1990 Mercury Grand Marquis n00b questions

[lizzza]

Last year we bought our car for $1K from a family friend. It was in so-so condition. I've never worked on a car before but I'm wanting to get it into a much better condition than we received it.

Over the past four months, my oil light has been flickering when the car is in idle. Today, I learned how to change the oil and replace the oil sensor. Doctor Google lead me to wonder if it was the oil pressure sending unit, but I cannot find where this is at all Anyone experience a flickering oil light while idling?

We discovered where I was leaking antifreeze and refilled those fluids, apparently my head gaskets need replaced. Then, when going for a test drive the heater control valve blew for the second time in six months. These are all fairly basic repair needs.

Another issue has been my A/C and heating. The A/C is fully charged, but when we try to use it the only thing that comes out is super heated air. Sometimes it seems to flip the heater on, which during the heat of summer was miserable to say the least. Any ideas?

[HiFiMerc]

Oil light flicker is not unheard of on those motors. It means you have about 6 or so pounds of oil pressure. They have been known to run for a long time in that condition. Does it go off when you give it some gas?

[lizzza]

Oil light flicker is not unheard of on those motors. It means you have about 6 or so pounds of oil pressure. They have been known to run for a long time in that condition. Does it go off when you give it some gas?

Yes, when I give it gas or switch it into neutral or park, the light will go off. Although if I flip to neutral or park, it will often times die on me altogether.

[HiFiMerc]

Sounds like it's a bit tired. I wonder if the stalling could be a sticking IAC. Perhaps it's sticking and slamming shut, stalling the engine.

I've had a similar issue, but it was opposite of yours. It would run fine in park or neutral, but when you put it in gear it would die.

[P72Crazy]

Have you done a self-test on it? You should be able to run a diagnostic test on it with a STAR tester or analog volt meter and jumper wire. Anyone know if the Hayne's manual or Chilton's details this test?

[lizzza]

I made the 40 mile drive home last night with no oil light. So that is promising.

[87gtVIC]

The sensor for the oil idiot light is next to the oil filter. You have no sending units.

[sxcpotatoes]

When the oil light comes on solid, you're done, the motor is toast. BUT here's what you can do, put in some "Engine Honey" thick goop to thicken up the oil this time. Next time you change the oil, go with 20w50 racing oil (it's not marked racing oil, but the 20w50 will keep the pressure up somehow). Might have to let it warm up on colder/freezing days, but I had an '88 Country Squire that started the flickering light of doom & I nursed it along for awhile until the exhaust fell off piece by piece completely disintegrating.

The thicker oil will keep you from having to replace the engine, perhaps for decades, as long as there aren't other problems. But with the head gasket, and the time you're going to have to put into that job, I wonder if it wouldn't be more cost-effective to buy a junkyard motor and just swap it in (or have it swapped).

[sly]

if you're currently using a 5w-something oil... switch to 10w30... if using 10w30, go to 10w40... if 10w40... 20w50. once 20w50 doesn't cut it, you'll be soon to replace that engine.