606 cooling system purge procedure? - PeachParts Mercedes-Benz Forum

KarTek · #1 12-22-2008, 03:21 PM

Guys,

I'm really needing my heat, it's so friggin' cold here now.

A couple weeks ago, I finished up my glow plug repair, during the course of which, I had to disconnect the water line from the back of the head. Well, now, despite having reconnecting everything properly and re-filling the reservoir, nothing seems to be happening.

When I feel the lines going into and out of the duo-valve, the one line is warm and the other is cold (relatively). I checked and the aux water pump is working and I've disconnected the duo-valve to make sure it stays wide open. This is telling me that no water is flowing through the system.

The car did this early on when I first purchased it. I fiddled around with the duo-valve but nothing seemed to work. Some time later, like magic, the heat started working again.

Could there be a bubble that just needs releasing?

Thanks for any insight.

TMAllison · #2 12-22-2008, 04:08 PM

May need to be burped.

You (may - my 99 doesn't) have a bolt/plug where your upper rad hose connects to the engine. You can fill through that plug; or failing that disconnect the upper rad hose at the rad and fill there, then re-fill overflow res.

DieselAddict · #3 12-22-2008, 06:11 PM

The bolt is a bleed bolt, not meant for filling, but for letting air out. With a cold engine, undo it until coolant comes out, then add coolant to the reservoir as needed. If you don't have it, fill through the upper radiator hose like TM suggests. As with any car, you need to run the engine until warm with the reservoir cap off and heater on. The heater should eventually produce some heat, but the car may need to be driven first, then topped off again (after it cools).

TMAllison · #4 12-22-2008, 06:36 PM

Thanks for clarifying DA. Mine doesnt have that port and I didn't know how it was meant to be used.

KarTek · #5 12-22-2008, 07:06 PM

I looked just now and my car doesn't have any kind of bolt. I removed the upper radiator hose at the block and it was full.

One thing I found however, and I don't know if this is a factor, but anyway, the upper hose was installed too close to the power steering pump pulley. I felt along the bottom and sure enough, the pulley has chewed into the hose enough to cause a small leak. This may have been enough to either suck air or prevent the system from generating any pressure.

So you 606 guys, run your fingers under the upper hose and make sure you have at least a fingers width clearance between the hose and the pulley.

sokoloff · #6 12-23-2008, 06:38 AM

Could collapsed or collapsing motor mounts cause that issue with that hose?

KarTek · #7 12-23-2008, 10:19 AM

Quote:

Originally Posted by sokoloff

Could collapsed or collapsing motor mounts cause that issue with that hose?

It most likely has everything to do with it. At best, the hose only has about 3/4" of clearance. I recently replaced both front mounts which had the effect of raising the engine something close to 3/4". I believe that if the hose was installed with proper clearance and collapsed mounts, replacing the mounts probably ate up 99% of that clearance. From that point on, every time a load was placed on the engine, it torqued over and the pulley made contact.

That's my theory at least...

It should probably a matter of course to re-check the clearance at that point after a mount replacement.

KarTek · #8 12-28-2008, 12:13 PM

Update: Today I started poking around testing things and I believe I found the problem. I took off the duo-valve and it appears to be stuck shut. I don't have a t-10 handy to take it apart so I have to run to the store and buy one.

Details later...

OK, it's now about a quarter to 5 PM and I finally have heat!

This morning it was about 65 deg here at 8 AM so I swore to myself that I would fix the heat before it gets cold again.

I started with the aux water pump. It was running but I took it off to make sure everything was in place and nothing was broken inside. Turns out it's a very robust design with a magnetically coupled impeller and there's not much chance it's not pumping if you can hear it running. However, the impeller can be jammed with a foreign object and the motor will still sound like it's running fine.

Just for giggles, I used the "rest" button and ran the pump with the hose off that runs to the engine. Curiously, it did not produce the geyser of water that I would have expected, rather it just sort of bubbled over the edge.

Next, I moved on the the duo-valve. Upon opening the bottom part, I imediately saw the problem. The two "floating" brass plungers were fused to the rubber seals, effectively blocking 99% of the water flow. I dug a little further into the valve and began to find large chunks of torn rubber as well as most of the other rubber seals displaying signs of dry rot.

I believe what happened is that during the 3-4 months the car sat idle, the water level was somewhat lower due to me removing the rear water feed line. This allowed the duo-valve to dry out and the rubber seals to disintegrate.

Anyway, it's working now temporarily and I'll be ordering a rebuild kit if it's available or possibly, just the seals.