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View Full Version : boil over? air in coolant issues


ausie
08-29-2004, 10:30 AM
The 4.6L engine seems to be sensitive to air in the coolant. Since I bought the car new, it occasionaly dumped coolant out of the resivior after parking it. 15 or 20 minutes the coolant would start spewing out. I decided to change the cap with an aftermarket one, which corrected the problem for a short time. This spring I decieded to flush the cooling system out. It took a long time to get all of the air out. Now since this August it began to spew again. It does not come out when driving, but only when the motor is off. So far it has dumped the entire contents of the resivior out. I replaced the cap again and that sort of corrected it problem but yet once again it still looses coolant through the cap. I am thinking about replacing the radiator and resivior with something better but I am uncertain that the problem will be fixed.

The oil stays clean, there is no white smoke in the exhaust, and the coolant is clean (however there are some tiny white/tan chunks on the cap which may indicate some oil in the coolant). It was like that when new and did not change after flushing the coolant.

To my amazement, I ran the diagnostic mode to read the temperature of the coolant. The values are displayed on the odometer in degrees C. It seems that the highest temp reached is 104 C (219 F) but on average the fan kicks in at 100 C (212 F). With the A/C on, temp stays at 98 C (208F)

I either have a damaged head gasket or the system was never purged of air properly from the factory. Any thoughts or ideas on this will be greatly appreciated. Thanks for your reply.

Abneriel
08-29-2004, 02:10 PM
I had a similar problem in my 96...my wife took it in when I was at work and they never told her what it was (it was under warranty)

If your car is still under warranty I would suggest taking it in to have ford fix it...

ausie
08-30-2004, 06:44 AM
Thank you for your reply and suggestion Abneriel.

I should have stated my Cobra is an 01. I do recall hearing of overheat issues with previous years to 97 and Ford had a fix for it.

Unfortunately, I do not think Ford has a fix for the 01. I was a bit successful when adding coolant (basically water) to the overflow tank. I first took off the bung on top of the forked pipe and added water wetter to it made by red line oil. What had to be done was to burp the system which took a while. This time I remembered to run the heater. I took a short test drive and lost some coolant. The aftermarket cap was on too tight (have to love plastic since it became warped when over tightened). I loosened the cap up and things were back to normal no-leaks.

I always thought that the thermostat was a 180 degree stat, it turns out to be 195. Time to replace the thermostat to a lower temp. Also, after burping the coolant and adding the water wetter I took a long trip to see if things were operating properly. It was so hot I could not drive without the A/C. This was the first time I did not get any pings with the A/C on under acceleration. I will probably have to flush the coolant again before the winter since the mix is probably not what it should be.

Abneriel
09-05-2004, 03:07 PM
the recall on the 96 was due to the A/C fins (in front of the radiator) being too close together to let air flow through to the radiator. I had that fixed...the boil over problem didn't occur until I had about 60k miles on the car (luckily I had an extended warranty...), so I don't think it was the original problem with the 96's that was affecting my vehicle...(at least I hope not :dunno: )

Don't have the foggiest idea what it could be on your vehicle...good luck though! :thumbsup:

casey99COBRA
09-05-2004, 06:27 PM
i'm not so good with the whole radiator stuff but it sounds like to me that the thermostat is doing something it shouldn't. And all of those things you mentioned i would have done. Have you checked to see if the oil pressure is higher than normal ? and have you checked all the hoses?

ausie
09-06-2004, 08:52 AM
It appears that everything is back to normal. However, I am surprised to see what temperatures the coolant reaches. With that said, it explains alot with the pinging issue with the 99 and 01 cobras. Too much heat causes pinging to occur. I also know that the 4.6L is extremely difficult to get all of the air out of the coolant system. The plastic resivior does not seem to be strong enough to hold the cap on tight either. It seems that it will not hold pressure if the cap is too tight.

I may just get a 180 degree thermostat and re-flush the coolant. But I have plans on adding a supercharger which will use a 160 degree stat with re-programmed chip.

ausie
09-06-2004, 09:02 AM
As for oil pressure, hard to say. I do recall since changing the oil to synthetic 20w-50 a few years ago I did not get coolant overflow issues. However, since I now am using 0w-30 the overflow issue has returned. The engine runs hotter with the 0w-30 and sometimes the idle climbs to 2000 rpm. This could all be related to operating temperature.

ausie
09-07-2004, 06:46 AM
I decided to replace the thermostat. It took me a while to find a parts store that even had one. After the install, I decided to add royal puple - purple ice to the anti-freeze mix. I decided to get the pre-mixed coolant so I did not have to put in the dirty tap water (which has more chemicals in it than the coolant itself). Had a massive eruption before the first burping, but after that everything was working as it should. The thermostat which was a direct replacement (I was trying to find a 180 F) turned out to have a temp of 188 F. After monitoring the coolant temperature, the average temperature was 88 to 90 C (190 to 194 F) which is far better than 104 c (219F).

It very well could have been the thermostat. For now I will settle with no more boil overs.

casey99COBRA
09-07-2004, 01:45 PM
I decided to replace the thermostat. It took me a while to find a parts store that even had one. After the install, I decided to add royal puple - purple ice to the anti-freeze mix. I decided to get the pre-mixed coolant so I did not have to put in the dirty tap water (which has more chemicals in it than the coolant itself). Had a massive eruption before the first burping, but after that everything was working as it should. The thermostat which was a direct replacement (I was trying to find a 180 F) turned out to have a temp of 188 F. After monitoring the coolant temperature, the average temperature was 88 to 90 C (190 to 194 F) which is far better than 104 c (219F).

It very well could have been the thermostat. For now I will settle with no more boil overs.
sounds like it, and lets hope it was.

ausie
09-08-2004, 07:23 AM
Actually the boil overs are related to loss of pressure in the coolant system by means of a weak cap. The stock cap was faulty, and so far the aftermarket caps are just as poor in design. The motor runs normal with normal anti-freeze in it too. Just for the record, I did not notice boil overs until I changed to synthetic oils except for when I was using AMSOIL 20W-50 racing oil. One mistake I changed the coolant this spring to the AMSOIL coolant which is supposed to be less harmful than ethelene glycol (green stuff). Avoid the yellow or orange coolant since it is organic acid technology (OAT) which is not compatible with many motors.

The overflow started again when I changed the grade of oil from 20W-50 to the AMSOIL 0W-30. I will not use mobil 1 since I had problems similar to the 0w-30. Since I changed the coolant (again) I also changed the oil to 5w-30 Royal Purple (lower in price than AMSOIL, 6.18 /qt as compared to 8.65/qt). So far things are working normal. It looked strange, here is this guy wearing an AMSOIL t-shirt and buying Royal Purple products. Since I am not affiliated with AMSOIL I had no problems doing that. AMSOIL is a good product, but I had to try something else to see if this corrects the issues I have.