108 heater valve repair (AGAIN!) - Page 2 - PeachParts Mercedes-Benz Forum

Tomguy · #16 12-25-2003, 11:15 PM

I only want to flush my core - I can NOT get my block drain plugs out (in fact, the 6mm allen bit snapped off inside the driver's side plug and, to my knowlegde, is still stuck in it...). I just wanted to clean the heater core out - my engine doesn't overheat nor does it get close to. I figured if I put hot (boiling) acetic acid into the core and let it sit a bit, it'd soften hard stuff up; then putting in baking soda would cause the whole thing to bubble and foam through the core like rapid backwashing. Then I'd flush it out (w/pressurized water) backwashing first, then the proper way. Reattach my hoses and I'm off to the races (with HEAT!)

psfred · #17 12-26-2003, 11:53 AM

Tom:

If you have calcium carbonate deposits in the heater core, it's gonna fizz anyway.

Acetic acid will work you you really don't want to dribble it all over, it's corrosive, and it will REALLY foam up when you add backing soda -- we used to make cannons from airline liquior bottles, vinegar, and baking soda. Luckly, we never blew the bottles up...

Flush the heater core backwards -- the worst deposits are going to be in the coolest part anyway, and that will also help shove any stuff plugging the tubes on the inflow side out.

I would repeat the acid "flush" -- filling and washing out -- several times. If you get about 8' of heater hose, you should be able to get it to siphon pretty good over the fenders and down to a bucket, easier on the paint, etc. Won't hurt a thing to get the vinegar up to almost boiling, either, then let is sit in there for half an hour before rinsing.

I may try this this weekend on the 280 to free up the heater valves and get some head in the old girl.

Peter

Tomguy · #18 12-26-2003, 01:19 PM

When I blew the coolant out of the core with air (mouth) pressure, it looked clean (I used a (new) fuel line with duct tape around its outside, then pressed into the line going into the heater core). But the next day I noticed that the ground where the coolant landed had a streak of beige-ish crud! (looked like an amalgam of oil and water, but lighter in color). That's when I knew the core itself was gunked up.

I didn't think about it before but you may be right, the acetic acid may just fizz on its own in there w/o the baking soda. Sodium Bicarbonate lets out twice as much CO2 per molecule as Calcium Carbonate, but the CaCO3 itself should still fizzle!

I have red wine vinegar (only) and need to get to the store to get a gallon or so of cheap white vinegar - although the red wine is 5%, I don't want to waste it or dilute it because there's only half a bottle of it left as it is

This will be a good chance for me to use that old hotplate from chemlab that I fixed (it was busted so I snagged it before it was sentenced to the trash). If I want to get fancy I can even put a magnet in it to stir the vinegar (ooooh!

) I don't want to ruin a GOOD burner (like the stove or the one on the grill) should any boil over

psfred · #19 12-26-2003, 04:12 PM

Tom:

I'd guess that the heater core holds at least a quart, maybe two, so a gallon of white vinegar is the ticket.

I did (another) tuneup on the 280 today -- new points again since the first set seemed to crap up pretty fast -- gets annoying cleaning the points every time you want to use the car, plus it won't start cold worth diddly.

So far, so good. Now, if I can just get that window regulator fixed so I don't have an icy draft all the time....

Peter

Tomguy · #20 12-26-2003, 06:41 PM

Went to Wal*Mart, got some PB Blaster, more Dex-Cool, a gallon of Wal*Mart vinegar and a box of Arm+Hammer. Tomorrow I'll clean her out and I'll post pics of any crud that comes out if you want

psfred · #21 12-26-2003, 07:44 PM

Sounds good!

I'd use Xerex G-05 coolant, though, instead of DexCool.

Peter

Tomguy · #22 12-28-2003, 12:17 AM

Flushed it today - not too much came out but some stuff that looked like fiberglass fibers did

Couldn't test heat output though - when I was changing the injector seals, the bottom half of one fell down into the manifold - I have to get that out before I start her up! (don't want to defeat the purpose of the air filter by injecting dirt directly in...)

#23 12-28-2003, 02:33 AM

Those fibers may be part of some good old-fashioned Stop-Leak that someone put in sometime back. That could also explain the beige residue you discussed earlier.