John Harlowe's Moonlight Engineering Automotive Fabrication and Design Company

Custom design, fabrication, restoration-modification ( restomod ), sales and service of classic era General Motors vehicles by John Harlowe's Moonlight Engineering Automotive Fabrication and Design Company. Electrical system design, diagnosis and repair. ASE Master Automotive Technician.

ENGINE VALVE SEAL STEM REPLACEMENT

This is a “ How-To ” Article illustrating Replacement Procedure and Skill Technique

Illustrative cut-a-way rendering of a positive type valve stem seal.

ENGINE: Chevrolet 350 Cubic Inch Displacement V8 Engine

VEHICLE: 1971 Chevrolet C-10 Pickup

Date of Publication: 2011-05-18



This web page has technical "how-to" information with photos regarding the procedures required to replace valve stem seals on a General Motors small block V8 with the heads still installed on the engine.


Small Block Engine Valve Seal article was written by , Re-Certified by ASE as a Master Automotive Technician for the third consecutive time in June of 2011

Certification Expires: June 30th, 2016

ASE Certification ID: ASE-1785-9774




John Harlowe for the third time was re-certified by ASE as a Master Automotive Technician on June 30th, 2011.
John Harlowe has been re-certified by ASE as a Master Automotive Technician three consecutive times. Current certification expires on June 30th, 2016. ASE ID : ASE - 1785-9774.


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 need, the independent, non-profit National Institute for Automotive Service Excellence (ASE) was established in 1972.



PLEASE NOTE: PHOTO ENLARGEMENTS and LINKS OPEN A NEW WINDOW IN YOUR BROWSER


Where to Begin?


Before attempting any type of mechanical repair one should have the factory service manual and special tools on hand.

PHOTO ONE — TOOLS NEEDED


NOTE: Before attempting any type of mechanical repair one should have the factory service manual on hand.

Oil fouled spark plugs or that dreaded blue smoke coming out of the tail pipe is definitely a sign that there is something askew 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 easy enough "on car" repair if one has an air compressor in their garage capable of maintaining at least 120 PSI, any less pressure than that, then there is a good chance the valve will drop down into the cylinder bore.


Build yourself a rocker arm / push rod cylinder order holding tool.

PHOTO TWO — ROCKER ARM HOLDING TOOL


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

Before re-installing these items a quick bath in solvent is in order.

Additionally, this would be a good time to measure and record push rod diameter and length for future reference, in this particular case the push rod diameter is 5/16 " and 7.8125 " in length.

Cylinder air hold device.

PHOTO THREE — AIR HOLD DEVICE


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

CAUTION : Make sure there are no obstructions in and around the fan belts / fan because as soon as you connect the air hose to the air hold device the pressure will force the piston down and rotate the engine approximately a quarter turn.
Now that the cylinder has air inside it, use the valve spring compressor tool to compress the valve spring. 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 need to have a socket that is slightly smaller than the diameter of the valve spring retainer at hand. Place the socket over the valve spring and tap it lightly a few times with a brass hammer before installing the valve spring compressor tool. This will help to vibrate the keepers which will make their removal just a little smoother after the spring is compressed.

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

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

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

Pull the spring compressor tool straight up to expose the valve stem. At this point you can clean the valve spring ( still compressed in the tool ) and the valve stem in the head with a little bit of solvent.

Close-up photo of valve seal location.

PHOTO FOUR — VALVE SEAL GROOVE LOCATION


As you can see in both PHOTO THREE and FOUR, 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 be left on the valve ( as illustrated in PHOTO FOUR ) and the spring installed on top of it, but it can not.

The compressed valve spring must be installed FIRST, then the valve seal installed, then the valve keepers. Once these items are installed, then you can turn the valve spring compressor counter-clockwise to extend the valve spring.

If the valve seal is installed first, when you place the valve spring assembly over the valve stem, the spring retainer will rip / cut the valve seal and all your work will amount to nothing but blue billowing smoke out of the exhaust.

Rest assured this is a very tedious operation, however, if you have the correct compression on the valve spring with the tool, you should be able to just barely see the valve seal groove from the top of the valve spring.

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

Make sure the valve seal does not turn itself inside out during the installation.

Valve seals installed.

PHOTO FIVE — VALVE SEALS INSTALLED


Now all you need to do is to repeat this process 15 more times.

Rocker arms and pushrods installed.

PHOTO SIX — REINSTALL ROCKER ARMS and PUSH RODS


Reinstall the rocker arms and push rods.

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

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

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

Install oil stoppers / deflectors on rocker arms.

PHOTO 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 whatever other items you had to remove for access.

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

NOTE: If you want to avoid steam cleaning the engine bay after this procedure, then I would suggest placing heavy duty aluminum foil over the exhaust manifolds and engine bay area as oil splash protection.

With the engine warm and running, back off the rocker arm adjusting nut until you begin hearing a distinct " clacking " sound, then turn the adjusting nut in until the " clacking " sound stops, then turn the adjusting nut in another ¾ turn.

Repeat this process for the other 15 valves.

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

Inside of valve covers coated with Glyptal.

PHOTO EIGHT — INSIDE of VALVE COVER COATED with GLYPTAL


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

PHOTO NINE — VALVE SEAL REPLACEMENT COMPLETED: JANUARY 2012


There you have it, the engine all buttoned up and ready to run once again without oil fouling the spark plugs.

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





1971 INDEX 1971 BODY / PAINT 1971 INTERIOR 1971 MECHANICAL 1971 PHOTO PAGE


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