Mazda MX3 - cold start troubles.

"Robert Hancock" wrote

Any way to test that? Something like an excessive voltage drop in the electrical system when the car is started?

10w30, I think. I'm reluctant to switch to a lighter oil--it will mask the problem rather than solve it; I don't think it will be caused by oil alone.

Nikita.

Surely, but another possible cause that hasn't yet been mentioned is bad battery cables. If the cables are internally corroded or broken so that only some percentage of the original number of copper strands is available to carry current, the voltage drop under heavy current loads (e.g. cold cranking) will be severe. Start here. The way to check the battery cables is to put a voltmeter across first the length of the positive cable and then the length of the negative cable while cranking. If one is substantially higher than the other and/or the total of the two readings is higher than normal (post your results) your battery cables are at fault.

THe starter motor can be tested for amperage draw while cranking, but this requires a clamp (inductive) ammeter.

DS

Approximately 11/10/03 20:14, Nikita Synytskyy uttered for posterity:

The easy way is to have an auto electrical shop check the starter drain, as well as the ability of the battery to supply that drain properly. If you have 4 hands, try a voltmeter across all connections, including those at the battery, looking for voltage drops while cranking.

Oil that is too thick for the weather will usually allow the engine to crank over...perhaps more slowly than it should. If the engine fires, it will usually die quickly. Don't overlook the oil as a cause, and if you don't know what the current weight is, the oil has very likely been in the engine too long anyway. Is cheap.