I had a fair bit of work done to my 1999 Subaru Legacy last week with the main fix/problem being a timing belt replacement. Additionally they replaced oil seals, 2 hose clamps, the radiator cap, the water pump and the thermostat. They also topped up my coolant, bleed the system and checked for any leaks at the end.

However, I drove the car for the first time today after getting it fixed for around 6-7 minutes with the temperature gauge remaining normal but when I arrived home I noticed a constant stream of clear/light grey smoke coming from the hood. I then opened it and found the engine smoking at a moderate level predominantly from under where the cylinders are, this lasted around 4-5 minutes. My coolant levels have not dropped but there was a slight hissing coming from some of the hoses, leaving a minuscule amount of coolant (a few drops) on one of them which has still never happened to my car before.

My mechanics are very trustworthy and I was told to 'keep an eye on the water levels'. If anyone could help me diagnose the problem or come up with a solution that would be very much appreciated as I am currently too scared to drive.

Thank you

  • Also I heard a noise that sounded like water sloshing around behind my dashboard while driving (before the car overheated) Commented May 25, 2016 at 2:22
  • If there is a sound of sloshing inside the cabin, maybe they didn't bleed the air out of the heater core in your dashboard...
    – cdunn
    Commented May 25, 2016 at 2:49

1 Answer 1


You should not have a leak in your cooling system, period.

You need to get the car back to the mechanic if you have a coolant leak (albeit a small one). Over time you'll continue to lose coolant when the system pressurises and this is unacceptable as the car won't be reliable. Eventually the coolant will boil and the engine overheat when enough coolant has escaped.

It may also be some oil from the repairs dropped on some hot parts of the engine and are contributing to the smoke or steam you are seeing. This would not be a problem if there is no slow leak, and the oil droplets will eventually burn off.

If the coolant is leaking onto hot parts of the engine then it will evaporate as steam and leave some residue behind. Coolant is mostly water, but also contains chemicals and dyes and over time you'll get a good idea if this is occurring by a visual inspection.

You'll be OK to drive, as long as you first check the engine oil level and make sure the coolant level is adequate before setting off and keep an eye on the gauges (as people should do all trips anyway).

I would be driving to your mechanic though first thing, and explain your situation and have them address it. Keep in mind, it is absolutely not OK to have any leak in the coolant, no matter how small. You mechanic must address this if this is the case.

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