I hate to start yet another coolant leak thread, but...

I can't figure out where it's leaking. I noticed a good puddle of coolant in the garage a couple of hours after I got home this evening. It's actually dripping off of the front differential, flowing down the oil pan and over the backside the diff. I've been under there for a about an hour trying to see where the flow is starting, but no luck.

Where the heater hoses go into the firewall is fine, but I can't see where they go into the engine, so that could be a place. I checked the thermostat housing, and the throttle body area, as I read those could be culprits, but no dice.

My oil is fine (not milky), so I'm hoping my gaskets are ok, but my coolant was down about 5 cups in the radiator. Tonight was the first time I noticed the leak.

Any suggestions would be great. Thanks.

TJ's and mine leaked from the headgasket at the front outside corner of the drivers side head. It was very hard to tell where it was leaking from. Good luck.

There is also a thread about a leak from the oring around the wax pellet which is right near the throttlebody.

Just methodically inspect the entire head gasket perimeter.

If still flumoxed, add UV dye to the coolant, and use a matching UV light to hi-light the leak point(s).

Eitherway...you should be able to find it.

If you lose coolant, but not oil...and not TO the oil...it would be like mine...coolant to the engine exterior.

My leak was the drivers side as mentioned, but more to the rear of the engine, facing the back actually...tucked WAY up there and hard to see.

A jar of stop leak, and it was cured.

Well, for a few thousand miles, including to Canada and back, etc...and then I hydrolocked the engine and swapped in a new engine altogether...so the stop leak never failed at least.

Edited to:
Did you use "Bars Stop Leak"? After some searching, it seems that's a standard across the field, although with mixed results and longevity.

There is also a tiny little bypass hose next to the distributor that can leak (that's what happened to Carlton). You pretty much have to take the timing belt rear cover off to get to it.

there is 2 hoses under the upper intake manifold that I have had to replace.

How has my Xterra leaked? Let me count the ways....

1) Passenger side head gasket. External only, no leak into the oil. Was caused by a faultily cast head - they replaced the head too (after overnighting it in )

2) Six months later rear heater hose. Where the metal ones behind the engine meet the rubber. Ran down the top of the engine and looked like it was the water pump.

3) Two months later - Bypass hose - also on top of the engine, leaked out the front - was pissed they didn't change the water pump the first time - turned out to just be the @%#$ hose.

First was covered by the powertrain warranty. I ate the second Third was covered by the extended warranty.

I'm almost afraid to look under the truck in the morning....

So, a little update. I have driven the Xterra twice now, taking it easy and watching the temp guage - about 5 miles yesterday, and about 25 miles today, both with some highway, some street. I haven't lost a drop of coolant. The areas I had seen moisture around the block are completely dry, and nothing dripping to ground. Radiator is full.

So here's a theory. My drive from work is about 3 miles, easy driving. Is it possible that during this short drive, my thermostat didn't have time to open, and once I parked, the excess heat caused a little "spew"? Not saying that I don't have a leak, but maybe just one prevelant only during high-pressure situations. If it's not dripping to ground, I'd rather not have anyone try to work on it. Thoughts?

dunno.. hey - do you still have the original hoses and hose clamps? The spring type clamps suck and may have loosened up over time. The last 2 times I smelled coolant it was because my upper radiator hose clamps had loosened up (screw type).

My advice is to keep driving it and keep an eye on the coolant level both in the overflow bottle and in the radiator (check when cool only ). Most leaks in my experience don't lead to catastrophic failures that you have to stop immediately for (unless a hose flat out splits open - when then makes it easy to identify ) - so hopefully over time you'll be able to find the problem.

btw - I'll be in town on weekdays starting Monday if you need any help. I've now been involved with 3 timing belt replacements including my own - so I'm pretty familiar with how things are put together in there.

Looks like leaks aren't all that rare. I just had my 04 in to have the upper rad hose clamp replaced. My wife took it to work while I was fixing her Grand Prix, and calls to tell me all the coolant had leaked out of my truck. Not a good day. At least it was coverd under warranty.

Something bad happened to my cooling system tonight!!! Smelled that lovely burning sugar sweet smell and saw a nice puddle in the drive way. Took off the front skid plate and it was covered in coolant as was the pasenger side suspension!!!! Checked the upper/lower hoses and they are fine??? Checked the radiator and no visible dents, dings, holes, etc???? Then i noticed that the radiator cap was almost completely off?????? As in i could simply lift it off the radiator. Im gonna take a closer look tommorow and if i cant find anything ill have my wife take it to work and have one of her techs look at if for me. Ill post up what the issue was as soon as I find out!!! If anyone has any ideas just let me know!!!

Tim

Mine is leaking now too, I replaced a hose and gasket earlier this year. But now I notice antifreeze on the underside of the hood on my X. I guess something is flinging it up there

Well mine finally sprung a leak too. Been smelling the not so sweet smell of antifreeze for the last week. Reservoir tank is still full. From the top I could see several spots where antifreeze had dripped into a small "dips" and dried on the front center part of the engine. Don't see any antifreeze on any of the hoses.
But I can't see where exactly it's leaking from. Oil still looks clean (not milky).

So basically, it's a small leak. Most likely from somewhere on the head gasket, right? From as cluttered as it is in there, I'm going to assume that replacing the head gasket is pretty expensive. So is a can of "leak stop" is my best bet? Any reccomendations on brands?

TJ, this UV die you talked about, is it just a liquid you add to the antifreeze? I've never seen it for antifreeze, just for A/C. Available at Advanced auto or the like?

Not necessarily. Two of my three leaks were hoses. One set of hoses was in the back of the engine, but the coolant ran along the top of the block and down the front (I thought it was the water pump at first).

Water can be a PITA to trace....

Quick update - so 3 months, a couple of thousand miles later and no leaks, no overheating.

I drove 2 hours to Giddings and back on Sunday and 5 miles from the house notice my temp gauge climbing. I turned on the heater full blast and equalized the temp, but by the time I got home I had coolant pouring out the truck and hissing and steam from under the intake. I put almost a full gallon of coolant in after the truck cooled down and drove to the mechanic yesterday. He called today, confirmed the bypass hose had ruptured and charged me $100 total for parts and labor. Hopefully that has me covered.

Always an adventure...