White residue under oil cap - Peugeot 405

Blown Head Gasket ? Keep an eye on your expansion tank for its water level

Hi Dominic Have come across this in a 405 (petrol, ca. 140.000 km) and a 605 (petrol,

176.000 km). In both cases it was cured by using a flushing agent just before renewing the engine oil and filter. Comma produces an exxcellent flusing agent, which cleans the soot and grime from the oilways in the engine. IF you are unlucky, the coolant has found a way into the oil - probably a blown head gasket. Try flushing first, but check whether you have a coolant loss.

Good luck

Ivar Petur

I think that's the head gasket going, and the white stuff is an emulsion which is a mix of water/anti-freeze and oil.

You will find power dropping, very smokey exhaust and increased running temperature.

If the car is worth saving then you will need to get the head done now, or risk some engine damage with a bigger repair bill.

Maybe some of the mechanics on here can advise you further.

Good Luck,

John

i had it on my 98 306 xsi i spoke to a engineer at work and was told due to damp weather and short trips it was condensation built up in the engine.i flushed the engine and cleaned all the pipes out ran it and its fine so you may get away with cleaning it out but keep an eye on the expantion tank if it needs topping up all the time then yes the head gasket has gone

Years ago I saw this on a car and rushed around to my mechanic. He said 'mayonaise' as he called it was not uncommon. He checked everything and found no water ingress. I'm not saying ignore it - just don't panic.

By expansion tank, do you mean the tank at the front, at the radiator? I've just done a 250 mile (400km) round trip and it hasn't lost a drop!

Dom

| John

Yeah, power seems to be there but juddery. Smoky at starting but the engine temp seems to be normal. I don't seem to be losing any fluid from the radiator; is this a slow process or would I notice after, say, 250 mi / 400 km?

Thanks,

Dom

Not sure about the 1.6 but there was a problem with the filler caps on the early 1.9 models which had a mesh system in them. From memory (which is a bit sketchy!) you were advised to remove the mesh (which connected to various breather hoses) and discard it as it was a contributory factor to 'mayonnaise'. My father's 405 had this problem but after flushing the engine through with some cheap oil and then adding semi-synthetic and discarding the mesh it was fine. Any breather hoses coming up to the oil filler cap will probably be full of gunk as well. Smoke upon start-up alone isn't necessarily something serious. Give the car a good service - change filters etc. before drawing any conclusions.

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I did have this on a "G" reg 1.6 petrol 405. It could be a blown head gasket but could also be the type of oil and stop start driving. I partially solved this by using semi-synthetic oil and using a flushing agent.

Car lasted for 122k - until a pikey b****** decided that his HGV would take me out.

| >

| > Blown Head Gasket ? Keep an eye on your expansion tank for its water | level | | I did have this on a "G" reg 1.6 petrol 405. It could be a blown head gasket | but could also be the type of oil and stop start driving. I partially solved | this by using semi-synthetic oil and using a flushing agent. | | Car lasted for 122k - until a pikey b****** decided that his HGV would take | me out.

Yes, perhaps I'm being a bit of a pikey here myself; the car has already done 140k so I don't suppose I can expect it to go on forever.

Hi,

Come on, you still have some years of good fun with it if you drive properly. Correctly driven & serviced, a XU just can't die !

Regards, G.T snipped-for-privacy@worldonline.fr

205 Diesel & turbo-Diesel :