Is my stock coolant tank Cap bad?

[robs1280]

Everytime I fill my coolant/water level to the fill mark on the coolant tank/resivour, coolant starts phewing out under the cap after a nice little run. This is probably a no brainer, but is my cap not holding the pressure it's supposed and therefore letting water out? I mean, come on, plastic cap and resivour, ford dropped the ball on that design.:shrug: Is fixing this problem as easy as getting a new cap from Ford. Or should I spend my money on the niffty aluminum tanks, any suggestions? Oh yeah, anyone else have this problem? Thanks, and sorry for all the questions.

 

[pimpdout98gt]

you may have air in your system. try burping it and make sure you are not overfilling it. you shoudn't top off from the reservoir.

 

[speeddemon2000]

Crack the plug on the crossover tube and make sure you don't have air in the system. That's where you should always fill from. Second off the coolant cap is a common problem you should be able to buy one at your local auto parts store. If it continues you may have to buy a new overflow tank too.

Keep a close eye on your temps. The stock temp gauge is absolutely worthless. Don't even look at that thing. If you go into the diagnostic mode on you stock digital odometer you can see the actually temp. This is done by holding down the trip meter as you turn your key to the on position. Wait for Test to appear on the digital readout and release the button.

Pushing coolant out of the overflow tank can indicate more serious issues. I had an issue with head gasket where every time I went into boost I would push coolant out of the overflow tank then I would start to overheat.

 

[jm@ReischePerf]

Crack the plug on the crossover tube and make sure you don't have air in the system. That's where you should always fill from. Second off the coolant cap is a common problem you should be able to buy one at your local auto parts store. If it continues you may have to buy a new overflow tank too.

Good advice.

Also feel free to use this refill procedure if the system is very low on coolant: Cobra & Mach 1 Ford 4.6L DOHC Coolant Refill & Burp Procedure by Reische Performance Products

 

[robs1280]

Good advice.

Also feel free to use this refill procedure if the system is very low on coolant: Cobra & Mach 1 Ford 4.6L DOHC Coolant Refill & Burp Procedure by Reische Performance Products

I "burped" the cobra as per your instructions and the car drove fine, no running hot/overheating. But as soon as I shut the car off, coolant started to seem out of the reservior cap again.:fm: I think I need I new res. cap? Is there a chance that I overfilled the system? It was passed the fill mark on the reservior. I have noticed that when I used to drive the car before, the reservior cap would never leak/run hot etc. as long as the coolant level was about an inch below the reservior fill mark. Any suggestions?

 

[speeddemon2000]

I "burped" the cobra as per your instructions and the car drove fine, no running hot/overheating. But as soon as I shut the car off, coolant started to seem out of the reservior cap again.:fm: I think I need I new res. cap? Is there a chance that I overfilled the system? It was passed the fill mark on the reservior. I have noticed that when I used to drive the car before, the reservior cap would never leak/run hot etc. as long as the coolant level was about an inch below the reservior fill mark. Any suggestions?

Buy a new cap at advanced auto. Burp your system again. Closely watch your coolant temps. Use the diagnostic mode on your Odometer. With Highway driving at constant 60 to 65 mph (don't go into boost) with the AC off on an 80 degree day you should see temp around 90C giver or take. If you are driving in the manner above if you see temps start to clime above 100C you definitely have something wrong.

 

[jm@ReischePerf]

Is there a chance that I overfilled the system?

Possibly. The cap will expel extra coolant from the overflow channel under the cap if the system is overfull. But after a few heat cycles it should stop. However if it continues to expel coolant every time you shut the car off and the level of coolant in the system starts dropping then you're not getting a proper seal at the cap.

 

[robs1280]

Thanks for all the input guys.. One more question though. I have noticed that the car will not drip a drop of coolant if the coolant level on the reservoir is below the fill mark, about a couple inches below, Is this too low, is it normal? When the car is at operationg temp, the level on the reservoir goes up to about an inch from fill mark....

 

[jm@ReischePerf]

Is this too low, is it normal?

I'd say no. The reservoir should not expel extra coolant even if the reservoir is filled a bit above the full line. Sounds like you have sealing issue at the cap.