A backwards t-stat could do the same thing. I don't know your mechanical aptitude so it's just a thought.
Can't get Mustang to quit venting coolant!
- Thread starter j_mac
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I'm thinking head gasket, exhaust into coolant jacket leak. Sorry. My dodge 2.5 did this and I got some time out of it before I felt like fixing it. You may not be able to see this on a compression test.
The exhaust is causing air bubbles that disable your heater core until they work loose.
The exhaust is causing air bubbles that disable your heater core until they work loose.
Also, the newly filled system has to stabilize and purge itself of air. Keep the reservoir 1/2 filled cold until it settles down.
it may be all right.
But as you fear and surmise, it may be a bad head gasket or cracked head.
it may be all right.
But as you fear and surmise, it may be a bad head gasket or cracked head.
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There is a test available to check for exhaust your coolant. I'd pick one up and give it a shot.
Originally Posted By: mechtech2
Also, the newly filled system has to stabilize and purge itself of air. Keep the reservoir 1/2 filled cold until it settles down.
it may be all right.
But as you fear and surmise, it may be a bad head gasket or cracked head.
True on the stabilizing thing, but in my experience, the 4.6 is really easy to bleed. Fill it up, start it, add some more and you're done...
I say "Stick a fork in it"... It's done.
Also, the newly filled system has to stabilize and purge itself of air. Keep the reservoir 1/2 filled cold until it settles down.
it may be all right.
But as you fear and surmise, it may be a bad head gasket or cracked head.
True on the stabilizing thing, but in my experience, the 4.6 is really easy to bleed. Fill it up, start it, add some more and you're done...
I say "Stick a fork in it"... It's done.
Thanks for the advice guys. Keep the ideas coming! I'm just wanting to rule out all possibilities before I tear into the engine to do the head gaskets.
I'm fearing a cracked head or something as Mechtech2 suggested. How would I know. How would I check?
If this car was one of the old pushrod Mustangs I would have already put new head gaskets on it as a matter of course. But the SOHC thing is kinda making me sick to my stomach. I got rather proficient at doing head gaskets on the old 5.0L cars as me and my buddies used to supercharge them to 500-600 horsepower and the [censored] stock gaskets and head bolts just didn't like it when they were subjected to more cylinder pressure than a NASCAR engine. I'd say I'm an expert doing those. Probably installed 50 sets for one reason or another over the years. But this 4.6 [censored] isn't turning me on.
Any ideas and advice is really appreciated! Thanks guys.
I'm fearing a cracked head or something as Mechtech2 suggested. How would I know. How would I check?
If this car was one of the old pushrod Mustangs I would have already put new head gaskets on it as a matter of course. But the SOHC thing is kinda making me sick to my stomach. I got rather proficient at doing head gaskets on the old 5.0L cars as me and my buddies used to supercharge them to 500-600 horsepower and the [censored] stock gaskets and head bolts just didn't like it when they were subjected to more cylinder pressure than a NASCAR engine. I'd say I'm an expert doing those. Probably installed 50 sets for one reason or another over the years. But this 4.6 [censored] isn't turning me on.
Any ideas and advice is really appreciated! Thanks guys.
I believe you can place the car in diagnostic mode to read the Coolant Temp more accurately.
http://www.ehow.com/how_5309405_activate-1999-2004-ford-mustang.html
http://www.ehow.com/how_5309405_activate-1999-2004-ford-mustang.html
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I had a slow evaporation issue and a simple rad cap replacement fixed mine. Just a thought. I didn't do that until almost a year of head scratching.
Eric,
The cam holding fixtures for the 4.6's. Are these absolutely necessary or could it be done another way like 2 people (one on each cam holding it still while the chains are put on by a 3rd person.
Or is it that the valves may hit the pistons when the heads are bolted down without the cam holding tool?
The cam holding fixtures for the 4.6's. Are these absolutely necessary or could it be done another way like 2 people (one on each cam holding it still while the chains are put on by a 3rd person.
Or is it that the valves may hit the pistons when the heads are bolted down without the cam holding tool?
I have yet to see a 4.6 SOHC with blown headgaskets unless you did something very stupid with the motor like overheated it.
Even overheating it, it will run in limp home mode and "shut down cylinders" so to speak to protect the engine.
Did you replace the cap? I have had a dozen 4.6L engines, and had one 96 thunderbird that had a bad coolant cap. Mine didn't leak, but wouldn't hold pressure.
They should hiss a little bit when you pull it off when hot, but I haven't seen one leak..
Even overheating it, it will run in limp home mode and "shut down cylinders" so to speak to protect the engine.
Did you replace the cap? I have had a dozen 4.6L engines, and had one 96 thunderbird that had a bad coolant cap. Mine didn't leak, but wouldn't hold pressure.
They should hiss a little bit when you pull it off when hot, but I haven't seen one leak..
Originally Posted By: JustinH
I have yet to see a 4.6 SOHC with blown headgaskets unless you did something very stupid with the motor like overheated it.
Even overheating it, it will run in limp home mode and "shut down cylinders" so to speak to protect the engine.
Did you replace the cap? I have had a dozen 4.6L engines, and had one 96 thunderbird that had a bad coolant cap. Mine didn't leak, but wouldn't hold pressure.
They should hiss a little bit when you pull it off when hot, but I haven't seen one leak..
Ditto on 4.6 head gaskets. I too suspect a failed gasket or cracked head at this point.... I think the best thing to do now is to get a chemical type sniffer tester and take a sample from the overflow/degas bottle-any positive sign of CO and you know you're looking at a top end teardown. With the coolant blowing out, it's probably impossible to see any oil in the system, but any coolant in the oil?
I have yet to see a 4.6 SOHC with blown headgaskets unless you did something very stupid with the motor like overheated it.
Even overheating it, it will run in limp home mode and "shut down cylinders" so to speak to protect the engine.
Did you replace the cap? I have had a dozen 4.6L engines, and had one 96 thunderbird that had a bad coolant cap. Mine didn't leak, but wouldn't hold pressure.
They should hiss a little bit when you pull it off when hot, but I haven't seen one leak..
Ditto on 4.6 head gaskets. I too suspect a failed gasket or cracked head at this point.... I think the best thing to do now is to get a chemical type sniffer tester and take a sample from the overflow/degas bottle-any positive sign of CO and you know you're looking at a top end teardown. With the coolant blowing out, it's probably impossible to see any oil in the system, but any coolant in the oil?
Haven't seen any oil in the coolant, nor any coolant in the oil.
I was about ready to invest in a tester. The one that goes in the pressure cap's hole and uses a fluid that changes colors if the gasket is bad. So do they work by detecting carbon monoxide in the cooling system? Another question I've had is that this problem seems to come and go. What if the head gasket is maintaining its seal when the test is done? Can the tester still detect a bad gasket from residual CO?
Its like sometimes the head gasket is sealing and sometimes it leaks.
And yes I've replaced the pressure cap and the thermostat with a new one.
I was about ready to invest in a tester. The one that goes in the pressure cap's hole and uses a fluid that changes colors if the gasket is bad. So do they work by detecting carbon monoxide in the cooling system? Another question I've had is that this problem seems to come and go. What if the head gasket is maintaining its seal when the test is done? Can the tester still detect a bad gasket from residual CO?
Its like sometimes the head gasket is sealing and sometimes it leaks.
And yes I've replaced the pressure cap and the thermostat with a new one.
Originally Posted By: j_mac
Eric,
The cam holding fixtures for the 4.6's. Are these absolutely necessary or could it be done another way like 2 people (one on each cam holding it still while the chains are put on by a 3rd person.
Or is it that the valves may hit the pistons when the heads are bolted down without the cam holding tool?
I'm pretty sure I did it my self, so if you're coordinated, you can too. You'll only do one bank at a time so no need for extra people. Sometimes the links are marked and sometimes not. If not, fold the chain in half and mark the end two. If you were looking at it straight on, there will be two rows of links. All parallel, except for the end two, which will be standing up. Those are the two you mark.
Personally I say if you've done engine work before and are a gear head, you can do this too.
Eric,
The cam holding fixtures for the 4.6's. Are these absolutely necessary or could it be done another way like 2 people (one on each cam holding it still while the chains are put on by a 3rd person.
Or is it that the valves may hit the pistons when the heads are bolted down without the cam holding tool?
I'm pretty sure I did it my self, so if you're coordinated, you can too. You'll only do one bank at a time so no need for extra people. Sometimes the links are marked and sometimes not. If not, fold the chain in half and mark the end two. If you were looking at it straight on, there will be two rows of links. All parallel, except for the end two, which will be standing up. Those are the two you mark.
Personally I say if you've done engine work before and are a gear head, you can do this too.
Thanks again Eric,
The only thing I'm worried about is without the cam holding tool in place is it possible that as you tighten the head bolts you may have piston to valve interference, possibly bending a valve.
An alternative would be to remove the cam followers and reinstall after the head and chain install.
Anyone else know?
The only thing I'm worried about is without the cam holding tool in place is it possible that as you tighten the head bolts you may have piston to valve interference, possibly bending a valve.
An alternative would be to remove the cam followers and reinstall after the head and chain install.
Anyone else know?
Wait a minute...
What was I thinking? I'll just do it the way I've always done OHC engines. Put lots of marks (with a paint marker) on everything including chains, sprockets, heads, block etc. And then when reassembling, just make sure ALL marks line back up! No need for a manual or any tedious alignment [censored].
What was I thinking? I'll just do it the way I've always done OHC engines. Put lots of marks (with a paint marker) on everything including chains, sprockets, heads, block etc. And then when reassembling, just make sure ALL marks line back up! No need for a manual or any tedious alignment [censored].
Is the radiator in good shape? I had a 89 5th Avenue that puked coolant...It turned out to be the radiator...Just something to check before you tear into it...Radiators get plugged and brittle over time...
heres a long shot. air lock. fix: drill 1/8 hole in stat. thats the short story. a real long shot
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