7mge Head Deterioration..

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SupraStoked

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Apr 26, 2012
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So I'm in the process of replacing the head gasket on my 7m, just wondering if these water ports look 'usable' on the mating surface of the head..

All the pics ive seen of 7m heads after coming back from the machine shop dont have this much corrosion around the water ports. Is this head junk?..

(The blue liquid was used to check the seating of the valves after lapping. Ive already reseated the the valves that needed it and theres no more leaking.)

I just hope all the work ive been putting into this head hasn't gone to waste..

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hvyman

hvyman

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Apr 17, 2007
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Its looking pretty bad. Can lay the gasket down on it and see if it effects the sealing surface. other than that replace it.
 
hvyman

hvyman

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It would have been like that before but was prolly covered up with gasket material and other junk.
 
I

IJ.

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SupraStoked;2003202 said:
Nope, dont know if thats a service at the shop i took it to. How would that affect it?
I know what a hardness test is and why its done, im just wondering if theres a direct connection between it and the erosion
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No Direct connection other than I wouldn't spend a cent on a 7M head without getting it tested first....

You might want to look closely at the grounds in the car and do a Stray Current test when it's back together, the erosion "might" be as simple as it's had water in the system but quite often it's Stray Current.
 
I

IJ.

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Yes it's quite common, anywhere there's a dirty ground in the car, to test for it you need an Analogue MultiMeter one probe to ground and one in the coolant, it needs to be under .05v to be safe, it will attack the softest metal in the System, usually Aluminium.

In the case of an Al radiator the tubes are typically only 20 thou thick so can be eaten away enough to leak within weeks :(..
 
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IJ.

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SupraStoked;2003216 said:
Damn, learn something new everyday. Thanks for the info and suggestions IJ.
I will definitely test for that once i get it all back together..
If i get this problem dealt with.
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Welcome!

Been playing cars 37 years now and still learning ;)
 
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SeeUSmile

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Nov 22, 2012
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Wow that's very interesting IJ. Probably gonna go do that now haha!

My head had pretty bad pitting around the water ports too... since the plans for car was to just daily drive it and replace it with another built 7m once the current motor on it dies after Road worthy and rego is done since I'm a lazy bum to get the whole paper work of engine vin done.
I decided to get it welded up at the machine shop disregarding the hardness test too...
 
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SeeUSmile

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Cost wise? Getting it welded then decked was around the $130au mark for me. That is of course giving the head to them already disassembled.

Im still in the process of getting the engine back together.

Btw IJ you mentioned about using an analogue meter, would a digital do as well?
 
Nick M

Nick M

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SupraStoked;2003205 said:
So your saying maybe some electrolysis occured because of the stray current and water in the system?
Click to expand...

Dissimilar metals, iron block and aluminum head are two of the three things needed for a battery. Factory over priced red coolant was made specifically to combat the third.
 
I

IJ.

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SeeUSmile;2003355 said:
Cost wise? Getting it welded then decked was around the $130au mark for me. That is of course giving the head to them already disassembled.

Im still in the process of getting the engine back together.

Btw IJ you mentioned about using an analogue meter, would a digital do as well?
Click to expand...
No has to be analogue.
 
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