Car Care Question - Car Won't Start on Cold Mornings

Factual Questions
1

Mrs. Rastahomie’s 1987 Ford Thunderbird won’t start in the mornings (the 7:30 AM temperature around here has been in the 40-50F range for the past week or so). It will attempt to turn over but can’t quite get there. It will, however, start just fine when we get home from work in the early evening (temperature = 70F or thereabouts).
[ul]
[li]My boss says “you need a new distributor cap and spark plug wires, and possibly new spark plugs”, as the cold weather is causing water to condense on the minute cracks in the wires.[/li]
[li]My stepdad says, "you need a new battery", as cold weather drains older/weaker batteries.[/li]
[li]One of my clients says “blah blah blah choke blah blah blah cold air is denser than warm air blah blah blah take it to a mechanic”.[/li]
[li]The guy at Auto Zone® says, “put this here magnetic warmer gizmo on either your engine block or your oil pan and you should be good to go.”[/li][/ul]

Right now I’m going the Auto Zone® guy’s route, and the warmer is attached to the engine block as we speak, in preparation for tomorrow morning.

However, as I know that there are people on the SDMB who are familiar with the ins and outs of automobile maintenance, I’d be interested to hear your thoughts as well.

TIA

2

New engine thermostat.

3

The guy at Auto Zone is trying to sell you a bandaid to your problem. 40 to 50 degrees is hardly cold enough to cause starting problems caused by cold oil. Your stepdad is very wise. Listen to him.

4

Battery. All the way. A car in good repair with a good batter should start unaided in -30 weather… even though it isn’t good for it.

Replace the battery. How old is the one you are using now? If it is newer than a couple years, it may not be a bad idea to get the charging system checked out via an AVR.

Your Boss and Client’s ideas have virtually zip to do with the cars worsened ability to “turn over” in colder weather.

Sorry, Bosada, a Thermostat doesn’t have anything to do with this unless the car isn’t heating up after it is started, or heating up too much.

5

Yah, my admittedly low-caliber level of Automotive Know-How agrees, “Get a new battery.”

Just what I’ve picked up over the years, from listening to the Better Half natter on about car stuff. :smiley: If it groans and cranks slowly on chilly mornings, it’s the battery.

6

Another vote for the battery…I’d lose the engine warmer. While it may help, it’ll really help the power company more. Trade it back in on a new battery.

Also, you might consider a tune-up and fluid change, not that it’s related to the problem, but winterizing now wouldn’t hurt.

7

If your thermostat was removed by some tinkerer ( to overcome overheating when it sticks or clogs) then you won’t be able to start in cold weather.

Adding 5W oil is the easiest way to tell if your oil is too thick ( don’t put in 20W50 in the winter).

8

Even though you’re banned, I just wanted to point out this guy is still wrong.

9

Buy the battery.

10

Bernse is right. The thermostat plays no role whatsoever in the starting process. A car will start just fine without one. It controls how much of the coolant flows through the radiator, and thereby controls the temperature of the engine. When the engine is cold, the thermostat is closed, so very little of the coolant in the engine flows through the radiator. As the engine warms up, the thermostat gradually opens and allows more coolant to flow through the radiator. This keeps the coolant temperature in the range the engine designers want it to be in.

11

I agree with everyone above assuming when you say it “almost turns over” you mean the engine cranks very slowly (or not at all) when you turn the key, as opposed to cranking at normal speed but just not starting.

If the engine is cranking at full speed in the cold, I doubt you have a battery problem, though I have no other advice.

12

Check the terminals and cables on your battery too. If they are corroded, get a stiff wire brush and clean them with some baking soda and water.

Make sure you remove the cables from the terminals and clean the insides too. You want a nice metal to metal connection. Just a little corrosion can have an adverse effect on your battery.

13

YES YES YES, that’s what I meant. It’s cranking at full speed but not starting. I should have been more clear :smack: .

14

“Turn over” = “crank”, but unfortunately the term is widely misunderstood and many people use it to mean “run”. Therefore I avoid using the term. Thanks, rastahomie, for clarifying your message.

While it’s not totally impossible that a new battery would help, it sounds very unlikely to me given that the engine seems to be cranking at full speed.

Ignition parts (cap, rotor, plug wires, plugs) are not indicated by the symptom described, unless there’s a high degree of humidity on these cool mornings. Spraying these parts with WD40 should displace any moisture and temporarily alleviate that situation, if that is the situation, which again is unlikely.

The density of cold vs. warm air is not the issue, it’s a relatively minor factor. The volatility of gasoline in a cold vs. a warm engine is probably the significant factor here, and it may well need professional evaluation to pinpoint the problem.

The oil pan warmer may help alleviate the symptom, but it won’t address the root cause.

As mentioned, the engine thermostat has absolutely nothing to do with the problem described.

Gasoline vaporizes much more readily in a warm engine than in a cool one, and cars have to accomodate this. In the days of the carburetor, this was the job of the choke. If yours happens to be carbureted, this is the first item to check.

With modern electronic fuel injection systems, there are a number of system components that can play a role here. Number one shoot-from-the-hip-and-I-haven’t-even-seen-the-car guess, a faulty coolant temperature sensor. That’s sensor, as in a key input device for the electronic control system (“computer”); not sending unit, as in what sends a signal to the temperature gauge. Other possibilities include weak fuel pump, restricted or weak injectors, faulty air temperature sensor, faulty ECU (electronic control unit, or computer), and no doubt several more that don’t spring to mind right away.

If it’s fuel injected and you want to try diagnosis by parts replacement, I’d start with a coolant temperature sensor. If that doesn’t do it, or you don’t want to do the guesswork approach, I’d recommend a competent professional.

15

A way to get it to start if it is indeed the type of problem I suspect is to spray some starting fluid (ether) down the air intake. If it starts right up with a shot of ether, that pretty much confirms that it’s a fuel system problem.

It’s not out of the question that you have summer blend gas in the tank, and temperatures that need fall blend gas. While ideally this shouldn’t keep it from starting, it could be a factor.

16

Last afterthought (I hope)–I’m assuming the engine is in a reasonable state of tune. If the spark plugs are way overdue for replacement, get a new set installed.

17

This changes things. Thanks for fishing the clarification, Gary T.

I believe it is fuel injected and as Gary mentioned there are several things it could be… albeit some more likely than others. Still, unless you’re a semi-competent back-yard grease monkey I’d now recomend you take it to a shop instead of just buying components and putting them in.

A new battery won’t do squat for you.

18

All of the above after the clarification… also might try before or after the starting fluid check is to get an extra spark plug, pull a wire and put on the spare plug, ground the plug and crank over the engine to see what kind of spark you are getting. No fire, weak fire = no go anyplace. Might help to narrow down where in all the electrons to go looking. YMMV

19

Spark plugs & battery: How old are these?

20

I’m fairly sure the '87 Ford T-Bird is fuel-injected.

Listen to GaryT, very sound advice.
But diagnosis-by-parts-replacement can get costly for the non-mechanic. I’d say go to a mechanic who has equipment that can read the engine parameters in the conditions when it has a hard time starting (i.e. Coolant temp reading, air intake temp, etc.).

The battery-thing sounded weird to me, but then again we don’t have 40-50 degree weather here. EVER. :smiley: