460 problems
Thread Starter
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Laughing Gas
Joined: Jul 2000
Posts: 851
Likes: 15
From: Elkton, MD
460 problems
I just put a built 460 in a 78 crewcab and I have a compression problem. It runs decent, but cyl #7 has only 60psi when I did a compression check, all others have 150-155 psi, I replaced the head gasket, but it did not help. The cylinder head looked fine, and the top of the piston looked fine, the part of the cylinder I could see looked fine. Any opinions on what to do next?I also have water getting into the oil, I did not build the motor, it was built, run for 9000 miles, then the truck was wrecked and it sat for about 10 years covered in someones garage, he put oil in the cylinders. It runs great except for needing a tune up.
Thanks,
Bill
Thanks,
Bill
New User
Joined: Jan 2008
Posts: 0
Likes: 24
460 problems
"Leak Down" test with air.
Take out the spark plug for that cylinder and attach an air supply with both valves closed:
1)if you hear air coming out the exhaust manifold = exhaust valve pronlem
2)if you hear air coming out the carburetor,the intake valve is the problem
3)if you hear air coming out the dipstick,valve cover,it's the rings on the piston.
Is the oil looking a little milky?
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
Take out the spark plug for that cylinder and attach an air supply with both valves closed:
1)if you hear air coming out the exhaust manifold = exhaust valve pronlem
2)if you hear air coming out the carburetor,the intake valve is the problem
3)if you hear air coming out the dipstick,valve cover,it's the rings on the piston.
Is the oil looking a little milky?
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
Thread Starter
|
Laughing Gas
Joined: Jul 2000
Posts: 851
Likes: 15
From: Elkton, MD
460 problems
The oil is not milky, but thin, it runs really easilly, like it is watered down, but not milky. There is a little milky white residue in the valve covers, breather, and a little in the lifter valley, I will try the leakdown tonight,
Thanks,
Bill
Thanks,
Bill
New User
Joined: Jan 2008
Posts: 0
Likes: 24
460 problems
[updated:LAST EDITED ON 19-Feb-02 AT 03:32 PM (EST)]1st Change the oil & filter soon
Loss of water > Head Gasket > small leak to intake or exhaust ?
That engine ahd not been run to normal operating temperature for long enough in you daily travels.
It's a short trip /barely warm start-stop problem.
Hmmm, 1 cylinder low on a re-build.
Rings on that one piston improperly installed ?
(all the gaps are all aligned & gapped improperly end to end)
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
Loss of water > Head Gasket > small leak to intake or exhaust ?
That engine ahd not been run to normal operating temperature for long enough in you daily travels.
It's a short trip /barely warm start-stop problem.
Hmmm, 1 cylinder low on a re-build.
Rings on that one piston improperly installed ?
(all the gaps are all aligned & gapped improperly end to end)
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
Senior User
Joined: Nov 2000
Posts: 231
Likes: 2
460 problems
There could be a slight crack in the cylinder wall of #7, though a bit rare on a 460 block, it could happen. This would allow compression to escape the cylinder and allow water into the oil. Piston rings "clocked" wrong on the pistons will definitely cause a low compression condition as will burnt or bent valves and of course a broken ring.
Todd
BB79RANCH
Todd
BB79RANCH
I would get the head magnafuxed at a shop sounds like there is a crack some were
