Flushing Radiator - PeachParts Mercedes-Benz Forum

iceman3876 · #1 10-17-2005, 01:08 AM

Can one of you dieselers give me the proper procedure in flushing my radiator in my 93 300D 2.5L 602 engine. I have heard guys talk about using different things to flush with...just need some good advice..I'm ready to tackle this

DieselCJ · #2 10-17-2005, 04:04 AM

Sounds good, I am going to change my coolant too.

Anyone know where the engine drainplug is on the 602?

Brian Carlton · #3 10-17-2005, 09:10 AM

You mention "flushing your radiator".

Is it your intention to change the coolant in the system, or, do you need to flush the entire cooling system with acid to remove any corrosion present?

The decision to go one way or the other is not to be taken lightly. One procedure will take less than an hour. The second procedure will take all day.

I would reserve the acid flush for engines and radiators that are known to have cooling problems and for which there is evidence of rust and corrosion in the cooling system.

Can't confirm the location of the block drain on the 602, but the 603 has it on the right side of the engine, approximately in the middle of the block, a bit forward of the block heater. It's a hex head cap screw that sticks out away from the block. Not all that easy to access, but, you can't miss it, once you look from underneath.

mike2005 · #4 10-17-2005, 09:13 AM

Plug is in the same location on my '82 240D, just in front of the starter. Don't forget to flush the heater core and associated hoses.

Brian Carlton · #5 10-17-2005, 09:23 AM

Quote:

Originally Posted by mike2005

Plug is in the same location on my '82 240D, just in front of the starter. Don't forget to flush the heater core and associated hoses.

............602 starter on the right side?????

iceman3876 · #6 10-17-2005, 12:43 PM

Quote:

Originally Posted by Brian Carlton

You mention "flushing your radiator".

Is it your intention to change the coolant in the system, or, do you need to flush the entire cooling system with acid to remove any corrosion present?

The decision to go one way or the other is not to be taken lightly. One procedure will take less than an hour. The second procedure will take all day.

I would reserve the acid flush for engines and radiators that are known to have cooling problems and for which there is evidence of rust and corrosion in the cooling system.

Can't confirm the location of the block drain on the 602, but the 603 has it on the right side of the engine, approximately in the middle of the block, a bit forward of the block heater. It's a hex head cap screw that sticks out away from the block. Not all that easy to access, but, you can't miss it, once you look from underneath.

Brian, I want to do the acid thing and remove any possibility of corrosion. I can do this since this car only goes on my 2 trips back and forth from New smyrna Beach Florida and North Carolina. round trip for each trip is 1000 miles each month.
I guess the better question should have been, what coolant do I replace with?, What acid do I use? are there any necessary precautions to take during procedure??? Thanks to all ahead of time.......

boneheaddoctor · #7 10-17-2005, 12:51 PM

Quote:

Originally Posted by iceman3876

Brian, I want to do the acid thing and remove any possibility of corrosion. I can do this since this car only goes on my 2 trips back and forth from New smyrna Beach Florida and North Carolina. round trip for each trip is 1000 miles each month.
I guess the better question should have been, what coolant do I replace with?, What acid do I use? are there any necessary precautions to take during procedure??? Thanks to all ahead of time.......

Citric acid....cheap tp by on ebay....its used for soap and lots of other stuff.

You use a degreaser first...flust well do the citric acid flush...when draining I recomend pulling the block drain plug near the pass side engine mount pedistal..you will have scale coming out....do that at least 4 times...

it takes 2.2 lbs of citric acid to do a flush....I by it in bulk on ebay. way way cheaper than the dealer.

Brian Carlton · #8 10-17-2005, 02:04 PM

Follow exactly what BHD has advised regarding the flush.

However, it is mandatory to flush the system at least four times with water after you use the citric acid. The acid should probably run in the system for 100 miles or so. Then it must be drained, the system refilled with fresh water.........drive the vehicle.........drain the system again..........allow the engine to cool.........then refill it with fresh water......................

This process takes all day because you must be absolutely sure that you remove all the citric acid. If the water feels "slippery", you have not removed it all.

When you are satisfied, drain it for the last time, get some Zerex G-05 in the gold container. Mix a 50-50 mixture with distilled water outside the vehicle. Add the mixture to the expansion tank (should take about 11 quarts) and also add it to the head via the upper radiator hose.

Drive it and get it up to temperature, return it and park it. Check the level again when cold.

Also, all the driving to flush the system should be done with the temperature dial all the way up to the stop. You'll get more heat than you want, but, the fluid must circulate through the heater core.

It's a long and involved process to to the job correctly. If you don't do it correctly, then just drain and refill with fresh Zerex 50-50 mix.

iceman3876 · #9 10-17-2005, 03:43 PM

again I appreciate all you guys do in helping us new comers...

Brian Carlton · #10 10-17-2005, 03:46 PM

Anytime.

Help is what we do here.

300DPETE · #11 10-22-2005, 10:14 AM

Looks like I'll have to do this....I found a LOT of rust in the coolant hose I replaced (installed an inline block-heater).

Without citric acid available to me this weekend, could I do the same procedure with just regular flush (prestone or zerex) from Autozone? (then drive it for 100 miles with the flush, than flush it out with clean water). Even if it's not as effective as driving for a while with citric acid, would it still help dig out the rust better than just following the directions which call for a shorter time with the flush at operating temperature?

Thanks,

Pete.

Brian Carlton · #12 10-22-2005, 10:30 AM

Quote:

Originally Posted by 300DPETE

Without citric acid available to me this weekend, could I do the same procedure with just regular flush (prestone or zerex) from Autozone? (then drive it for 100 miles with the flush, than flush it out with clean water). Even if it's not as effective as driving for a while with citric acid, would it still help dig out the rust better than just following the directions which call for a shorter time with the flush at operating temperature?

I used one of the flushing agents commercially available from Autozone. I drove it for 300 miles over the course of one week. When I drained the fluid, it did not appear to contain much corrosion, however, this may simply be due to the fact that the system was in decent condition.

I'm sure the flushing agents are better than simply exchanging the fluid, but, certainly can't match the effect of a proper acid flush. The chemical is not a very powerful acid (you can get it on your hand without trauma) and the amount of the chemical added to the system is relatively small compared to the volume of the cooling system.

300DPETE · #13 10-22-2005, 10:45 AM

How much of the powder do you put in?

Thanks,

Pete.

Brian Carlton · #14 10-22-2005, 10:50 AM

Quote:

Originally Posted by 300DPETE

How much of the powder do you put in?

Thanks,

Pete.

Most of the commercially available agents are in liquid form. You add the entire bottle (less than 1 pint).

300DPETE · #15 10-22-2005, 10:57 AM

Okay, I'm looking around, and I'm not sure which bottle of citric acid I'm supposed to get. I don't see one made specifically for flushing.

Anyone got a link?

Thanks,

Pete.

P.S. thanks Brian.