Another Coolant Dilemma! (UPDATED!)

[switch96]

I bought this car a week ago -- '96 Cobra. When we test drove it we saw a coolant leak which subsequently stopped before I bought it. The car had sat for a couple weeks (and quite a while before that) before I bought it, so I figured the leak stopped when the engine got warm, and all the seals kind of "mated" when the parts expanded. The car stuck at 190? the whole 2 hour drive home. Haven't seen any leaks since, until today. I got on the highway and was running 250? within 5 miles. I shut it off and got to the side, and saw a pretty decent leak, but I'm not sure from where. I babied it home and was still running 240? at 1100 RPM in 5th gear after letting it cool down to 180?. It's 25? out! One thing that I noticed was that the reservoir on top of the radiator was still full when the engine was so hot -- and the coolant inside was very cool. SO, it seems pretty clear cut that no water is circulating. BUT, the previous owner claimed he had just installed a new thermostat before I purchased the car. That makes sense -- it was running fine for a whole week. The only thing I can figure is that there is some crap or sludge in my coolant (from sitting for so long) that clogged up the thermo or something else.

Any ideas??

 

[mike97gt]

Re: Another Coolant Dilemma!

the coolant in the top reservior will not circulate through the system but it should warm up abit. take a temperature gun and see if you can find the hot spots of the system and check to see if it is cooling down enough through the rad (compare upper and lower rad hose temps)
try to find and repair the leak as well. pressure up the system and use an LED flashlight to see if you can watch it drip out of somewhere.

 

[switch96]

Re: Another Coolant Dilemma!

Thanks, I'll take a look!

 

[switch96]

Re: Another Coolant Dilemma!

Also, after shutting the car down the last time, all of the coolant in the reservoir evacuated, which was confusing. What is the reservoir for if it doesn't circulate through the system?

 

[GDTrumbo]

Re: Another Coolant Dilemma!

Be carefull! The modular Cobra cars are very difficult to air bubbles out of the cooling system.
2 things:
1. Make sure the thermostat has a small (about 1/8") hole drilled into the plate near the edge. This hole should be placed at 12:00
when installed. This allows air to escape easier from the block but will effect warm up very little.

2. To be sure the block is full, remove the rad cap. There is a small plug in the X-over tube in front of the block that connects the heads. Remove the plug and pour coolant into here until the "burp bottle" is full. Replace the cap. Continue to fill until coolant runs out this plug. Replace the plug.

Now run until at operating temp. Watch the temp closely! If it gets too hot, turn it off and let it cool all the way down. Retry. You may have to do this a couple of times. This method seems to get the best results.

Good Luck,

GT

 

[switch96]

Re: Another Coolant Dilemma!

Thanks! I used the method you mentioned, and so far so good. It stayed cool for the 15 minutes it was running (around 170 degrees). I'm letting it cool off and then I'll top it off.

 

[GDTrumbo]

Re: Another Coolant Dilemma!

Good. I do something similar to this with my GT. The technique works well.

GT

 

[switch96]

Re: Another Coolant Dilemma!

So, it's been running great for the past 3 days. Today it happened again. I did two spirited pulls and it stayed at 200* (it has a 200* thermo). Then, 10 minutes later it was at 240*! I popped the hood and there was quite a bit of antifreeze around the reservoir cap. The fluid inside was cold. I had excellent heat the whole time. Now what??

 

[GDTrumbo]

WOW! At this point I'm at a loss dude. I know the '96 cars had a cooling problem and Ford had a Tech Sevice Bullitin out on them. Seems like they were going in and replacing the radiator or something.

I would google a search for TSB's on the '96 GT's & Cobras. Not too hard to find.

Seems like it only does this when you lean on it. Almost sounds like the cooling system is restricted somewhere.

Search this site too.

GT

 

[switch96]

I've heard about some of the lower intakes cracking and burning off coolant, but that's not the same intake that's on my car, correct?

 

[GDTrumbo]

Right. The Cobra's intake is an all-aluminum set up. '96+ Cobra's = lots of plumbing and a reversed cooling system.

GT

 

[switch96]

Haha, greeeaaaat.

Well I think I have a lead -- the dealer installed a water temp guage at the port in the crossover tube. It's leaking just a little bit, which could explain why I was low on coolant after a week with no leaks onto the garage floor...

Time to bust out the silicone and teflon!

 

[GDTrumbo]

Leave the silicon out of the picture. If I remember correctly, the X-over tube is made of steel. Silicon + steel = corrosion & rust.
The teflon tape should be more than enough.

GT

 

[switch96]

It had Teflon on it before, still leaked. I suppose I could be very liberal with it!

 

[GDTrumbo]

Make a few extra turns around the sensor with the tape. Make sure the tape is trimmed away from the business end of the sensor as well.
Inspect for cracks around the bung your threading into.

GT

 

[switch96]

Will do, I'll keep you updated. Thanks!