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Speedometer Issues

By: Toby Peterson

The speedometer drive system that was designed for the DeLorean is very simple and straightforward. However, the system's simplicity also means that the failure of any of its few components will cause the entire system to become partially or totally nonfunctional. The system is composed of the following primary elements:

Bouncing Speedometer

If you notice that the needle on the speedometer is starting to bounce at low speeds, the culprit is usually damage or contamination in the lower speedometer cable. The best way to approach this is to start by unscrewing the lower end of the cable from the right angle drive. You may find out that water has accumulated in the cable, leading to rust and the build-up of debris. Drain any water out. Then, unscrew the upper end of the cable from the Lambda counter, and pull the inner drive cable out of the outer sheath from the upper end. Inspect the inner cable to make sure that it is free of damage. Wipe the inner drive cable off with a shop rag soaked in brake cleaner or other solvent, and then coat the inner cable with light grease. Place a suitable container under the lower end of the cable that was attached to the right angle drive, and then spray brake cleaner or solvent down the outer sheath to flush out any debris. Insert the inner cable back into the outer sheath, and reattach the ends to the right angle drive and lambda counter. Make sure that the ends of the inner cable properly engage the square drives at each end. Speedometer bounce can also be caused by a failing right angle drive or a loose dust shield, but these factors are less likely.

Failed Speedometer

If the speedometer has completely failed, it is important to identify which element(s) in the system is at fault. One possible step-by-step procedure for identifying the failed component is as follows:

• Jack up front of the car and remove the left front wheel.
• Unscrew the lower end of the lower speedometer cable from the right angle drive.
• Obtain a reversible drill, and grip the exposed end of the inner cable in the drill's chuck. Be careful to avoid damaging the end of the inner cable. Spin the drill in the reverse (counter clockwise) direction, and have a helper observe the speedometer. If the speedometer is registering a steady speed with the drill operating, this proves that everything "downstream" from the lower cable is working. This would suggest that the fault is in either the dust shield or right angle drive. If the speedometer does not register using the drill in reverse, then the fault is likely in the other end of the lower cable or with one of the other components "down stream". You can work your way along the system, testing each element in turn until the faulty part is found.
• Observe whether the dust shield fits tightly in the front hub. If the shield is very loose, then it should be replaced. Examine the small square drive that is molded into the shield. If the hole is rounded out, replace the shield.
• Spin the exposed end of the right angle drive input shaft. The shaft should spin smoothly with a slight resistance. Observe the square drive end that the lower cable attaches to, making sure that the square drive spins when the shaft is rotated either direction. If the input shaft is seized, damaged, or is very difficult to spin, the right angle drive should be replaced. This task requires a degree of mechanical skill, knowledge, and the correct tools. Refer to the DeLorean Shop Manual for details on right angle drive replacement.

Replacement components for the DeLorean speedometer system are readily available from DeLorean Motor Company - Northwest or from your favorite DeLorean vendor.

DOT - 4 Fluid Spills - Brake and clutch fluid

When filling up the DeLorean brake master cylinder or clutch master cylinder reservoirs, it is very important that fluid spills be avoided. Use an appropriate funnel to make sure that no fluid spills onto the frame below. Make sure that the reservoirs are not overfilled, which leads to fluid spillage as well. DOT-4 brake fluid will damage the epoxy coating on the frame, leading to corrosion and damage to the frame. The best way to avoid the expense of frame repairs is to take care of spills immediately, or (better yet) take great care to avoid them altogether.

If brake fluid is spilled, wipe it up as much as possible with shop rags. After that, flood the area with spray brake cleaner. This chemical combines with the brake fluid to help disperse it. After this, flood the area with water to flush everything out. If this is all done as quickly as possible after a spill, you can avoid the type of damage shown in the photos.

Electrical Bulkhead Connectors - Where and How

There are a number of different electrical circuits that are connected in the area under that coil cover on the right hand side of the engine compartment. Many of these connections are critically important for the function of various systems in your DeLorean. After 25 + years in service, these connectors should be inspected and thoroughly cleaned for optimum performance and reliability.

• Remove the coil cover, being careful to avoid cracking or damaging it while extracting it from the forward right hand corner of the engine bay.
• Remove the bulkhead connectors one at a time to avoid mixing them up.
• Gently tug on each wire going into the connector to make sure that all the pins are securely seated. These pins can sometimes work themselves loose and "back out" of the connector when it is plugged back in. If the retention barb on a pin is broken off, the pin should be replaced. You can obtain replacements from DMC - Northwest or your favorite vendor who stocks these difficult-to-find pins.
• Spray the pins generously with electrical contact cleaner, and then scrub each pin with a stiff toothbrush or small wire brush. Flush with contact cleaner again.
• Turning to the female halves of the connector anchored into the backing plate, gently poke each socket with a small screwdriver or similar tool to ensure that it has a secure seat.
• Clean these connectors with the contact cleaner and brush in a similar fashion to what you did with the male half of the connector. If any of the sockets appear stretched out and loose fitting on the pin, you can "tighten" the sockets slightly be prying on the sides of the sockets with a small screwdriver. Don't get too carried away with this, or you will have a hard time reinserting the connectors.
• If everything looks okay, plug the connector back in and move to the next connector and repeat the process.

Performing this bit of maintenance can improve the performance of many of the electrical devices and lights that are served by these connectors. This method of cleaning electrical connectors can also be extended to all connectors in the DeLorean electrical system.

Note on Self - Bleeder Systems

The cooling system self-bleeder system, which was first introduced to the PNDC around 1994, has been widely accepted as the best method for removing trapped air in the DeLorean cooling system. In fact, this system has been shown to be so effective that it can mask the symptoms of potentially serious mechanical issues that might be developing in a DeLorean engine. For instance, if a head gasket starts to fail in certain ways, it will leak air into the cooling system. When this air is noted by the owner or mechanic, steps can be taken to replace the head gaskets before the condition gets worse. However, with the self bleeder installed, this air might be eliminated from the cooling system before it can be found by the mechanic. In response to this possibility, DeLorean Parts Northwest has introduced an exclusive shut-off valve which can be used to deactivate the self-bleeder system temporarily in order to perform diagnostic tests on the cooling system. This valve is included in all new systems sold by DPNW and DMC - Northwest, and is available for purchase to owners who already have a system installed. If you are concerned about this issue, contact Toby Peterson for further information.