Replaced coolant, overheated, think I screwed up - HELP!

So I drained the coolant out of the cobra to do some other work that needed a quick connect disconnected at the heater core, and filled new Ford coolant back in (50/50 premix). But I think it had air in the system or something. Drove it till warm, parked it and checked everything. Seemed OK. Went for another ride and I could smell coolant and see the steam. Gauge quickly went up to 3/4 hot. Parked it right away and has been cooling down. Coolant all over the engine.

Somewhere I F'd up.

Question:

1 - Does the cap have a pressure spring like the classics? Seems so, at 16 lbs. I found a video of it spewing out at the cap and posted it down in this thread.

2 - What step did I miss? My guess is there is air in the system. I filled things up to the overflow marker. Is there a place on the engine I need to open and fill (to get air out and fill into it)?

One of those "learn the hard way days". But car seems OK. Did not have a running issue when over-heating, just saw the steam and gauge was moving up fast. But ran fine. Also I just changed the oil, so I feel better it had some fresh Mobil 1 synth in it.

Cars fine, you need to fill it up from the crossover tube. Loosen that cap add coolant/water and start the car and let it run, keep adding it as needed.

Your car is ok. I've seen you post a number of threads recently seeking advice. That's a good thing, but you should read through CobraBob's FAQs (once more if you have already). These cars have so many idiosyncrasies. Nothing happened this time but I don't want something to happen that you could've prevented.

https://stangshiftergaskets.com/2003_2004faqs.htm

The coolant refill procedure is very specific to these vehicles. The link I posted and Reische Performance both have a very good guide. When I first got my car, I filled the coolant like I did with every other vehicle I've owned. I got coolant everywhere. Followed the procedure and never had problems since.

yup it's very important to fill at the crossover tube (the highest point), otherwise coolant wont get into the engine side of the system when you fill it.

as long as you shut down your car as soon as you saw a problem you should be fine. it's usually when you continue to drive/run it after it starts to overheat that damage is done.

So it was down the road about 1 mile. Waited couple hours, filled it best I could and got it home at 1am (happy to have it back at the house). Washed everything down and dried it to ensure no paint damage (don't see any) and get rid of the smell. But my neighbor thinks I am crazy washing my car at almost 2am. Everything seems fine.

I will go over everything and check on the procedure. Thanks for posting the reminder of the FAQ. I have not looked at that in a very long time.

I admit I have still far more comfort working on my 69 Mach 1 and the early 90's GT's I had than this (since it is the first mustang I have keep generally stock) and agree it is far more particular to work on than the older mustangs. Also when I look at write-ups before I try things, I am finding some holes and always try to post back what I found was missing on any steps or considerations.

I fixed about 5 things at once over the past 2 weeks and this one bit me in the a$$ for not looking into it more before finishing it. But lesson learned.

This is a good vid of someone having a similar bad day:


I see that cap pop right open under pressure. Thanks for the replies.

I can't even continue to watch that..... so much coolant.... everywhere.

The exact same thing happened when I had my coolant go everywhere. I'd just changed the oil/COPs/spark plugs and gone over a bunch of things. I didn't even think about the burp procedure when I was messing with the cooling system. Everything else distracted me. One thing is certain: I won't forget again!
Glad you got her back home.

The simple factory procedure - which is right from the Ford service manual:

http://www.termi-stat.com/index_htm_files/Cobra coolant filling procedure.pdf

Speaking of service manual, anyone that works on their car and does not have one is doing themselves a disservice. You can download the Ford program or PDF right here:

http://www.terminator-cobra.com/svt_documents.htm

The procedure in the FAQ is great and direct to follow (solid write-up), wish I had seen that in the first place (and didn't overlook it with several improvements at the same time). I have not compared the difference, but I am sticking with the FAQ version since they claim it includes considerable extra research and discussions with SVT.

Thanks very much for the service manual. This will absolutely help prevent headaches going forward.

"The simple factory procedure - which is right from the Ford service manual:"

I have never had a cooling system fill go that easy on one of these. Maybe they forgot the part about hanging the car from the front bumper? Its always a warm then cool, fill the port by the supercharger. Wait to the next day and repeat and repeat and repeat. Just keep doing that until you cant get any more coolant in.
My failure over the weekend when filling mine was a leaking res cap. If you fill the res and start the car and notice the coolant is down in the res do yourself a favor. Turn the car off, put your ear next to the cap, when its cool, while squeezing the upper rad hose. If you hear air, take the cap and launch it into a low level orbit.

Interesting point on the cap. As it tuns out, I just noticed the sound of air leaking out on my overflow cap. Since it overflowed at the cap the other day, I suspect something warped.

Also I noticed past threads that mention the cap is generally done if it overheats and sometimes the overflow tank warps where the cap is as well. Not sure how true that is, but I will let it warm up and cool down a few more times to listen more. Likely need a new cap (or at least would start there). Thanks.

ruthless said:

"The simple factory procedure - which is right from the Ford service manual:"

I have never had a cooling system fill go that easy on one of these. Maybe they forgot the part about hanging the car from the front bumper? Its always a warm then cool, fill the port by the supercharger. Wait to the next day and repeat and repeat and repeat. Just keep doing that until you cant get any more coolant in.
My failure over the weekend when filling mine was a leaking res cap. If you fill the res and start the car and notice the coolant is down in the res do yourself a favor. Turn the car off, put your ear next to the cap, when its cool, while squeezing the upper rad hose. If you hear air, take the cap and launch it into a low level orbit.

Click to expand...

Have done this many times using the procedure in the service manual and it's been simple every time with no glitches. Pouring the coolant in slowly and squeezing the upper hose as necessary to get the last of the air out is common sense. People make way more out of this than it is.

jrgoffin said:

Have done this many times using the procedure in the service manual and it's been simple every time with no glitches. Pouring the coolant in slowly and squeezing the upper hose as necessary to get the last of the air out is common sense. People make way more out of this than it is.

Click to expand...

Correctamundo.

jrgoffin said:

The simple factory procedure - which is right from the Ford service manual:

http://www.termi-stat.com/index_htm_files/Cobra coolant filling procedure.pdf

Speaking of service manual, anyone that works on their car and does not have one is doing themselves a disservice. You can download the Ford program or PDF right here:

http://www.terminator-cobra.com/svt_documents.htm

Click to expand...

Downloaded now

Not trying to hijack thread but I might still have air in system, I have an upgraded thermostat, mishimoto rad, head cooling mod, and fluidyne HE and my car runs in the 200/205 temp area. Last time in the garage (not sure if it's normal but it got up to 210 while idling).

I've done this multiple times following these instructions and have had zero issues. I do have a drilled thermostat, so I am getting some coolant flow at all times. Temp runs a max of 192 F in Texas with a 35% glycol mix and Redline water wetter. You need the fan settings lowered in your tune.

http://www.reischeperformance.com/refill.html

it helps if the car is on the driveway with the radiator elevated

Some of you are very lucky to not have to fuss around with the cooling system. I wish I could make post saying I never had an issue instead of giving people ideas of what to look out for. My luck just sucks. I have had multiple 03-04 cobras over the years with diffrent builds so I will give my advice when I can. You will never read a post where I try to make some one with and issue or question feel like a dumbass.

So I replaced the coolant overflow cap with a factory Ford one since I could hear a hiss as things got hot. All is well. That seems to be the only issue from this event. I learned the hard way, but happy things are good now.

I am also thinking of getting this crossover plug replacement so I can more easily check the coolant there (looks to use a socket).

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&products_id=440

Thoughts on this part? Anyone using it?

texas_snake said:

So I replaced the coolant overflow cap with a factory Ford one since I could hear a hiss as things got hot. All is well. That seems to be the only issue from this event. I learned the hard way, but happy things are good now.

I am also thinking of getting this crossover plug replacement so I can more easily check the coolant there (looks to use a socket).

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&products_id=440

Thoughts on this part? Anyone using it?

Click to expand...

I'm not using that particular one, but they are very helpful. There is a guy on here who sells em, I have one of his and it was high quality. I think his handle is "markvii98" or similar. I saw him post just the other day, so I think he's still making them.

I think Billetproshop makes a coolant crossover plug as well.

I've never had any issues filling my coolant system even after having my motor out. Just fill slowly from the crossover and work the radiator hose to help get air out. I usually run it and once the car begins to get warm I back out the coolant crossover plug enough to get a little coolant to leak out, that should have purged any air caught in the system. Never an issue.

Now my old LT1 4th gen Fbody I had issues with air in that cooling system, lol.