Cooling system flush - PeachParts Mercedes-Benz Forum

H-townbenzoboy · #1 07-26-2005, 12:52 PM

I'm going to go ahead and drain, flush, and refill the coolant. I've read some conflicting statements regarding the removal of the engine block drain plug. Some say remove it, some say don't remove it. Its in a hard location to access anyway. Can I just drain and flush using the radiator drain plug only? Even the tech guy at the MB dealership didn't even mention the engine block drain plug.
-Joe

boneheaddoctor · #2 07-26-2005, 12:57 PM

Quote:

Originally Posted by H-townbenzoboy

I'm going to go ahead and drain, flush, and refill the coolant. I've read some conflicting statements regarding the removal of the engine block drain plug. Some say remove it, some say don't remove it. Its in a hard location to access anyway. Can I just drain and flush using the radiator drain plug only? Even the tech guy at the MB dealership didn't even mention the engine block drain plug.
-Joe

That block plug is easy to get out with a 10 or12 inch extension if you take the aircleaner off the car...

And having done this myself...I recomend doing it...you will see rust and debris come out thats too heavy to exit by other means.

Pete Burton · #3 07-26-2005, 01:00 PM

I agree - you'll get a lot out of there, you really should remove that plug.

H-townbenzoboy · #4 07-26-2005, 01:34 PM

Ok then, will do. Although, I'm going to have to put it off for now. I had a little leak where quite a bit of the coolant leaked out. I've fixed the leak, but I need to add some green coolant to get me through till thursday, since I can't just add MB coolant to the green stuff that's already in there. Will any "McParts" brand coolant do for now until I can get the proper stuff in?
-Joe

Brian Carlton · #5 07-26-2005, 01:44 PM

I had an interesting experience with the 617.

I'm in the process of redoing the head. The radiator was drained, the thermostat housing was completely removed.

I'm staring at the return hose to the water pump. The hose is filled with coolant. So, the 617 is filled up to level of the head (lower part) after you have fully drained the radiator.

Got underneath and removed the block plug. About 3 quarts of coolant headed out of the block in short order.

There is no possible way of changing the coolant properly on the 617 without removing the block plug.

dieseldiehard · #6 07-26-2005, 01:46 PM

Quote:

Originally Posted by H-townbenzoboy

Ok then, will do. Although, I'm going to have to put it off for now. I had a little leak where quite a bit of the coolant leaked out. I've fixed the leak, but I need to add some green coolant to get me through till thursday, since I can't just add MB coolant to the green stuff that's already in there. Will any "McParts" brand coolant do for now until I can get the proper stuff in?
-Joe

I would simply add water, there isn't any need for adding antifreeze provided you plan on flushing sometime soon. a 20% mixture will have some anti-corrosion protection left (not like 45% but still ok for a few weeks).
As for the drain plug, I saw one that wouldn't come out even with a 5 ft breaker bar extension, the engine was lifting off the mounts with the force and it was simply stuck! One risks a cracked block if heat is applied unevenly (ie. this is delicate process!)
Just be aware that it might be really hard to get an old drain plug out!
__________________

dieseldiehard · #7 07-26-2005, 01:51 PM

Quote:

Originally Posted by Brian Carlton

I had an interesting experience with the 617.

I'm in the process of redoing the head. The radiator was drained, the thermostat housing was completely removed.

I'm staring at the return hose to the water pump. The hose is filled with coolant. So, the 617 is filled up to level of the head (lower part) after you have fully drained the radiator.

Got underneath and removed the block plug. About 3 quarts of coolant headed out of the block in short order.

There is no possible way of changing the coolant properly on the 617 without removing the block plug.

Brian, I believe that removing the thermostat and replacing it with the "stuck-open thermostat looking device" that MB describes in their service bulletin on flushing will allow one to use a flushing machine, attached to the radiator inlet somehow and that should do a fair job of getting all the coolant mixture out. I don't know about heavier residue though. I know an Indy that has such a machine but I've never asked how he likes it. I've always drained and refilled 4 or 5 times till the water runs clear.
I've never seen the special temporary thermostat either, has anyone ever used one?

boneheaddoctor · #8 07-26-2005, 02:02 PM

Quote:

Originally Posted by Brian Carlton

I had an interesting experience with the 617.

I'm in the process of redoing the head. The radiator was drained, the thermostat housing was completely removed.

I'm staring at the return hose to the water pump. The hose is filled with coolant. So, the 617 is filled up to level of the head (lower part) after you have fully drained the radiator.

Got underneath and removed the block plug. About 3 quarts of coolant headed out of the block in short order.

There is no possible way of changing the coolant properly on the 617 without removing the block plug.

Plus if you do a citric acid flush you are going to have chunks of calcium and rust floating around in it.....

Take my word on that....I got out lots of that stuff on my W116.

I will be doing my W123 in about a month when I put my block heater into that at the same time.

t walgamuth · #9 07-26-2005, 07:49 PM

my indy said getting the plug out was a bear when he installed my block heater!

tom w

Brian Carlton · #10 07-26-2005, 08:03 PM

Quote:

Originally Posted by dieseldiehard

As for the drain plug, I saw one that wouldn't come out even with a 5 ft breaker bar extension, the engine was lifting off the mounts with the force and it was simply stuck! One risks a cracked block if heat is applied unevenly (ie. this is delicate process!)

I can only relate to one drain plug. This plug came out with almost no effort. It's quite a bit smaller than the plug for the block heater (which I found laying behind the starter..........apparently some mechanic dropped it in there some time in the past)

I have a suspicion that the struggles are with the larger caps (for the block heater) that sit above the drain plug.

I'd be interested to see if anyone else has difficulty with the 617 drain plug. The threads are very short and they don't seem like they ever would be impossible to remove.

boneheaddoctor · #11 07-26-2005, 08:55 PM

Quote:

Originally Posted by Brian Carlton

I can only relate to one drain plug. This plug came out with almost no effort. It's quite a bit smaller than the plug for the block heater (which I found laying behind the starter..........apparently some mechanic dropped it in there some time in the past)

I have a suspicion that the struggles are with the larger caps (for the block heater) that sit above the drain plug.

I'd be interested to see if anyone else has difficulty with the 617 drain plug. The threads are very short and they don't seem like they ever would be impossible to remove.

Thats correct Brian..the big plug where the block heater goes is a bear,,,but the drain plug near the motor mount pedistal is fairly light being far smaller.

Thats the only one where you can really get the heavy crud out.

But I took advantage of the oportunity with both out to use garden hose presure to encourage the debris to exit the block.

#12 11-21-2005, 02:45 PM

Where exactly is this plug on a 85 300D (CA Model)?

I looked for it, but did not find it. What I did find was the green coolant during a succussful monovalve repair. No good. Need to flush.

Real specifics would be great. Thanks in advance.

boneheaddoctor · #13 11-21-2005, 02:52 PM

Quote:

Originally Posted by rblookc

Where exactly is this plug on a 85 300D (CA Model)?

I looked for it, but did not find it. What I did find was the green coolant during a succussful monovalve repair. No good. Need to flush.

Real specifics would be great. Thanks in advance.

Citric acid flush, no step in the instructions for REALLY stupid people like me!

Read post #14 adn click on the photo link.....all will be revealed.

#14 11-21-2005, 03:14 PM

Which way is the plug facing? I presume it points to the passenger side of the car (i.e. not at the street, not forward, not left). Also, how far aft of the back edge of the right front tire is it, ballpark?

Thanks, sorry to be a pain in the arse.

boneheaddoctor · #15 11-21-2005, 03:18 PM

Quote:

Originally Posted by rblookc

Which way is the plug facing? I presume it points to the passenger side of the car (i.e. not at the street, not forward, not left). Also, how far aft of the back edge of the right front tire is it, ballpark?

Thanks, sorry to be a pain in the arse.

passenger side...look at the bottom of the photo close on the right side you well see the passenger side motor mount pedistal.....its just behind and obove that. Where the red circle is....which is near the front edge of the starter and just above.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Do I have trapped air in my cooling System?	pberku	Tech Help	8	03-28-2005 12:15 PM
Summer behind the door, another A/C thread	Jassper	Diesel Discussion	3	04-13-2003 02:47 PM
Cooling System Service Questions	R Leo	Diesel Discussion	10	03-20-2003 01:44 AM
82 300D cooling problems	DIESEL	Diesel Discussion	6	05-03-2002 12:47 AM
Cooling system flush in 420SEL???	fredsegal	Tech Help	1	07-12-2001 05:09 PM