Some Very Basic Coolant Change Questions - Page 3 - PeachParts Mercedes-Benz Forum

shertex · #31 01-02-2011, 04:56 PM

So....when I run the garden hose water through the heater core inlet hose...both directions, toward heater core and toward engine....will that water, in both cases, come out the block drain?

Also, what key position gets coolant moving through the heater core?

Sorry for the overabundance of questions....by bent of personality, I have a habit of doing things half cocked and then end up screwing stuff up....so I'm trying to compensate for that!

shertex · #32 01-02-2011, 05:49 PM

Re hydrometer, will this do the trick, or can you recommend something more suitable?

http://www.amazon.com/E-Z-Red-S102-Anti-Freeze-Hydrometer/dp/B000JFL7RG/ref=sr_1_13?ie=UTF8&qid=1294008410&sr=8-13

gsxr · #33 01-02-2011, 06:08 PM

Quote:

Originally Posted by shertex

No, I mean how much residual water. Capacity of system is 9.5 liters in 602. Radiator is emty, block is empty, but there's still water sitting in the system.

Maybe a quart or so, two at the absolute most. I'd say 1.0-1.5 quarts on average.

Quote:

Originally Posted by shertex

I notice there are torque specs for radiator drain and block drain. Can I do these by feel (good-n-tight), like I do, for example, with the oil filter housing? Or do I really need to pay attention to the torque number?...which means getting another torque wrench.

Forget the torque wrench. The block drain is good-n-tight. The radiator drain is plastic and is screw in finger tight (it uses O-rings for a seal, so the torque is not important).

Quote:

Originally Posted by shertex

So....when I run the garden hose water through the heater core inlet hose...both directions, toward heater core and toward engine....will that water, in both cases, come out the block drain?

If you hold the hose there long enough, and with sufficient supply, it will come out the block drain, the reservoir neck, and possibly the radiator too.

Quote:

Originally Posted by shertex

Also, what key position gets coolant moving through the heater core?

Key must be fully on (i.e., in diesel "glow" position) with heater temp set on max. If the air coming out the vents turns cool very quickly, the pump isn't working. It should remain hot for several minutes and gradually cool down as you see the dash gauge needle start dropping. If the needle stays put and air blows cold, the pump is dead. It's a common failure, forunately a new one is only ~$60 or so.

Quote:

Originally Posted by shertex

Re hydrometer, will this do the trick, or can you recommend something more suitable?

Yep, something like that should work fine. I've got a Thexton 106 myself. I'd like to get a nicer one someday but it works well enough for general testing.

shertex · #34 01-02-2011, 06:24 PM

Quote:

Originally Posted by gsxr

Key must be fully on (i.e., in diesel "glow" position) with heater temp set on max. If the air coming out the vents turns cool very quickly, the pump isn't working. It should remain hot for several minutes and gradually cool down as you see the dash gauge needle start dropping. If the needle stays put and air blows cold, the pump is dead. It's a common failure, forunately a new one is only ~$60 or so.

Thanks for all the help!

I'm sure I'm missing something here....but how will there be any heat at all if I'm doing this on a cold engine?

scottmcphee · #35 01-02-2011, 06:27 PM

Your local car parts shop should have the antifreeze tester for about $5.

Shop internet, but buy local if it's handy and equi-priced, or better.

gsxr · #36 01-02-2011, 06:42 PM

Quote:

Originally Posted by shertex

I'm sure I'm missing something here....but how will there be any heat at all if I'm doing this on a cold engine?

Oooops! That was only if you're trying to cool down a hot engine so you can work on it without burning yourself. Not applicable to a cold motor. Sorry for the confusion...

HuskyMan · #37 01-02-2011, 07:18 PM

Everyone has their own medicine but here's my way.

1. Drain both the radiator and the engine block. reinstall drain plugs. Take a gallon bucket and fill with Shout Ultra Gel Prelaundry Gel along with a half gallon of warm water. Pour solution into expansion tank. Fill the expansion tank with a garden hose. Start engine and run with heater on high for 15 - 20 minutes. Drain radiator and engine block again. reinstall drain plugs.

2. Install a Prestone antifreeze back flush kit into heater line. Take an oil drain cap purchased from an auto parts store into top radiator inlet. Allow top radiator hose to hang loose over top of the radiator. Connect garden hose to Prestone back flush "T". Turn garden hose on high. Start engine and run for ten minutes or so (heater set on high). You will see a LOT of gunk come out of the top radiator hose. Turn off garden hose, reinstall drain plugs and disconnect garden hose. Install cap onto prestone backflush kit.

3. I use the Mercedes Citris radiator flush at this point. There are some who claim it can ruin a water pump, I've never experienced this but do this step at your own risk. If not, do another Shout Ultra Gel prelaundry 1/2 bucket warm water mix into the expansion tank and run the car for 15 - 20 minutes, then drain.

4. Perform another Prestone backflush, you will see MORE gunk come out of your cooling system. I did this four times and more crud kept coming out! I then ran the car for three days (summer time) on just tap water, drained again and reflushed using Prestone backflush kit. MORE BLACK stuff kept coming out!

5. Use a 50/50 mix of DIESEL RATED antifreeze and distilled water. NOT ALL ANTIFREEZE IS RATED FOR DIESEL USE. NON DIESEL RATED ANTIFREEZE CAN RESULT IN OVERHEATED CYLINDER WALLS. The only two I'm aware of that meets diesel standards are Cummins Anti Freeze and Amsoil Antifreeze.

6. Happy motoring!

shertex · #38 01-02-2011, 08:00 PM

I appreciate the advice several of you (at least Scott and Dave) have given on getting the right mix.

But how 'bout this simplified approach?

If I know the capacity of the system (in my case, 10 quarts), if I know the exact amount of coolant that I need (5 quarts), and if there is an indeterminate amount of residual water in the system (probably somewhere in the 1-2 quart range), then why not just put in 5 quarts of straight coolant and then add water till it's full? In the end you would necessarily have a 50-50 mix, right?

gsxr · #39 01-03-2011, 09:46 AM

Quote:

Originally Posted by shertex

If I know the capacity of the system (in my case, 10 quarts), if I know the exact amount of coolant that I need (5 quarts), and if there is an indeterminate amount of residual water in the system (probably somewhere in the 1-2 quart range), then why not just put in 5 quarts of straight coolant and then add water till it's full? In the end you would necessarily have a 50-50 mix, right?

Correct. This is basically what I do on my cars. The only time I've had issues is with the 124 V8's where the factory spec was wrong. Never had any problems with other 124's.

If you're not sure, capture all the drained fluid and measure it (I put it into empty antifreeze jugs). You should be able to drain out ~80% of the fill spec or better, i.e. for a 10-qt system, you should be able to get out at least 8 qts. On the 124 V8's, I could only get 9-10 qts out of an alleged 16-qt system, which was the tipoff to do more investigation.

No need to worry on your 124.128 though, the spec is correct, drain / flush / pour in 5 quarts G-05 and you should be very close to a 50/50 mix.

shertex · #40 01-03-2011, 01:29 PM

In this thread:

http://www.peachparts.com/shopforum/showthread.php?t=284550

the OP states:

Made some interesting observations. Thsee are specific to the 95 E320 but may also apply to your car:

1. You do not need to drain the block if your car is on a forward incline. Coolant will flow forward from the block into the radiator. The 95 naturally E320 slopes towards the front, plus my carport is inclined. Each time I drained the coolant, 9 qts came out, the 10th presumably remaining in the heater core. The fluid which came out last (from the block) was much hotter than that which came out initially (from the radiator).

That's surpising to me: that this guy got 9 quarts out just by having the car on an incline. That must be a steep incline!

I don't have any intention of adopting this method...just found it curious.

shertex · #41 01-10-2011, 08:04 AM

Just wanted to make sure I understand the necessary conditions for coolant to be flowing through the heater core.

If the following are true:

1. Key to Glow Plug On position

2. Cold Engine

3. Heat Set to Max

4. Fan Set to Max

Then coolant with flow through the heater core....even though engine is not running and coolant is cold.

Is this correct?

gsxr · #42 01-10-2011, 09:36 AM

Quote:

Originally Posted by shertex

Just wanted to make sure I understand the necessary conditions for coolant to be flowing through the heater core.

If the following are true:

1. Key to Glow Plug On position

2. Cold Engine

3. Heat Set to Max

4. Fan Set to Max

Then coolant with flow through the heater core....even though engine is not running and coolant is cold.

Is this correct?

The above is correct when the engine is hot and you want to cool it rapidly... the pump will push hot coolant through the heater core, the fan blows the heat out the vents. The engine temp will drop significantly in 5-10 minutes as long as the aux pump is functioning.

For the coolant flush on a cold engine, none of the above is needed. The pressure from the garden hose pushes water through the heater core and flushes out the coolant inside. No need for the key on or anything else.

shertex · #43 01-10-2011, 09:45 AM

Quote:

Originally Posted by gsxr

The above is correct when the engine is hot and you want to cool it rapidly... the pump will push hot coolant through the heater core, the fan blows the heat out the vents. The engine temp will drop significantly in 5-10 minutes as long as the aux pump is functioning.

For the coolant flush on a cold engine, none of the above is needed. The pressure from the garden hose pushes water through the heater core and flushes out the coolant inside. No need for the key on or anything else.

Sorry...I wasn't clear in my description. I'm talking about FILLING the system AFTER it's been flushed. I'm wanting to make sure what to do to get the new coolant into the heater core.

gsxr · #44 01-10-2011, 09:51 AM

Quote:

Originally Posted by shertex

Sorry...I wasn't clear in my description. I'm talking about FILLING the system AFTER it's been flushed. I'm wanting to make sure what to do to get the new coolant into the heater core.

Oooops! Yes, in that case, your procedure above is correct, although the fan doesn't have to be on max - just the temp wheel on max heat. Note that coolant can't flow until the aux pump has liquid available to it; the system has to be nearly full before the pump will do anything. This is more important when you start the engine after filling and let it warm up.

shertex · #45 07-10-2011, 03:34 PM

Thanks to everyone's great advice, I successfully changed the coolant on my 91 300D. Today I'm changing the coolant on my 92 300D. To the best of my knowledge, I followed the same procedure: filled system through expansion tank, turned key to ensure coolant flowed to heater core, waited till I was sure there was coolant in the upper radiator hose, then started car.

Comes up to and stays at operating temp, level in expansion tank seems stable, but I can't get any heat. So I'm assuming that, even though I THINK I got coolant into the heater core, I didn't....however, the heater inlet hose has HOT coolant in it.

So what am I doing wrong? What do I need to do to get heat operating, to ensure that I get coolant into the heater core?

Thanks.