Possible coolant leak

[PrinceMiro]

Ok I've done my research, but wanted to start a thread to get some advice. My oil cap has the mustard looking gunk on it, indicating there is moisture/coolant on it. There is some (barely any though) of the gunk on my dipstick. I know many people say this is due to condensation caused by short drives. However, some people have said it can be an oil separator, expansion tank, or (worst case scenario) a head gasket issue.

I thought I'd post this to get some advice as to the steps I should take (e.g. change oil first and wait to see if it reoccurs then, if it does, replace the......)

Thanks in advance!!

[WestCDA]

Unfortunately a worst case scenario is a cracked block - but that's not something you see frequently. A compression test will often expose a blown head gasket.

[G80indy]

let's start with a few basics:
what's your OCI, the oil you use, and how consistently you use it.
all kinds of variables in play.....

[BruceJ]

Originally Posted by PrinceMiro

I know many people say this is due to condensation caused by short drives.

Is that your situation? if so I would tend to agree with them. short drives are the death of engines, nothing ever heats up, burns off, blah, blah blah, etc....

Same thing happend to my Dad in his 87 Buick Regal about 2 years ago. He bought it new and it only had 69k on it.

Since the cooling system is pretty much a closed system, you can test it. Not as easy if we had clear expansion tanks but can be done.

Equip - You'll need a turkey baster - No laughter please!
1. Find a flat level surface - ie your garage hopefully - you can even mark where the tires are, note the pressure in all 4 tires, note the temperature in your garage if you want to get anal about this.
2. Let the engine get STONE COLD - i.e. sits overnight
3. Open the expansion tank
4. Check the little coolant level indicator that hopefully pops up when you opened the cap.
5. Now, using the Turkey baster pull fluid out until the indicator is at bottom of its range, then slowly fill it back up until you can tell two things.
a. Its clearly NOT maxed out
b. Its at an exact height you are able to note exactly. You can match some interior line or mark the height with a scribe.
c. Take picture.

After doing the above drive the car DAILY for a week. Engine needs to get up to temp every time, 30-40 min drives daily.
NOTE: If you dont enjoy this part bring it to me and I'll do it. Your car will look satisfied!!!! No complaints about your tires though!!
Then put the car back where you first tested it, let it get STONE COLD again and check the level again. In a weeks time you probably shouldnt normally loose anything noticeable. if it does change you can even tell exactly what it lost by measuring any fluid you add first.

On Cars that have clear expansion tanks this is much easier, you just mark it at its visible level with your fine tip marker and check it in a week or so.

Even if you have a noticeble change - dont immediately think cracked block/head/head gasket. Start looking for leaks.

No change, I'd do it for a month - if still no change then its been thoroughly tested.