Thirsty 99 GT

SOHC05 · May 26, 2009

A friend of mine just purchased a 99 GT from a buy here pay here lot. The car of course, was sold as is. After driving the car around for one day it started to overheat and spit coolant. We found the source of the leak (crack at the thermostat housing). We replaced the intake manifold with a new one that had an aluminum crossover pipe, a new thermostat, did a coolant flush and fill, and thoroughly burbed the coolant system.

The above steps stopped the coolant loss, and overheating for one day. The car is still loosing coolant. Although the coolant loss is not visable. We have not let the car overheat again as we are continually adding coolant and burbing the system. Every time the car is taken for a drive the coolant tank is drained completely. And there are no (not even one) visable leaks. The car does not smoke either. I am torn as to what the problem could be.

We have already taken the following steps to figure out the problem....

- put dye into the coolant system. No visible leaks with black light. (Other than on the broken intake, and that was replaced).
- checked oil pan for coolant. None there.
- tried to pressure test coolant system with Autozone kit. They did not have the correct cap.

Any help that you all could provide would be much appreciated! And before you say just search. I have gone over old threads on this subject for over a week now.

hobbes80 · May 26, 2009

Very strange problem indeed... what about the Heater Core? I suppose it is possible that the leak is somehow involved with it, even if you aren't running the heater.

SOHC05 · May 26, 2009

I knew I would forget some stuff... I checked the heater core. I pulled back the carpet ran the heat on full blast while driving the car, and nothing... There is also no crust or rust at the firewall where the heater core connections are.

GettinThere · May 26, 2009

I've read that it may take a week's worth of daily driving to fully burp the system. Keep adding coolant as needed and hopefully in a few days, your problem will go away.

jomull55 · May 26, 2009

GettinThere said:
I've read that it may take a week's worth of daily driving to fully burp the system. Keep adding coolant as needed and hopefully in a few days, your problem will go away.

+1

d98gt · May 26, 2009

How is the car running when you are out in it? The valley on the block isn't holding any coolant? If possible--check the back rear on the intake as leaks can also be back there.

Car sluggish at all?

squeak93 · May 26, 2009

If you have no leaks, smoke or wet plugs then you just don't have the system fully burped...... Keep adding and see if it stops. How much have you guys put in total yet?

eliteJAE · May 26, 2009

Check temps in realtime using the diagnostic system. Try to do a compression test as well, I won't say it might be cracked head gasket because it doesn't spew coolant out of the resevoir cap.....or does it???

SOHC05 · May 26, 2009

d98gt said:
How is the car running when you are out in it? The valley on the block isn't holding any coolant? If possible--check the back rear on the intake as leaks can also be back there.

Car sluggish at all?

As far as the engine feeling weak, no. She pulls pretty hard. After every drive we poor over the motor so I am fairly confident that there are no leaks by the intake.

SOHC05 · May 26, 2009

squeak93 said:
If you have no leaks, smoke or wet plugs then you just don't have the system fully burped...... Keep adding and see if it stops. How much have you guys put in total yet?

I really hope that is it. I would say we have probably put 6 to 7 gallons in, this whole time.

SOHC05 · May 26, 2009

eliteJAE said:
Check temps in realtime using the diagnostic system. Try to do a compression test as well, I won't say it might be cracked head gasket because it doesn't spew coolant out of the resevoir cap.....or does it???

It has been a while since I had my 03. How do I get the diagnostics screen to pull up again? The car did spew coolant out of the resevoir cap, but it does not now after we changed the intake manifold, thermostat, and burped the coolant system.

squeak93 · May 26, 2009

6 or 7 gallons!!!!!!! OMG... You sir have something blown. There is NO WAY the system will hold that much. LIke 3-3.5 iirc.

tag4car · May 26, 2009

SOHC05 said:
It has been a while since I had my 03. How do I get the diagnostics screen to pull up again? The car did spew coolant out of the resevoir cap, but it does not now after we changed the intake manifold, thermostat, and burped the coolant system.

press and hold trip reset while turning the key to start

jlds91389 · May 26, 2009

not to hijack this thread or anything but what exactly does all that stuff mean on the diagnostic screen? i never knew it was there so i went and pulled it up in my car i just dont know what all that stuff means. sorry if this is a newb question

GettinThere · May 26, 2009

jlds91389 said:
not to hijack this thread or anything but what exactly does all that stuff mean on the diagnostic screen? i never knew it was there so i went and pulled it up in my car i just dont know what all that stuff means. sorry if this is a newb question

Mustangworld HEC Instrument Cluster Diagnostics

jlds91389 · May 26, 2009

thanks

SOHC05 · May 27, 2009

squeak93 said:
6 or 7 gallons!!!!!!! OMG... You sir have something blown. There is NO WAY the system will hold that much. LIke 3-3.5 iirc.

There is definately something wrong. What it is, right now escapes me. This weekend we are going to pull, clean, and regap the spark plugs. And while we are at it check the cylinder heads and oil pan for coolant. However, I doubt that the head gaskets are blown. If they were with the amount of coolant we are going through the car would be smoking like a train, and there is absolutely no smoke. There is a little (and I do mean little) water vapor but that is normal, as my 05 has it.

Do you guys think that the water pump could cause coolant consumption (1 full resevoir per 10-20 miles) like this with no coolant being dump on the ground? What about the radiator? I do not think the coolant temp sensor would cause a lose of coolant. Is there a way to test the water pump and radiator? And again thanks for the help!

squeak93 · May 27, 2009

Why not put fresh plugs in? They are cheap (ngk's or autolites at least).

I can't see how your loosing that much coolant w/o A: burning in the motor itself which would cause a TON of smoke by the amount you've had to put back in or B: dumping it somewhere but I am sure a blind man would notice that. You sure the back floor boards are dry? The heater core goes and gets the passenger rear floor board all nasty.

Can you smell coolant? I had a 351 swap fox that a head cracked, it didn't leak till it stalled up and u ran it out hard. No water till then but once u made pass it was everywhere.

SOHC05 · May 28, 2009

squeak93 said:
Why not put fresh plugs in? They are cheap (ngk's or autolites at least).

I can't see how your loosing that much coolant w/o A: burning in the motor itself which would cause a TON of smoke by the amount you've had to put back in or B: dumping it somewhere but I am sure a blind man would notice that. You sure the back floor boards are dry? The heater core goes and gets the passenger rear floor board all nasty.

Can you smell coolant? I had a 351 swap fox that a head cracked, it didn't leak till it stalled up and u ran it out hard. No water till then but once u made pass it was everywhere.

The plugs that are in the car now are less than a month old. They just were never gapped. And if I am pulling them out to check for coolant anyway, I might as well clean them off and gap them. I thought the heater core was under the passanger side part of the dash? So if the heater core goes out it leaves the passanger side floor dry, but the rear floorboard is soaked? Please excuse any ignorance in the above question.

I can't explain the coolant loss either, like I said there are absolutely no leaks (no puddles, nothing in the floorboards, and no smoke). The car has to be burning/evaporating the coolant away somehow though. There is a faint coolant smell coming from the engine bay. But like I said no leaks or smoke that would lead to the source. This is so frustrating!

squeak93 · May 28, 2009

The coolant does leak on the pass side front but it runs to the back floor board.

Is there any steam or anything while the car is running? Like I said above, you may try to bring the rpms up a bit to see if its a leak that is opening up.

What kind of shape are your hoses in? My Dad has a 87 t-bird with a 3.8 in it, we chased an overheating gremlin forever. It ended up being a small hose from the waterpump to the thermostat.

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