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Old 01-06-2004, 11:32 AM
Posts: n/a
Question electrolysis???

Here's a question regarding electrolysis on my 91CE, (that I have not seen addressed yet on this forum). I had my head gasket replaced by an independent about 4 years ago. At the time he had showed me on the block & head some electrolysis damage to these surfaces. He sent the head out for repairs & used some sort of "epoxy" on the block & smoothed it out. The damage I assume was caused because some previous "bonehead" had not flushed the coolant enough, and or did not use MB antifreeze, is this right?. Of course I feel that this epoxy fix was kind of a mickey mouse way of fixing the block, but he said that this was fairly common & was all he could do, (other than get a new block). Has anybody else ever heard of having this problem?, if so, how was it solved??. I had considered selling the car at the time because I figured it would just get worse. (The mechanic did say that it would not last forever), somehow, I understand that he was just trying to cover his butt.
Well, I have kept the car (and am very glad I did, I love this car), however my local dealer has informed me that the head gasket is leaking again!!, oh goodie!!. I do not want to sell the car, but is my only option a new engine??, they say that it will probably only leak oil (no big deal), & not water. The damage was on the passanger side toward the front of the engine, I guess this is where most of them leak. One can not shave the block, ( I forget what the hotrodders call this),any ideas from the pros would be greatly appreciated, as this has me concerned about the long haul with this car.
I know this is getting long, but one last thing. How about putting a sacrificial Zinc in the cooling system (just like we do in our boats for elecrolysis), to late for me, but might help someone out there. Thanks for any replies

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Old 01-06-2004, 12:08 PM
G-Benz's Avatar
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Join Date: Apr 2001
Location: Dallas/Fort-Worth
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I assume this is an M103 engine. Had you been referring to an M104, I would assume the leak would be the seal on the front timing cover, not the head gasket, which typically leaks at the rear on the M104.

If the head is not badly warped, it can be "resurfaced" within manufacturers specs. The block is either cast iron or iron alloy, so it's not likely to be the source of the leak. Removal of too much material affects the compression ratio dramatically.

My engine doesn't appear to be too hairy, so I've foregone "electrolysis" for now...
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
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2016 Mustang (32K) - Daughter's car
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Old 01-06-2004, 12:13 PM
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Join Date: Mar 2003
Location: Southern California
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The corrosion is due to not changing the anti-freeze often enough regardless of the type of anti-freeze used. MB recommends three year coolant changes (regardless of mileage) using MB antifreeze. Zerox G-05 is the same.

It is very easy to change the coolant on the 103 engine - about as easy as changing the oil.

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Old 01-06-2004, 12:44 PM
Posts: n/a
Thumbs up electrolysis??

Thanks for the reply, I have the m 104 engine in my 91CE, (dual overhead cam), this is the 104, right?. Please excuse my ignorance, I thought this car had an alumminum block, not cast iron. I believe I saw corrosion on both the head & block. Boy, I am confused now!. It was not leaking out the timing cover, it is coming from the side of the head, not the front. These cars do have an aluminum block, don't they?. If I had a magnet handy I would go out & check. Thanks for your help!
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Old 01-06-2004, 01:12 PM
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Join Date: Nov 2002
Location: Milford, CT
Posts: 19,307
If the coolent is changed it there should not be a problem. Did the previous owner ever change the coolent?
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Old 01-06-2004, 02:14 PM
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Thumbs up electrolsis

to the "hatterasguy", I believe the coolant was changed at some point by the previous owner, but probably not enough. By the way do you own a Hatteras boat?, I assumed so by your name?.,if so, so do I, we live on ours, want to chat about Hatteras's?
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Old 01-06-2004, 02:22 PM
I told you so!
Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,852
Get a magnet and check. You'll find the block is cast iron.

As your mechanic did, I too would have opted to salvage the head deck surface the first time. The other option would have been to remove the block and remachine (skim, shave, dust) the surface. This is costly. Unfortunately, this maybe your only option now.

Is the head gasket leaking in the same place? The best you could hope for is that the epoxy has held and the leak is there for another reason, such as a blown head gasket, and that it may be fixable without removing the block.

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