Thermagasket

[rfishing]

Just checked coolant level with engine barely warm. It took another half gallon. I Will have cap checked next. I did see some gunk around the gasket of cap, cleaned it off. Thinking this was excess Bars Leak.

[NickySantoro]

With all you have done, it's not unreasonable that there could have been enough air in the system to account for the 1/2 gal deficit when it finally 'burped". That being said, it will still require close scrutiny. I don't need to tell you that.

[rfishing]

Update:

Just had Radiator Cap pressure tested and it failed. Was lifting at 10-12 psi. Is that significant? Cap has 15 psi on it. I bought new one, pressure tested it at 16psi. then test drove car as before.

Temp stayed at 199 for 7 miles. Then I raced it up to 4500 rpms, let down speed to cruise behind cars too close by, and repeated. Temp only went up to 212. I turned off at my exit, and temp flashed 223 for a instant, then 216 and went down to just above 200 before arriving home. I opened hood, no signs of water on ground or overflow hose either.

I guess the thing to do is check water level soon as its cool to see if there is any loss.

Do you think I should drain the water, and add coolant at this point?

[Kev]

Once you are sure that you have a good solid system you need adjust the coolant to 50/50 with the GM pellets or Barsleak equivalent. Very important for the future well being of your cooling system and engine.

Good luck!

[AlBundy]

If I did'nt know anything about overheating repair or blown HGs this is one thread that has informed me. Rfishing I encourage you to continue posting, I find this very interesting. BTW the testing your mechanic feels is not necesary should be done. What do you have to lose? A big blown HG or a little blown HG, both are bad.

[mtflight]

Originally Posted by ALBUNDY

BTW the testing your mechanic feels is not necesary should be done. What do you have to lose? A big blown HG or a little blown HG, both are bad.

15 psi will not do any harm to a headgasket whatsoever. The type of pressure that a headgasket sees routinely is at least triple digits.

The mechanic that did not want to do this was clearly BSing... or is completely ignorant... in either case run in the opposite direction--you don't want someone like that workng on your Northstar.

[rfishing]

I hate to keep swinging back and forth on this coolant level but...

Just got home tonight, checked the coolant level from earlier test drive which was performed after replacing the defective radiator cap. Found level to be low, and needed to add yet another 1/2 gallon of water.

The water has to be going some where, so I think I am back to this is a blown headgasket problem? This has been going on with the coolant loss since beginning of summer.

[Kev]

What is the time period for loosing this last 1/2 gal? If it was from this morning then I would think a leak that allows that much fluid out would be noticeable one way or another. If it is leaking that much through a head gasket you would surely experience a miss.

How is the engine running through all of this?

[rfishing]

Originally Posted by Kev

What is the time period for loosing this last 1/2 gal? If it was from this morning then I would think a leak that allows that much fluid out would be noticeable one way or another. If it is leaking that much through a head gasket you would surely experience a miss.

How is the engine running through all of this?

The test drive after replacing the Radiator Cap took about 15 minutes. Car sat in driveway after that, and has not been driven. I got home tonight about 6 hours after the test drive, and checked coolant (water) level.

Engine when cold runs smooth, like a perfectly balanced and timed machine. After it is hot, its not as smooth at idle, I supposed it could be a miss (the mechanic who performed Combustion Gas Test indicated there was a miss), during exceleration I did notice some hesitation in response time to the pedal. Interestingly enough, after replacing radiator cap the hesitation seemed to deminish. Car has 96,000 miles, and Major Tune up was performed at 70,000 miles. Air filter is dirty now, but I can see through it. Oil needs to be changed soon (getting dark).

[SteveThefolkie]

Originally Posted by NickySantoro

Crapola! If this "mechanic" did one of the combustion gas tests, discount it.

Your last post tells me you need to do some more road testing. I'm not sure you still have a problem. Verify the integrity of the cap as was previously advised.

I agree - if the headgasket is indeed blown then it's blown - "make it worse" - making a blown gasket worse is akin to making a corpse "more dead" - if it's blown then finding out in a controlled environment running a static test would be (to me) far better than looking in the rear-view mirror only to see a cloud of steam coming from the tailpipe (I've been there - it evokes a sinking feeling at best).

I ran a compression (not a leakdown) test on my Seville last night - compression was within 5% across all eight cylinders so I'm fairly sure that the head gasket is not the source of my cars woes - while a leakdown would have been preferable since I have a compression gauge and adapters but do not have a compressor - I went with what I had. Compression gauges are fairly cheap and easy to use (if you run a check, however, with the engine cold, don't expect to see full compression as full compression comes in concert with thermal expansion of components - a table spoon of oil down each cylinder before doing the test will - however - compensate for the thermal expansion to some extent - so if you see a low number at least you'll be able to eliminate ring blow-by).

If you're consuming coolant or water the spark plug in the offending cylinder should look quite different from the other seven.

Also keep in mind, if you are ingesting coolant and sending it through the exhaust system, you're buggering up your oxygen sensor - that said - I'd suspect an oxygen sensor code to come up on my diagnostics were that the case.

As for opening my own thread - as suggested - I did - but was directed to this thread which was already active - such is life.

Best of luck -

Steve

[rfishing]

After sleeping on this, I am reconsidering the boiling point of water under pressure theory.

1. We add coolant to keep water from boiling, and if you check the coolant with a tester, it tells you that you now have increased the boiling point up to 250-260 degrees.

2. Is the system really under 15 pounds of pressure, or is it designed to relieve pressure at 15 pounds. I am thinking system is not under 15 pounds of pressure unless there is a problem, that is why the radiator cap is designed to relieve pressure at 15 pounds.

3. What is the normal operating pressure inside an engine? Without knowing that pressure I cannot assume the boiling point of water.

I checked my notes. When I test drove the car, the temperature seemed to hold fairly well in the beginning stages of test drives. It was after stressing the engine with rapid excelerations that the temperature increased.

Questions I am now asking are;

A. Could it be that the water began boiling over at this point of rapid exceleration?

B. Is it possible to boil over 1/2 a gallon in just a few minutes?

C. If I drain water, and fill with antifreeze will this solve the problem, or will I be right back to the beginning with this mysterious head gasket problem?

[mtflight]

Originally Posted by rfishing

After sleeping on this, I am reconsidering the boiling point of water under pressure theory.

1. We add coolant to keep water from boiling, and if you check the coolant with a tester, it tells you that you now have increased the boiling point up to 250-260 degrees.

2. Is the system really under 15 pounds of pressure, or is it designed to relieve pressure at 15 pounds. I am thinking system is not under 15 pounds of pressure unless there is a problem, that is why the radiator cap is designed to relieve pressure at 15 pounds.

3. What is the normal operating pressure inside an engine? Without knowing that pressure I cannot assume the boiling point of water.

I checked my notes. When I test drove the car, the temperature seemed to hold fairly well in the beginning stages of test drives. It was after stressing the engine with rapid excelerations that the temperature increased.

Questions I am now asking are;

A. Could it be that the water began boiling over at this point of rapid exceleration?

B. Is it possible to boil over 1/2 a gallon in just a few minutes?

C. If I drain water, and fill with antifreeze will this solve the problem, or will I be right back to the beginning with this mysterious head gasket problem?

I am concerned that the temperatures could get to the freezing point, and you're running straight water. You could crack your block easily if it does freeze wherever you are.


Antifreeze/coolant will raise the boiling point further. Make sure you use a 50/50 mix. Look around the water pump area for loss, also look by the firewall... do a search on the forum for crossover leak. I have heard this happens.

The best, definitive test, is the pressurizing to 15 psi with a system pressure checker... described as #2 on my earlier post. Anything else is speculation.

if you do have a coolant leak, and it's not on the headgasket... I would suggest the Bars leak golden powder, or the supplement tabs (4 at min). They do work to slow down and stop these leaks.

You would have to put them in, after draining the system, in the upper or lower radiator hose (recommend lower, but I dont think it really matters that much).

[mtflight]

Originally Posted by rfishing

A. Could it be that the water began boiling over at this point of rapid exceleration?

B. Is it possible to boil over 1/2 a gallon in just a few minutes?

I don't think you're boiling. If you were, you would get all sorts of bells and whistles going off telling you to shut engine off.

Your operating temperatures are normal. At 220 degrees the system will turn on fan #2 and bring them back down. Low coolant, can cause an overheat too, though.

Coolant is cheap. I believe if your model is a pre 1996, you can use the green stuff. 50/50 distilled water.

[rfishing]

MTFlight,

1. I live in southern california desert, so temps outside temp is in 70s. Goes down to mid 40s at night.

2. If not boiling, where is the water going?

3. I never see steam in tail pipe.

4. I never see coolant level low messages. I have not seen those since Head Gaskets were replaced 16k miles ago.

[mtflight]

Originally Posted by rfishing

MTFlight,

1. I live in southern california desert, so temps outside temp is in 70s. Goes down to mid 40s at night.

2. If not boiling, where is the water going?

3. I never see steam in tail pipe.

On aluminum engines, the supplement tabs are prescribed to prevent / correct leaks due to casting porosities. It may be leaking out at the crossover pipe or somewhere else. Do an advanced search on the forum here... many different cases of "mysterious" leaking--some originally mistaken for headgasket failures.

Steam in tail pipe would imply it IS the headgasket. It could be leaking, for example, between the engine and the firewall, externally. The engine is hot enough that it evaporates and never makes it to the ground. This is where the Goldenseal powder (or supplement tabs) excels.

EDIT: the "coolant level low" message takes place when your reservoir is empty. 1/2 gallon apparently isn't low enough to trigger it.