North American Turbocoupe Organization



Magnafluxing VS Pressure Testing
Pete D Offline
Administrator
#1
Looking for comments, opinions and facts on the pro and cons of the two testing methods, especially in regards to cylinder heads.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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gtbird Offline
Member
#2
I recently inquired at a local machine shop about magnafluxing a head and I was told that this method would wipe out the cam bearings and I believe he said it would best be done with the head completely stripped down, whereas if you were interested in checking a prospective head (for purchase,maybe) for less money/labor pressure testing was the prescribed method.
Rick

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Dan E Offline
Posting Freak
#3
Pete:

I honestly don't know ? What I would wonder is if pressure testing would catch a surface crack in a valve seat ?

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Dan Eaves
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Pete D Offline
Administrator
#4
I got to thinking about this today after I took a head to a new (for me) shop and got an estimate. The guy said they do pressure testing because magnifluxing may not pick up all cracks??? I have ususally heard people talk about magnafluxing. I also remember the factory did pressure checking on new heads after the machining operations. Just thought I would see what others know

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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B D Offline
Member
#5
Pressure testing only works if the crack goes into the water jacket. The same method can be used with vacuum. Mangnafluxing will show up small surface cracks,but the head must be clean,oil free,and dry. Gtbird, the guy at the machine shop may have said that because most heads or blocks are vatted before Magnafluxing to get ride of oil. In that case you have to remove the cam bearings before you can put the head in a hot tank. You can get the same effect of Magnafluxing in a small area with a large horse-shoe magnet and the magnafluxing powder (Iron powder), if the surface is clean. You could use this to spot check valve seats on a head that you were buying.
B D

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Hawk Offline
Senior Member
#6
The reason you see both methods out there is magnufluxing won't work on aluminum heads. It has to be a ferrous material before you can magnuflux it. When properly done, I would personall prefer magnufluxing. Pressure testing can easily miss cracks that have just started.

Hawk
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Jeff K Offline
Administrator
#7
Quote:Originally posted by B D:
Pressure testing only works if the crack goes into the water jacket. The same method can be used with vacuum. Mangnafluxing will show up small surface cracks,but the head must be clean,oil free,and dry. Gtbird, the guy at the machine shop may have said that because most heads or blocks are vatted before Magnafluxing to get ride of oil. In that case you have to remove the cam bearings before you can put the head in a hot tank. You can get the same effect of Magnafluxing in a small area with a large horse-shoe magnet and the magnafluxing powder (Iron powder), if the surface is clean. You could use this to spot check valve seats on a head that you were buying.
B D


I agree.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
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Pete D Offline
Administrator
#8
Thank you all for the info. I got the head back today and pressure testing gave it a clean bill of health. I can generate my own iron filings through porting work. How big a magnet would I need to do my own magnafluxing and where would I get one??

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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B D Offline
Member
#9
The Iron powder is usually very fine. The type I have used is normally applied by "Dusting" it on almost like talc powder. A magnet is positioned ACROSS the likely path of a crack or 90 degress to the crack. The powder is lightly applied, and if a crack is there it will show up. Too much powder will hide a small hairline crack. The most important aspect of crack detection is knowing the likely location of the crack. Most heads or blocks crack in the same places. If you know where to look, that is half of the battle.
Most shops use a electro-magnet. A "U" shaped magnet that has a gap of a least a inch might work.
B D

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NATO Member
87 TC 5-Speed, Remote mount K&N filter system,Steeda Shifter
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87 Turbocoupe 5-Speed, Remote mount K&N filter system,Steeda Shifter,New Heater Core,new clutch.
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88 Thunderbird Sport 5.0 (Retired)
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