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

 

[Ron Ward]

Check the simple things first. Check for an air pocket in the coolant, foreign material (RTV, gasket material, chunks from the bad pump) in the radiator, etc....

 

[resq302]

Ron,

There was no RTV sealant on the old pump, just the cork gasket which appeared factory as it was super hard and brittle. Radiator flowed nice and easy when I back flowed the rad to double check that. Also, the nose of the car was raised up and this happened a total of three times. After each time, I refilled it back up. Once it was done boiling over, it looked like there was no coolant left in the rad as it took quite a bit (maybe a gal and a half) to fill it.

My personal feeling is that the T-stat is not opening causing the coolant to boil and the only place for it to go is up and out the overflow.

 

[ga66mopar]

It takes some time to get all of the air out of the coolant system once it's been opened up. Just keep letting it idle until it warms up than release the cap and let the air out.

 

[resq302]

Id say that the car with all 3 times combined probably idled a good 20 mins to a half hour. I would have imagine all of the air would have been out by then.

 

[snakeoil24]

Put the car on an inclince and start it. Open the radiator cap for 20 seconds, close it and repeat the cap opening. If this does not solve the issue get a co2 tester to see if you have a bad head gasket, crack or bad intake seal in coolant.

 

[Dennis H]

OK. Green coolant, 180 Napa Superstat. Leave 2 inches to radiator neck do not overfill. Use a laser temp gun to be sure of temps. A brief 220 splurt or splat ok.

 

[resq302]

Yes, I am using the green Prestone coolant. I will try to pick up a new stat tomorrow and install it on Wed when I am at Dad's next. I also have one of those laser temp guns so I will bring that just to double check. I seem to recall only filling it just to the top of the baffle that is in there.

The problem that I have now is that when it "burbs or splurges" it shoots straight up like a geiser which I have never seen before in all the years of working on cars.

 

[nm9stheham]

Sad to say it sounds like a bad head gasket or a crack somewhere, especially with the bubbles blowing out like that. Your thought/observation that there is excess pressure in the cooling system would be another clear indicator. Power and smoothness can feel 100% normal even with a fairly large combustion gas leak into the coolant.

Try bleeding the air out as suggested and drive it for some short drives doing the same. Use th CO2 kit or try to borrow a cooling system pressure guage.

 

[resq302]

Ah, that is an idea. I do have one of those coolant system pressure gauges / pumps to check and see if there is a leak somewhere. Thanks for the reminder as I had totally forgotten about that.

I really question if it is a crack or a head gasket issue as wouldn't it be like that or see small bubbles, not one large rush or surge of coolant?

 

[Photon440]

If it is a head gasket...a quick way to find out is to pull all the spark plugs. If one of them looks a lot cleaner - or is covered in coolant - then I'd suspect the worst.

Fortunately these aren't some modern OHC engine that takes all day for a gasket.

 

[Dennis H]

Maybe time for BarsLeaks. Nothing to lose if the worst a has happened. I just dodged a bullet today when replacing all of the rods. Tap went away, flirting with disaster.

 

[bm02tj]

Check the stat before anything else after a hard boil they can drive the pin out the top
then warm up and check flow

 

[khryslerkid]

Man, what an assortment of remedies!

After draining a cooling system you'll get air trapped when you refill. Fill the radiator about a half an inch over the core. (rods, tubes). Leave the radiator cap off. Start car and let it idol. Watch the coolant start to rise, from expansion. Add small amounts if needed. You are waiting for the thermostat to open. A thermostat won't open without coolant contacting it. When the thermostat opens the coolant will start to travel across the cores. (Rods, tubes) The top hose will be hot as well as the bottom. Once these things have taking place, and your coolant level is correct, then you can apply the cap...

 

[miller]

These days it's a good idea to test a stat, even new, to make sure it works. Just in water in a sauce pan, sittin' on the stove. When the water gets to temp, the stat 'should' open. Not worth the trouble to put one on your motor, unless you know it works.
Also creats a problem when their installed upside down! You'd be surprised how many times that's been done.

Assuming your new water pump is working right. Pressure test the system. That will tell if there's any unknown probs.

 

[71GTX440]

When i install a new stat, i drill two holes on the outside ring so any trapped air can bypass the stat when it is cold.

 

[resq302]

71GTX,

I typically do that but this Mr. Gasket high flow stat did not have any extra flat area to drill the usual 1/8" hole like I usually do.

The stat had been working as when I was tuning the timing and carb, it was idling for quite some time and did not go over the half way point on the gauge. I have been reading up on the Mr. Gasket stats and they seem to be a real problem with sometimes failing in the closed position even though they are supposed to be a fail safe and fail in the open position. Looks like I will go back to the usual Stant thermostats.

 

[milit73]

I had the same T-sat (Mr. Gasket and it failed right away. Shame on me for not testing it first. My car reacted the same way yours is and for me that was the second one in a year that had gone bad. Removed the T-Stat and just left the system open for now just for testing purposes and all is good. I bought a mopar performance one this time and will install this soon. Good Luck!!!!

 

[resq302]

Milit73,

Thanks for chiming in. I'm still leaning towards the stat as I really think if it was a head gasket or a crack, I would find coolant mixing with the oil and / or the engine idling rough due to the loss of compression. I will double check the system on Wed. as I have a pressure tester for the cooling system so if anything does not hold, I know I have more issues than a possible bad stat.

 

[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.