Peugeot 306 coolant leakage?

[clifford1]

1996 306, 1.4 litre

There are two presumably connected faults:

1) The coolant level slowly falls. There are no leaks I can find, I have replaced the cap, there is no water in the oil, and no steam in the exhaust.

2) Brown oily mayonaise collects round the radiator filler neck


The car runs perfectly, starts well. There is no sign of water leaking into the combustion chambers, the exhaust is clear.
There is no sign of combustion leakage into the coolant - no pressurisation or bubbling, and the temperature is constant and normal.

Is it possible for oil to leak from the camshaft lubrication oilway into the coolant?
Where can the lost coolant be going?

 

[Mursal]

As its a petrol. no I cant think of how oil could get from the oily bits into the water without an internal fault (head gasket etc).
The carpet isn't wet so the water must be going somewhere? Boiling off, or a leak? Is it overheating, electric fan working? Water pump belt ok?
Would the coolant have been topper up with an oily can? If not, it looks like you have low levels of engine oil in the coolant?

Keep water in the boot (get you home), because I don't think its going to get better

 

[Burnerman]

I would hazard a guess at the leak coming from the water pump, hidden behind the timing belt cover.
John

 

[ahmotorsport]

It's uncommon for oil to get into the coolant system via head gasket failure.

Are you losing oil?

The best way to determine head gasket failure is to do a sniffer test, if there are Hydrocarbons in the cooling system, it's a head gasket, if there isn't, it's definitely not.

 

[clifford1]

Thanks all.

The water pump certainly sounds a possible source of the leak - I'll investigate that.

The oil/water mix is certainly only one way. There is no oil loss, and no signs of water in the oil. So unless someone poured oil into the radiator once, and it is taking 3 years for the last traces to emerge, the source can only be from the head gasket. I have flushed out the cooling system and replaced with fresh, but the mayonaise returns after the first run.

Does the oil supply pass through the block/head joint? Is it possible for a small amount to leak via the gasket into a water passage?

I've never done a sniffer test - is that a DIY job with a test kit?

 

[Mursal]

Yes DIY test
http://www.ebay.co.uk/itm/Car-Engin...003?pt=LH_DefaultDomain_3&hash=item3ccba0fc7b

Cheaper kits are available.

Head gasket has an oil supply drilling (under pressure) to the cylinder head and many return paths back from the head.

 

[ahmotorsport]

Sounds like there is an oil cooler fitted. Where the oil filter is, does it screw onto a body that has cooling pipes attached?

 

[Burnerman]

The brown mayo isn't an issue, and affects all car petrol engines in cold weather......since we aren't allowed to vent crankcase fumes into the atmosphere any more!
If it has an oil cooler, its usually what the oil filter screws on to....and they are prone to corrosion from the outside.
John

 

[Mursal]

No oil cooler on a 1996 1.4 petrol Peugeot that I know of?

But John, the oil mayo is collecting around the radiator cap not the oil filler cap? So we have a problem unless it was contaminated with an oily can when filling (ok, I'm an optimist).

 

[Burnerman]

No oil cooler on a 1996 1.4 petrol Peugeot that I know of?

But John, the oil mayo is collecting around the radiator cap not the oil filler cap? So we have a problem unless it was contaminated with an oily can when filling (ok, I'm an optimist).

Whoops bang on mate - I missed that bit!
John

 

[ahmotorsport]

Have a look for one, it will be a coolant oil cooler, basically the colony circulates around the oil and take the heat away. Some manufacturers do it.

 

[clifford1]

There is no oil cooler.
Pressure test shows no radiator or system leakage.

Previously, after every trip, the water level was always down about 2", whether a long run or a short it never went any lower, and there was always a scum of mayonaise round the filler neck

But suddenly, it has stopped doing it. I topped up a day ago, wiped the mayonaise clean, but after a 20 mile run the level is the same, the coolant clear blue, and no trace of mayonaise.

Of course, whatever is going on may well return, but I'm at a loss to know where to look. Can there really be an intermittant leak in an oilway at 50 psi?
Can a water pump seal be breaking down, letting a quantity of grease into the coolant, now dispersed?

 

[Mursal]

Unless it is overheating slightly in different driving conditions, like traffic? As long as doesn't go below the minimum mark just leave it alone. The oil must have been a dirty can, well hopefully.
Double check that the electric fan out on the radiator comes on with the engine hot in heavy traffic/standing still with the engine cunning.

No, head gaskets don't usually fix themselves.

Happy days .............................