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Coolant leak, dont know where to start.

C

Cheap5.0

NAXJA Forum User
Location
MI
Today i am digging out/moving my vehicles around to make sure i can get out tomorrow for work when i noticed coolant on the snow. A pretty good amount, maybe 1/2-1 cup total spread over the range which i drove the XJ.

Warmed up temp stays at 210, but my heat has been lacking (i just bought it 2 weeks ago). I checked the top rad hose, the bottom of the rad and the overflow container. The hose and radiator look good, old...but good. The overflow container however was empty. I can smell a very faint coolant smell (no smoke out of the exhaust), like its hitting the header/exhaust...? I cant tell.

Any ideas where i should start on this? I popped the cap on the rad, and because it was warm some coolant spilled. But after removing the cap, i could see coolant directly under it...so does this mean the radiator is full?
 
I'd check underneath the front of the engine for a coolant trail down onto the lip of the oil pan and/or dripping from the lower hose.

When coolant leaks out of the weep hole of your water pump this is where it usually goes.

Good luck.
 
Thanks, i was already all cold/snow covered so i was crawling around under there looking for the green stuff and i could not see a thing. I spent 10 minute scouring it all over, and other than the stuff in my driveway i did not see anymore coolant.
 
Ive been thinking, the first thing i wanted to rule out would be catastrophic problems (blow head gasket/cracked head). Im downloading the FSM now to get familiar with the layout. Are there any quick tests to rule out a big problem? I dont have a leak down tester handy either...
 
Found this on JF. Since i am seeing it in the driveway, and not getting smoke its safe to assume at this point (still have to check my oil) that a catastrophic issue is not the cause here?

When a head gasket goes coolant can either leak into a cylinder, where it burns up with the combustion process OR it leaks into the oil (causing your oil to look brown and milky) OR it leaks into the cylinder and doesn't all get burned up, the remainder ends up in your crankcase (there we go with the brown and milky again).
Click to expand...
 
If you can't see a trail of any kind, I'm gonna guess that it may be your radiator that is leaking. All the other cooling system parts usually have dead giveaways when they are failing/have failed. If a hose, water pump, and maybe even a cap have failed, they will have trails of coolant originating from the point of failure. When my radiator started leaking, however, it showed no trails, but there would be a small puddle of coolant under the front of the XJ every morning, like it was just slowly weeping out. I replaced it last week with a CSF radiator and haven't had a single drop of coolant under the XJ since.

First, verify to the best of your ability where the leak is coming from. Second, get replacement parts and take care of the problem. I thought I would just keep feeding mine coolant cause it is so inexpensive, but for a little over $130, a new radiator didn't break the bank either. Good luck.
 
jeeperguy21 said:
If you can't see a trail of any kind, I'm gonna guess that it may be your radiator that is leaking. All the other cooling system parts usually have dead giveaways when they are failing/have failed. If a hose, water pump, and maybe even a cap have failed, they will have trails of coolant originating from the point of failure. When my radiator started leaking, however, it showed no trails, but there would be a small puddle of coolant under the front of the XJ every morning, like it was just slowly weeping out. I replaced it last week with a CSF radiator and haven't had a single drop of coolant under the XJ since.

First, verify to the best of your ability where the leak is coming from. Second, get replacement parts and take care of the problem. I thought I would just keep feeding mine coolant cause it is so inexpensive, but for a little over $130, a new radiator didn't break the bank either. Good luck.
Click to expand...

Thanks, i just went out and took another look. No puddle/drips anywhere. The overflow container was empty though, so i added to the "add" line and left it there.

I took a 200 lumen LED flash light (super bright) out and looked at the upper hose, the two heater core hoses, the bottom of the engine/front bottom of engine and the radiator. No coolant anywhere on those items. I do have a black light though, if the problem is still there tomorrow ill black light it before hand and mark any spots that glow...then add some of the UV additive, drive it and see if any new spots show up.

Im still not clear on how to determine if the radiator is full or not though...?


EDIT: Forgot to ask, is there a good way to check the weep hole on the front of the pump? I could not get a good angle no matter what... I did inspect the hell out of it, and i could not see any coolant on or below it.
 
If you take of the radiator cap, see coolant, and can't pour any more in without it overflowing, it's full.

If the water pump is failing, you'll see a trail of coolant coming from it, which usually ends up dripping off the bottom of the lower radiator hose. No trail/coolant and it should be working fine. The UV light idea is great. Let us know what you find.
 
Ill keep an eye on it. By the above standard the rad is full, but i gotta wonder where all the coolant came from?

Ill grab a UV lamb tomorrow at work, then try to get some dye somewhere local.

Is there any way a failed catch can can leak the coolant over rough terrain? I was kind of bouncing around moving through the 2 ft of snow we just got...it was a rough ride.
 
Since you said hitting the exhaust, and smell it after it has reached the operating temperature, sadly my guess is a bad core/welsh/freeze plug. Why? Because i`m going through the EXACT same issue and have really ruled everything else out. When you turn it off listen if you can hear the drops drip on the down pipe and sizzle...

I just don`t know if mine is one of the "easier" side plugs, or the dreaded back of the head/ even more dreaded back of the engine block covered by the trans plug



Good luck either way and please share what you find.
 
What year/engine?

Leaks can be difficult to find. And fluid "migrates" and where it leaks on your driveway is not always where the leak has started.

Best to get it up on a hoist and inspect carefully with a GOOD light. Usually you can find it this way and best to do this with a hot/pressurized engine.
 
willsmysticcobra said:
Since you said hitting the exhaust, and smell it after it has reached the operating temperature, sadly my guess is a bad core/welsh/freeze plug. Why? Because i`m going through the EXACT same issue and have really ruled everything else out. When you turn it off listen if you can hear the drops drip on the down pipe and sizzle...

I just don`t know if mine is one of the "easier" side plugs, or the dreaded back of the head/ even more dreaded back of the engine block covered by the trans plug



Good luck either way and please share what you find.
Click to expand...

Ill hope and pray its not on of these. Since this is a budget ride, whats the best option if this is it? Just keep topping the system off and watch the temp gauge?
 
birchlakeXJ said:
What year/engine?

Leaks can be difficult to find. And fluid "migrates" and where it leaks on your driveway is not always where the leak has started.

Best to get it up on a hoist and inspect carefully with a GOOD light. Usually you can find it this way and best to do this with a hot/pressurized engine.
Click to expand...

Sorry, im used to JF.

1999, 4.0 auto.

I just checked it again when i went out and started it to warm it up, and now i cant see anything. Looks like this one will be fun...
 
Cheap5.0 said:
Ill hope and pray its not on of these. Since this is a budget ride, whats the best option if this is it? Just keep topping the system off and watch the temp gauge?
Click to expand...

Either a rubber expanding plug or just take the intake manifold off and try to go around the header to fix... if its the one on the head or behind the block... God help us lol
 
hehe

I just got home from work, i backed out of the spot i was parked in all day and again not a drip of anything (oil, green, mud....nothin).

So far this was a one time thing that i can not recreate. What should i make of it?
 
Freak occurence maybe...My rear main seal started leaking, causing plumes of smoke on the highway one day. I pulled over and verified it was in fact the RMS. Once I got to my destination, I let the XJ cool over night; pricing out parts to fix it the next day. Have not been able to recreate it since and that was like 3 months ago. Weird
 
willsmysticcobra said:
Either a rubber expanding plug
Click to expand...

Using the rubber plugs really isn't a good idea - just use the correct-sized brass replacement. Take the time to remove the old plug and prep the area properly; it'll be much better in the long run.
 
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