Advice on lost of compression

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Advice on lost of compression

Tallyho
After changing the oil using amsoil 10-30 zrod I ran the truck about we 100 miles trouble free.
Next day went out for a short ride and only got about 2 miles when it started running rough.
Got it home and after not finding anything obvious I did a compression test.  Here are the numbers.  Warm with throttle blocked open...
#4      0psi.         #8.    132psi
#3.    149psi.     #7.     148psi
#2.    155psi.     #6.     157psi
#1.    140psi.     #5.     145psi

Pulled the valve cover and everything looks great and operating properly.
There is absolutely no compression on #4.  Wont even move the gauge.
Did find the casting # on the head...
D3ve a2a
Any thoughts?
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

85lebaront2
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Do both valves appear to be the same height? If nothing else, can you use the compression gauge hose with the valve core removed and put air in the cylinder so you can at least get an idea whether it is valves or rings.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Advice on lost of compression

Gary Lewis
Administrator
To further what Bill said, he's suggesting a quick and dirty leak-down test.  You'll have air coming through something, and most likely a valve that is stuck open.  So put air into the cylinder and listen in the tail pipe and in the intake and you should hear a lot of escaping air sounds in one or the other.

But, if not listen in the sump by placing a hose to your ear and placing the other end to the dip stick tube or into the valve cover oil fill hole.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

Tallyho
Thanks Guys.  I'll work on trying the leak test and get back to you..
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Tallyho
I have surgery escaping from the carb
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Tallyho
I meant air
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Gary Lewis
Administrator
In reply to this post by Tallyho
You have an intake valve stuck open, which is why you have no compression.  Some times you can rap a rocker arm with a mallet and get the valve to spring shut.  But you'll have to figure out why it is stuck open.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

Tallyho
I got ahead of myself... I should find tdc on that cylinder first...
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Gary Lewis
Administrator
YES!!!!  Should have said that.  And, it should be TDC on the compression stroke.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

Tallyho
I'm struggling with find tdc on the compression stroke without compression.  Its the rear cylinder which is too tight to insert something.
Can I use the rockers position to find it?
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Gary Lewis
Administrator
Yes, but should be able to use the rotor on the dizzy to tell. Trace the plug wire to the cap, note the position, pull the cap and turn the engine until the rotor is pointing at that position.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

85lebaront2
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Find TDC #1 on the balancer, rotor pointing back. rotate the crank 180° clockwise and you will be on #4 TDC (firing order 15426378).
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Advice on lost of compression

Tallyho
I got it using the rotor.  Brilliant idea by the way Gary!  I was really struggling trying to get my air chuck to stop leaking when I noticed the furthermost spring kinda looked clocked a bit.  I spun the spring around and sure enough its broken
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

85lebaront2
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At least you found it! I had a similar problem with my son's 1965 Corvair Corsa, at least that one was easy to change, just had to be underneath to do it.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Advice on lost of compression

Gary Lewis
Administrator
In reply to this post by Tallyho
If you can get the valve to seat by pulling up while you have air pressure on it then it should seat and stay. Then you can pull the keeper, get the spring off, put the new spring on, and replace the keeper.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

Tallyho
Thanks,
I've never replaced a valve spring before.  Are there any special tools required?  Once I found tdc on that piston the cylinder was going up in pressure.  I had it at 40 psi when I was fiddling trying to get the air chuck to stop leaking.  I'm sure it could go more.  
It looks like there's a chance I might get lucky wish this fiasco.   What are common causes of spring failure?  If a new spring fixes this should I replace them all?
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Gary Lewis
Administrator
I suspect it is just a flaw in the spring, but I’ve not had one break so I don’t know. Anyway, I don’t think you need to replace them all.

As for tools, it takes a valve spring compressor. You may be able to rent/borrow one at your local parts store, but if not you may want to take the truck to a shop to have it done. That way you don’t have to buy the spring compressor.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Advice on lost of compression

85lebaront2
Administrator
If you can borrow or rent one that hooks under the spring and pushes down on the retainer, it will work quite well. Use a small magnet to retrieve the keepers. Take everything off and unload the broken spring, put the new one in the tool and compress it until it will go over the stem far enough to put the keepers in (use a dab of grease to help hold them). I usually pull the spring and retainer up against the keepers so the won't slip while I release the pressure.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Advice on lost of compression

Tallyho
Thanks for that.  I'm trying to decide if I should use my pancake compressor or use rope to hold the valve.  Right now with the piston at tdc the compressor will fill the cylinder.  When I release the little tension I have on the valve will the pancake be enough?  Or do I need a compressor with more volume?
Tallyho
1984 f250 4x4 460 4 spd
Raymond maine
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Re: Advice on lost of compression

Gary Lewis
Administrator
What kind of pressure is the compressor holding in the cylinder?  And, how often does it have to run?

If you are able to keep something like 100 psi in the cylinder then the size of the compressor, or I should say the volume of the compressor, doesn't matter.  The pressure is what holds the valve in place, and if yours will do it then a bigger compressor wouldn't make any difference.

Where a bigger compressor would help is if your compressor is having to run continuously to keep the cylinder filled.  A bigger compressor would have enough volume to be able to handle the leakage you have without running as long or often as yours.  But if yours isn't having to run a lot then a bigger one won't help.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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