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Discussion Starter #1
Gentlemen,

Here is my basic info
2002 Mustang GT 5-speed
145,000 miles
just bought it at 144,000
it's my DD

I had a nasty suprise the other day when i went to top off my oil. I pulled off my oil cap and it was milky on the inside of the cap and the visible areas when you look down at the cam.

I am have done a head gasket replacement on a 4 cylinder back in college, so I am not a foreigner to the job and how extensive it is. However the lack of symptoms my car is showing leaves me a little confused in the full diagnosis process. Below are some of the things i have done to try and identify what kind of Head Gasket failure i may be having or if it is something else entirely.


- Dipstick shows no sign of coolant. Looks clean. (I will be changing the oil soon, so when I do that, I'm sure it will show me a lot more.
Oil and Coolant both have a slight leak, but nothing drastic. I put 0.5 qts of oil and 1 liter of water into coolant in about ever other week

- no Check Engine lights, or anything at all, oil pressure and operating temperature have never fluctuated from dead center

  • no white smoke out of tailpipe
  • the block seems to have a darkened/stained look on the driver's side where the head meets the block. below the intake. Other than that, no visible exterior signs of leaking oil or coolant.
  • Bottom side of engine seems to have pretty typical high-milage wet spots near the oil pan and bell-housing mate surface. (this could be the ATF fluid though as i am also in the process of diagnosing a slow trans leak. ) but no signs of milky residue, just oil.
- did a cold start with the radiator/overflow cap off to see if it would bubble at all (I believe this would identify an intake/exhaust gas leak into one of the coolant paths on the head or block). Ran the car for ~5 minutes and didn't see anything at all. the coolant was low, but was completeley still.

Some tests I plan to do soon
  • Compression test - gauge in spark plug hole and see if each cylinder holds compression
  • Block tester (with fluid) - it draws air in from the radiator and the test fluid will turn yellow if exhaust gases are present.

Based on the information I gave you any tests, assumptions or further direction in this process would be appreciated. I am determined to work smarter, not harder. Instinctively I want to rip the top end off and just assume the worse, but I have done things like that before only to find out it was a simple fix if I had just done my due diligence in research and thinking it all through.

Cheers!

P.S. - I will try and keep this thread posted with further tests, final diagnosis and pictures of the repair process.
 

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FYI. there are other possible failures that could result in coolant and oil mixing. For example
  • the oil filter adapter gasket
  • the intake manifold. It is possible that cracked intake at the coolant crossover where the coolant could leak into the valve covers.
Suggestion. Perform a compression test.
 

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Discussion Starter #3
thanks! I will look into those things. I plan to do a compression test and I will update with the results. I also am going to replace my PCV valve and check my vacuum hoses to make sure that is functioning properly. The OEM part is $37! lol
 

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Personally I’d start with a leak down test, but all good tests to try. Another possible failure point is a ruptured oil cooler.

Or... a blocked pcv system will prevent the crankcase from venting properly leading to moisture buildup in the oil. Hope for that one.
 

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Many times , the slight appearance of moisture in the oil fill cap , with a clean and clear dip stick , are confused with a head gasket problem .
In climates that have high humidity , and a car that is not driven regularly to full temperature , this will happen .
 

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Discussion Starter #6
That's helpful @ashleyroachclip. However, I am in a relatively dry winter in Virginia right now and I drive the car almost daily. However, it seems relevant to bring up that my engine seems rather slow to get up to operating temp.
I realized that my engine fans turn on immediately when i start the car. I think this is having a significant impact with the slow temp buildup. Does anyone think this may contribute to the moisture, because of excessive amounts of running the car under temp?
My drive to work is short enough to where I probably drive the car more under temp than at operating temp....
 

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In my opinion ,this is most likely your problem .
If the engine is not at 190 plus for enough time , it will just exacerbate the condensation that builds in an engine .
I would reprogram the fans to only come on at the proper temperature.
My fans never come on while driving on the hiway , unless i have the a/c on , and only in heavy in town driving .
 

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Fan turning on immediately and running full-time is not correct unless you have the AC or defogger on at the same time. If neither of those is the case, then you have a wiring issue, someone incorrectly reprogrammed the fan on/off temps, or you have a bad temp sensor that is registering a temp above the fan-on temp. (A bad sensor is unlikely because '02 only has one sensor that not only reports to the ecu but is also responsible for the gauge reading. If you're seeing your gauge reading Cool on startup, the sensor is likely fine. 96-98 would be a different story.) However, a running fan should not cause you to run excessively cool. The fan cools the coolant in the radiator, not the engine. If the coolant in the engine is below thermostat temp, then the thermostat will (should) remain closed, and the cool coolant in the radiator will not be drawn into the engine. The coolant in the engine will increase in temperature at the same rate regardless if the fan is on or not.

While I agree that short trips that don't allow the oil to get hot can lead to condensation buildup in the oil, it's more common for this to become a noticeable amount of buildup in cars with breather caps and without PCV systems as these cars absolutely require heat to more or less evaporate the water out of the crankcase. With a positive crankcase ventilation system, you're actively drawing out fumes and water vapor with or without heat whenever the engine is in vacuum. (That's why I suggested a clogged PCV above.) If you're seeing milky residue on the cam, that doesn't fit my description of a "slight' amount of condensation buildup.

So, while I think it's possible that it's just condensation, I'd still be running tests starting with a leak down and a cooling system pressure test. I'd want to know that nothing is wrong rather than just hope that everything is ok.
 

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Discussion Starter #9
Thank you very much @John Janek. That makes a lot of sense regarding the fans having no impact on the slow warm-up assuming that my thermostat is operating correctly.
I just received the PCV in the mail last night so I plan to replace it today. Cross my fingers!
To your point though, even if I solve my issue I still plan to do a compression test and leak down test to make sure my engine is not hiding any other surprises.

P.S. - when I do the compression test I will be replacing all my spark plugs. My assumption is that the NGK IX Iridium Spark Plug 7164 is a good fit for my application of daily driving with some performance capability. Do you have a strong opinion on this? a specific type and if the gap of the plug needs to be modified?

thanks again
 

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Thank you very much @John Janek. That makes a lot of sense regarding the fans having no impact on the slow warm-up assuming that my thermostat is operating correctly.
I just received the PCV in the mail last night so I plan to replace it today. Cross my fingers!
To your point though, even if I solve my issue I still plan to do a compression test and leak down test to make sure my engine is not hiding any other surprises.

P.S. - when I do the compression test I will be replacing all my spark plugs. My assumption is that the NGK IX Iridium Spark Plug 7164 is a good fit for my application of daily driving with some performance capability. Do you have a strong opinion on this? a specific type and if the gap of the plug needs to be modified?

thanks again
You might get lots of opinions with spark plugs. Here are mine.

If staying naturally aspirated, I'd run Motorcraft AGSF22FM1 plugs gapped at 0.050.

If running boost, it will depend on how much.
Anything 12 psi and under I'd typically go NGK TR6 gapped around 0.030.
Over 12 psi I'd switch to Autolite Racing AR103 or NGK BR7EF depending on specifics. Gap will depend on what your ignition system can handle. Might need to go tighter.

Also, I'm gonna push for the leak down test. With a very small head gasket leak, a compression test might still come up in an acceptable range, and you can't hear anything with the engine cranking. With a leak down, you'll hear a pinhole leak bubbling when you pump 100 psi into the combustion chamber if the breach is between the chamber and the water jacket. If you do a cooing system pressure test, you can hear if coolant drips into the crankcase from a breach somewhere while the system is pressurized. I'd suggest doing that cold as leaks sometimes seal when hot as things expand.
 
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