9.0 to 1 compression for the MB isn't high compression at all, heck even 10 to 1 isn't all that high when you look at 17.5 to 1 for diesels. Besides cavitation is always an issue whenever there is negative pressure in a liquid. you get cavitation damage on propellers on boats, pumps get eroded by cavitation for example.

 

The 96 v12 was 10:1 the 2004 I believe is 12.5/13:1

 

Farmerphilco,
You were partially correct in that it is the "torque" of the piston inside the cylinder that causes the negative pressure on the exterior area of the cylinder wall, therefore creating the cavitation bubbles. Not torque as in crankshaft. As stated earlier in the shouting match, 10% green to gold mix is the max acceptable without additional SCAs. Once again I have learned exactly why I come to this website, correct information. Thanks to all who participated in this thread, we all learned a great deal.
Renron

 

By that do you mean an axial torque in the cylinder, or a minute lateral flexing of the cylinder as the rod angle reverses at the top of the stroke?

 

i would be asking another question to myself.

if they topped it off, where is it leaking from???

then change the coolant.

a little green will not hurt.

test what is left, make sure you pressure test it first.
you should not need to add if there is not a leak!

 

Good question 18vtx00...I never have known "where it goes". But I've never had a vehicle (and I've had many), that at some point in time, didn't need a little coolant added.

To call a coolant system on a vehicle "closed" is a far stretch to me. The caps on overflow/expansion tanks are hardly air and water tight as compared to a truly sealed sytem like refrigeration.

Any thoughts?

To be quite honest, the posts to my original question have been conflicting to say the least. So far (and about 8,000 miles since I made the original post), I have noticed no decrease in coolant volume or other adverse effects (gummy bears, bubbles, etc.) and have erred with the "don't worry about it" responses; thus I have decided to wait until about 75K miles to change it out.

The posts concerning torque, cavitation, compression, etc. have been interesting, but also have me somewhat buffaloed. I fully understand the cavitation concept as it has to do with the impeller/tip speed/contact with coolant/presence of air in the system and the presence/lack of anticavitation additives, but how does this relate to torque and compression? The coolant never comes in contact with the pistons, cylinders, valves, etc. (at least you hope it doesn't), so what's the relationship to compression? The pump impeller is driven by the belt (isn't it?), so torque is limited to whatever forces may possibly be exerted through the belt which is driven by the crankshaft...I'm trying hard to see a relationship here, but all this starts getting really fuzzy.

Anyone care to help me out?

 

The cavitation is caused by the shock waves of each combustion event flexing the cylinder walls. It pushes out the cylinders walls, stretching them like a ballon at the microscopic level. When they snap back into place it creates a tiny area of vacuum and the water in the coolant flashes to steam. The pressure returns to normal and the steam bubbles collapse. The extreme pressure exerted to the cylinder walls when the bubbles collapse slowly but surely chip away at the outer layer of the cylinder walls and eventually eat it's way through into the combustion chamber. At that point you obviously get a leak into the piston and cylinder. Hydrolocking on a cold start, ruined engine block, etc. The additives purpose in life is to make and maintain a self sacrificing layer in the water jacket. During the each combustion event, that self sacrificing layer is what get's eaten away, not the actual metal that the engine is made from. It's constantly replenishing itself and that's why you need to check with test strips and add on a regular basis.

 

Kwikk, you do it again – my hats off to you. Clear, concise explanation with no cut and past directly from a babbeldy-gook technical post. You truly understand how it works.

 

Man! I wouldn't, in my wildest dreams, have ever considered all that!

Thanks for the short, straightforward, cut through the bull****, reply. I learn something new everyday.

 

Yep,
As I understand it from my son, who is a fluids and mechanical engineer thats what happens inside the "block"
He designs and verifies the country's state regulations on smog.
Good one Kwik.

Renron

 

Could this be the quote of the year? Well spoken sir.

 

Wow guys, thanks.

 

Ok so answer me this kind gentlemen ... as a first time psd owner and seeker of knowledge, what and where should I buy as coolant for my 2002 PSD.( 7.3) I have never even heard of the ford Gold stuff until recently
And should I purchase and add SCA's to the new coolant upon flushing and refill?
Finally , should I ever add SCA's and where do I get them if necessary?
Thx all,
cphill58