Solved Aftermarket Radiator Pressure Issue?

[ThatOneGuy99]

So when we bought my 99 ex the guy said he put a 3 row all aluminum radiator in, it does great (never seen temp go above about halfway in the gauge), but if we fill the coolant reservoir it starts to leak. My guess is it builds up too much pressure as even after it cools down if I open the cap it shoots fluid out. The leaks look like they come from the cap and looks like a smaller one at a fitting back by the heater core. I was just curious if anyone has seen this or had it happen to them, for now we're just keeping the reservoir empty though.

 

[Mbrooks420]

Is your reservoir dirty inside?

 

[CDW6212R]

The cap is supposed to open to the vent hose as it cools, which allows coolant to go back into the reservoir. How long are you waiting for it to cool down before removing the cap?

It sound like your cap may be bad, possibly both leaking and not opening properly. The reservoir should only be holding about half of the capacity, the lines on it are close but not perfect.

 

[ThatOneGuy99]

The cap is supposed to open to the vent hose as it cools, which allows coolant to go back into the reservoir. How long are you waiting for it to cool down before removing the cap?

It sound like your cap may be bad, possibly both leaking and not opening properly. The reservoir should only be holding about half of the capacity, the lines on it are close but not perfect.

Usually about a day or two to cool off. It's fine when it's filled to the lid of the radiator.

 

[ThatOneGuy99]

Is your reservoir dirty inside?

No not really

 

[CDW6212R]

Usually about a day or two to cool off. It's fine when it's filled to the lid of the radiator.

...My guess is it builds up too much pressure as even after it cools down if I open the cap it shoots fluid out. ...

So does it gush out when it's cold? The coolant should be right at the top of the cap whenever it's removed, any air inside is bad. The coolant level in the reservoir should vary constantly as the system heats up and cools down. It should never get empty or overflow if the level is set between the lines.

 

[ThatOneGuy99]

So does it gush out when it's cold? The coolant should be right at the top of the cap whenever it's removed, any air inside is bad. The coolant level in the reservoir should vary constantly as the system heats up and cools down. It should never get empty or overflow if the level is set between the lines.

We filled the reservoir to the fill line. It goes down and then leaks from random lines and fittings it never leaked from before. The reservoir then doesn't go back up once it cools down. The radiator throws a bunch of fluid up when I take the cap off (once it's completely cold). There's no air in the system as far as I can tell, we burped it pretty thoroughly last time we flushed it.

 

[Mbrooks420]

I’d start by replacing the cap, and making sure the line between them is completely clear.

 

[ThatOneGuy99]

I mean is it really an issue? It's not overheating, never goes over about 1/3 on the temp gauge, and like I said the radiator stays full after it cools off. I just don't want to go tearing the thing apart for something that's a non-issue

 

[Mbrooks420]

It can’t stay totally full hot and cold. If it is, you have a sizable air bubble in the system. You can do anything you wish, it’s your car. But it surely isn’t right.

 

[Turdle]

Whenever doing stuff coolant related, get the front of vehicle as high as safety allows. Since the heater core is higher than radiator cap, coolant may gush out when cap is opened, especially if the vehicle is level or facing downhill.

Raising the front of truck will force air to highest point, hopefully the cap.

 

[ThatOneGuy99]

Whenever doing stuff coolant related, get the front of vehicle as high as safety allows. Since the heater core is higher than radiator cap, coolant may gush out when cap is opened, especially if the vehicle is level or facing downhill.

Raising the front of truck will force air to highest point, hopefully the cap.

We did lift the end up as much as we could when we were burping it, it did have an air bubble in it for a while, but we managed to work it out. Maybe we'll flush the whole thing again

 

[CDW6212R]

The cap and thermostat are more fragile parts than people think, often they fail early for no obvious reason, or are bad out of the box.

It sounds like there is some small leak, but without and obvious source(fix it ASAP when you find it), I'd also replace the cap and verify the vent hose is clean and sealed properly at both ends. I've had a vent hose leak slightly at the radiator, due to old age and swelling there, I cut off an inch and pushed it back on(fixed it).

 

[ThatOneGuy99]

The cap and thermostat are more fragile parts than people think, often they fail early for no obvious reason, or are bad out of the box.

It sounds like there is some small leak, but without and obvious source(fix it ASAP when you find it), I'd also replace the cap and verify the vent hose is clean and sealed properly at both ends. I've had a vent hose leak slightly at the radiator, due to old age and swelling there, I cut off an inch and pushed it back on(fixed it).

There's one underneath the radiator but it looks like the radiator cap spat some out and it ran down and dripped, then there's one on the passenger side towards the firewall but I can't see an obvious trail

 

[Turdle]

Could be leaking heater hoses, heater bypass valve also may leak

Switch to hot temp, and floor vent only
Look for coolant drips behind passenger fender area, onto frame or cat converter

 

[ThatOneGuy99]

I may get some UV dye too and pressure test it, make it a bit easier to spot

 

[ThatOneGuy99]

I have to add this, I went to pick up the pressure tester and the guy behind the counter told me the 4.0 OHV V6 was one of the worst and most unreliable engines Ford ever made. He then claimed to work at a shop and later on in the conversation asked me if the triton V10 was a diesel. Last time I attempt an intelligent conversation with young AutoZone employees

 

[BKennedy]

The leak at the firewall could be the heater core diverter. They are plastic and fall apart over time. There is also a weep hole in the firewall, passenger side about 2/3 down behind the front tire. If it's leaking coolant there, the heater core has failed.

The pressure not dissipating is most-likely the radiator cap. They are cheap and readily available.

 

[CDW6212R]

Watch the radiator cap when you put it on, they are small and don't have a great sealing surface. It's not uncommon for one to not really seal perfectly, either drip then or later when it gets hot. I've had a couple of caps that would barely leak sometimes, and turning it around 180* helped(they can fit better in one of the two possible positions).

 

[ThatOneGuy99]

So I pressure tested the system at 25 PSI (it's kinda high I know), I found three leaks.

I don't know what this one is, I checked all above and around and there isn't a trail and it wouldn't drip for me.

This one started at the front of the block where the water pump meets at the right side and ran down the seam to the oil pan and collected there.

This one is leaking like a sieve under pressure.

The brand of radiator is Tong Yang (pretty sure they supply several Asian brands as well as Mopar) but their website doesn't list a part for the explorer so idk what this radiator was meant for.