VW Golf Mk3 VR6 - Head Gasket? - VR6
I need some advice about some 'mayonaise' I found onthe oil filler cap.

I check my oil quite regulary, and have never seen a white deposit before yesterday, also coolant level never needs topping up. Last time i checked was a few days ago - and found no mayonaise.

On Friday after a 30 mile m'way trip, the car starts to stall / kangaroo at low speeds and the engine is generally running like a dog (some rattles and no steady idle). I drove it about 1 mile to a car park where it stayed until Saturday morning. On Saturday morning I call out Green Flag who start the car rev it hard(whist cold) to find the problem.

It turns out to be a corroded wire to the MAF (air flow sensor). Green flag do a temporary repair and the car now works fine.

Would the above stalling / poor running cause the 'mayonaise' or is it likely to be the HG? I had a recon engine block fitted about 1 year ago, so I assume the HG would have been changed then.
VW Golf Mk3 VR6 - Head Gasket? - Roger Jones
My dearly beloved VR6 has now moved on after 9.5 years of ownership. However, . . .

Any oil in the coolant? Any drips? Any deposits on the underside of the car? If not, has the car been left unused for long periods of time and then used only for short trips? If so, the mayo may disappear after some intensive use, especially if there's not much of it.

In all my many Web readings about the model I do not recall head-gasket failure featuring much, if at all; timing chain failure, yes, but not HGF.

I'm no technical expert. Someone technically familiar with the VR6 engine may pop up here shortly.
VW Golf Mk3 VR6 - Head Gasket? - jc2
Also check that none of the hoses in the crankcase ventilation system are partly or completely blocked.
VW Golf Mk3 VR6 - Head Gasket? - VR6
There are no drips that I can see, and the coolant doesn;t seem to have an oily deposit on the surface.

Not too sure where or what the crank case ventilation system looks lke, but the Green Flag guy did run the engine with a small hose - about 5mm dia. -disconnected for a few minutes. When he disconnected it you could hear air coming out the hose. It was located on the corner of the manifold - does this sound like it?
VW Golf Mk3 VR6 - Head Gasket? - yorkiebar
the small amount of mayo type stuff you saw was probably condensation caught by the oil (means the oil is working).

head gasket failure (with mayo like sympyoms) is when all the oil or coolant or both is all like mayo but more browny than white.

hth
VW Golf Mk3 VR6 - Head Gasket? - George Porge
Could also be an internal leak inside the oil / water heat exchanger thats sandwiched between the oil filter and the engine block. These are well known for being troublesome. I paid £45 6 or so years ago for mine, so is a lot cheaper (and more likely to be) than a head gasket. ;-)