Terminal Droop

By Kiyoshi Hamai
Chapman Report – January 1980

Hidden headlights are fashionable, Esprit, Elites, Eclat, TR7, Porsche 924, Mazda RX7, Magnums, LTD, T-birds, Porsche 914, Ferrari GTS & GTB, Ferrari Boxer, DeTomaso Mangust, De Tomaso Pantera, Corvette… to name a few. Lotus, of course, not to be out done, jumped on this band wagon early, the introduction of the Elan. But, unlike these other examples of peek-a-boo lights the Elans have a unique characteristic – when accelerating onto a freeway or climbing a large hill at night you may find your Elan headlights slowly sinking back into their wells. Needless to say this act is NOT fashionable. The cause is basically age, you know, wearing out, like everything else on your plastic fantastic. But, take heart, this unique event can be cured, with a bit of Lotus owner elbow grease.

The first sign of deterioration is usually when the headlights are slow to come up on an early Elan and the lights are popping up after being parked a short while on later Elans. An Elan headlight system in good working order should stay erect at least 5 minutes and at least 1 minute as a lower limit. Any less than 1 minute and it is time to break out the can of Lotus Owner’s Elbow Grease.

The events described above can be simply explained. The Elan headlight lowering or raising system is vacuum operated, with age and deterioration the system develops tiny leaks. Hence reconditioning requires a complete inspection of the system for leaks and/or blockages of the vacuum. We must note at this point that the early Elan systems (S1 and S2) held the lights up and later Elans (S3 on) held the lights down (a "safety" feature). The remainder of this discussion will follow the vacuum flow and discover the possible failings of each component of the system.

The vacuum is obtained at the #1 cylinder intake manifold. This can be the first failing. Pull off the hose from the tap and check the tap for crud. Clear the crud with a stiff wire (it is a good idea to have a vacuum cleaner right next to the tap as you clear it out, this will help prevent the loosened crud from going into your engine).

Next check the hose from the tap to the "T" joint at the frame reservoir. Disconnect it and check the hose for leakage and flow (I use water to do this). If clogged, clear or replace. When replacing this hose I recommend the use of hose clamps at each union.

Now the "T" joint (coupling) – This "T" coupling has within it a special "one way" valve. To inspect the coupling first remove it from the car, clean it thoroughly. Find a short piece of clean tubing and fit it onto the end which is connected to the headlamp switch on the dash. By alternately blowing and sucking on the tube you will be able to check the valve for proper operation. Next block with your finger the end which connects to the frame. Blow into the "T" and check for leaks (use the same tube). If the "T" coupling fails either of these tests replacement is necessary. Note, when checking for leaks if you are a smoker you will find this operation a bit easier by blowing smoke into the part and watching for leaking smoke. Non-smokers will either have to find a smoker to assist you or find a quiet place and liisten carefully for leaks. Another trick for non-smokers is to place the inspecting part in water and then blow into it. Leaks will be detected by tell-tale bubbles.

The next element of the headlamp system is a "biggie", the frame reservoir. The frame reservoir consists of the entire front cross member of the chassis. Close inspection will show that the reservoir is hollow and capped at each end beneath the front suspension carrying the frame upright (shock tower).

Again, check for leaks. Connect a clean hose to the inlet and blow into the reservoir. Again smokers are in luck because with a long enough tube you will be able to stand at the wheel arch and blow into the reservoir at the same time. Non-smokers can also use the long tube, but may find that soapy water will aid in locating leaks. If a leak is found, usually at the end caps at the bottom the shock tower, there are only temporary fixes. The only permanent one is to weld the hole or replace the chassis! The reason the end cap is most susceptible is because water can collect at the base of the shock tower if the drain hole has become plugged over the years. It is therefore excellent preventative maintenance to clear the drain hole at the base of the shock tower periodically.

To repair the rusted and leaking end cap the shock tower must be cut off, the old end cap ground off an a new stronger end cap welded in its place (or buy a new chassis!). This is also an excellent opportunity to enlarge the drain hole to prevent future plug ups.

The following description is highly simplified as the reconstruction requires the removal of the suspension, removal and rebuilding of the upright, shielding the body and brake parts during welding. Finally, before reassembling the whole mess, a liberal coating of epoxy primer and epoxy paint is highly recommended. Another thought is to scrap the frame reservoir and fabricate another. The osbstacle is where to put such a reservoir in the confine of an Elan.

Next a leakage inspection of the hose between the Tee coupling and the dash switch is in order. This should be done in a similar fashion to the hose between the tap and the Tee. Again liberal use of hose clamps is recommended.

Now the dash control switch must be checked. The switch is to be checked in the operational mode. This means for early Elans in the on position and late Elans in the off position. Checking for leaks is simple, block off one side and blow into the other. Again the smoke trick helps. If a leak is found replacement is the rule.

The next step is to check the hose from the switch to the vacuum cylinders. Check for blockage and leaks as you did with the previous hoses. This is also a good time to do a similar check for the hose between the two vacuum cylinders (early Elans only). When reassembling remember those hose clamps.

Finally, the vacuum cylinders are a story in themselves. It is as if the Peter Principle were in action – "If something can go wrong, it will." Let us explore the failings on one of these cylinders.

First, if your lights suddenly fail – suddenly drops, early Elan or sudden pop-up, late Elan, in all likelihood the activation rod has broken. In many instances with an early Elan one headlight will suddenly drop, and with late Elans both lights will pop-up. The usual cause for the vertical activation rod to fail (break) is rust. The remedy is replacement of the cylinder assembly. However a number of things can be done to help future failures. Paint the pull rod with rust preventive paint. Also create a splash shield out of an older inner tube. Cut a circle about 2-3 inches in diameter. Cut a slit in the center and slip over the pull rod. This will help prevent water from getting inside the cylinder. A bit of silicon sealant will help to hold the shield in place on the cylinder.

Second, the diaphragm in the cylinder will develop a leak(s). This can be checked as was done with the switch (blowing smoke). Usually a leaking diaphragm affects both headlamps in a gradual manner. Replacement is the only cure.

Lastly, the body of the vacuum cylinder may fail. This is usually in the form of rust holes. This can be repaired by grinding out the rust and fiberglassing over the hole (if small enough). Remember that this solution is only good for minor leaks, major rust will require replacement. In either case good preventative practice of either painting the entire cylinder with rust proof paint or encase the entire cylinder in resin will do wonders for eliminating future failures.