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440 Compression Test Results-Head Gasket or ??? Update
#1436683
05/15/13 01:41 AM
05/15/13 01:41 AM
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Joined: Mar 2003
Posts: 3,358
Berwyn, IL
challenger70
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Berwyn, IL
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So I have been getting exhaust out the breather at high rpm and did a compression check. Engine is an iron headed 440 in my '70 Challenger with about 10,000 miles on it. Test was done hot, at first anyway. #1=170, 2=40(yes 40), 3=174, 4=15(yes 15), 5=169, 6=171, 7=185, 8=170. Other than the exhaust out the breather, the car runs fine, no coolant in the oil, doesn't seem to be going through unusual amount of oil or coolant, but clearly something is up. The pamphlet with my tester says 2 adjacent cylinders down more than 20 psi from the others (2&4) is probably a head gasket.  Any advice is appreciated 
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: challenger70]
#1436684
05/15/13 01:53 AM
05/15/13 01:53 AM
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Joined: Jun 2004
Posts: 3,319
Chicago Burbs
sthemi
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Chicago Burbs
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There is a leak down test, that can better determine if it is a valve or gasket. Might as well pull the heads and take to the machine shop. If the gasket is blown, it may be warped heads, they will need to be checked 
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: challenger70]
#1436687
05/15/13 11:00 AM
05/15/13 11:00 AM
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Joined: Jan 2003
Posts: 75,062
U.S.S.A.
JohnRR
I Win
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I Win
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U.S.S.A.
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Quote:
Thanks for the help, having never pulled a head before, how do I determine what replacement gasket I need? I am pretty sure my engine is .030 over but do not know what thickness I need to maintain my current compression. Can I measure the existing gasket once I pull the head or Do I need new head bolts or can I reuse the existing ones assuming they are in good shape? Any tricks to it or is it just pull, remove old gasket replace w/ a new one and retorque? I don't mind venturing into new territory as long as I see a road home  Thanks for the help 
The gasket will have a part number on it , if it's a Fel Pro composite it's probably the 8519 , if it's a steel shim it's probably a mr. gasket or the MP gasket.
Pull the head and go from there.
How long has it been like this ? Hopefully you didn't torch the block or head surface between the cylinders.
also you aren't seeing exh out the breather , it's blowby gas past the rings
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: RapidRobert]
#1436689
05/15/13 11:53 AM
05/15/13 11:53 AM
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Joined: Mar 2003
Posts: 3,358
Berwyn, IL
challenger70
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Quote:
Quote:
How long has it been like this ? Hopefully you didn't torch the block or head surface between the cylinders.
I was concerned about that too. If a visual shows an obvious problem you'd have to dissassemble & take it in but even if there's no damage that you can see I'd still have your machinist check the block/head decks for flatness/warpage. Reuse your head bolts
Honestly, it's been a while, few hundred miles or so at least since I noticed it, who knows how long before... Hopefully it's ok  Should I do both head gaskets while I am at it? Engine build is about 10 years old now. I guess I will pull the head and see where I am at. Thanks for the help, I am sure I will need more!
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: JohnRR]
#1436692
05/15/13 02:23 PM
05/15/13 02:23 PM
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Joined: Feb 2003
Posts: 18,582
Rust Belt, SW PA
Silver70
I Live Here
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Posts: 18,582
Rust Belt, SW PA
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By the time you pull the intake and such off, I would do both sides and be done with it.
68 Road Runner, 69 Belvedere, 71 Challenger Vert
340 barracuda, 01 Ram CTD, 95 Ram, 04 Ram, 85 Daytona turbo Z
66 GTO, 06 Magnum RT AWD. 07 Ram CTD, 07 Ram
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: stumpy]
#1436694
05/16/13 02:47 AM
05/16/13 02:47 AM
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Joined: Jun 2004
Posts: 3,319
Chicago Burbs
sthemi
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Chicago Burbs
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Do both sides,
drain the radiator, pull the valve covers, intake, spark plugs, rocker arms and exhaust. Dont disassemble the rocker arms, pull them as a unit and lay inside a valve cover with the bolts still in it.
unbolt the head bolts and lift off.
I personally prefer the steel shim gaskets, but everyone will like something different..
If you run into trouble, I am pretty close by and can swing by.
One of the posters mentioned torching, that is when the lit gases travel from one cylinder to another and erode a portion of the block.
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: sthemi]
#1436695
05/16/13 12:00 PM
05/16/13 12:00 PM
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Joined: Mar 2003
Posts: 3,358
Berwyn, IL
challenger70
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Berwyn, IL
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Quote:
Do both sides,
drain the radiator, pull the valve covers, intake, spark plugs, rocker arms and exhaust. Dont disassemble the rocker arms, pull them as a unit and lay inside a valve cover with the bolts still in it.
unbolt the head bolts and lift off.
I personally prefer the steel shim gaskets, but everyone will like something different..
If you run into trouble, I am pretty close by and can swing by.
One of the posters mentioned torching, that is when the lit gases travel from one cylinder to another and erode a portion of the block.
Thanks, out of curiousity these steps all make sense except pulling the shaft rocker system off the heads. Is that neccasary to remove the heads? Just curious what this step accomplishes, thanks for the advice, explanation and help
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: challenger70]
#1436697
05/16/13 12:04 PM
05/16/13 12:04 PM
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Joined: Jan 2003
Posts: 75,062
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,062
U.S.S.A.
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Quote:
Quote:
Do both sides,
drain the radiator, pull the valve covers, intake, spark plugs, rocker arms and exhaust. Dont disassemble the rocker arms, pull them as a unit and lay inside a valve cover with the bolts still in it.
unbolt the head bolts and lift off.
I personally prefer the steel shim gaskets, but everyone will like something different..
If you run into trouble, I am pretty close by and can swing by.
One of the posters mentioned torching, that is when the lit gases travel from one cylinder to another and erode a portion of the block.
Thanks, out of curiousity these steps all make sense except pulling the shaft rocker system off the heads. Is that neccasary to remove the heads? Just curious what this step accomplishes, thanks for the advice, explanation and help
How would you get the pushrods out if you didn't pull the rockers ? How would you hold the pushrods upright so you could get the head back on if you left the rockers in place ?
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: dogdays]
#1436698
05/16/13 12:25 PM
05/16/13 12:25 PM
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Joined: Mar 2003
Posts: 3,358
Berwyn, IL
challenger70
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Berwyn, IL
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Quote:
It's a lot easier to take off the heads if the pushrods aren't in the way. Taking off the rocker shaft assembly allows the pushrods to be removed easily. It's a 5-minute job.
Keeping all the parts together and in order helps the reassembly, too.
R.
Thanks, it made more sense on aligning the pushrods for re-assembly to me, minds well do it when you take them off to make that easier too, thanks for all the help.
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: challenger70]
#1436699
05/16/13 12:41 PM
05/16/13 12:41 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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Dont forget to FIRST pull the block drain plugs (1) on each side of the block/roughly in the middle/down at the pan rail
live every 24 hour block of time like it's your last day on earth
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Re: 440 Compression Test Results-Head Gasket or ???
[Re: RapidRobert]
#1436700
05/16/13 10:52 PM
05/16/13 10:52 PM
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Joined: Mar 2003
Posts: 3,358
Berwyn, IL
challenger70
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Quote:
Dont forget to FIRST pull the block drain plugs (1) on each side of the block/roughly in the middle/down at the pan rail
Do I need to do this if I drain the radiator?
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You should go ahead and do both sides while your at it. Not that much more work or money and you'd be sure not to have to do it all over again.