QuestionQUESTION: I'm not getting a spark on any of my plugs on a 1979 MG Midget 1500. How do I test the coil? Using a light tester I get power on the positive side of the coil terminal but it doesn't seem to get spark from the coil to distributor.
ANSWER: Hi Lynn
I presume this Midget has a regular distributor with points, and you have not modified it by fitting electronic ignition.
I also assume that you don't have access to any sophisticated equipment such as a timing light.
The fact that you get power to the +ve terminal on the coil is good.
There are two ways of checking for a spark:
1) Disconnect the high tension cable that plugs in to the centre of the distributor cap, peel back the rubber cup, and reveal the metal terminal. With a pair of insulated pliers, grip the plastic part of the cable and hold the metal terminal about 1mm or 2mm away from one of the nuts on top of the cylinder head.
Be careful with the next bit, because if you touch the metal terminal you will get a 30,000 volt shock. It won't harm you (unless you have a pacemaker), but it will feel very nasty.
Get someone to turn the ignition on and operate the starter momentarily. You should see sparks jumping between the terminal and the nut.
2) Safer method. Unclip the distributor cap and look at the points. The engine usually stops with the points shut, but if not, put the car in 4th gear, let the handbrake off, and push the car forward a few inches at a time until the points close. Remember to put the handbrake back on and return the gearlever to neutral.
Now turn the ignition on but do not operate the starter. Get a small electrical screwdriver and push the points apart. As they open, you should see a small spark jump across the gap. If it sparks, then you have a good coil.
Let me know how you get on.
---------- FOLLOW-UP ----------
QUESTION: I have spark at the coil, plugs. Compression is fine. Battery is strong. Fuel pump is operational but I still can't start the Midget? should I plan a rebuild of the carb? It has been sitting up for a few years. If I have to rebuild the carb, how hard is it to rebuild. Do I have to rebuild the whole carb? Are there any quick fixes to do to the carb so that I can start the car? Also since the car has been sitting up the brakes are spongy? Would a bleed job solve this problem? Also the clutch pedal will not compress...any suggestions on freeing it up? Thanks, Lynn
ANSWER: Hi Lynn
If your Midget has been sitting for some years then the first thing I would do is drain the fuel tank and fill up with fresh fuel. Old fuel gets stale and becomes impossible to fire up.
I very much doubt that you need to strip the carb to fix the problems that you have described. If a Midget has a spark at the plugs and fresh fuel in the carburetter, the engine will usually fire.
Do you live in a damp part of the world? Spongy brakes often result when the brake fluid has become contaminated with water (from moisture in the air). You need to do a full bleed of the braking system. If they are still spongy afterwards, drive the car and notice if it pulls to one side. If it pulls to the left, then the left side is good and a piston is sticking on the right (or vice versa). You may need a replacement front calliper or a replacement rear brake cylinder.
The clutch is also hydraulic. It could be the clutch master cylinder has frozen, but my guess is that the piston in the clutch slave cylinder has frozen (rusted in the cylinder). Once again, this is usually due to water in the hydraulic fluid, but you need to remove the cylinder, clean it, fit a new rubber seal, then re-fit it and finally bleed the system.
Ah, the joys of owning an old sports car !
---------- FOLLOW-UP ----------
QUESTION: I thought the gas tank was empty to begin with. It sounded hollow and I just put gas in it but it only took about 3 gallons to top up so I guess it had some old fuel in it. I took the gas cap off and smelled inside the tank and it didn't smell varnished. Since it's probably 1/2 fresh and 1/2 old gas should I just siphon it all out and start with a fresh tank? Can I get all of the gas out by siphoning through the gas cap hose area? The car has been sitting in a garage for a few years so I'm sure your correct about the moisture in the master cylinder and clutch cylinders. Should I order the rebuild kits for the master cylinder, slave, and clutch cylinder? Thanks again!
AnswerI guessed right. You have 7 gallons of bad fuel mixed with 3 gallons of new. Unfortunately, the whole lot is now ruined. You need to drain the tank by syphon. Also, you need to clear the stale fuel from the carburetter float chambers, or else it won't start until you have done a LOT of churning on the starter.
As regards the hydraulics, I would take all the cylinders out and rebuild them with new kits, except the rear brake cylinders are so cheap that I would just replace them. The front callipers should be OK, but you could take a pad out and press the brake pedal to check each one in turn. I usually put a large bolster (chisel) in place of the pad so that it only comes part way out. If the piston come out clean, push it back in again. If it comes out with goo on it, clean it with denatured alcohol (meths). If it comes out rusty, best to replace the calliper unless you are confident about stripping and rebuilding brake callipers.
Enjoy
