sr head crack ok or bad? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

sr vegas 240 · 08-02-2018, 06:24 PM

So i had a machine shop do some work on the head and i asked about the hair line cracks on all the cylinders he said its fine its just surface cracks and there was no leaks as he did pressure test on the head.
So i took the head to a second machine shop to do some other work and they have told me the head is bad due to the cracks.
can anyone tell me if these cracks are bad to where i need to replace my head.

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supramon808 · 08-02-2018, 07:09 PM

which machine shop did u go to if u dont mind me asking? been trying to find a legit machine shop in vegas..

tb13 · 08-02-2018, 09:18 PM

Metal expands and contracts under heat and pressure, they may not leak when the head is on a bench being tested, but is it worth it to reassemble the engine and wait for them to get worse? Having them repaired now or replacing the head is probably in your best interest if you plan to have it hold up for any extended period of time.

sr vegas 240 · 08-03-2018, 02:06 AM

Quote:

Originally Posted by tb13

Metal expands and contracts under heat and pressure, they may not leak when the head is on a bench being tested, but is it worth it to reassemble the engine and wait for them to get worse? Having them repaired now or replacing the head is probably in your best interest if you plan to have it hold up for any extended period of time.

I appreciate that. Already have a new head sourced just want to check.

tuzzio · 08-03-2018, 08:10 AM

Are they discussing the linear indication in between the red circled areas? The issue with castings is that define the word "crack". It gets thrown around an awful lot. Casting is porous. Those very well may have been cast like that. Maybe they're parting lines or something that was missed in cleaning. A light gust of wind can drop sand into the mold (assuming they're sand cast) and cause a condition like that. I guess it may be linear shrink as well.

Sorry. I work at a foundry and i'm a nerd. I'd probably replace/repair.

sr vegas 240 · 08-03-2018, 08:16 AM

According to the first shop it passed pressure test and I was told it passed. The second shop said they magnaflux it and it's bad needs to be replaced.

tuzzio · 08-05-2018, 07:20 AM

What do they use for a spec to magnaflux it?

The issue with magnaflux is if they're just spraying it, letting it sit for X amount of time and then putting developer on it, of course its going to bleed out.

If the valves still seat, and its not a through doing indication (an actual crack) its probably just a sub surface casting flaw that became present during machining.

sr vegas 240 · 09-13-2018, 12:08 PM

I just had the head looked at by a 3rd shop pressure test and said the head was good. So I will go and use this head hope it will last a year or 2.

EFITTZY · 09-13-2018, 01:57 PM

If it passes pressure test it will be fine. SEND IT

08-02-2018, 06:24 PM	#1
sr vegas 240 Zilvia Junkie Join Date: Dec 2013 Location: vegas Age: 33 Posts: 301 Trader Rating: (12) Feedback Score: 12 reviews	sr head crack ok or bad? So i had a machine shop do some work on the head and i asked about the hair line cracks on all the cylinders he said its fine its just surface cracks and there was no leaks as he did pressure test on the head. So i took the head to a second machine shop to do some other work and they have told me the head is bad due to the cracks. can anyone tell me if these cracks are bad to where i need to replace my head. [IMG][/IMG] [IMG][/IMG]

08-02-2018, 09:18 PM	#3
tb13 Zilvia Addict Join Date: Feb 2014 Location: Arizona ٩( ᐛ )و Subaru Parts Consultant Age: 26 Posts: 813 Trader Rating: (3) Feedback Score: 3 reviews	Metal expands and contracts under heat and pressure, they may not leak when the head is on a bench being tested, but is it worth it to reassemble the engine and wait for them to get worse? Having them repaired now or replacing the head is probably in your best interest if you plan to have it hold up for any extended period of time. __________________

09-13-2018, 01:57 PM	#9
EFITTZY Zilvia Junkie Join Date: Mar 2016 Location: I n d i a n a Age: 25 Posts: 323 Trader Rating: (0) Feedback Score: 0 reviews	If it passes pressure test it will be fine. SEND IT __________________ (づ｡◕‿‿◕｡)づ T E A M B L O O M

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08-02-2018, 07:09 PM	#2
supramon808 Zilvia Member Join Date: Oct 2009 Location: Waipahu, HI Age: 36 Posts: 198 Trader Rating: (11) Feedback Score: 11 reviews	which machine shop did u go to if u dont mind me asking? been trying to find a legit machine shop in vegas..

08-03-2018, 08:10 AM	#5
tuzzio Nissanaholic! Join Date: Oct 2013 Location: Western Mass. Posts: 2,254 Trader Rating: (3) Feedback Score: 3 reviews	Are they discussing the linear indication in between the red circled areas? The issue with castings is that define the word "crack". It gets thrown around an awful lot. Casting is porous. Those very well may have been cast like that. Maybe they're parting lines or something that was missed in cleaning. A light gust of wind can drop sand into the mold (assuming they're sand cast) and cause a condition like that. I guess it may be linear shrink as well. Sorry. I work at a foundry and i'm a nerd. I'd probably replace/repair.

08-03-2018, 08:16 AM	#6
sr vegas 240 Zilvia Junkie Join Date: Dec 2013 Location: vegas Age: 33 Posts: 301 Trader Rating: (12) Feedback Score: 12 reviews	According to the first shop it passed pressure test and I was told it passed. The second shop said they magnaflux it and it's bad needs to be replaced.

08-05-2018, 07:20 AM	#7
tuzzio Nissanaholic! Join Date: Oct 2013 Location: Western Mass. Posts: 2,254 Trader Rating: (3) Feedback Score: 3 reviews	What do they use for a spec to magnaflux it? The issue with magnaflux is if they're just spraying it, letting it sit for X amount of time and then putting developer on it, of course its going to bleed out. If the valves still seat, and its not a through doing indication (an actual crack) its probably just a sub surface casting flaw that became present during machining.

09-13-2018, 12:08 PM	#8
sr vegas 240 Zilvia Junkie Join Date: Dec 2013 Location: vegas Age: 33 Posts: 301 Trader Rating: (12) Feedback Score: 12 reviews	I just had the head looked at by a 3rd shop pressure test and said the head was good. So I will go and use this head hope it will last a year or 2.