay from now on... . Suggest you remove the hose and drain that way).

I always warm the car up a little to get the juices flowing and motivate any residue that would otherwise stick. Make sure you open the heater core to the coolant also to ensure you get full circulation. (But don't over heat the coolant; it gets hot quickly, and pressure will build up. Be careful opening the rad cap if you end up putting the tank on again first. Actually, I suppose you can't warm the coolant up with the tank off. I'd stick it on first, personally, then warm up, then drain).

When you remove the hose, 7-8 litres of coolant will spew out. You should flush it but sticking a hosepipe in the coolant tank and flushing water through. I have very hard water, so I used bottled water to do this. If the radiator is cruddy (yours shouldn't be as it's recently re-cored) you could reverse flush it (put water in the other way). I also elected to remove the thermostat (easy) and check its operating temp (put in a saucepan of cold water with a thermometer, and heat up. It should open at the temp stamped on the thermostat body. If it doesn't get a new one). (Obviously). (Since it can't be fixed). (They're cheap). I also flushed through the thermostat pipes to get the old coolant out of the engine water jackets.

Replace the hoses, tighten clips. Replace thermostat. I premix my coolant with distilled water (actually got from the tank on my dehumidifier) checking the specific gravity and getting it right for my temp range, then, having got the right temp range, pour it back in via the tank. It should take about 6 litres then it will be full. Put the expansion tank cap on, and run the car gently bring it up to temp. Check for leaks from the hoses you undid during this time. Stop the car, top off the tank. May need to do this more than once. The old coolant is an environmental hazard and should be disposed of correctly.

Check for leaks. I think that's about it.

I didn't use MB coolant, but only because of the cost here. I just used one that's recommended for MB with alu engines.

As for the tank, it doesn't get hot enough to require hi temp paint, if you mean manifold paint. I used normal hammerite on mine and it's been fine. Wouldn't have bothered with primer. It's copper I think. I'm sure someone who knows something about paints will tell me I'm wrong!

JH

[Jordan]

James, don't forget to drain the coolant from the engine.  I drain the rad first and then the engine.  There is a 22mm bolt on the passenger side of the engine that you will have to remove.  I think it is in a different location on the 280SL but you have a 230.  There is lots in the engine so it will come gushing out and make a mess.  Once you refill the overflow tank you can run the engine without putting the cap on just to see if you need to top it up.  Don't leave the engine running too long.  The 230SL will take 10.8L of coolant if I recall correctly.  Have fun.  Its a messy job.
Marcus

[bogeyman]

Eastwood (www.eastwood.com) makes a radiator paint that is specially formulated for radiators.  I think the gloss is close to the original MB paint.

I have used it with good results.

[J. Huber]

James, don't forget to drain the coolant from the engine.  I drain the rad first and then the engine.  There is a 22mm bolt on the passenger side of the engine that you will have to remove.  I think it is in a different location on the 280SL but you have a 230.  There is lots in the engine so it will come gushing out and make a mess....
Marcus

Now, see. This is where I need you guys. I get J. Howard's idea of draining from the lower hose. If I flush with hosewater, will I still need to drain the engine? If so, can anyone pin-point the exact location of the drain plug?

And James, I followed you up until "checking the specific gravity and getting it right for my temp range"... can you explain? Do I mix coolant and distilled water 50/50?

Thanks all. and I apologize if I need spoon-feeding.

[Jordan]

James, I think you would need to back flush the entire system to get the coolant out of the engine and then it would just be full of water, which you do not want as it will dilute your coolant.  I access the engine bolt from under the car.  I don't have a picture but it is below the exhaust manifold in front of the starter.  I wasn't 100% sure I had the right one the first time I did it so I cracked the nut a bit and when I saw a drop of green fluid I knew I had the right bolt.  Unfortunately my coolant is no longer green but a light yellow (MB brand).  I mix the coolant 50:50 which makes it good to -40C.  Your jug may tell you what ratios to mix for different temperatures or talk to whoever you are buying it from.

[ja17]

Hello,

The drain plug on the 280 and 250 engines is near the starter.  On the 230 engines it is on the other side (near the oil filter canister.

Primer will improve paint bond to bare metal. Right, it may not be necessary but depending on the paint you use you could have adhesion problems. I use plain isopropyl alcohol to clean the surface of oil before painting. It is available at the corner grocery store and is cheap.  A very light coat of primer is all that is needed unless you are using it to smooth and sand blemishes. Most enamels will hold up just fine on the engine since the temperatures are not that high.  Two stage paints, paint with a catalyst is most durable since it resists solvents and is tougher. However you can still get good results with a "rattle can" but it may not last as long.

For the more adventurous or pros, a two stage urethane enamel is great. I use the PPG Urotech Industrial Grade Urethane Enamel. I buy it in black gloss then mix the PPG flattening paste in it to get the exact gloss desired. The paint  resists oil grease, brake fluid, thinners, solvents and impact. I use the zinc wash primer which eats into the bare metal for good adhesion before the paint. The system works very well on engine blocks, radiators, and other misc. engine parts. Do not use it on exhaust manifolds. You will need spray equipment, and a good respirator since the paints and primers are toxic.

[Jordan]

I guess they must have moved the drain plug some time during production of the 230SL since mine is on the side of the starter.  James, from Joes comment yours must no doubt be on the side oil filter being an early 230.  Unfortunately can't help you pinpoint where, maybe someone else has a picture.  Keep lots of papertowels handy.

[J. Huber]

Well Thanks all so far. I am in a holding pattern as I prepare for paint and getting the MB Coolant. The nearest MB Dealer is hour away so that will take a trip. They should know what kind of coolant I am talking about, correct? I have asked them for 113 things before and they were really lost. M-class they know about, Pagodas not so much.

In the meantime I searched for the engine drain bolt. Tight squeeze! Now, complicating matters is my engine is a replacement 230SL. Things are historically different than the original. So it could be on either side... I see a bolt on the passenger side just forward of the starter and just rear of the motor mount supports. Appears to be a 19mm Regular Bolt. On the engine side, there is nothing but a recessed hex bolt (similar to the differential plug). Any one have a clue?

Thanks for the tips on painting. I'll probably prime to be safe and use spray-can of some sort. Gloss black.

[thelews]

You can use Zerex G-05 instead of the MB.  Gold bottle

[jacovdw]

...and if you really want to take a drive to the dealership, then ask for the following part number: A000 989 08 25 (MB antifreeze).

They should at least know what that is and where to find it on their system...   

As to their blank responses about your pagoda queries, I have encountered the same problem with some parts guys at some dealerships here in SA.
Just let them punch in you pagoda's chassis number into their EPC and then you should not have a problem. The EPC follows the same logical grouping of assemblies for all Mercedes cars, irrespective of whether it is a 2010 CLS or a 180b Ponton from the 1950's.

I suppose that happens when they spend too much time working with more modern cars... 

[jameshoward]

James,

I think you can flush the block by flushing through the thermostat housing. I've never removed the block drain plug, my theory being that the more nuts and bolts I don't have to mess around with, the less I'm likely to break. It is the case that flushing the block will leave water in there, hence check the gravity of the coolant once done to see if you need to top it up a bit. Of course I could simply be seen as over-cautious, but I'd prefer to do that than screw up another car part attempting something as simple as a coolant flush. (The radiator was expensive enough!)

JH

[Jordan]

James, it could very well be a 19mm bolt.  I remember my mechanic thinking it was a 19mm bolt when I asked him about it.  Mine is definitely a 22mm bolt however, I just checked.  Mine is located as you state, between the starter and where the motor mount bracket bolts to the engine block.  Definetely not recessed.  As John mentions, you can use Zerex G-05 as it is half the price of MB brand.  I will be using it the next time I change the coolant.

[Rolland]

I'm attaching a pic of my coolant tank.  After having the tank repaired at the radiator shop and having it come back without a speck of paint, I just couldn't keep my hands off it and not polish it.  While not "factory", I really like the looks with the freshly painted engine bay (had it painted before getting the exterior done).

Rolland

[J. Huber]

Thanks John, Joe, Jaco, James, and "Jordan" -- just have to hear from Jeff and I'm set!  

I will check locally for the Zerex G-O5 just to have the option. When I get to that point, I will probably put a wrench on that 19mm and see if what happens...

James, as for the thermostat, I recall that 3 of the 4 housing bolts were easy, but the 4th a challenge because of fuel line -- did you find that the case?

JH

[J. Huber]

Thanks Rolland. Your engine bay and tank look sweeeet! Cannot wait to see it all!

[Rolland]

Thanks James, we did get a bit anal on the engine bay.  Glad you like it as well.  Good luck on your coolant project, hope it all goes well!

Rolland

[Iconic]

I've read somewhere that it is better to use "tap" water than distilled water for mixing with antifreeze.
Anybody have anything to add to clarify if this is true or not?

[J. Huber]

I've read somewhere that it is better to use "tap" water than distilled water for mixing with antifreeze.
Anybody have anything to add to clarify if this is true or not?

I'd love some feedback on this before I get to mixin'... I found the Zerex G-05 locally, bought 3 bottles. That should more than cover it I think... But is it supposed to be pinkish color? Bottle is gold.

[thelews]

Mine's yellow, unless they changed the formula.

[wwheeler]

The tap vs. distilled water is a raging debate.

I think it really depends on the tap water you have, hard vs. soft. Distilled water is more of a consistant product. There is no way distilled water could be worse than tap water for coolant.

Being how inexpensive and easy to find distilled water is, it is a no-brainer to me. And you use very little (2 gallons?). A very small cost to pay for peace of mind.

[ja17]

Hello,

Unless you really know about the PH level of your tap water, go distilled.   I read a discussion on the subject with charts and maps of the PH levels of tap water in different parts of the country. It just gets crazy complicated as you will then need to determine the difference of PH levels in city water as opposed to well water also. In my area the township has well fields that supplies public water for the township. In town the water comes from rain run off and is collected in a resevour for Columbus city use. In my case I have my own well for water. With public city water your dealing water treatment with added chemicals (chlorine etc). With well water minerals in the water could cause sediments to form in your cooling system. 

Most expert information I have read in recent history says go distilled water for best results. However in many cases tap water is acceptable.

[J. Huber]

Distilled it is! Thanks all. Getting closer to the job -- have to wait for sunshine to paint coolant tank -- and then I will dive in...

BTW I poked around internet about Zerex G 05 and its color. Apparently different batches used different dyes? Identical stuff from what I see. I checked NAPA and the bottles they have appear pinkish as well. Mine came form O'Reilly, and it clearly states Mercedes approved... And now my daughters will enjoy checking my coolant for me   

JH

[dseretakis]

I don't know if this is an acceptable method but I drain coolant from the lower radiator hose, back flush with a hose. I then fill up with water and run the engine to full operating temp. I then drain, refill and again run to full operating temp. I keep repeating this process until the coolant comes out clear water. Then I add antifreeze. I measure how much comes out and knowing the engine coolant capacity I can figure out how much undiluted antifreeze to add to get a 50:50 ratio. Please someone tell me if my procedure is flawed!

[J. Huber]

Ok so I am finally about to do the change. I first had to get my coolant tank repaired. The bracket that attaches it to the firewall had broke loose. I sent it to a radiator shop who reattached it and also boiled and cleaned the tank. Then I primered and painted it. Came out pretty good. (see pic)

One thing I want to be clear on though before I get too far: once I drain the radiator and the engine block, what will I do with the hose before I refill the system with the 50/50? Do I run it through the coolant tank until water comes out the drains? (I am not planning to touch the thermostat or housing so cannot go that way)

Thanks guys, I'm a step by step charity case...