Ducman82

from what i have read it is alum IN stainless that is an issue over a long time. from my experiences its the different type/grade of stainless that is the issues.

GlenL

A Real Man.

Pulling the engine by myself isn't hard. Even preferred as helpers are often "helpers" and make jobs run long. Putting it back requires extra hands to guide it in.

blown 87

And some don't.

hacker-pschorr

I just call a friend with really small hands. Case of beer sure beats permanently damaging my 928

jcorenman

I don't know much, but owning a sailboat does encourage one to learn something about corrosion. Any two different metals will form a battery and corrode, what's missing here is any sort of electrolyte.

Any conductive material has a natural galvanic potential (electrical voltage, when made part of a battery). Metals with similar potential won't corrode in combination. Here's a table of galvanic potential from corrosionist.com:



Electrical potential is the horizontal scale-- metals close together horizontally have a smaller difference and make a lousy battery. Note zinc in the upper-right and graphite (carbon) in the lower-left-- a common drycell battery. The material that is more anodic-- farther to the right-- corrodes and gets converted to something else (the ubiquitous white powder), while the material to the left is protected. Zinc is used on boats to protect other metals, and if you get magnesium anywhere near a boat it just goes away.

Cadmium, steel, aluminum are all pretty close together. Stainless is all over the place depending on alloy (most fasteners are 318 I think).

But it takes an electrolyte to make the battery work, nothing will happen if it is dry with no conductive path to complete the electrical circuit. Salt water makes a terrific electrolyte, but the 928 exhaust studs are pretty well protected against road stray (assuming belly pans). Suspension parts, not so much.

So cad-plated steel is better than stainless, but in any event the guy was right-- his stainless studs are not at risk. If there is any corrosion, it will be the aluminum block. And that is only an issue if conductive (salty) water gets to it.

Zinc plating is theoretically better at protecting steel bolts than cad plating, the problem is that the zinc plating is thin and goes away quickly in the process of protecting the steel. But it's what we've got.

Imo000

Never mind the galvanic reaction. Stainless is usually really soft and shouldn't be used in exhaust satuds or collector bolts.

Ducman82

iv had no issue with either spots... on this car or my old mopars. but it is softer to be sure....

dcrasta

What about good ole anti-seize on the bolts (Smear) as they are installed. I've always used it on header studs/bolts and never had a problem with them becoming stuck from corrosion.

jeff spahn

You mean there are people out there that can help! Gads, I did the pull and install both times by myself.

Second pull and install was done in less than 8 hours. Seems like 2 of them were dealing with the damn wiring harness through the firewall.

jcorenman

It helps keep the moisture out, and lubricates the threads-- all good stuff.

17prospective buyer

You learn something new everyday, thanks for the insight on fasteners, especially jcorenman, that was very interesting. I've also heard of engine blocks corroding if the pH is at the correct level to form an electrolyte and thus a large battery that, like you said, corrodes the anodic material (would this be the negative as the positive or less anodic material draws electrons from the anodic material that wish to be positively charged?).

S4ordie

Butt sore?

fbarnhill

Jeff, how the heck did you get the engine between the motor mounts without an extra set of hands? Mine were new from Roger. They were very tight. I thought I was going to have to install it myself but my son showed up for a visit just in time...However, it was a b%#*&ch even with help.

Man, that must have been some day,

Imo000

Loosen the two top bolts at the block and the mount will have enough play to easily guide it in.

GlenL

I'm guessing you guys are talking about different motor mounts. The old style are tough to get past and those heat shields don't cooperate well, either.