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Rusty Manifold. Should I bother replacing

Should I replace my rusty manifolds?

  • Yes, the car is going to be much better with new

    Votes: 0 0.0%
  • No, you won't really notice any difference

    Votes: 0 0.0%

  • Total voters
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Those manifold bolts are like ingrowing toe nails. The sooner it's addressed, the easier the pain. You're just ramping the bill up leaving it.
 
I have new manifolds (see above) but they have gone very dark - even look rusty! Is that normal????? I was expected the shiny manifolds to stay shiny
 
The clue's in the name - Stainless, not Stainproof.
 
alex yates said:
The clue's in the name - Stainless, not Stainproof.

Thanks Alex. :) I'm not that good with stuff like that. Can I get bolts that don't corrode? The new ones already have surface rust.
 
INWB said:
alex yates said:
The clue's in the name - Stainless, not Stainproof.

Thanks Alex. :) I'm not that good with stuff like that. Can I get bolts that don't corrode? The new ones already have surface rust.

Yep, titanium ones. Poppopbangbang on here sells them :thumb:
 
Marine grade Stainless (A4 I think) is probs the best.
 
I fellow Engineer (Aerospace Quality Engineer) was telling me the other day not to mix Titanium with Aluminium as they react with eack other and corrode. Don't know how true this is, only found out on Thursday.
 
alex yates said:
I fellow Engineer (Aerospace Quality Engineer) was telling me the other day not to mix Titanium with Aluminium as they react with eack other and corrode. Don't know how true this is, only found out on Thursday.

Your fellow engineer is correct Alex.

The Galvanic Series Chart explains that the "anodic" or "less noble" metals at the negative end of the series such as magnesium and aluminium will be subjected to bi metal galvanic corrosion when in contact with "cathodic" or "noble" end of the series materials such as gold or titanium, in the presence of an electrolyte. Salt water is a particularly effective electrolyte, so consideration of metal combinations is particularly important in Marine engineering for example. Better to choose material combinations that are closer together in the series and stainless steel is a good example of this. The potential (voltage) difference of Al v Stainless Steel is much smaller than Al v Ti. Heat also promotes this galvanic corrosion

That is the theory out of the way. An electrolyte has to be present for corrosion to take place, and would suggest that the screws into the head is potentially dry, though any dampness in there will cause corrosion and seize the stud. This is more likely to happen with a Ti stud. In theory, it should also accelerate corrosion around the stainless steel flanges / fasterners.
 
:worship:

Yep - I totally get all that and understand the Chemistry of it (working in Cathode manufacturing for TVs and also spark and wire eroding in the Toolroom). Usual case of good stuff used in the wrong application with regards to ti and Ally.

My Stainless bolts have now been in there 3.5 years but look like they were fit last week.
 
Yes pure titanium is more reactive than stainless.

However both stainless steel and titanium form a passive oxide layer when freshly cut, it is this that protects the metal and resists corrosion.

Titanium's oxide layer is more protective than the layer that forms on stainless. This oxide layer also insulated the titanium from other metals in contact.

This is why medical implants use titanium, it is least prone to corroding because the inert oxide layer protects the rest of the metal.
 
But wouldn't the layer get sheared off when torqueing the bolts up?

As a side note, I have Titanium implants in the front of my face. The pain when they drill and tap into the bone is purely excruciating........like a teet I had the operation done whilst conscious :nooo:

They use Titanium because the bone fuses with the metal and locks it in place.

Its ability to physically bond with bone gives titanium an advantage over other materials that require the use of an adhesive to remain attached. Titanium implants last longer and much higher forces are required to break the bonds that join them to the body compared to their alternatives.

Source: https://en.m.wikipedia.org/wiki/Titanium_biocompatibility
 
I hope I don't have to have mine removed.......that will be excruciating!!!! :-|
 
I've got titanium Rawl plugs in my jaw as well, did they tell you how it was discovered that bone bonds onto Ti?

It was a researcher who was working with Rabbits - something to do with blood chemistry IIRC. Anyway, the experiment (for a specific rabbit) was over so the researcher decided to "recover" the titanium capsule that was inside the rabbit - and made the discovery that the rabbits bones had bonded to it.
 
:thumb: Kool.

I know I also had a bone graft as a lot of the bone had rotted away. They used cow bone to do the graft then cover it in pig skin while it knits, stitching the flesh up over the top. Then 3 months later, open me up and remove the skin.
 

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