Valve Stem Seals
Page created by T Apr 27th 2011 from info provided by the Members listed in Thread 1 (under links):
- 1 Valve Stem Seals:
- 1.1 Failed Valve Stem Seals:
- 1.2 The Cause:
- 1.3 Testing Valve Stem Seals:
- 1.4 Replacing Failed Valve Stem Seals:
- 1.5 Umbrella Seals:
- 1.6 Removing The Head:
- 1.7 Using Rope To Hold the Valves In Place:
- 1.8 Step By Step Valve Stem Seal Replacement:
- 1.9 Special Tools:
- 1.10 Links:
- 1.11 Terms:
Valve Stem Seals:Holden Grey, Red, Blue, Black Sixes and Red and Blue V8's have Valve Stem Seals located inside the Retainer at the top of each Valve. They are fitted just under the Collets. Each Seal travels up and down with its Valve and as a result doesn't see any frictional Wear. They are a small round Donut shaped ring of Rubber.
They have to be fitted after the Spring and Retainer have been fitted to a Valve and before the 2 Collets are installed on that Valve Stem. This is because the Seals use the Taper in the Retainer to help them form their seal properly. You cannot fit them to the Valve Stem first or they will tear and result in Oil Burning. See the MGB video in the Link section where Buddy Craig has to remove and replace them correctly.
Smother the Stem Seal in Oil then fit the Stem Seal to the top of the Valve Stem, then use a Pen Cap with a 9mm inside diameter to push them down the Stem and into the 2nd lowest Groove on the Valve Stem. The Seal will not locate within the Retainer properly unless the space between the Retainer and the Valve Stem is even all round.
A fitment test is to make sure the Valve can be pushed down into the Retainer far enough to seat the Seal and when pulled out again frictional resistance should be felt. The Valve should pop out and pop when you push it back in. If the Valve presents no frictional resistance, the Seal is not gripping the Retainer's inner diameter hard enough. One cause may be that the Seal is too thin or that the Retainer is worn out. Inspect the inside of the Retainer and make sure the Taper is smooth and even and has no Ruts or Grooves worn in it. If it does, the Retainer will need to be replaced to make the Seal do its job properly.On Blue and Black Engines, the Retainer may also be a Rotator. Rotator style Retainers are fitted to the Exhaust Valves only. A Rotator makes its Valve rotate on opening and closing to extend the life of the Valve Seat. See this photo on this page for identifying the parts.
Failed Valve Stem Seals:
A Car that blows blue smoke immediately after a Cold Start, but doesn't blow blue smoke otherwise likely has failed Valve Stem Oil Seals. An Engine that has been unused for years is a likely candidate for failed Valve Stem Oil Seals. Really bad cases will blow blue smoke whenever the Engine is at idle, but not above 1000 RPM. Above 1000 RPM the Oil will be flung from the Retainer and not be able to drip down to where the Seal is.
The Cause:The last time the Engine was turned off some Rockers stopped in such a position that they were left holding their Valves open. Oil from the Rocker dripped onto the Valve Stem, the Retainer and the Collets. Overnight the Oil seeped under the Collets to where the Valve Stem Seal is supposed to have stopped it from proceeding. If, however, the Valve Stem Oil Seal has failed (gone hard or become cracked) it doesn't hold back the Oil anymore. The failure allows Oil to flow down the Valve Stem and the Valve Guide. It then collects on the top of the Piston and during the next Start causes a bluing of the Exhaust. A typical symptom is that the blue Smoke from the Exhaust after a cold start may look streamy like the smoke coming directly from a Cigarette rather than a cloud of featureless Smoke that would signify failed Oil Rings.
Testing Valve Stem Seals:
Use a 1 Metre length of 5/8" Heater Hose to check that the Seals are working. Remove the Rocker(s) and put Oil on top of the Retainer, then place one end of the Rubber Hose over the Valve Stem and Collets and make a good seal with the Retainer. Blow into the Hose and make sure pressure can be held. If no pressure can be held, the Stem Seal is leaking on that Valve and its Seal will have to be replaced.
Replacing Failed Valve Stem Seals:
Failed Valve Stem Seals can be replaced with the Head still attached to the Block and the Engine still in the Car by using the right Valve Spring Compressor and holding the Valves in place with Nylon Rope. Valve Stem Seals were intended to be installed and replaced in the days when the Head had to be taken off to perform this work. Now that new Tools allow the Job to be done without removing the Head, be aware that some Tools were designed with Umbrella Seals in mind and not the Stem Seals being discussed here.
The most appropriate Tools for Grey, Red, Blue and Black Engines is the Lever type Tool or the Comp Cams 5462 LS Engine Valve Spring Compressor type device at the bottom of this page. These 2 Tools provide adequate acccess to the Stem and Retainer to fit each Seal properly.
An Umbrella Seal is fitted under its Valve Spring. It's found on Engines made later than Grey, Red, Blue or Black Engines. A Mushroom Seal makes frictional contact with its Valve Stem and wipes the Valve Stem each time the Valve opens. When the Valve is shut, Oil streams over the Valve Stem to lubricate it. These are easier to replace since there is no precision effort involved in locating the Seal.
Removing The Head:
You could also remove the Head(s) to do the same job using a traditional Lever type Valve Spring Compressor but that is a much more time consuming and expensive a job.
Using Rope To Hold the Valves In Place:
By ben simpson 29/09/10@22:19
forget the compressed air.
as the piston is about halfway down the bore, thread in some rope (i like new nylon stuff) til you cant get any more in. then slowly by hand rotate toward TDC til it locks up. you will now be able to compress the spring easily, especially a stock spring.
i can do this on race heads with stiff springs 130# seat pressure using only basic hand tools to lever the retainers off. so should be quite easy with low pressure stock springs and no time limit to be ready for the next race, ha ha...
one tip - GENTLY with a hammer and socket, tap the retainer to break the seal between the collets and the retainer. be sure the rope is in so if you go too hard, the valve doesnt fall down the bore. (you can actually remove the collets this way but i do not recommend it - its butch!)
End of submission by Ben Simpson
Step By Step Valve Stem Seal Replacement:
I tried Ben's Rope method and it works. This method is for Non-Adjustable Valve Gear (173, 202, 2850, 3.3 Sixes; 253 and 308 V8's). Adjustable Valve Gear will need the use of the Lever Type Valve Spring Compressor (149, 179, 161, and 186 Engines) because the Rocker Stud is used as a Pivot by the Lever.
1: After removing the Rocker Cover, I removed all the Spark Plugs (which made the Crankshaft easier to rotate) and used the Firing order 153624 as a work sequence since minimum Crankshaft Rotation would be needed. As Ben said, I stopped the number 1 Piston halfway up the Bore by watching the Number 1 Inlet Valve bob down and start to come up again. Coming up again meant that Number 1 Pistion was on the Compression Stroke. I then rotated the Crankshaft until the TDC mark on the Harmonic Balancer stopped at the 270 degree mark.
2: I filled number 1 Cylinder with a new length of 6mm Nylon Rope, then rotated the Crankshaft towards TDC. At about 15 degrees before TDC the Crankshaft jammed.
3: Then I removed the Rocker Arm Bolts and the Rocker Arms keeping everything together so that the Bolts, Rockers and Saddles would go back in the same place.
5:After performing the same steps on the 2nd Valve, I refit the Valve Spring Compressor and recompressed both Springs. Then came fitting a new Stem Seal to each Valve Stem and then refitting the Collets. I then removed the Valve Compressor Tool and made sure the Collets had seated properly by tapping each Retainer with a Socket and Hammer to make sure they would remain seated correctly.
Next step was to test each Seal by blowing through a Rubber Hose as mentioned under Testing Valve Stem Seals.
Then came refitting both Rocker Arms and Saddle, then torqueing the Rocker Arm Bolts evenly to 23 ft/lbs with the Piston still at 15 deg Before Top Dead Centre. This makes sure both Valves are in the closed position meaning that minimum stress would be put on the Bolts by the Springs and the Lifters. Tighten 1/2 turn for each one at a time after reaching Finger Tight to allow the Lifters time to compress. After final torque, give both the Pushrods about 10 mins to compress the Lifters then test that each Pushrod can rotate freely. If both the Pushrods don't rotate freely, investigate the cause. Try leaving a few more minutes before making another test to give the Lifters more time to compress.
I rotated the Crankshaft backwards about 30 degrees and removed the Nylon Rope from Cylinder number 1.
I proceeded to Cylinder 5 stopping the Crankshaft at 30 degrees of Crank Rotation and filled Cylinder 5 with a new length of Nylon Rope since stiff new Rope is easier to guide into the Cylinder than soft used Rope. The next step was to rotate the Crankshaft until it jammed at about 105 Degrees (15 Degrees before Number 5 TDC). 8. Continue with the rest of the Valves in the Firing Order Sequence until done.
Stem Seal fitment Tool:
A Special Tool is listed in GMH Manuals for fitting the Stem Seal and checking that it seals properly. I didn't find one available, but the Rubber Hose and Pen Cap mentioned in this page do the same job ideally and are readily available.