How To Change Valve Seals On A Chevy 350

ENGINE VALVE SEAL Stalk REPLACEMENT

This is a " How-To " Article illustrating Replacement Process and Skill Technique

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ENGINE: Chevrolet 350 Cubic Inch Displacement V8 Engine

VEHICLE: 1971 Chevrolet C-ten Pickup

Date of Publication: 2011-05-18

Small Block Engine Valve Seal article was written by John Harlowe, Re-Certified by ASE as a Master Automotive Technician for the 3rd sequent time in June of 2011

Certification Expires: June 30th, 2016

ASE's mission is to improve the quality of vehicle repair and service through the testing and certification of repair and service professionals.

Until the early 1970s, consumers had no way to distinguish between incompetent and competent mechanics. In response to this demand, the independent, non-profit National Institute for Automotive Service Excellence (ASE) was established in 1972.

Please Notation: PHOTO ENLARGEMENTS and LINKS OPEN A NEW WINDOW IN YOUR BROWSER

Where to Begin?

PHOTO ONE — TOOLS NEEDED

Note: Earlier attempting any type of mechanical repair one should have the manufacturing plant service manual on hand. Oil fouled spark plugs or that dreaded blue smoke coming out of the tail pipage is definitely a sign that in that location is something beveled inside the engine.

The first step should be a dry / wet compression check followed up by a cylinder leak down test. If the result of these two diagnostics reveal the rings and valves are in the minimal acceptance range, then the valve seals are responsible for the blue smoke.

Valve seals are an piece of cake plenty "on car" repair if one has an air compressor in their garage capable of maintaining at least 120 PSI, any less pressure than that, and then there is a good run a risk the valve will drib downward into the cylinder diameter.

SPECIAL TOOL LIST
• Factory Service Manual
• Air Compressor
• Head on Engine Valve Spring Compressor
• Spark Plug Air Hold Tool

REMOVE
• Distributor cap and spark plug wires as a unit of measurement
• All spark plugs
• Both valve covers
• All rocker arms and push rods

PHOTO TWO — ROCKER ARM Property TOOL

If you are not replacing the rocker arms or push rods, then, earlier removing them, make yourself a belongings tray with the cylinder number and Intake and Exhaust designations, so yous can reinstall them in the same order.

Earlier re-installing these items a quick bath in solvent is in club.

Additionally, this would be a good time to measure and tape push rod diameter and length for time to come reference, in this particular case the push rod diameter is 5/16 " and vii.8125 " in length.

PHOTO 3 — AIR Concur DEVICE

With the rocker arms / button rods removed, yous tin can now install the valve air hold device in the spark plug hole.

CAUTION : Make sure at that place are no obstructions in and around the fan belts / fan because every bit soon as you lot connect the air hose to the air hold device the pressure level volition force the piston down and rotate the engine approximately a quarter turn.

At present that the cylinder has air inside it, use the valve bound compressor tool to compress the valve bound. The tool comes with instructions on its use and an additional long arm, I would suggest using one short arm and one long arm on the tool to make compressing the spring easier. You will also demand to have a socket that is slightly smaller than the diameter of the valve bound servant at hand. Place the socket over the valve jump and tap it lightly a few times with a brass hammer before installing the valve bound compressor tool. This volition assistance to vibrate the keepers which will make their removal merely a little smoother afterwards the spring is compressed.

With the spring compressed, remove the valve keepers ( having a small telescoping pocket magnet will aid greatly in this ) and you should exist able to run across the valve seal at this point.

Sometimes the seal is so deteriorated that very little of information technology, if any, remains on the valve stem.

If you lot do see the seal, use a dentists pick and remove information technology. The seal volition most likely be very brittle and will break off in tiny pieces.

Pull the jump compressor tool direct upwards to expose the valve stalk. At this point you can make clean the valve jump ( still compressed in the tool ) and the valve stem in the head with a little bit of solvent.

Photo Four — VALVE SEAL GROOVE LOCATION

As you can see in both Photo 3 and 4, the valve seal is installed on the valve, this is shown to illustrate where the valve seal is to be installed.

NOTE: It would make life a heck of a lot easier if the valve seal could exist left on the valve ( as illustrated in Photograph Iv ) and the spring installed on top of it, but it can non.

The compressed valve leap must exist installed Starting time, and so the valve seal installed, then the valve keepers. Once these items are installed, so you can plough the valve spring compressor counter-clockwise to extend the valve spring.

If the valve seal is installed commencement, when y'all identify the valve bound assembly over the valve stalk, the bound retainer will rip / cut the valve seal and all your work volition amount to nothing but bluish billowing fume out of the exhaust.

Residuum assured this is a very tiresome operation, yet, if you have the correct compression on the valve spring with the tool, you should exist able to simply barely run into the valve seal groove from the top of the valve jump.

With a little petroleum jelly over the valve stem and a pointed dentist pick, y'all should be able to work the valve seal downwardly into its groove.

Brand certain the valve seal does not turn itself inside out during the installation.

Photograph FIVE — VALVE SEALS INSTALLED

At present all you lot need to do is to repeat this process 15 more than times.

PHOTO Six — REINSTALL ROCKER Arms and Push button RODS

Reinstall the rocker arms and push button rods.

Install a compression tester to #1 cylinder and bring the engine up to TDC.

# 1 CYLINDER on TDC
• ADJUST EXHAUST VALVES: — 1 3 four 8
• ADJUST INTAKE VALVES: — 1 2 5 7

Install a compression tester to #6 cylinder and bring the engine upward to TDC.

# half dozen CYLINDER on TDC
• Arrange EXHAUST VALVES: — 2 5 6 7
• Accommodate INTAKE VALVES: — 3 4 vi 8

Accommodate each valve until all valve lash is eliminated and then plough the adjusting nut clockwise ¾ turn.

Photograph SEVEN — OIL STOPPERS / DEFLECTORS INSTALLED ON ROCKER ARMS

Install oil stoppers / deflectors on the rocker arms.

Reinstall the spark plugs, distributor cap / wires and plug any vacuum ports that may have been opened by removal of the air filter, valve covers, brake booster hose and any other items you had to remove for admission.

Now start the engine and let it warm to operating temperature.

NOTE: If you desire to avoid steam cleaning the engine bay afterwards this procedure, then I would advise placing heavy duty aluminum foil over the frazzle manifolds and engine bay area as oil splash protection.

With the engine warm and running, back off the rocker arm adjusting nut until y'all begin hearing a singled-out " clacking " audio, then plough the adjusting nut in until the " clacking " audio stops, then plough the adjusting nut in some other ¾ plough.

Repeat this process for the other 15 valves.

Shut the engine off, clean up the tin can foil and bank check the engine oil level.

Photo Eight — INSIDE of VALVE COVER COATED with GLYPTAL

While I had the valve covers removed and cleaned I decided to requite them a good coating of Glyptal to help in oil drain back. This coating is really corking, oil just does not stick to it and that'southward what we want in a valve cover. The oil splash hits the acme and sides of the valve cover and rains back down on the rockers rather than sticking and burning to the valve cover. It as well makes make clean-up a breeze when it is time to replace the valve cover gaskets.

PHOTO Ix — VALVE SEAL REPLACEMENT COMPLETED: January 2012

There you accept it, the engine all buttoned up and fix to run once more without oil fouling the spark plugs.

Should you exist interested in the theory behind valve stem seals, click here, to read my technical commodity.

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_{© 2011 John Harlowe. Permission for reproduction granted for non-commercial public use. All other rights reserved.}

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