Coolant suddenly poured out of lower radiator petcock

blacksun43

blacksun43

Member
Supporting Member
Joined
May 25, 2018
Messages
50
Location
West Texas
So it’s about 106 degrees here in the southwest today. 06 TJ running fine. Stop, park and shit off the engine and guess what? Coolant began flying out of the radiator petcock/drain. It appears that I can close it properly, but why would that happen? Lost a lot of coolant. thx in advance


Sent from my iPhone using Tapatalk
 
That sounds to me like your radiator burst. Either that or your radiator cap burst and needs to be replaced. If it's the latter, replace it with the following cap: Stant #10234
 
I had this happen to me several times this past summer.

My engine sits on 100 degrees celcius (AU spec) once warm on the gauge.
On hot summer days (35-40 degrees celcius) if I leaned on it a bit hard it would dump a load through the over flow.

I connected up the scan gauge and started monitoring the temps through it.
On cooler days I couldn't replicate it, even after giving the motor a hard run up to red line though the gears. But the next hot day it did it again.

My findings were that these motors run quite warm, and combined with an old radiator cap where the spring has probably lost some strength it only took a rise in 3-5 degrees in engine temp for the cap to blow it's relief.

In conclusion, planned on replacing the cap but instead I stopped thrashing it on hot days and I've not had the issue since.

Before next summer I will flush the cooling system and replace the cap, but it's winter here at the moment so I'm not overly fussed.
 
  • Like
Reactions: Arrcee
Radiator didn’t burst and cap is good. I was able to fill the radiator again, but I’m thinking the pump or thermostat isn’t working. I just drove it about 5 mins and the temp gauge shot up to the red 260 mark. Thoughts?


Sent from my iPhone using Tapatalk
 
Check the basics.
-Is the serp belt there? make sure it hasn't snapped an come off. (usually your alt light will come on)
-Check the radiator cores, are they blocked and full of mud.
 
blacksun43 said:
Radiator didn’t burst and cap is good. I was able to fill the radiator again, but I’m thinking the pump or thermostat isn’t working. I just drove it about 5 mins and the temp gauge shot up to the red 260 mark. Thoughts?


Sent from my iPhone using Tapatalk
Click to expand...
Could be a stuck thermostat, any idea of when it was changed last? Might be a good idea to just replace it. Mine stuck a few times last year and it overheated like that, replaced it and its been fine ever since. Though I did replace the water pump too cause I had no idea when it was last changed. Easy fix.
 
EJD said:
Could be a stuck thermostat, any idea of when it was changed last? Might be a good idea to just replace it. Mine stuck a few times last year and it overheated like that, replaced it and its been fine ever since. Though I did replace the water pump too cause I had no idea when it was last changed. Easy fix.
Click to expand...

Yup. My thoughts too on the T-stat and pump. I bought the jeep used last year, so it’ll be a good idea anyway. I’ve also heard that a bad radiator cap can cause problems.


Sent from my iPhone using Tapatalk
 
blacksun43 said:
Yup. My thoughts too on the T-stat and pump. I bought the jeep used last year, so it’ll be a good idea anyway. I’ve also heard that a bad radiator cap can cause problems.


Sent from my iPhone using Tapatalk
Click to expand...

40FF8853-B435-4FCD-A115-3A7C09E03DB4.jpg
stopped for a slurpee



Sent from my iPhone using Tapatalk
 
  • Like
Reactions: EJD
Any ideas on what to do with this Tong Yang Group radiator made in Taiwan? [emoji57][emoji848]

25b490fdb79c1685034ef2f1858d85c0.jpg
 
Last edited:
Stockli said:
I do t understand how the petcock was opened?

It opened on its own? Or pressure built up and blew by it?
Click to expand...

I think pressure built up and blew by it. Never seen that on any of my vehicles in the past and I’ve been in some extreme heat.

Orrrrr...I didn’t tighten it correctly last time I opened it? [emoji51]


Sent from my iPhone using Tapatalk
 
That's coolant from the heater hose.
The hose might still be ok, but replace that clamp with a jubilee clamp.

The cooling system is sealed and under pressure as the coolant boils at a higher level when under pressure.
Having a small leak would make the system not under pressure.
 
  • Like
Reactions: Arrcee
blacksun43 said:
Yup. My thoughts too on the T-stat and pump. I bought the jeep used last year, so it’ll be a good idea anyway. I’ve also heard that a bad radiator cap can cause problems.


Sent from my iPhone using Tapatalk
Click to expand...
Yes, 100% true. This one with red tab is bad to my two TJs. They over pressurize the system and the hoses bulges. And so I threw them away and put back my old ones.
th?id=OIP.mJP2aMdnqSGpBzYkL8c8ugHaHa&pid=15.jpg
 
  • Like
Reactions: KCsTJ
blacksun43 said:
I think pressure built up and blew by it. Never seen that on any of my vehicles in the past and I’ve been in some extreme heat.

Orrrrr...I didn’t tighten it correctly last time I opened it? [emoji51]


Sent from my iPhone using Tapatalk
Click to expand...
Pressure should not cause coolant to blow past the petcock that is what the spring in the cap is for. It compresses and allows coolant into the reservoir tank.
The issue may be the aftermarket rad that allows the drain to open due to vibration. Is it easy to turn?
 
05 Blue Unlimited said:
Pressure should not cause coolant to blow past the petcock that is what the spring in the cap is for. It compresses and allows coolant into the reservoir tank.
The issue may be the aftermarket rad that allows the drain to open due to vibration. Is it easy to turn?
Click to expand...

It seems to have decent grip, not easy to turn. I removed the drain valve yesterday, inspected it and the o-ring/gasket and it had some particles on it I removed. Seemed to fit better when I reinstalled.

Then Filled up with water only, idled for 10mins. No leak. Drove it about 4 miles round trip and it started dripping slowly then a bit faster. Because I bought this jeep used and I’m noticing a lot of rust and particles in the coolant, I’m going to go ahead with replacing the radiator to stock Mopar. While I’m there, I’m going to install an ATF cooler.

I’m going to try a replacement drain valve today just to see what happens. It’s an inexpensive part that may be a temporary fix until the radiator gets here.

Thanks for the assistance all!


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: KCsTJ and 05 Blue Unlimited
Top Bottom
Back