I have been kicking around the water pump installation on my motor for Jr. I am curious as to how stainless bolts will act in the motor and in the aluminium timing cover.I thought the water issue is what corrodes them. However, I am hearing it is the electrolysis from the aluminum front cover they go through that causes all the problems.

How does stainless react in aluminum? How does it react in ferrous metals?

 

Chrome and nickel are much higher on the noble scale than aluminum, zinc or magnesium.
The pot metal timing case will not corrode much against an aluminum water pump.
Chrome creates a protective oxide layer much like aluminum does.
I REALLY think it is the carbon freed from steel and cast iron when they start to rust that eats up timing covers.
(This is my conjecture. I'm NOT qualified in material sciences)
Seal the threads to keep it dry and grease the shanks so they can't seize in place.

 

It depends on the stainless. They have different alloys of stainless, some alloys still rust. But usually a stainless bolt is very good at resisting any type of corrosion.

The product of electrolysis is corrosion, when steel corrodes or "oxidizes" it turns into a brown powder commonly known as "rust". When aluminum "oxidizes it turns into a white powder.

A good grade of stainless bolt should stop the corrosion. The only problem with stainless bolts is the threads are not very strong and like to get "stuck" in certain applications. A good grade of stainless tends to be "gummy", somewhat like aluminum, but holding a waterpump in place should be well within it's capabilities.

 

Btw, I have stainless bolts for everything on my engine. (Except the alternator pivot, a couple of brackets and the internals)
No problems with seized/corroded fasteners

 

Stainless on stainless REALLY tends to gall and seize.
A nickel based antisieze is critical in that application.
Most common fasteners are 304 or 316 series, maybe some 416 for cut threads.
When cast iron or steel oxidizes into rust where do you think the carbon goes?
What is the most cathodic element on the scale???

Yup

 

So.... Should I be looking for 304,316 or 416?

 

304 is good for fasteners.
You might get a little discoloration but the fastener is sound.

316 has more corrosion resistance but is more 'gummy'. (nickel is soft)
More for 'show' or a marine environment.

416 is easier to machine and weld but corrosion resistance isn't as good. Use this grade for bending up your exhaust system.

 

^ Good info there. Keep in mind, you may see some fasteners listed as "18-8". This is generally equivalent to 304, but may also cover 302,303, and 305. If seizing (galling) is a concern, you can use a graphite lubricant. You'll only experience galling if using a stainless nut and screw, so if you use a carbon steel zinc plated nut, no worries.

Electrolysis can happen between aluminum and stainless due to the fact that they're "dissimilar metals". However, I have many customers who like to use the two together due to their overall corrosion resistance (I sell fasteners).

 

Thanks Dadx6

Yes I tried to make it clear that galling was only an issue with stainless on stainless (bolt *and* nut, or tapped into something like a pipe flange)
Hadn't considered graphite paste instead of antisieze.
Ford already recommends this for sealing exhaust manifolds.

You sell fasteners.
Ever consider making up a 'kit' for our Ford engines?

 

Hmm... not a bad idea. I've only had my truck a couple months, so I haven't had to replace many pieces of threaded hardware as of yet. Perhaps you can PM me or email me some common thread sizes and lengths that you think would be useful!

 

Gary has got a verbose thread in excruciating detail about fasteners here someplace.... probably entitled something like Dad's Fasteners, An In-Depth Study and Reference Guide

 

Chris asked me to cite some details about the galvanic scale and corrosion.
I'm on my phone so hopefully these links help:

http://www.smex.net.au/reference/Corrosion02_NobilityScale.php

https://www.corrosionpedia.com/2/1403/corrosion-101/an-introduction-to-the-galvanic-series-galvanic-compatibility-and-corrosion

Anyway you can see that graphite (carbon) is right up there next to gold.
A very noble element indeed.

When cast iron or steel rusts it becomes one of the oxides (Fe*x*O) and these don't incorporate the carbon that is held in solution in steel or cast iron.
The free carbon may combine with another element to become something like carbon monoxide or it may just wreak havoc with whatever less noble metal it comes in contact with in the presence of the electrolyte that caused the rust in the first place.

 

_____

LOL

 

Sort through this Dad if you have time. I need a set for my water pump. Maybe even an intake manifold set too.
https://www.ford-trucks.com/forums/1...t-lengths.html

 

I bought a cheap bolt set from Ebay and had to augment only a few pieces.
The washers were much heavier than the tinfoil ones in the bin at the local hardware stores.
Here's one listed for '87 and down 351 W's, though the photo says Cleveland.
Idk what's up w/ that, but it's easy enough to ask.

http://m.ebay.com/itm/310156759136?_trksid=p2055119.m1438.l2649&_mwBanne r=1