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#1 |
Registered User
Join Date: Oct 2011
Location: phoenix, az
Posts: 508
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Testing 454 Heads for Leaks with WATER?
I'm considering buying a set of used heads for my mid '70s 454. On YouTube there are videos on using water to check for leaky valves, they just pour water in the ports and look for leaks. Heads are off the engine of course! But people are saying that even new heads will leak a little, is this true or is the water test fool proof?
![]() THIS IS NOT A 454 HEAD, JUST USING PIC FOR REFERENCE! |
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#2 |
Senior Member
![]() Join Date: Dec 2013
Location: nephi , utah
Posts: 2,308
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Re: Testing 454 Heads for Leaks with WATER?
the best thing to do is have them magnafluxed , it will find the demons , if any
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#3 |
Registered User
Join Date: Jul 2011
Location: WV
Posts: 946
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Re: Testing 454 Heads for Leaks with WATER?
I think he's looking at valve condition vs cracks. You can use that test to get a reasonable idea of condition. If they weep a little, you can still lap them when you throw a set of valve seals on before you install.
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72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold ![]() 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD |
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#4 |
Registered User
![]() Join Date: Oct 2006
Location: Southern Kalifornia
Posts: 3,066
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Re: Testing 454 Heads for Leaks with WATER?
Gasoline or better yet, rubbing alcohol is better that water. I've been doing that for about 20+ years....works great. Will also find a bent valve.
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
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#5 |
Registered User
Join Date: Oct 2011
Location: phoenix, az
Posts: 508
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Re: Testing 454 Heads for Leaks with WATER?
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#6 |
Registered User
![]() Join Date: Oct 2006
Location: Southern Kalifornia
Posts: 3,066
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Re: Testing 454 Heads for Leaks with WATER?
"some" seepage is to be expected on a used head. The valves may be able to be lapped back in, but a GOOD valve job would be better. The reason I say use Gas or rubbing alcohol is it will dissipate and not cause rust.
__________________
------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
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#7 |
Post Whore
![]() Join Date: Aug 2014
Location: Sacramento, CA
Posts: 10,826
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Re: Testing 454 Heads for Leaks with WATER?
like Lance said use gasoline (smaller particles) and you will know right away if there is a leak rather than waiting for hours or over night
I put a large dry clean piece of cardboard on the garage floor then put something under the head when I set it down upside down so it is nice and level yet I can easily see the drip or puddle stains below then poor gasoline from a 2 gallon red jug canister into a small glass jar (don't use a red party plastic cup cause it will eat right through it) then from the jar carefully into each chamber (oh yeah with the spark plugs screwed in of course) this way you don't make a mess and have false positives cause you missed the chambers and pored the gas all over the head fill one chamber at a time and look under it for stains, take a pic when you see the stains so you can document which valves leaked dirty valves with carbon deposits won't sit / seal tight so all you have to do is take a leaky valve out one by one so you know where it goes and wire push it off with a soft wire brush wire wheel then put it back in and re test if it still leaks re lap them with some lapping compound and a rubber hose on the end of a drill |
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#8 | |
Registered User
Join Date: Feb 2014
Location: Northeast Iowa
Posts: 1
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Re: Testing 454 Heads for Leaks with WATER?
Quote:
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#9 |
Registered User
Join Date: Jun 2008
Location: Lubbock, TX
Posts: 2,047
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Re: Testing 454 Heads for Leaks with WATER?
Put a few drops of soap in a spray bottle and fill with water. Spray in the chamber, use an air gun to pressurize the port. Watch for bubbles, just like with a tire.
All this shows is how well the valves seat. It won't show cracks in the chamber, etc. - have 'em magged! |
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#10 |
Registered User
Join Date: Jun 2008
Location: Lubbock, TX
Posts: 2,047
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Re: Testing 454 Heads for Leaks with WATER?
May be cheaper but it'll cost you a ton of flow as compared to a modern valve job. It's not that expensive to have someone do either a 3-angle with stones or 5-angle with a cutter on a Serdi or similar machine. Particularly for street machines, the valve spends much more time at low lift where flow is more affected by the valve job.
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