Fluid Leak and Smoke (pics)

[Chris_94]

1994 Explorer XLT
4x4
4.0L V6
automatic trans
170k miles and well maintained

Drove to the store tonight. 5 mile trip. Ambient temp 104F. Had the AC on. Spent 1/2hr in the store. Came back out. Started the truck. White smoke coming from underneath the truck. Turned it off and popped the hood. Fluid on driver side of intake manifold.

Fluid looked tan. My first thought was HEAD GASKET!!! :frustrate Then thought maybe the A/C compressor took a dump and decided to vent itself all over the engine compartment.

Please take a look at the pics and tell me if you know what would cause this mess. These are mostly taken from the driver side fender. Looking at the intake mainfold.

Dipstick:

Engine:

 

[arco777]

Does the AC work still? If so it's probably not the AC.

Check your coolant level, perhaps a weak seal at a hose or the cap or somewhere vented the pressurized coolant all over until it cooled off. Check all fluids for that matter.

 

[Chris_94]

Coolent is full in the radiator. No water in the oil. Cap did not vent. No signs of wetness around the cap.

Is there a coolent hose underneath the intake manifold?

There's a wet spot on the insulation thats attached to the hood. The spot on the insulation is right smack over the top of the the intake where all the moisture is. I'm almost sure it's coolent.

It that a coolent temp sensor on the side of the intake? Orange seal and a wire clipped to the back of it. Check pics please.

 

[arco777]

It that a coolent temp sensor on the side of the intake? Orange seal and a wire clipped to the back of it. Check pics please.

That's your IAT (intake air temp) sensor. Coolant temp sensor and coolant temp gauge sender are located below the throttle body near the water neck.

The factory clamps for the upper radiator hose aren't the best and I had the one on the water neck leak before. Worth checking.

 

[Chris_94]

I think the PRD (pressure relief device) on the back of the A/C compressor vented. I charged the system a couple weeks ago because it wasn't cooling very well. I bought a charging can with a guage on it and kept the guage in the "safe" zone - although I did charge it up to about 75% of the recommended 'safe" pressure.

As I indicated in my first post, it's been hot as balls here in the midwest. Temps are in the low 100's. I think the system pressure in the A/C lines went sky high when I shut the truck off. Just like your coolent temp raises when you shut the vehicle off and the engine heat soaks the coolent. I think the freon pressure spiked when the compressore turned off - then top that off with heat from the exhaust manifolds pushing the pressures even higher inside the liquid freon line.

When I started the truck, I still have the A/C button on the dash activated, so the compressore was engaged as soon as I turned the key to start the engine. I think the high pressure in the lines caused the compressor to vent as soon as it began to turn over.

I checked oil and coolent this morning. Looks ok. I started the truck and let it come up to operating temp. Watched the t-stat guage cycle up and down a couple times. It moves about 1/16" up and down as the thermostat cycles open and closed, so I know the thermostat and cooling system is functioning.

No smoke or sweet smell out of the tailpipe. Don't think I blew a head gasket.

It's still smoking up around the intake mainfold, but I think thats residual compressor oil burning off. The smoke is getting to be less and less as the engine runs for a longer period of time. I think if I had a leak, the smoke would be constant.

I put my hand unde rthe A/C compressor lines and felt around where the lines connect to the compressor. There's oil on the liquid line terminal around the bolts that secure the line to the compressor. There's oil all over the PRD nipple and everything behind it - in direct line with the PRD - back to the firewall. I really think I just overcharged it on that day a couple weeks ago and it vented yesterday.

Thats my story and I'm stickin' to it. Hope I'm right.

 

[arco777]

Good deal. Hope that was it. Thanks for posting your find

 

[ppbskis]

Chris you are correct about the a/c expansion vent. I had the same thing happen to me. If the system is overcharged it will blow out just like your pics show. I had to replace my fan motor for the engine to correct the problem.