blew the water pump, now over heating big time!

[resq302]

On the way to a show today with Dad's 69 GTX vert with the 440, he called me up and said that he was overheating and pulled off to the side of the road. I met up with him and saw coolant flowing like a faucet was turned on from the lower part of the pump. We had the car towed back home and swapped out the water pump with no problem. What I saw that was strange was on the back (impeller) side of the pump, it seemed the seal / gasket had backed off and was being pushed out by a spring. The water pump was the original dated one for the car so I figured the seal just gave up after 44+ years of use. After I got the new pump installed, I took it for a short trip around the block and noticed the temp gauge rising very quickly after about a 5 minute drive. I get back into Dad's driveway and shut the car off and it started puking coolant out of the overflow hose and you could hear the coolant boiling inside the radiator.

What would cause this? I just put in a high flow Mr. Gasket thermostat which is supposed to fail in the open position. When I put the engine and everything back together, I had the rad flow tested and it was flowing 20 gals per min which is what the factory radiator is rated for so I know that is fine. The car also idled perfectly fine and had plenty of power so I am guessing a bad head gasket could be ruled out. There is no oil in the coolant and no coolant in the oil nor the trans.

Something seems to be causing the engine to make more than 16 or 15 psi (whatever the factory cap is rated for). I am kind of leaning towards the Mr. Gasket high flow stat going bad (again, been installed for 2 weeks! and ran perfectly fine last week when I tuned the timing and carb)

What is everyones thoughts?

Thanks,

Brian

 

[69hemibeep]

Either the stat is bad which you can check on a stove and a pot of water or its installed upside down or you have a blown head gasket

 

[resq302]

even with a blown head gasket, would the car still idle fine, have plenty of power, and have nothing cross contaminating?

 

[69hemibeep]

If the gasket gives out between a cylinder and a water passage yes, but it will cause high pressure in the cooling system and the cylinder will take water in when parked. Do you have a spring in your lower hose???? It will collapse when cruising without one!

 

[resq302]

now that I think of it, no spring in the lower hose, however, the thing still over heats at idle. I could see it collapsing the hose when you are running it hard but not collapsing at idle.

How can I tell if a head gasket is bad? Compression test?

 

[Big John]

Sounds like a bad head gasket to me.

Compression test will tell, but much better yet is a leakdown test.

 

[69hemibeep]

Just a quick test. Take the cap of the radiator cold of course, start the engine and see if you get bubbles as it runs and warms

 

[resq302]

I had the car start when I filled it up the second time while I was looking for the "burb" to get the air bubble out. I did not see any tiny bubbles. The thing just started almost like backing up like a toilet would and then seemed to be getting pressured ad the same time which is why it shot upward like a geiser.

 

[1967 'cuda]

I'd start to wonder if you can tell an unusual amount of water vapor making it's way through the exhaust. How do your plugs look? Do you have an adjacent pair that are unusually clean?

 

[resq302]

I have not noticed any unusual amount of steam or water condensing when it is coming out of the exhaust. Just the typical stuff when you first start the car up till it gets up to temperature.

I will have to pull the plugs on Wed when I am at my Dad's house.

 

[Big John]

I had the car start when I filled it up the second time while I was looking for the "burb" to get the air bubble out. I did not see any tiny bubbles. The thing just started almost like backing up like a toilet would and then seemed to be getting pressured ad the same time which is why it shot upward like a geiser.

Yep, head gasket.

 

[ACME A12]

Exterior of the water pump needs to be put back to factory specs...:basketcase:

 

[resq302]

Acme A12, our original will be rebuilt and reinstalled once we get it back. No worries. Want something to just get Dad to and from the car shows for now.

 

[resq302]

Great news! Today while I was at my Dad's I started off with doing a pressure test on the cooling system with the Stant Pressure Tester I have. No drop in pressure so that told me that everything was pretty much good and reaffirmed my thought on the head gasket being good. I then drained the coolant and removed the lower hose to install a spring in there even though it was not collapsing before, I figured it couldn't hurt to put one in while I had the system drained. I then removed the thermostat and replaced the Mr. Gasket high flow thermostat with a Stant Super Stat. (prior to installing it, I had tested it in a pot of water on my stove to see when it opened up (opened up between 180-190) yesterday. After I reinstalled everything, I did the same test to the Mr. Gasket t-stat...... nothing! The thing wouldn't even open up in boiling water! I can say this, that is the last Mr. Gasket item I will ever own. Their quality seems to be horrible from what I have read on the web. Once I filled up the system to just above the tubes, I backed the car out of the garage and pulled the car up onto a set of ramps to raise the front end to get all of the air out of the system. Once the coolant was circulating in the rad neck, I topped it off to just above the baffle inside the upper rad tank. Since the road was wet, I just let the car idle for quite a while periodically checking the gauge on the dash as well as taking a reading with my infrared thermometer. The temp at the sending unit never went above 203. Keep in mind, this car never seemed to have a factory shroud installed as the original dated rad does not have those nuts for attaching the brackets to it which would mount the fan shroud. Either way, the gauge never went above the 11 o clock position and seemed to be just above the "warm" mark on the gauge. Looks like we lucked out again big time.

 

[Big John]

Glad that it seems to be working out.

One thing... the radiator pressure test won't give you any insight into the head gasket sealing. Think about it, that pressure test checks leaks to the outside and not to an internal closed cylinder.

I would do a leakdown test anyway. You have already shown some engine "issues" with the scored bearings.

 

[resq302]

Hi John,

I'm sure I will do a leak down test at some point but I did not have the time today. Also, wouldn't the needle on the gauge drop if there was coolant leaking into the cylinder? Air in the cylinder would compress which should show up as the needle dropping of some significance. That did not show up though. Also, there is still no steam once the car warms up. Also, no coolant in the oil or raise in oil level. While I can't be 100% certain (as the only certainty would be to pull the heads, in which case a head gasket would be necessary), I am pretty certain that the head gaskets are still good for now.

 

[Big John]

The pressure gauge checks the system by pumping the air pressure up in the system. It won't know the difference if it's in a cylinder or the top of the radiator.

If the engine was at a spot where the valve in the affected cylinder was open, then you might see the leak. The valves closed and you won't see the leak.

 

[Budnicks]

glad to hear it worked out for ya', cheap & easy peasy fix too

 

[A31PKG]

The pressure gauge checks the system by pumping the air pressure up in the system. It won't know the difference if it's in a cylinder or the top of the radiator.

If the engine was at a spot where the valve in the affected cylinder was open, then you might see the leak. The valves closed and you won't see the leak.

Agreed - a cooling system pressure test, a compression test, or leak-down test are all best performed with the spark plugs removed. A cylinder leak-down test is by far your best bet for finding stubborn cooling system leaks. Additionally, there have been many cases where a head gasket is in fact the problem, but it will only leak when engine is at operating temperature. It is not however a good idea to remove a spark plug from a hot engine. I would apply a small amount of anti-seize compound to the spark plug threads and then do not tighten them completely. Start the engine and let it idle until it reaches operating temp, shut it off & remove the plugs. Bring the cylinder being tested to TDC (much easier to do BTW with plugs out) remove the radiator cap, fill it to the top with water, pressurize the cylinder and look for bubbles. It may take a few minutes, or you may see them right away. If you do, it's likely a head gasket, but it could also be anything from a crack to a porous casting. By doing this, you will get a much more reliable dynamic reading. And stay away from fancy "hi-flow" aftermarket thermostats... O.E. or equivalent is just fine for a stock engine, and many performance applications as well. Good luck!