Citric Acid wash with a busted radiator? - PeachParts Mercedes-Benz Forum

JumpinJehosipha · #1 08-08-2007, 09:46 AM

Sorry for the dupe question, thought I would give this its own thread.

I've got a leaking radiator on a (somewhat) new to me 82 300SD. Found DexCool bottle in trunk and looks like dex in the system. So... I'd like to give it a good flush before putting in the new radiator and the proper coolant.

But the radiator leaks pretty bad, at least under pressure. Can I just run it up to temp with the cap off an dlet it dribble a bit and be OK, or am I asking for trouble? I could always just flush with water and drain it out and hope for the best, but I've read about the weird things dex can do, like putting a sludgy coating on the interior of the block. Besides, I'm sure I've got some rust after 25 years and that might be nice to clear out too.

Any consensus on my best move here? I need to get this thing back on the road ASAP.

#2 08-08-2007, 10:28 AM

If it was mine I would want to flush it as well as possible before installing the new radiator. I would probably drain the radiator, block, and heater hoses then force some tap water through the system to get out as much as possible. If the radiator isn't too bad, I would probably refill with an acid flush an let it get up to temperature with the cap off, maybe drive it around a little with the cap on if it doesn't leak too much. I would then flush with clean water and replace the radiator, that should keep almost all of the old stuff out of the new radiator.

vstech · #3 08-08-2007, 10:55 AM

best way to get DEATHCOOL out of a system is with air/water mixed.
make up a fitting where you hook your air compressor into a line that has full flow water going in. works great! THEN do the detergent, water, citric acid flush rinse flush thing.

JumpinJehosipha · #4 08-08-2007, 11:02 AM

Thanks Craig, that's what I was hoping to hear. The leak dribbles pretty badly, but I think with the cap off it will hold long enough for a flush (and I can watch and top up if needed)

I didn't want to do the flush with the new radiator in place for fear of clogging it all up before it even got 1 mile on it. I guess I'll try running it with the cap open and just water first to see if it holds well enough.

Now all I have to worry about is the condition of my heater core. Things smell a bit funny when I run it.

JumpinJehosipha · #5 08-08-2007, 11:03 AM

VSTech,

How many PSI on the air for that flush technique?

vstech · #6 08-08-2007, 11:07 AM

psi don't matter, just run it off the air gun. ya want bubbles in there, not pressure.
have the cap off the system, and have full flow of water before you dump in the air. AMAZING how much crud comes out this way!

#7 08-08-2007, 11:07 AM

Quote:

Originally Posted by JumpinJehosipha

Now all I have to worry about is the condition of my heater core. Things smell a bit funny when I run it.

If you use a hose to flush out the core (like I do), be careful not to use too much pressure. Hopefully you are just smelling antifreeze from under the hood, not from a leaky core.

Douglas.Sherida · #8 08-08-2007, 11:27 AM

if you know where the leak in the radiator is, you could seal it with JB weld then do the flush, then replace the radiator.

JumpinJehosipha · #9 08-12-2007, 05:59 PM

Well, I got around to dumping some water into they cooling system just to mover the car around. No way is it going to hold for long enough to do a proper soak with the citric acid. it drains in a couple of minutes. My plan? I'm going to bypass the radiator and loop the hoses right back into themselves. seem OK? Do I need to have some sort of expansion tube/tank in there just for a runup to temp? I could put a T fitting in to hook it to the expansion tank easily enough.

Citric acid was hard to locate locally, made a bunch of calls with no luck. ordered online, so it should be here in a few days. Always something...

Anyway, let me know if I'm insane to just try bypassing the radiator for the flush.