Coolant disapearing and random start problems

I have been back to college since August and my 2000 Grand Marquis is still my ride of choice, hopefully for a long time to come. Anyway, I've been experiencing a few issues I was hoping someone can steer me in the right direction.

1. The coolant reservoir used to be filled right up to the top of the cold fill line. It remained there most of summer until about early August, when it started to dwindle down. It is now at the bottom of the cold fill line. At first I thought it was because of temperature as we go into winter, but even on the hot days we've had a few times it's the same. I've looked for fluid in the ground and saw nothing yet. I have yet to see any traces of it in the oil, and there doesn't seem to be any leaking around the intake manifold (it's the original manifold). So could this stuff be burning without my knowledge? I haven't seen any unusual smoke coming out of the tailpipe.

2. Once in a while I will start my car and it turns over just fine as usual and actually get the high rev when the engine actually starts, but immediately after the car goes to such a low RPM I think it dies. Once it did die, but most times it just comes to nearly a stop, and then revs back up to normal RPMs. It happens most often when cold, however it has happened when at operating temperatures.

3. Another odd thing I've been experiencing when starting the car is once in a while there is a high pitched noise coming from the engine for up to a minute, whether I'm in gear or not, and remains relatively constant despite RPMs. At first I thought it was the belt, but that doesn't seem to be it. I had a PCV valve other than a Motocraft one and thought maybe that was the culprit after a friend mentioned that happened to him before. I changed it over the weekend and haven't experienced it again yet. Has anybody else experienced something like that?

4. I can sometimes here a slight hissing sound from the passenger side of the engine compartment. I am unable to determine exactly where it's coming from, it's easier to hear in the passenger cabin than under the hood. I just started noticing this after my last oil change about 500 miles ago. I was wondering if this sounds like a vaccuum hose leak. If so, I guess I'll have to follow all of the lines unless there's an easier way to diagnose a loss of vaccuum?

Thanks for your help!

Well regardless of the new Motocraft PCV valve, it still makes that noise periodically. Infact, yesterday it made that noise after driving the car to class, and putting it into park. It did that twice yesterday when I put it into park. Any ideas?

Hey "Blue"

1) Could be coolant "weeping" around a hose and burning off on the motor. If they are original or old radiator hoses you may wish to change them.

2) Idle problems COULD be the Idle Control Motor. It has a connector to it and two bolts off the throttle body. It is usually NOT easy to get to but an easy replacement when you do.

3) I believe there is a TSB on that "high pitched sound". Look it up or call a dealer's Service Dept.

4). The "hiss" could be vacuum related or the "pipe" that connects the EGR to the Intake. They develop cracks and give off a noise!

Hope this all helps!! I had a "Mint" '93 until some moron "T-boned" it!!! MB

This all assumes you have the vehicle properly "tuned up". Start there first.....MB

Hi Bob,

thanks for the input. I do keep the vehicle pretty tuned. I just started noticing the occasional hissing and this other noise after my last oil change which I did myself 1,000 miles ago. There was nothing unusual about it, and the oil seems to be flowing and lubricating properly. All of the hoses are the original hoses, but seem to be in pretty good condition. No weak or worn spots.

And today I got that sound when I took the car out of park and into drive while heading to my morning class. But later today I took it for a half hour drive for lunch and back and hadn't had a hiccup out of it. Just perplexes me that it happens when the transmission shifts to or from park and it occasionally does that, yet the sound is from the engine compartment.

I dont know if you have an auto brake switch which automaticly knocks off the emergency brake but I had one on my 88 crown vic and never knew it untill I also had a hiss and a miss when going from park to drive,Like I said I dont know if you have one but its worth a look see,good luck.

Missing fluid could be a leak in your head gasket, check your oil for discoloration or a leak in the heater core, check your carpet on the passenger side to see if its wet, Both are major repair problems.

Just a thought on your coolant leak........see class action law suit on cracked manifolds.

http://fordmanifoldsettlement.com/index.html

I am aware of the problem with the original intake manifolds on my year/model, and it's a concern of mine. However, I looked at it and haven't seen any indication of a leak around it. I checked for any discoloration in both the coolant and the oil and both are clean. I just did a full oil change a 1,000 miles ago and all the oil looked normal.

About a month ago I suspected the heater core being a problem too when I turned on the heater for the first time since last winter. But to date there's still no wetness on the pasenger side floor.

Mind you, I don't know if it's normal or not for coolant to dissipate over time. It has been slow but noticable. I haven't had to add any yet.

@auto trainy, it's not at all like the sound from the parking brake release. Infact, a parking brake component on the cable was bent a while back ago and was disabled when I took it into the dealer so the peddle won't even move.

Since my last post it hasn't happened again yet. I suspect it will, but I can't seem to make any sense of the odd loud noise yet. It's not a quick pop, it actually lasts for about a minute at a time.

Look at the back of the intake on the passenger side and check where the heater hose attaches to the intake. It cracks where the metal is attached to the plastic. We have had a lot of these crack there also. Look under the intake to be sure the heater hose under there is not leaking too.

The noise you hear on startup may be the air tube that runs from the air inlet tube to the throttle body. Is the noise like a hooting noise? If so, there is a replacement for that tube that has a "muffler" on it.

The low rpm could be a faulty IAC valve. This also may cause the noise you are hearing on startup.

When does the hissing occur? If it is on shutdown, it is the a/c belleing off which is normal. If it is during movement, look for a place for air intrusion to the vehicle. Good luck.

i am having very similar problems with my 2000 marquis too... but i figured out it was the intake manifold

2000mgm, what were the symptoms? Did you end up replacing the intake manifold?

So over Thanksgiving break I had a chance to crack open the hood at home and try to find the culprit. I changed the PCV valve with a Motorcraft one and now the vaccuum seems fine, so I think that problem is avoided. But the loud sound when starting/shifting cold still occurs.

I was pulling out of my garage the other day after topping off coolant in my car (cold). When I shifted into reverse, the loud noise started. I put it back in park, ran around to the front and opened the hood. After looking everything over, it's coming from right around the s-belt or fan. I don't see how it could be the belt unless an accessory is failing intermittantly. And the fan was not moving, as I suppose it shouldn't since the coolant was no more than 50F at the time.

Anything in that area that could make a loud continuous noise? Oh, and it does fluctuate a little bit with engine RPM which makes me lean towards an accessory going bad, but after I rev the engine to 1500RPM or so and back to idle, it starts to lessen in vloume and then fades away after about 30 seconds.

Check the idler pulley or the pulley on the tensioner.

In case anyone cares, I have some news on the loud noise issue.

Yesterday (while snowing and miserably cold) I determined the noise was from the air box. Thinking maybe it was a cracked airbox I removed the top half from the bottom half to expose the filter. No cracks or any indication of any problems. With the engine running, the noise is extremely loud from the air intake tube. I removed the little tube from the air intake tube that goes to the IAC. The noise became even louder from that air hose when removed and engine is idling.

After determining the noise was from the IAC, I removed the IAC and cleaned it with carb cleaner. After a good clean and reattaching the IAC, the noise has not returned yet.

Also, I have a brand new idler pulley put on about 2,000 miles ago since the original one siezed. A new belt was put on as well.

All of us are interested in what fixes a problem. You had disappeared and the thread had gone dead. Thanks for the update.