Brass water fittings on alloy head

Submitted: Thursday, Mar 25, 2010 at 20:26
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Just removed the head from my sons petrol 4.2 GQ patrol and found most of the steel heater and by pass hose fittings on the inlet manifold/head/engine rusted beyond use.
Would there be any long term with corrosion using brass fittings with the alloy head and inlet manifold?
Before i go to Nissan pay an arm and a leg for the genuine steel parts.

Rob
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Reply By: Member - Toyocrusa (NSW) - Thursday, Mar 25, 2010 at 20:52

Thursday, Mar 25, 2010 at 20:52
Hi Rob. Corrosion to that extent is normally caused from lack of maintenance to the cooling system. EI regularly flushing the system and replacing the coolant with the recommended inhibitor. If brass fittings are suitable and cheaper I don't think they would cause a problem provided there is no electrolisis in the cooling system and the coolant is changed regularly. I use Nulon Four year coolant mixed with distilled water in mine to 40% ratio. I also use distilled water to flush the system. I started when it was 2 years old so there was no sign of corrosion to start with. This one sounds like it will need a good flush with some cleaning agent as well. Regards,Bob.

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Follow Up By: dbish - Thursday, Mar 25, 2010 at 21:30

Thursday, Mar 25, 2010 at 21:30
Hi Rob. Been using brass fittins for years on alloy head on Falcon now, no sign of corosion. Steel fitting are always a pain, when working as a mechanic always replaced customers steel fittings with brass no more probs, & are not expensive. Cheers Daryl
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Follow Up By: Member - Rob S (NSW) - Thursday, Mar 25, 2010 at 21:34

Thursday, Mar 25, 2010 at 21:34
Thanks Bob
Lack of maintenance your not wrong,the previous owners!!!
We just picked up the 92 QG patrol Ute,very cheap.
My son is wants it for a weekend warrior when we sort out the mechanicals
get some new suspension and wheels, the things are built like a tank.
I also use Nulon coolant in my cruiser and change it as recommended, found it to be very good over the years.


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Reply By: Michael ( Moss Vale NSW) - Thursday, Mar 25, 2010 at 21:33

Thursday, Mar 25, 2010 at 21:33
Rob, Im sure that Nissan use steel fittings because they are cheap!! Use the brass , i do and have no problems. Michael
Patrol 4.2TDi 2003

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Follow Up By: Member - Rob S (NSW) - Thursday, Mar 25, 2010 at 22:01

Thursday, Mar 25, 2010 at 22:01
Your right there Michael.
allot of money to be saved on the thousands of fittings.
and generaly the steel will last the life of the car with good coolant.
I can get the brass fittings cheap as against Nissan parts. or make up up my own special fittings.
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Reply By: Keith Berg - Thursday, Mar 25, 2010 at 21:34

Thursday, Mar 25, 2010 at 21:34
Rob,
I just today found a rotten thread on an aluminium tank with a brass fitting screwed into it, after it refused to stop leaking. Dissimilar metal corrosion had rotted out the aluminium thread. Steel fittings will rot out in preference to the alloy in your head whereas brass will make the ally go first. So will stainless fittings. Maybe some Duralec jointing compound will help out, but I'd want someone to cross their heart and say it was OK before I'd put brass fittings into something expensive made of aluminium.
Keith
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Follow Up By: Member - Rob S (NSW) - Thursday, Mar 25, 2010 at 21:45

Thursday, Mar 25, 2010 at 21:45
Thanks Keith.

We just googled this before i put up the post.
And was also surprised to find Stainless steel will corrode alloy.

But think of the marine industry out board motors etc, they only use stainless steel on every thing with alloy, but they generaly have a sacrificial anodes attached.



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Reply By: GerryP - Thursday, Mar 25, 2010 at 21:37

Thursday, Mar 25, 2010 at 21:37
Hi Rob,

Just looked up the galvanic series and brass is a lot further up the scale than steel, using aluminium as a base. This would indicate that steel would be less reactive.

However, using a good coolant and proper maintenance should prevent most problems in any case.

Cheers
Gerry
AnswerID: 410379

Follow Up By: Star Bug - Thursday, Mar 25, 2010 at 22:03

Thursday, Mar 25, 2010 at 22:03
brass or copper are probably the worst combination you can use with aluminium.
it will survive with the correct corosion inhibitor, but I would avoid using them.
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Follow Up By: Member - Rob S (NSW) - Thursday, Mar 25, 2010 at 22:15

Thursday, Mar 25, 2010 at 22:15
Thanks Gerry

Good coolant a must.
And as i replied above, we did look at that and surprised with stainless steel and alloy not a good mix.

The engine reconditioner i saw today was fitting stainless steel welch plugs in an alloy head. go figure i am more confused now.

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Reply By: Bob of KAOS - Thursday, Mar 25, 2010 at 22:36

Thursday, Mar 25, 2010 at 22:36
Stray current.
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Reply By: Eric Experience - Thursday, Mar 25, 2010 at 22:39

Thursday, Mar 25, 2010 at 22:39
Rob
Zinc is the most compatible with aluminium, that is why zinc plaited steel fittings are the best to use on an ally motor. Brass fittings will not corrode but the ally will, the thinnest part of the ally will go first. Brass fittings will cause your heater core to leak that is why you should never use copper in a shower heater. Eric.
AnswerID: 410390

Reply By: kev.h - Thursday, Mar 25, 2010 at 22:47

Thursday, Mar 25, 2010 at 22:47
check with your local irrigation shop i have bought alloy hose tails before they vary in quality but the billet machined ones are good
Kev
AnswerID: 410392

Follow Up By: dbish - Thursday, Mar 25, 2010 at 23:33

Thursday, Mar 25, 2010 at 23:33
Fords used to use alloy hose fittings on alloy heads. They go brittle & snap off when you try & remove them, replace with brass end of problem & definitly no corosion problems with brass fittings. Most ally heads removed with corosion problems was not from dissimilar metals. Was generaly caused by over heating in localised areas the boiling action actualy eats heads & looks like corosion, Same thing can hapen to cast iron sleeves in diesels. Daryl
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Reply By: splits - Friday, Mar 26, 2010 at 09:01

Friday, Mar 26, 2010 at 09:01
This article on electrolysis in cooling systems is worth reading. Electrolysis is a very much misunderstood and overlooked problem in cooling systems.


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