[Landiah]

Saw this when moving into my new garage. Can’t lift the car, wondering if it could be from the A/C? Those are the front wheels visible in the pic, leak is what looks like is staining the exhaust. Strangely never noticed anything on the ground d under the car. Any ideas?


Edit: no idea why my photos are coming out upside down and sideways when I upload from my phone

[Tag]

Hard to say, could be cosmoline.

Here's the pic right side up.

[Landiah]

Could it be coolant?

[RockCrusher]

Originally Posted by Landiah

Could it be coolant?

That would be my guess. White residue is the remains of dried anti-freeze.

A hot cooling system pressure test can help you determine if the cooling system is leaking.

I'd rinse the area with a garden hose to remove any residue. Where you see it and above where whatever the fluid is is leaking from.

Then be sure the cooling system level is topped up. If low you can use distilled water. Do not over fill the system but the fuller the better. Be sure the cap is screwed on correctly and properly tightened.

Turn off the A/C.

Start the engine and drive the car around on city streets until the engine is fully up to temperature. Coolant and oil.

You then want to continue to drive the car until the radiator fan comes on. If I can't tell by sound I've used an OBD2 scan tool to monitor coolant temperature. I observe the coolant temperature rising then note at which point it begins falling -- as the fan is switched on.

Once the engine is hot enough to switch the radiator fan on head home. On your driveway then raise RPMs to ~1K and hold until the radiator fan is switched on. Turn off the engine.


The heat load of the engine will raise the coolant temperature and pressure. And all the cooling system hardware is hot.

Carefully observe the engine compartment for coolant leaks. Check under the car for coolant dripping. Use your nose. Any odor of anti-freeze is a sign of a leak.

That you see the white residue on the exhaust is a sign coolant is dripping down on the exhaust and I would believe the odor of anti-freeze would be present.

There may be a leak but it is above the coolant level. This is a pressure leak. But what this can result in is the hot coolant boiling and this raises the coolant level and pressure and can force coolant out of an overflow valve.

I've done the above test several times over the years and found a leaking pressure cap. (Tented the cap with aluminum foil and it collected condensation arising from water vapor leaking past the cap.)

Another time I found a leaking plastic coolant tank. With the coolant hot and the tank hot (and the plastic pliable) the pressure caused the tank to open along its bottom mold seam and gush hot coolant. At the dealer the tech removed the tank and it was obvious the tank had been seeping coolant from that crack for some time. (My SOP is to give the engine time to cool down some before shutting it off so parking the car with the engine hot enough to have the radiator fan(s) running is a rare event for me.)

Yet another time the hot coolant test found a pinhole leak in a radiator.

Then another time -- years later with another car -- coolant leaking past where the bottom tank was attached to the radiator core was found to be leaking.

To be sure the stain doesn't have to be from a coolant leak. That is I've seen white residue from a coolant leak but it is possible the leak is not coolant. Could be windshield washer fluid.

Could it be brake fluid? I don't know. I've never seen brake fluid leak onto a hot exhaust. However, I've seen oil. The oil doesn't leave a residue but the odor of hot oil is unmistakable. Also if the leak is bad enough one can see white oil vapor wafting up from the engine.

[k-m2-j442]

Looks like coolant. I had a number of coolant leaks on my old mini and all left a very similar white residue. Depending on where the residue is...it could be not a leak and just some spilled coolant from topping off at the dealer or something that burned off when it got hot. I'd rinse it off and monitor the coolant levels/temps/area for more residue.
Note: I don't know whats above it as I don't have my M2 yet so I can't say oh sure the reservoir is right above it or anything like that.

[Landiah]

That’s good test to know. Unfortunately I don’t have an OBD tool and won’t be able to run that test. I’m going to rinse it off and keep an eye on it. Sending some photos to my dealer and see what they think. Might bring it in. Glad I noticed it before I bought a new exhaust… if it is a leak I wonder what could have caused this.

[DomMuc]

in this area is the a/c condensation drain....

[Landiah]

Originally Posted by DomMuc

in this area is the a/c condensation drain....

That’s what I thought at first but the white streaks wouldn’t make sense with just water. Or am I missing something?

[DCC]

Doesn’t look like coolant.
It’s so clean looking it could be assembly oil or grease of sorts imo

[RockCrusher]

Originally Posted by DomMuc

in this area is the a/c condensation drain....

I've never encountered a car with an A/C putting water from the evaporator onto any part of the car. The drain hose/pipe is designed to put the water on the ground. Underway the drain hose/pipe opening is in a low pressure area to avoid water building up and over flowing the catch basin.

Sure there could be a problem with the A/C water drain: Hose/pipe loose or something. An inspection of this by a tech should be able to spot something amiss in no time.

[RockCrusher]

Originally Posted by Landiah

That’s good test to know. Unfortunately I don’t have an OBD tool and won’t be able to run that test. I’m going to rinse it off and keep an eye on it. Sending some photos to my dealer and see what they think. Might bring it in. Glad I noticed it before I bought a new exhaust… if it is a leak I wonder what could have caused this.

Consider leaving the stains alone and having the car in to have it checked out.

Really I think it worth having the car in to have this looked into.

In the meantime if you can't run the hot pressure test you can still after you park the car after some use check for any odor of anti-freeze. Any odor is a sign there's a leak.

And look under the car for any signs of liquid. Just plain water is probably from the A/C evaporator. If the liquid feels slippery between your fingers and is water soluble that's coolant.

Slippery and not water soluble can be oil. Not sure what brake fluid might feel like but I believe it would be water soluble.

If the stains are from a coolant leak there are a number of possible leak points. Hose connections. Water pump seals. Radiators. Heater core. Sure a coolant leak with a new car is a rare event. But not impossible.

[Xeon555]

It's ac don't worry about it

[Lynn133]

New here and I can’t figure out how to ask a question a different way, but need to attach pic and not sure how to do that here. I have oil leaking on the passengers upper side. Below the plastic cover and around the area of the first set of screws maybe a little lower. Wondering what type of oil leak this is?

[Lynn133]

Is the silver thing circled a gasket? Oil leaking around that area

[DCC]

Looks like the valve cover gasket is leaking

[M_Power Rob]

Originally Posted by Lynn133

Is the silver thing circled a gasket? Oil leaking around that area

No offense but that engine looks filthy. What year and model, and how many miles?

[M4884T]

I’ve noticed a similar leak on my car aswell. Any update as to what this is?

[Landiah]

Originally Posted by M4884T

I’ve noticed a similar leak on my car aswell. Any update as to what this is?

Have an appointment in a week to get this checked out. I’ll let you know. I wonder if anybody else on here has seen anything similar under their car.

[DomMuc]

Still A/C

[Xspeedracer]

It may be body wax or something mine had this near the ac drain port but if it was coolant it would be stained the color of the coolant

[Landiah]

Got the car checked out by the dealer. It’s nothing to worry about. Something to do with some kind of rust protectant.

[RockCrusher]

Originally Posted by Landiah

Got the car checked out by the dealer. It’s nothing to worry about. Something to do with some kind of rust protectant.

Glad to read it was nothing serious.

My Cayman S came with a heavy coating of rust protection. (See pic below.)

No signs of any protection on the exhaust but the pic was taken at ~750 miles and if any had been on the exhaust it would have burnt off with that many miles of engine run time.