Coolant or Condensation?

[notsoeasyaspie]

To begin: This is my first project car. I'm an electrical engineer and have a fundamental understanding of cars but only have around 6 months of actual hands-on automotive experience.

My heart sank when only a week after buying my 1999 2.0L Z3, I ran the engine today to find a good amount of sweet-smelling (I think) exhaust vapour and pale yellow-ish liquid dripping out, I expected condensation so I revved the engine a bit and waited ~5-10 minutes to see if the vapour would clear. Fearing the worst, I shut the engine off and checked under my oil fill cap to find a layer of milky, pale yellow residue despite the oil on my dipstick seeming to be relatively normal presenting (the engine oil doesn't appear to be old i.e. black).

I haven't been able to check my coolant level yet because coolant flowed out as soon as I cracked the fill cap loose (I should note that when directly smelling my coolant, it didn't smell too similar to the exhaust fumes or unidentified yellow liquid). I'll have to check my coolant level tomorrow and account for some loss as I tried to open it today (around 50ml or so).

After a little bit of research, here are the facts and my thought process:

Suspect A: Condensation

• I bought the car on 28.01.23, on inspection I didn't find any symptoms of contamination in the oil. On the same day, I drove it around 178 miles, mostly at 70-80mph. I didn't see any reason to check the oil cap again after returning home since the temperature gauge was right in the middle the entire time.
• The car wasn't turned on again until today, 06.02.23 due to my seats having been removed in the process of removing the carpet and wanting to avoid an airbag warning light.
• The weather in the past week or so has been consistently between -5°C and 10°C, so pretty nippy.
• I only ran the car for about 5 minutes today at roughly -1°C ambient, the temperature gauge was still on the cooler half when I'd shut the engine off. Arguably not enough time to boil off any condensation that had accumulated.
• May not be relevant but despite disconnecting both terminals of the battery until today, it had still discharged to the point where a jump was required.

Suspect B: Coolant Leak/Head Gasket Failure

• The car had very patchy service history, the seller claims he serviced the car himself although there were no receipts to back this claim.
• The last entry in the service booklet was in 2010.
• The car was sold to me for £900 with a very short MOT, due 11.02.23
• Being an almost 24 year-old car, I wouldn't rule out a head gasket failure. The previous owner seems to have neglected its long list of problems.
• There's noticeable ticking from the upper engine, again I'm not sure if this is relevant.
• There is also a separate ticking/slapping from perhaps the timing chain (very uninformed guess)
• Milky residue on the oil fill cap is pale yellow, similar to the vapour sample collected at the exhaust. The coolant's colour is unknown.

I can't even drive the car as my insurance policy doesn't start until 17.02.23. Of course, I'm in way over my head at this point and I'll need a professional to inspect it, the way I see it I've got the following options:

1. Sort out as many of my problems on my long list as I can until my MOT appointment on 18.02.23. Mainly I'm concerned about my headlight being loose and causing a failure as well as potential rust on the underbody which I haven't managed to take a look at yet (the outer sills have rust holes and there is rust bubbling on various other panels). I haven't even managed to check my brake pads/discs yet.
   1. However I'm afraid of driving the 1 mile journey to the MOT in case the journey or subsequent test drive worsens the potential head gasket condition and-
   2. If the MOT fails, and I'm unable to drive it home, I seriously doubt I have the funds to pay for the fixes.
2. Change the oil, filter and coolant and see if the problem comes back.
   1. Seems like a waste of a lot of oil and coolant if the problem does indeed come back.
3. Flush the engine to try and get rid of any condensation
   1. I've heard it's generally a bad idea to flush the engine
4. Use a gasket repair sealant and drive the car to boil the condensation and isolate the gasket diagnosis
   1. Apparently gasket sealant is only a temporary solution(?)
5. Book the car in for a compression/leakdown test
   1. If the engine has weak compression, I won't even be able to sell the car at the same price I bought it and will have wasted more money, I've only used this garage once and I'm naturally afraid of being ripped off/taken advantage of. I definitely can't afford dealership service.

Before I call a mechanic, please give me your thoughts regardless of your qualification. I can only assume you're more knowledgeable than me. Is there anything in the diagnostics that I could possibly check? I was really hoping to get the chance to enjoy this car as I've wanted a Z3 for a long time, only I doubt I'll be able to afford the cost of fixing it as it accumulates more problems faster than I can save up the cash. Many thanks.

Terry

tl;dr There's milky yellow stuff under my oil cap, kinda sweet exhaust fumes, I'm in way over my head and kinda throwing my life savings at this car. Help please

 

[colb]

Milky gunk under the cam cover is usually down to short runs where the car never reaches optimal temp.
Check coolant level then start car and run it up to temp,, the guage should settle at 12 o'clock once the thermostat has opened with a fully warmed up engine. Try and avoid putting any leak sealer in the coolant better to replace the leaking componant if you have one. If the car struggles to achieve temp then suspect a jammed open thermostat and replace that, whilst your in there change the water pump as well. Refill and bleed the cooling system using a good antifreeze. Don't forget to use an oil cleaner to the oilk and then drain it and refill with fresh oil to get rid of the gunk, follow the directions on the oil cleaner product to do the flush.

 

[Richard29]

Milky gunk under the cam cover is usually down to short runs where the car never reaches optimal temp.
Check coolant level then start car and run it up to temp,, the guage should settle at 12 o'clock once the thermostat has opened with a fully warmed up engine. Try and avoid putting any leak sealer in the coolant better to replace the leaking componant if you have one. If the car struggles to achieve temp then suspect a jammed open thermostat and replace that, whilst your in there change the water pump as well. Refill and bleed the cooling system using a good antifreeze.

I had this on my 2.0, local specialist said nothing to worry about.