Help Me Diagnose My Cooling Issues - PeachParts Mercedes-Benz Forum

sailor15015 · #1 10-31-2006, 04:54 PM

Man what a can of worms I've opened up. A couple of months ago the water pump seal went out on my '84 so I replaced it. No big deal but I figured since I had the system open I should go ahead and do a citric acid flush. Temps always stayed between 82-85 so I should have known to leave well enough alone.

So I went through the whole ordeal of flushing and what-not and during that process, my t-stat, which I should have removed anyway, failed closed and the temp spiked in the red zone for a minute or two before I noticed. Crap. Waited about an hour for it to cool down, removed said failed t-stat, and continued home with no problems.

After finishing my acid flush, minus a t-stat, I made the mistake of leaving tap water in my system for about a week while waiting on the replacement t-stat. Now I've got a nice coating of light-brown stuff all over the inside of the cooling system so I need to do the flush again to get that out, and add coolant immediately after.

I put a new t-stat in after doing the flush and verifying that it opens at 85° C on my stove but now my car is wanting to over heat. Sometimes it stays at about 95, others up to 110 but never past that. I've still got regular water in there, along with the brown crap(oxidation?) in my system. I know its still got some air because coolant only gets back to my veggie tank about half the time, plus today when it was running at 110 I wasn't getting any coolant flow through the heater core either.

I had an oil analysis done by Blackstone Labs and it came back with a trace amount of coolant in it, along with a high concentration of lead from what they said was most likely the bearings. The thing is, I can't remember if I sent that sample in before or after the overheating episode and I've got all the dates on my laptop at home. I'm at college right now so I'll post back with the dates later tonight. I also did a cold compression test and got about 380 psi on all cylinders. For those of you that are into the milivolt readings, I took readings on my cylinders and got about 6.2 for cylinders 1-3 and about 4.5 for 4 & 5, for what its worth.

So my question is, is it more likely that I have a blown headgasket/cracked head or a combination of air in the system and the oxidation from my genious self leaving tap water and no antifreeze in the system?

P.S. Thanks for taking the time to read all this. Sorry its so long but I try to be as thorough as possible and do as much research as I can before starting a new thread.

Diesel Giant · #2 10-31-2006, 05:09 PM

The brown is NOT from tap water, its from the lack of corrosion inhibitors (antifreeze) in the water. Even if you used distilled water it will rust cast iron by itself.

sailor15015 · #3 10-31-2006, 05:44 PM

Quote:

Originally Posted by Diesel Giant

The brown is NOT from tap water, its from the lack of corrosion inhibitors (antifreeze) in the water. Even if you used distilled water it will rust cast iron by itself.

Hmmm. That's good to know since I was going to flush only with distilled water this time. Do you think it could be having a major impact on the ability of the metal to transfer heat to the water?

#4 10-31-2006, 06:06 PM

Quote:

Originally Posted by sailor15015

Hmmm. That's good to know since I was going to flush only with distilled water this time. Do you think it could be having a major impact on the ability of the metal to transfer heat to the water?

No, I think it's more likely that you still have some air trapped in the system someplace.

SirNik84 · #5 10-31-2006, 06:16 PM

Ok, I’m no expert, but I just dealt with this so here are my thoughts.

What did the water pump look like when you changed the seal? Mine was pumping fine, but then I took it out and compared it to a new one and you could see where corrosion had eroded the existing pressure relief holes in the impeller to twice their size. If the impellor was pocked with corrosion that could be having an effect on your car.

My next thought is you should get all the flush out of the car. I’d disconnect the upper radiator hose from the engine and hook it up to the hose and flush water thought the radiator and engine till it comes out clear.

I’d also pull the radiator and clean it with the hose and make sure all the bugs and leaves and dire is out of there. Clean the AC condencer while you are there too.

It’s normally the little things like bugs or dirt that builds up over time to cause the problem.

Don’t forget to refill with the yellow coolant.

punky · #6 10-31-2006, 06:19 PM

Are you presently running straight water or are you using coolant/anti-freeze? I couldn't make out from your posts.

sailor15015 · #7 10-31-2006, 06:44 PM

Quote:

Originally Posted by Craig

No, I think it's more likely that you still have some air trapped in the system someplace.

That's what I though. I drove it up on a hill and filled the upper hose to the brim but after driving it a bit it feels really squishy. Any advice on getting it out? That's one thing I really like about the bimmer. The t-stat housing is the high point on the system and it has a bleed screw.

sailor15015 · #8 10-31-2006, 06:44 PM

Quote:

Originally Posted by punky

Are you presently running straight water or are you using coolant/anti-freeze? I couldn't make out from your posts.

Straight water right now. Anit-freeze soon though because the temps are dropping here.

sailor15015 · #9 10-31-2006, 06:45 PM

Quote:

Originally Posted by SirNik84

Ok, I’m no expert, but I just dealt with this so here are my thoughts.

What did the water pump look like when you changed the seal? Mine was pumping fine, but then I took it out and compared it to a new one and you could see where corrosion had eroded the existing pressure relief holes in the impeller to twice their size. If the impellor was pocked with corrosion that could be having an effect on your car.

My next thought is you should get all the flush out of the car. I’d disconnect the upper radiator hose from the engine and hook it up to the hose and flush water thought the radiator and engine till it comes out clear.

I’d also pull the radiator and clean it with the hose and make sure all the bugs and leaves and dire is out of there. Clean the AC condencer while you are there too.

It’s normally the little things like bugs or dirt that builds up over time to cause the problem.

Don’t forget to refill with the yellow coolant.

Had to replace the radiator recently because I broke the plastic nipple on the old one. I've got all the old flush out and while I had it out I cleaned all the crap out between the fins.

rudolfgreen · #10 10-31-2006, 07:15 PM

Quote:

Originally Posted by sailor15015

Straight water right now. Anit-freeze soon though because the temps are dropping here.

if you're only running straight water, you are not nearly reaching normal cooling potential of a proper glycol mix.
head out to your local parts store, pick up a jug of zerex g-o5 in the gold jug (autozone now stocks this), and a gallon of distilled water.
drain your cooling system including the block plug, and then refill your system with the 50/50 mix. (topping off as needed).
wouldn't be worrying about any blackstone lab tests as much as would be worrying about another day anywhere near 110. good luck.

my123ca · #11 10-31-2006, 07:51 PM

Your radiator is probably plugged with all the crud you took out from the engine after you did the citric acid flush. Do a reverse flush to your radiator and cross your fingers. Flushing the cooling system of an old engine in my opinion is a bad idea. I think it should be left alone.