07 ST V8 3rd Radiator - Any idea's?

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Frank Zabski

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So going on my third radiator for my 07 ST 4.6L 03/06 with 86k. Drivers side leaking from plastic edge - from what I can see without taking off shroud.



Replaced the radiator about 9 months ago and now it is leaking again. I've done a bunch of searches both on this site and globally on Google. Seems to be three main issues that could be causing it.



Side note:

Battery would weep fluid so I cleaned area and installed a Optima red top. Could be coincidence but the leak started not long after.



1. Bad design for rad - I can't change this, I bought all new rads.



2. Electrolysis - going to spend time on this tomorrow - link to good article here I am going to go through with VM.



3. Saw on post about an update (software)....A coolant leak may develop from the radiator. Ford has released and updated radiator and powertrain control module (PCM) software update to address this issue. The software update includes revised cooling fan operating parameters. Failure to complete both service procedures may result in repeated radiator failures.



Anyone have the same issue and found a long term fix?
 
Yes, I looked quickly last night in the dark, I'm going to double check but pretty sure there is a hose going from top of rad cap back to white overflow tank.



I used the old rad cap



Coolant, not 100% sure but I buy everything at local carquest. Might have been their brand but definitely for my truck as I had them check. Pretty sure I tossed old containers out.
 
Where did you get the radiator from an what brand is it? We had a local radiator house that sold radiators dirt cheap and offered a lifetime warranty that the owner of the shop I run loved to use. When I came in I started noticing the high number of radiator failures that we were having for no apparent reason. I started buying radiators from another company, much to the owners dismay because they were more expensive, and wouldn't you know it but our radiator failure rate has all but disappeared. Moral of the strory is you get what you pay for.



Electrolysis used to be a HUGE problem with Fords. Not so much amymore but definetely worth checking for.
 
I think it is a TYC or something close to that. I specifically asked the parts guy for the "best" radiator he had not the cheapest. I am a firm believer in you get what you pay for and would never buy the cheapest. Anyway, here I am. I only paid $130-$150 for the rad so if anyone has any "best radiator" idea's the money is not an issue. I much rather buy a radiator that will last then have to change it in 12 months. My understanding is they are all very similar with the plastic sides and metal cores and the mating surfaces between the two.
 
The system requires special fluid, only available from Ford or Zerex makes it as well. It is classified as a HOAT fluid (Hybrid Organic stuff) And is Gold in color. G-05 is the spec. I'm replacing my radiator here in a couple of weeks because it is leaking in the same location. I got the Spectra Premium off of Rockauto for a heck of a lot cheaper shipped than Auto Zone or O'reilleys wanted for their junk.
 
Another solution is AMSOIL's propylene glycol antifreeze/engine coolant. Compatible with all ethylene and propylene formulations, as well as OAT and HOAT formulations. Has service life of up to seven years or 250,000 miles. It also adheres to metal and self-seals hairline cracks in welds and seams to help prevent leaks without additional stop-leak products or fibrous materials. Single gallons cost $39.45 retail, $30.25 wholesale; case of four gallons $156.10/$115.20. Sales tax and shipping extra either way. Buy wholesale by becoming a Preferred Customer @ $20 per year. Call or PM me for details.
 
Do you guys really think the wrong anti-freeze is causing this problem? I was not aware of the "special anti-freeze" that was required for this vehicle but I'm not having any overheat issues, etc.
 
IMO, not mainly a coolant issue. It's the radiator design commonly seen for some years now - metal core with plastic sides. The heat cycling in normal operation puts a lot of stress on the seams, hoses, etc. The anti-corrosion additives in the coolant deplete over time, allowing further deterioration. Coolant service every 2-3 years helps; another method is drain/refill radiator once a year.
 
First get a new radiator but not from where you were buying the other 3 radiators. I think what you are buying are cheaply made and probably have poor quality control.



Next, use the correct antifreeze/coolant. There is a reason this is important. There are many different metals and plastics used in modern engines and there can be some chemical reactions between antifreeze and some of the different materials the coolant comes in contact with. This was always and issue with cast iron block engines with aluminum heads. Most of that problem has been resolved now, but there is always the potential for the wrong coolant to cause problems.



Finally, spend a few extra dollars and get a new radiator cap, and while you are doing all that go ahead and change out the thermostat, and the radiator hoses. Hoses look good from the outside but rot from the inside. Pieces of rubber can clog up parts of the radiator including the radiator cap vent hose (overflow).



...Rich
 
the problem most likely is the factory 20 psi radiator cap. it's an unusually high pressure in my opinion.



I replaced my rad cap with a 16 psi cap and have never had so much as a drip from my coolant system.
 
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I echo Richard's suggestions.



As Vic said, Fast Parts Network for a Ford OEM might be best.



I would stay with the intended radiator cap. Maybe order an OEM one with the radiator.



Another suggestion: Make sure the mounts are all good. You want the thing mounted tight enough to not vibrate, but you need it loose enough so that it can expand/contract and not be put in a bind.



You might add some Ford stopleak pellets too. Some cars call for stopleak to be added as part of the regular flush/fill maintenance to seal small leaks.



Good luck. This problem sucks for you I am sure.
 
so you don't see any correlation between the 20 psi cap and the leaky radiators? the OEM cap for a 4.6 F-150 is 16 lbs...



Many explorer owners have switched from the 20 psi cap to a 16 which has resulted in no more leaks...
 
You really think that 4 psi makes any difference? That is only a 20% reduction. Plus, now you have lowered the boiling point of the coolant and it is more likely to overheat (which might cause it to fail even quicker).



I would stick with the OEM unless a TSB has ordered the change.



Not trying to be an A-hole here- I just don't think 4 psi is gonna change much of anything, and that the risks are greater than the percieved benefits. Of course, I didn't engineer the thing, so I don't know why they spec'ed a 20 psi cap. Obviously they had reasons to do so, I would hope.
 
For every psi of pressure the rad cap holds it raises the boiling point by approx 3 degrees, so a 15 lb cap would raise the boiling point to approx 255-260 degrees...if your coolant is getting that hot you have other issues. Temperature isn't the only thing that increases pressure on the cooling system though, the water pump introduces pressure also. Most water pumps are high volume low pressure but there are some that create alot of pressure. Chryslers have typically had 18 lb caps on them and anything lower would cause the overflow bottle to overflow because it dumped too much coolant into it even though there was never an overheat issue. You could try a lower psi rated cap but keep a close eye on the coolant level just in case. And yes, 4 psi is considerable when it comes to cooling systems.
 
I'm going to stick with Richards advice. It makes the most sense to me. I will contact Torrie for a price on a Ford rad. Only issue I have with that is that the Ford rad was the first to go bad so I'm not sold on Ford. I believe it's the design from what I have read so regardless of Ford or OEM it's a crap shoot. This is just my opinion. Ironically the "leak" has stopped. Last time it did the same but the overflow tank was empty and when I opened the cap the water level was low as it stopped leaking when it went below the leak. When I took the rad out the leak was way up top and you could see the crusting. It never ends. I do love the truck so I am willing to go the extra mile.
 
Mike beat me to it, but I would say #1 buy a better radiator. I had mine replaced at the dealer on extended warranty for a cracked tank and the replacement listed for over $300. #2, put a lower pressure cap on it. I did after I had the radiator replaced. My son's 2000 Mustang and my wife's 2003 Taurus use a 16 lb cap that is the same size, so ask for one of those. I haven't had any problems with the lower pressure cap.
 
My upper radiator hose pulled away ever so slightly to look like the radiator was leaking at the same spot. Pulled it snug and tightened the heck out of it and has not leaked since and overfill tank stays full, just a thought.
 

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