Pug 405 Oil Leak from engine mount - strobo
Hello all, especially those of you who have dismantled a 405 1.9TD (XUD) engine. :-)

Strange one this - when the recent spell of warm-ish weather started (approx mid-late June), a small oil leak began to make itself apparent from the timing end of the engine. Initially it was just an occasional drip from the lowest corner of the sump, leading me to think either the sump oil seal (Instant Gasket or equivalent), or the rubber rocker cover gasket had let go. Closer inspection suggested the latter.

The leak got worse, so I consequently replaced the rocker cover gasket, and found only a minor leak from each rear corner of it. Nothing anywhere near what was now dribbling from the sump. I decided at this point (and after perusing this very site), that it might just be the camshaft oil seal. As the timing belt was soaked in oil and needing a change I bought a new belt and both camshaft and crankshaft oil seals. The end of the block seemed pretty dry all over with the timing covers off, but the old belt had definitely been soaked in a mist of oil.

After reassembly, and a change of oil and filter, the leak returned immediately. At this point I decided to run the engine with the timing covers and alternator belt removed, just to see exactly where the source of the leak was. It appears that the source is BEHIND the engine mount, as it bolts to the head/block/crankcase. The whole bottom edge of this "plate" is running with oil, and oil is seen to be running down the plunger for the timing belt tensioner.

The addition of stop-leak in the oil has made no difference, and apart from a split hose (now remedied) I have no loss of coolant. It still pulls like a trooper too. Crankcase pressure DOES seem a little high, but all accessible breathers have been checked and are clear.

The car has never used any oil between changes, and I have always used Mobil 1. I have run the car for the last 4 years (bought with 99k, now on 126k & FSH before then), without it missing a beat.

Does anybody have any suggestions? The Haynes manual for 405 diesels isn't one of their best - I've found more info in the old Pug 309 manual. Is there an oil seal behind the right-hand engine mount that might be the cause? Or could it be the head-gasket?

Sorry for the long post, just wanted to avoid missing anything.

Cheers in advance

Pug 405 Oil Leak from engine mount - David_S
From what you describe I would suspect a Head gasket failure, the misting would suggest a leak under pressure. Does the engine mount bridge the head / block join if so even more suspect.

I had a similar experience at 200K in my 405 TD except it was coolant and not oil from the back corner adjacent to timing belt which was getting a good soaking due to the head gasket failing.

Not the easiest or cheapest of repairs but hell looked after these engines do have some life in them. Not sure on the costs it does take some time, I chickened out after reading the Haynes manual and had a Pug dealer do it for a small fortune, they owed me a few credits after diagnosing a waterpump problem in the first instance.

Ran car without a problem for another hard and fast 15k in 8 months before trading it in.

Pug 405 Oil Leak from engine mount - strobo

Yes, the engine mount DOES bridge the head/block join. I just find it strange that I'm not losing any coolant into the oil, or vice-versa. Or any performance, for that matter.

One very vague picture in the Haynes manual looks like the head-gasket may have rubber inserts around the oilways - hence my decision to use stop-leak, to re-swell all the old rubber. It hasn't worked thugh, and my faith in Haynes manuals is limited.

A drawing of the XU petrol engine in my 309 manual shows the routing of the oilways, and shows a very definite change in passage diameter just around the source of my leak. A good place for a little excess pressure to build up I think.

If it IS the head gasket, should/would I experience any performance problems? It seems fine at the moment, happily leaving Golf TDi's behind on the hills of Sheffield. Or am I just accelerating the inevitable?
Strobo - rapidly learning to hate Peugeot's!!!
Pug 405 Oil Leak from engine mount - David M
Strobo - I suggest you try posting a description of your problems on the Peugeot or Citroen forums at www.andyspares.com/discussionforum/
where you will find plenty of people with experience of the XUD engine. I have no connnection with the forums except as a signed-on member.

Pug 405 Oil Leak from engine mount - Bats
I see you are using Mobil 1 oil. Is it the 0-w40 turbo diesel type? This is a very thin oil when cold and may be this is causing the leak. You could try changing to a good quality semi-synthetic oil of 10-w40 or 15-w40 viscoscity range and see if the problem still persists.
Pug 405 Oil Leak from engine mount - strobo
Thanks to everybody who posted on this problem.

I gave up trying to find the problem and took it to the main dealer in Rotherham. It turns out it was indeed the head gasket. They've replaced the head with a recon unit (at least it doesn't look like my old one - too clean), given the engine bay a really good going over, replaced all the tired old leaky hoses, and the knackered o/s engine mount, topped up my air con (no leaks either), and generally recilabrated everything so it runs sweet as a nut now.

Cost a small fortune in labour and I've paid top dollar for genuine parts, but it seems to be fine now. I'm hoping it stays that way for a long while yet.

So, if you're in South Yorkshire and you need your Pug looking at I can certainly recommend Derek G Pike's. One thing to note though - they were VERY busy when I had mine done (school hols and all), but I can't really fault the job done (yet :-))

Strobo - rapidly learning to hate Peugeot's!!!
Pug 405 Oil Leak from engine mount - DL
Why was the head replaced? Usually a gasket change is sufficient!

Value my car