Valve Guide Seal Replacement
Background:
The rubber and teflon seals on top of the valve guides become petrified over the years and should be replaced on any old engine. I had noticed the amount of oil on the spark plug electrodes along with the tell-tale blue exhaust for years. The final straw that pushed me into action was our failure at the Aircare testing station in summer 2010. Bluebell was pushing out so much smoke that the testing station manager came out and evicted us from the 'idling line'.
How to do it
This is not a difficult job but it is awkward, particularly for an older gentleman who is not as physically supple as a youth. I got the #1811 seals from the Silver Seal company. In the box of 16 seals (obviously designed for a V8) there were two types - 6 of the older, US made BSF ones that are very accurately made and 10 more crudely made seals that I suspect are sourced from overseas. The lady at the company assured me that they had had no complaints about the new seals, but she added that nothing is as well made as it used to be. My confidence in the set of seals was destroyed, but decided to use them as delivered. I installed the US made seals on the back 3 cylinders which are the most difficult to deal with... |
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Tools required:
Clockwise from 12 O'clock: spark plug socket; Needlenose pliers; valve spring compressor (K&N brand); box of 1811 valve stem seals; a good bottled reward; magnet on telescopic probe; hammer & punch; pliers to pull old seals off; LED light; 12 feet of braided 1/4" rope; cloth and old bed sheet to cover the entire engine.
Not shown is the 'feeler gauge' necessary to set the valve rocker clearance, sometimes known as 'lash'. |
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To take off the Valve Cover on the Tornado 230 OHC engine requires removal of the wiper vacuum motor, plug wires and some gentle manipulation of the cover until you can extricate said casting. The casting is not very strongly made and should be treated with respect.
Install as much rope as possible down the spark plug hole using needle nose pliers. Make sure the piston is at the bottom of the cylinder before the compression stroke. Once you have pushed about 8 feet of rope in, turn the engine using the fan until it obviously won't go any further. You should have rope-filled the combustion chamber so that the valves can not open at all or very much.
Note: Use braided 1/4" or 5/16" nylon rope not the regular yellow twisted 1/4" polypropylene cheapest cord. The braided style compacts more readily. |
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Using the valve spring tool, compress the first valve spring. I started with the most accessible springs on cylinder No 2 since I had never done this procedure before. Make sure the 'grabbing ends' of the tool grip as low down on the spring as possible - this is not straight forward since the contour of the cylinder head at the spring base may not allow the best position. I was relieved that there were no double springs which would have made compression by the tool problematic.
With the spring compressed, gently tap the collet at the top of the spring with a hammer and punch until the collet lets go of the valve stem top and the "keepers" are loosened. Wobble things around a bit until you can free one of the paired "keepers" and draw it out with a magnet. Don't drop the little buggers (make sure that the carb throat is covered with a cloth!) |
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Completing the procedure on the back few cylinders is less pleasant - especially for the older mechanic. Here you can see that covering the entire engine with an old bed sheet so you can prop yourself up on one arm or a belly, might save your back. An 18 year old son, still living at home, would come in very handy at this time...
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Once the old valve stem seal has been levered off using pliers, the trickiest part of the job begins.
The new seal with its teflon ring is a tight fit on the valve stem. The seal will get hung up on the sharp machined recesses for the keepers. If you wiggle the seal and force it over the sharp edges, they will be damaged. A plastic condom-like sleeve that fits over the valve stem allows the seal to ride down safely without damage. Of course, everything needs to be oiled and positioned correctly for the job.
Once the seal is below the danger point on the valve stems, you work the plastic sleeve out and push the seal home over the protruding valve guide. You have to use both thumb nails to push the seal down in one smooth motion. The plastic sleeve gets a bit distorted in the process and will probably last for one set of installations at best.
It was annoying to realize that the set of seals I bought did not have this critical plastic installation sleeve included (I happened to have one from another job). |
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Here is another view of the new valve stem seal with the little plastic 'pecker' ready for installation. |
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With all 12 seals installed, check your work carefully. I discovered that one spring was not properly seated against the head and one set of "keepers" did not seat properly either.
Set the intake and exhaust valve rocker clearances to 8 thous. The cleaned valve cover (wipe down both mating surfaces) should be carefully refitted and checked for inevitable leakage.
Success! There was no more blue smoke from the exhaust pipe and we were allowed into the Aircare testing station. But did we pass? |
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Modest Costs:
- Valve stem seals (#1811 from Silver Seal Co.) $27.15
- K&M Spring Compressor tool $25
- Rewards: 3 X 500ml beer (Baron from Czech Republic) $7.50
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