Is there an issue with my head gasket?

MTBD

Hi I have a car that is showing slight signs that it might have head gasket issues.

There is a slight milky residue on the oil cap. I wipe it away and it's back within 2 weeks.

There is a very slight drop in the coolant level over the course of 500 miles. It's actually hard to tell if there is any drop because ground isn't totally level but I'm pretty sure the expansion tank coolant is 2-3mm lower since I it was filled after a recent hose leak.

There is white smoke from the exhaust on start up and it remains for quite a while even on a warm day like today. However it does eventually stop completely. The radiator hose don't feel hyper pressurized or anything when I feel them.

The car is running perfectly and the temperature gauge is running just below 90 consistently.

Im very tempted to put a good head gasket sealer as whatever leak might be there appears to be tiny at the moment. Any thoughts?

biko

What car/year?
Is it thick smoke or wispy?
Does it smell sweet or just like exhaust?
Is coolant still clear or murky?

MTBD

biko wrote: »

What car/year?
Is it thick smoke or wispy?
Does it smell sweet or just like exhaust?
Is coolant still clear or murky?

It's a 2001 166 v6 with 80,000 miles. The coolant looks pretty clear and I put my finger in it and there was no oily residue on it. I can't see any obvious oil in it.

I just turned it on now after being off for a couple of hours. No smoke/steam at first but after a couple of minutes some started coming out once the engine temp went to 70+. It is wispy enough I suppose, not that thick. I'm not sure if I'd call it sweet but it smelled a bit different to the exhaust gasses that were there at the start.

Edit: can't really be sure on the smell to be honest.

Also, once it is fully warmed up there is no more white smoke.

Edit 2: just took it for a spin there and as predicted the white smoke was gone. But I can now confirm that it was a sweeter smell than the non smoky exhaust fumes. If it was the head gasket wouldn't the white smoke continue even after warming up?

Toyotafanboi

Honestly, there's not much there that'd have me jumping straight to head gasket failure.

A little mayo under the oil cap wouldn't be too unusual for a car like that, particularly if it's not getting a lot of driving or is doing a lot of short trips. Similarly, steam from the exhaust at this time of year wouldn't be too unusual, head gasket steam is very very rich and thick and very apparent when the engine is up to full temp, if you aren't seeing that and only some wispy condensation you're probably ok, condensation is perfectly normal. In an older car like that, a drop of coolant could be getting lost anywhere over the course of 500 miles, leaky water pump, dodgy rad etc.

Regardless of whether it's the head gasket or not, I wouldn't put any of that stop leak muck into it.

jetfiremuck

There is a test that checks exhaust in the coolant. You may have a leak somewhere else that's evaporating and not showing up as drips. Have the coolant system pressure tested. Some cars engines /oil types leave that mayonnaise in the caps. It could mean a bad pcv valve or hoses.