I was told I can change the valve guides without pulling the heads on my 79 400 CI. Anyone done this before?

Thanks
Wrecker

1979 F250 Supercab 4x4 Towtruck 400CI 4 Speed

 

>
>I was told I can change the valve guides without pulling the
>heads on my 79 400 CI. Anyone done this before?
>
>Thanks
>Wrecker
>
>1979 F250 Supercab 4x4 Towtruck 400CI 4 Speed

OK Lets think about this?
To change the valve Guide one has to remove the valve, Ream the old one to except a new guide or Knerl the old one to tighten it up some for the old valve. Anyway I see it your going to have to remove the heads to do this.

Now you'll are able to replace the valve Seals without removing heads. But not the guides.. Sorry

 

>>Sorry.... I meant the seals


>>Thanks
>>Wrecker

 

OK changing the seals is easy . Get yourself a compression tester
and you'll need some compressed air.
Pull the spark plugs and take the check valve out of the tester. Insert tester in your first cylinder hook it to the compressed air and it will hold the valves shut as you remove the valve springs to change out the valve seals,replace the springs and move on to the next cylinder.

 

Thanks for the info...it's exactly what I was looking for. One more question about the seals if you on't mind...A Mechanic at work told me my problem may be the seals. My truck smokes most of the time, especially at start up. I realize I should do a complete rebuild,
but until the kids finish college, thats not an option. Do you think changing the seals will help until I can rebiuld, or am I wasting my energy?


Thanks
Wrecker

1979 F250 Supercab 4x4 Towtruck 400CI 4 Speed

 

That's a tough call without a crystal ball. Stock seals dry out and get hard over time. If the guides are worn, new seals are just a bandaid fix but it may fit the bill.

You need a special tool to compress the valve spring without removing the head. Retainers stick, it can be a real pain.

The other method without an air compressor is with a rope. If you feed a long piece of pliable rope onto the spark plug hole, you can turn the crank by hand and use the piston to press the rope against the valves holding them closed.

 

depends,how old are your kids?

 

[updated:LAST EDITED ON 28-Dec-02 AT 10:28 AM (EST)]I have used the method described by Shazam to change seals and springs on several engines. You need a lever-style spring compression tool. Crane makes the one I used. Use a bolt to hold it to the rocker mount, apply the compressed air, pull the lever a little to put some pressure on the retainer and give the retainer a couple of light smacks with a mallet to break the grip of the keepers. Use a magnet to pick up the keepers before they fall. It's simple, really. When reassembling the parts, use some grease on the keepers to hold them in place on the valve stem.

While you are in there, be sure to use some coat hanger wire to probe the oil drain-back holes in the heads. They should be clear into the crankcase. These can become clogged with gunk overtime, leading to mucho oil consumption around the seals.

 

I recomend changing seals most definitly, as a hardened seal can
crack apart plug the oil drainage and there goes a couple mains,
some rod bearings,warped head, and a blown head gasket.
Thats happened to a motor I took apart once, just thought I should
bring it up.


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