2000 GT Losing Coolant

Alright, here's the deal.

In mid winter the low coolant light came on. No big deal, I added coolant. Problem solved.

A month or so later...low coolant light came on. No big deal, added coolant.
Problem solved.

A week later...low coolant light comes back on, figure something is wrong, so I add coolant and park car in garage on white sheet for long time. Nothing ever shows up on sheet, coolant level fine.

Been driving car and it's been several 100 miles from home, wife drives it to work everyday, no coolant problems, temp at 190 or so constantly. Sunday, wife drives car 5 miles, comes back, temp is about 210. Check coolant...empty, I refilled coolant, drove car about 30 miles...car got up to temp...no heat, then started to overheat.

Figure thermostat went bad, (and it was) removed it (just cut the thermostat part out, left the ring and seal) last night since Autozone was closed when I got home, planned on replacing this weekend, since she has to have her car this week (and I just LOVE working on this car since everything is always so easy to get a wrench on). Refilled with straight water incase of something like a cracked head.

Car wouldn't start this morning...temp sensor...I figure since it got pretty hot last night (which by the way was what was wrong with it when it wouldn't start this winter....EGR Valve my eye).

My Dad came over this morning after the chill was out of the air, he checked coolant...it was fine...car started, he drove it to my wife's work (20 miles) checked coolant...coolant fine. Said car temp was around 190 the entire way. Wife drives car home from work...coolant system damn near empty...took 2 gallons.

This thing that puzzles me is it's emptying out the coolant system but not everytime, only every once in a while but very frequently now. Car runs fine, starts fine, all kinds of power, no water in crankcase. When driven the car temp is about 210 and stays there and sometimes normal at 190. I did notice a slight white smoke or steam from one of the exhaust pipes today. But the coolant is not leaking out anywhere I can find.

Question: What do you guys think...intake gasket or cracked head?

In my mind a cracked head would overheat the car instead of it sticking at 210, I would be getting water in the crankcase and I would think performance would suffer...but I didn't think a temp sensor would prevent the car from starting either so....

Let me know what you think, I'm tired of dealing with it and I'm taking it apart this weekend and going to find out what's what under there if it's a head I have to replace the gaskets anyway so...

Oh yea...and when we bought it...the deal proclaimed "We just replaced the intake manifold gasket because they've been known to fail on this engine." This would be the same dealership who put the belt back on wrong, and couldn't figure out why it made a squeeling noise...dee-ta-dee

Check the water pump area for a leak. Also check the area around the firewall on the passenger side of the car. The water pump may be leaking and it is only putting out coolant at certain times although once they start to leak they usually continue. The other thing is the heater core. There is a drain on the passanger side of the firewall. This can put out water and you may never see the loss. Finally, check the crank case to make sure there isn't water in the oil. Just a precaution since you have gone through so much coolant the engine would be swimming by this time.

A cracked head is a possibility but you should see some sign of this, like a loss of power, white smoke from the exhaust or water leaking around the sealing surface.

One thing to check is the little elbow in front of the manifold. They can crack and put out coolant when hot. Then seal back up for short periods of time. If this dealership that replaced the manifold gaskets is as good as you say! lol Then it is possible they cracked it when they removed the intake manifold.

Wife called this morning...she drove car to work.

Remember now, it doesn't have a thermostat in it...

20 mile drive, car temp 150...checked coolant level...coolant level fine.

This is the type of thing that makes me wonder if it is really a gasket or head issue...seems to me that if either of those were the case it would lose coolant everytime.

Thanks GTP Dad, I'll look for those things tonight.

Here's an update:

Tore into it saturday morning...by the way, who ever said 5 hours for the intake manifold gaskets is full of it. 3 hours tops, including oil and filter change. Here I had set at least 6 hours aside figuring I would screw something up or forget something during reassembly. But I didn't.

ANYWAY...

Replaced upper and lower intake manifold gaskets. Was sure problem would be solved. Upon inspection of the gaskets I saw no cracks or damage. However, the dealership where I bought the car told me before I bought it that they were going to replace the intake gaskets...as a "precaution". And they did...the upper manifold gaskets...not the lower. How can I tell you may ask...well, the upper intake gasket was Fel-Pro and the lower some other gasket, black rubber instead of orange, I believe the lower to be the original intake gaskets. I am going to take that up with the dealership tomorrow morning at 8:00 am and then with the better business bureau. I'm no Mr. Goodwrench but come on, my daughter could change the upper gaskets in about 20 minutes and not even get her nails dirty.

Put car back together...same problem. 205 temp, no heat. Car should run at 195, that is the termostat I put in it.

Was dwelling on my $90 failure all night last night, got bent out of shape and decided too far to turn back now. So today I replaced the head gaskets.
10:00 am start
2:30 finished including a parts run for a damn O-Ring on the fuel rail.

(intake manifold gaskets are a lot easier the 2nd time through by the way)

The reason for my post other than the update, is the head gasket water holes were ate up, gasket was severly damaged around some of the water ports. If you are still running Dex-Cool, GET IT OUT OF YOUR ENGINE TODAY!!!! My 00' GT has 75,000 miles on it, and it's head gaskets look worse than the gaskets off of my 91' GMC Truck that had 226,000 last year when I rebuilt it. I have never seen head gaskets look like these around the water ports. Some damage I understand but not holes eaten through.

I'll post pictures tomorrow if I get home in time to take them.

Also, in addition....just about every intake bolt was just over finger tight, the middle 4 head bolts were also very loose...20 or so ft-lbs. The torque spec says 37 + an 1/4 turn...mine weren't even close.

I would also like to take a moment to thank the genius engineer who decided to put the lower powersteering pump bolt in such a place that one can barely get that bolt out with the motor mount in the way, and for requiring the removal of the motor mount in order to replace the belt. Good Job Genius...apparently common sense is not your strong suit.

So in the past 2 days, I've torn it down replaced the intake manifold gaskets...put it back together, and torn it back down...replaced the head gaskets and put it back together again....and guess what...same problem!!!!!!!!!

So tomorrow...I'm putting in a new water pump and if that doesn't fix it, I'm trading it in. There is nothing left that could be causing the problem. I don't think my water pump is bad, I had it out, I looked at it, bearing is tight, weep hole not weeping, it turns, but for some reason, I don't think I am getting enough flow out of it. I don't know what it's suppose to flow at, but I know it's nothing like the pressure coming out of my GM 350 motor. Nothing is plugged, I've flushed and flushed and flushed and it's a clean system all the way through. The only things that are left is the water pump and the belt. The belt is tight and turns everything else, including the water pump. The system has also been bled out, I filled it that way since I'm running straight water in it until I get this problem sorted out...quick bleed advice, garden hose + heater core inlet, use hand to make fairly water tight connection, fill until water comes through, plug hose back on to connector = system air free.

Kind of an expensive weekend, but as it turns out, the head gaskets needed replacing anyway, I was getting slight white smoke in the exhaust but it's gone now, and besides, I have learned a lot this weekend, if you need to replace your intake manifold gaskets or head gaskets...I'm your guy, I can almost do it blindfolded....%@$# new fangled engines.

If you have no heat make sure to get all the air out of the system. It can be very difficult to do and that will cause it to overheat as well as give you the no heat condition. Bleeder screw located on thermostat housing.

Thanks for all the updated info.... Hope you finally track down the bug-a-boo. Please keep us undated...

Final update...then I will also post the process for anyone on this board who might have to go through it. It's not really that hard and by the 2nd or 3rd time, really quite easy.

The last we spoke, I had replaced the intake gaskets and the head gaskets and car was still losing coolant.

Found some heads at the local junkyard.
($75 for the pair...I'm a frequent customer, so I got a 50% discount, usually $150 per head)

Tore it back apart yesterday...replaced the heads.
New Head Gaskets.

Problem solved.

Spoke with a friend of mine, who is a mechanic, he said typically when these heads crack, they will crack around the exhaust valve and you won't get any water in your oil and the engine won't blow the water out the exhaust until the engine is put under load.

What really makes me mad is that when the problem first came up, I thought it was a cracked head, since if it loses coolant, there are only 3 places for it to go, either on the ground, in the crank case or out the exhaust. I was hoping someone here would tell me different, some kind of 3.4 secret...but nooooo.

So all in all:

Intake Gaskets - $85
Head Gaskets - $40 ($20 each??...like you would ever buy them seperately)
Thermostat - $7
Water Pump - $25 (just figure I would replace it too)
Junk yard heads - $75
Resurfacing of the heads - $20
Head Gaskets - $40

problem solved!