Spraying coolant from rad cap

[Volatile]

Sorry in advance for the long post, I hate cooling systems.

So after finally getting my brake issues addressed, I finally got my '91 through inspection after sitting for a little over 3 years. I've been driving it every day for about 4 days with no issues, but I have noticed that the temp gauge creeps above 210 when sitting in traffic. This is happening in 90*+ temps. If I hit ~230*, the e-fan kicks on and the temps fall back down. This is how I remember it running when it was on the road previously.

Today though I was running some errands and came out of the grocery store to find a puddle of coolant under the driver's side. I popped the hood and it looks like coolant was spraying from the radiator cap. I'm guessing this is the case because the hood blanket was damp directly over top of it, as well as the front of the airbox and the area where the hood latches was wet with coolant. It's about 94* today, and I had the AC running before I stopped, but I never got above maybe 220.

I drove it home, let it cool, popped the cap (which was on so the warnings were upside down) and the coolant looks fine. The overflow jug coolant is a brownish color though as opposed to the green under the cap. The hose coming from the thermostat housing was hot so I'm assuming that it's working properly. I squeezed the hose from the thermostat and the level drops under the cap.

I fired it back up after putting the cap back on (so the warnings were no longer upside down) and let it idle for a good half hour. No issues, no spraying, nothing. I ran the AC, still no issue. There are bubbles coming up into the reservoir while it's running.

Could it be that the cap just wasn't sealed properly? I'm at a loss here and don't want to risk an overheat scenario. I am hearing a really loud, rapid dripping coming from somewhere in the motor right after I shut it off. I took a video but can't find anywhere to upload it.

Edit: I took some pictures of under my cap and what looks like a drip from under the filler neck.

Coolant:

Drip from under cap. I can't tell if this is dripping from taking the cap off, or if it's coming from the filler neck itself.

Thanks!

 

[ehall]

I once had a cap on my Cadillac that only worked one way, relief spring was only on one side. Haven't ever seen another one like that though.

Does your cap show that its a relief cap? should give a PSI number as well.

 

[Volatile]

It's 16 psi, and I'm guessing it's the factory cap due to having the Chrysler logo right on top.

 

[old_man]

What year and engine is it? Radiator caps should be replaced every two years.

Hopefully the bubbles coming out of the radiator are simply the engine burping an air bubble, and not a cracked head or head gasket.

 

[Ecomike]

His post first post says 91. My radiator caps seem to outlast my radiators and vehicles, usually 10-15 years. But I have seen many off the store shelf that were junk when new. I always pressure test new ones.

But I agree, caps are cheap, and should be swapped first. I wonder if his overflow hose is leaking at the radiator neck?

Sounds like he may be ready for a new fan clutch (comments about heat up at idle), that drops when driving.

What year and engine is it? Radiator caps should be replaced every two years.

Hopefully the bubbles coming out of the radiator are simply the engine burping an air bubble, and not a cracked head or head gasket.

 

[ExpedBonnie]

I just bought my first XJ and I have the exact same issue with mine. It happens so randomly. I truly think its a cracked head or gasket. I plan to dig into mine in the next few weeks. I live in CO and want this resolved by winter.

 

[Volatile]

His post first post says 91. My radiator caps seem to outlast my radiators and vehicles, usually 10-15 years. But I have seen many off the store shelf that were junk when new. I always pressure test new ones.

But I agree, caps are cheap, and should be swapped first. I wonder if his overflow hose is leaking at the radiator neck?

Sounds like he may be ready for a new fan clutch (comments about heat up at idle), that drops when driving.

Correct, it's a 91. I checked closely around where the overflow hose meets the neck, and didn't see any evidence of leakage. I picked up and installed a new cap, but upon installing it realized it's rated at 13psi. Will this be an issue?

I also topped off my reservoir as it was just below the add line. I ran it for about 15 minutes in the driveway just to check for any overt leaks. I'll see how she fares tomorrow when I take it out.

 

[Ecomike]

I would never go under 16 PSI, and I always make them grab a rental tool (or bring the one I own) and test cap seal at 16 psi before I buy it. You'd be amazed how many fail at 70-80% of the rated pressure.

 

[mcguyver_xj]

wanna say stock is 18 psi and if its to low the pressure in the cooling system can overcome the spring and spray out from the cap whether or not there is another problem that would need to be diagnosed

 

[lawsoncl]

wanna say stock is 18 psi and if its to low the pressure in the cooling system can overcome the spring and spray out from the cap whether or not there is another problem that would need to be diagnosed

It shouldn't spray out the cap even if the spring is weak. If the spring is weak it should be dumping out the overflow tube.

 

[Green XJ Jeep]

It shouldn't spray out the cap even if the spring is weak. If the spring is weak it should be dumping out the overflow tube.

Unless the over flow is plugged.

 

[ParadiseXJ]

I don't believe there is an 18 lb. stock cap. If you go to any chain cheep-o auto parts place, the computer tells the counter guy that a 13 lb cap is OEM. I can't tell you how many times I've had to insist I want a 16 lb. cap.

Check the cap itself for cracks or imperfections, and the rim of the radiator hole for same, AND if you're feeling ambitious, remove the hose and blow into it to see if it is free flowing and not clogged or restricted. If not, go get some new bulk hose...about 4-5 ft. of hose Then replacing the cap with a with a good quality 16# cap.

If you've been driving it and CAN drive it for any distance without the oil turning into a milkshake, your head gasket is almost surely OK. If you haven't already, go rent/buy a pressure gauge to test not only the cap, but the rest of the system.

A compression test might be in order too...if you need to go that far.

 

[Ecomike]

I have had head gaskets leak just small amounts of exhaust gas into the cooling jacked with no other signs other than overheating and or overflow.

I don't believe there is an 18 lb. stock cap. If you go to any chain cheep-o auto parts place, the computer tells the counter guy that a 13 lb cap is OEM. I can't tell you how many times I've had to insist I want a 16 lb. cap.

Check the cap itself for cracks or imperfections, and the rim of the radiator hole for same, AND if you're feeling ambitious, remove the hose and blow into it to see if it is free flowing and not clogged or restricted. If not, go get some new bulk hose...about 4-5 ft. of hose Then replacing the cap with a with a good quality 16# cap.

If you've been driving it and CAN drive it for any distance without the oil turning into a milkshake, your head gasket is almost surely OK. If you haven't already, go rent/buy a pressure gauge to test not only the cap, but the rest of the system.

A compression test might be in order too...if you need to go that far.

 

[lawsoncl]

I have had head gaskets leak just small amounts of exhaust gas into the cooling jacked with no other signs other than overheating and or overflow.

Same here. I just did the head gaskets on an Equinox that was randomly overheating. It was just enough air into the head that every once in a while it wouldn't self purge the air and vapor lock the head and overheat. The wierd symptom was the overflow bottle making duck sounds when you reved the engine. All 6 people I know with 2005 or 2006 equinoxes have had to do the head gaskets about 150k miles.

 

[Ecomike]

Mine was the 96 Ford Taurus, 3.0 Vulcan engine. Twice in 10 years, between 180,000-300,00 miles. Son was driving on the freeway when the bottom radiator hose blew up. It never had a chance. 100% coolant loss in seconds at 75 mph. But I kept it running with Bars leak sealant pellets for ages. Finally the micro cracks in the head forced us to replace the heads.

Same here. I just did the head gaskets on an Equinox that was randomly overheating. It was just enough air into the head that every once in a while it wouldn't self purge the air and vapor lock the head and overheat. The wierd symptom was the overflow bottle making duck sounds when you reved the engine. All 6 people I know with 2005 or 2006 equinoxes have had to do the head gaskets about 150k miles.

 

[Volatile]

I don't believe there is an 18 lb. stock cap. If you go to any chain cheep-o auto parts place, the computer tells the counter guy that a 13 lb cap is OEM. I can't tell you how many times I've had to insist I want a 16 lb. cap.

Check the cap itself for cracks or imperfections, and the rim of the radiator hole for same, AND if you're feeling ambitious, remove the hose and blow into it to see if it is free flowing and not clogged or restricted. If not, go get some new bulk hose...about 4-5 ft. of hose Then replacing the cap with a with a good quality 16# cap.

If you've been driving it and CAN drive it for any distance without the oil turning into a milkshake, your head gasket is almost surely OK. If you haven't already, go rent/buy a pressure gauge to test not only the cap, but the rest of the system.

A compression test might be in order too...if you need to go that far.

Well I put around 100 miles on her over the weekend with the new 13psi cap and *knock on wood* everything has been back to normal with no more spraying or anything like that. The seal on the old cap did look pretty worn after 167k miles, and the new one physically fits much more snug. I'll take off the overflow hose and make 100% sure it's not clogged or anything still. Thanks for the tip.

When I find the time to do a proper flush in the next week or so I'll more than likely rent a pressure tester to give myself peace of mind that nothing else in the system is leaking.