2 years ago I replaced the timing belt, water pump, thermostat and a few small hoses back there. Along the way, during replacing the radiator hoses, the radiator upper pipe disintegrated. It was about 20 years old, so it gave it’s all in loyal and trusty service so no big deal, and I replaced it with an affordable denso. All worked fine and still does, but I noticed after about six months the occasional puddle of coolant when I reversed out of my fairly steeply inclined drive. Traced it to a cracked coolant reservoir, which literally crumbled when I pulled it out to replace, and all was good once again.

Last year I noticed a tiny drip of greeny/yellow fluid on the floor under the drivers side. Had a look, and the was a drop of apparently coolant on the bottom of the ac compressor, nowhere else. It was tiny, and given the amount of coolant that leaked out of the old cracked coolant reservoir, I assumed that it was probably some lingering residue sloshing about in the nooks and crannies down there. That was about a year ago.

Every few weeks, I just slide under the front of the car to wipe off the friendly deposit of my 8 year old rear main seal leak (which still remains undetectable on the dipstick), and now also wipe off the green/yellow drop from the bottom of the ac compressor that constantly reappears every few weeks. The coolant reservoir level isn’t noticeable impacted.

So I finally decided to try and trace this annoying , if as yet harmless coolant leak. Through the forums and inter webs , I compiled a fairly good list of things to check: water pump, throttle body housing, cold start valve, those annoying hoses just behind the timing cover near the distributor, those Satan’s butt hole pipes at the back of the engine, the area directly under the plenum, though I replaced those hoses when I put a new gasket in ages ago, and every single area I checked is bone dry. It’s an arid scorched desert, apart from the single lone, isolated and persistently reoccurring drop of fluid on the bottom of the ac compressor. And yep, the ac works fine.

What on earth am I missing? Any clues? I’ve spent all morning with the splash guard and air intake off staring up and down at the damn thing, hence the long winded vent, and if you read this far, many apologies.


1997 R50 Pathfinder

Minor update

Just cannot see any sign of coolant leak, residue or seepage anywhere. So tomorrow, I’m going to tape a small plastic bag around the rear or the ac compressor and run the engine with ac on for a while. Hopefully that will tell me whether the drop of suspicious looking coolant is dropping/squirting onto the compressor or if it is leaking from it’s drain port and so be inside the bag....Just can’t understand how the ac can be working fine if it has such a long term leak.

My bet would be refrigerant. A tiny leak like that can take a long time to affect cooling capacity.

Grab a blacklight. If it flouresces under the blacklight, it's refrigerant. If not, it's coolant.

You won your bet......bugger. Oh well, 22 years on the original charge is pretty good going. I’ll wait until it fails then replace the whole lot sans evaporator. Also noticed a hairline crack in the exhaust manifold while I was staring up from underneath. My cup runneth over

Ugh. Well, you've gotten a lot of good use out of it, so she's due for some maintenance and upgrades.

You may get lucky and just need to replace an 0-ring and the coolant charge. I'd ignore the manifold crack or maybe find one in a junkyard.