1987 300TDT Cooling System Flush Procedure - PeachParts Mercedes-Benz Forum

1987-300TD · #1 05-21-2014, 03:02 AM

Several weeks ago, my wagon was running "cool" at highway speeds but hot (100 C) at stoplights. I discovered that my coolant was low and added 3/4 of a gallon of distilled water. She now runs around 85 C in Las Vegas on a 100 F day.

I have been the proud owner of this wagon for approximately 4 years and have not flushed the cooling system. I have no maintenance records prior to me.

I would like to flush the cooling system this long weekend and am looking for sage wisdom...

I have been researching different recommendations to flush the cooling system in my '87 300TDT.

My search has led me to many sites and procedures. I found this procedure and am looking for comment. MB citric acid cooling system flush - Anyone know the recipe??? - Mercedes-Benz Forum

Is this the proper procedure? I also read about putting Dawn dish detergent through the system to clear out oil.

I believe I have a #18 head but again have no maintenance records so I do not know when the system was last flushed.

Should I change the thermostat? Can I convert the Thermostat Housing? (http://www.***************/search/product.aspx?sid=htqcf145ysy02u4540vxrrmk&makeid=800016@Mercedes&modelid=1195578@E320&year=1995&cid=16@Cooling%20System&gid=2204@Thermostat%20Housing) Is there a comparable part on peachparts.com?

Any other wisdom?

Thank You In Advance!!!

glenn

Maxbumpo · #2 05-21-2014, 10:43 AM

Quote:

Originally Posted by 1987-300TD

I found this procedure and am looking for comment. MB citric acid cooling system flush - Anyone know the recipe??? - Mercedes-Benz Forum

Is this the proper procedure? I also read about putting Dawn dish detergent through the system to clear out oil.

Should I change the thermostat?

Yes that is correct procedure. Only use the dawn detergent first if there is evidence of oil in the cooling system.

Replacing the t-stat pro-actively is not a bad idea, but please test the new t-stat in a pot of water on your stove to ensure correct opening temperature and correct full open stroke length.

vstech · #3 05-21-2014, 11:05 AM

I would drain the block, radiator, and flush out the heater core, and all other cooling system parts with tap water first and inspect the residue before resorting to the citric flush.

vstech · #4 05-21-2014, 11:28 AM

I think the cooling system on the OM603 is fairly critical, and while cleaning and having fresh coolant mixture (G05 or MB Coolant) with DISTILLED water is critical, the citric flush is for a poorly maintained system with heavy deposits.
pull the block drain and flush it well, make sure no rust or GUNK pours out, and inspect the tubes inside the radiator for buildup/blockage... if the metal in there looks good, do not bother with the acid flush. you may want to run a mixture of tide laundry detergent in there to remove any oil residue, then flush WELL with warm water, then tap water, then rinse that all with distilled water to remove any lime/etc that the municipalities treat the water with, and then fill from the upper radiator hose with the proper mixture for your area of G05, and drive happy.

if the cooling system handled Nevada's heat it's UNLIKELY the citric flush is needed, and the thermostat is likely in great shape. if you do change, I agree... TEST IT FIRST!!!

while you are doing all this, it's a great time to pull the radiator, and clean out the condenser coil of leaves and bugs, and verify the water pump is not worn, also, test the belt tensioner, and shock... they fail, and you loose the motor!

1987-300TD · #5 05-21-2014, 12:27 PM

Thank You Both for the replies!!!

VSTECH, you mention Tide detergent. Do you happen to have a preferred ratio of HOT water to detergent?

I was also going to hold off on doing anything more than flushing the system as I was hoping to do some of your cooling system upgrades this summer. I found one of your old posts and it refers to upgrading the fan and clutch. I need to dig up that post. Do you happen to have part numbers for the upgrade?

Also, since I have no maintenance records, would I be best served by just replacing the waterpump while upgrading the rest of the system?

Lastly VSTECH, my A/C is not working at the moment. I am hoping to pick your brain before it gets really hot out here. :-)

My G05 should be here by tomorrow! Zoro had some great prices (approx $13 for 1 gallon of concentrate).

Again, Thank You for sharing your knowledge!!!

glenn

vstech · #6 05-21-2014, 01:02 PM

just start a new thread when you are ready for the a/c questions.

DieselPaul · #7 05-21-2014, 01:32 PM

Quote:

Originally Posted by 1987-300TD

My G05 should be here by tomorrow! Zoro had some great prices (approx $13 for 1 gallon of concentrate).

FWIW, that's retail at Napa. Not sure who Zoro is but if you are paying for shipping on top of $13, considering pricing it at a local supplier.

1987-300TD · #8 05-21-2014, 03:46 PM

Thank you for letting me know about Napa DieselPaul. I just priced Zerex G05 Concentrate at O'Reilly and they want $17 per gallon. Also, it was free shipping over $50. I also added 3 Gallons of oil.

Thank You for the Head's Up though... :-)

glenn

1987-300TD · #9 05-21-2014, 03:46 PM

VSTECH, do you happen to have the proportions for adding Tide to the flush procedure?

TIA,
glenn

jay_bob · #10 05-21-2014, 10:24 PM

I posted this the other day in a thread on a W210/OM606 motor but this is relevant to your vehicle too. The proper way to fill it up so you don't get an air pocket in the head.

- don't forget to close the petcock and the block drain (BTDT)
- most engines and most climates call for 1 gal of G05 and 1 gal of distilled water mixed 50/50.
- elevate the front (ramps or a sloping driveway works)
- remove the upper radiator hose from the radiator neck. Be careful, if the hose is stuck on don't yank on it, you can crack the plastic radiator tank.
- set heater controls on full heat (click the wheel into the max position).
- Pour coolant mix into the disconnected end of the upper radiator hose until it holds no more. A funnel is helpful. Just be sure it's a clean funnel, not one you just used to fill the oil.
- Reconnect hose and pour rest of mix slowly into expansion tank until it is full.
- Leave the pressure cap off.
- Start engine and let it get up to temperature so thermostat opens. Watch the temperature gauge and monitor the heater, you should not go over 90C and you should be getting massive heat out the vents. No need to speed race the engine, just some gentle excursions to 1500-2000/min to get things warmed up and flowing.
- Top off reservoir as necessary. As mentioned above, do not introduce room temperature coolant mix directly into a head at operating temperature. Alway go through the expansion tank.
- Put jug with remainder of mix in trunk. So you'll have it handy as you are out and about.
- Keep an eye on the coolant level and watch the temperature gauge more closely than normal for the next couple days as the remaining trapped air escapes.

vstech · #11 05-22-2014, 10:45 AM

Quote:

Originally Posted by 1987-300TD

VSTECH, do you happen to have the proportions for adding Tide to the flush procedure?

TIA,
glenn

I would mix in 1/2 a load (depending on concentration and state...) for whatever is on the detergent label mix it in a gallon of HOT water then pour that into the radiator and drive around for 1/2 hour... Flush well... Really well

1987-300TD · #12 05-26-2014, 04:15 PM

Good Day All!

Thank You all for the sage wisdom. I have flushed out the old coolant. It was orange. For the most part clear with no signs of oil or gunk. I assume that someone was taking care of my girl before she made it to me.

I have run the engine with the coolant drain open until clear water was running out. Did that for around 3 minutes.

I have filled her with straight tap water. Ran her to the supermarket to purchase distilled water (approx 5 miles roundtrip). Interestingly, she ran around 82 C for the trip. This is on straight tap water!

I am letting her cool a little before I dump the tap water and run a gallon or 3 of distilled water through the system. Then I will refill the system with a 50/50 mix.

I am attaching several pictures.
Image 06 is the coolant drain. It is located on the passenger side of the engine. The view is from below the car. Visible are the block heater connection to the left and a turbo oil line to the right; the exhaust pipe above an engine mount below and to the right.

Image 04 is the top hose removed from the radiator. There is some calcium buildup around the neck but it appears to otherwise be in good condition.

Image 03 is from the front of the car with the top hose disconnected and sitting atop the radiator.

Image 01 is from the top of the engine with the top hose connected.

More updates as I continue through the flush...

Thanks Again!

glenn

1987-300TD · #13 05-26-2014, 10:58 PM

I have finished flushing the coolant as well as several other ancillaries while I was at it.

I removed approximately 1.75 gallons of coolant. I added back approximately 1 gallon of Zerex and .75+ gallons of distilled water. Drove her to check things and she seemed to get to 82 C and held. Whether I was on the highway or stopped at a light, 82 C was where she stopped.

I have more pictures:

10 is the petcock at the bottom of the radiator. It is located behind the little front grill flap. It is the round object to the right of my hand in the picture. It can be removed with a flathead screwdriver.

I completely removed it to flush the system.

11 is a picture of what I removed from the system.

07 is a picture of the overflow line from the reservoir toward the front passenger side of the car. It is very hard and cracked at the end. It is a braided material covering the line.
***** Should I replace this? If so, what type of hose is it?

08 is a picture of the reservoir. I have no idea if it has ever been replaced.
***** Should I replace this? Anyone have a part number?

I found several other questions but will ask them in different threads.

Again, Thank You All for your assistance!

glenn

vstech · #14 05-26-2014, 11:44 PM

if you did not remove the block drain from the engine block, you did not flush your engine... gunk WILL NOT FLUSH OUT JUST RUNNING WATER THROUGH THE ENGINE!

there is a block drain on the passenger's side of the block near the turbo.

1987-300TD · #15 05-27-2014, 12:37 AM

Thank You for the reply VSTECH!

In my first post from today, the first picture, I did release the block drain. I even kept it open as I flushed the block. I stuck the garden hose down the neck of the top radiator hose and let the water pour out the block drain.

Overall, it was a very cool experience. I had replaced my turbo and did not know what those things were sticking out of the block.

Again, Thank You for the insight!!!

glenn