405 TD What causes head gasket to go?

I have a '95 405 TD 127,000 miles and am worried the head gasket may go
as it's a common problem.

What causes them to blow?

Would replacing it with a new one (not a service requirement) allow
another 120,000 miles before any danger of going?

 

In my opinion the main cause is overheating. On Peugeots there is a
fine line between running temperature and overheating and if you don't
notice the temp gauge rising, by the time the stop light comes on it
is normally too late.
Other than that it is imperative to use good quality antifreeze all
the year round and change it every 5 years or sooner. I do it every 2
on my 307.

 

Overheating often caused by sludged up waterways.

No not really. I had one go in a BX 1.9D at about 120K but that was straight
out from the dealers and due to a sludged up radiator. My 1.9TD Xantia is
going fine at 140K and has got quite hot on a long run up to Aberdeen from
Norwich with no obvious damage. The main thing is to ensure the waterways
are clean. Change your water and antifreeze at least every two years as
Nigel suggests, five years is far too long on these engines. Keep an eye on
the radiator too, make sure it isn't losing the fins or whatever you call
that zigzag stuff.

 

The sludge can settle in the radiator. So a coolant change every two to
three years and keep an eye on the radiator, feeling around when the engine
is hot for cold spots on the rad. Caught my Dad's BX TD with a few cooler
parts on the rad at 140,000 miles, changed it and now at 160,000 it's still
running strong.

 

I've heard the head bolts may loose their torque over time which may
contribute.

So what should I do... here's what i think...

Refill coolant now - with new and a known amount of antifreeze (and
distilled water) , also find out if a 'header' is needed when filling
to prevent air bubbles (which may relate to the pug 405 TD engine)

Do a compression test now (would like to do this anyway - I dont expect
it to show up problems)

When I do valve clearances/timing belt check the torque of the engine
bolts - should I undo then re-do them to check they are moving OK, or
just check the max torque (or torque + angle?) Should I put new bolts
in? I'll also consider putting a new gasket in - probably not much more
work from this point.

Finally there is a simple adjustment I can make to up the power by
upping the boost- maybe from 0.6 to 1 bar - will these measures be
enough (definately new gasket and bolts?) to hold it together for
another 100K miles?

 

No don't use distilled water. It's actually an agressive solvent because it
doesn't have any impurities in it. Ordinary tap water is quite good enough.

I seriously wouldn't bother. Check the torque if you feel like it but don't
undo the bolts, just check they're up to torque.

Look, first you want to improve your reliability, then you want to undermine
it by upping the boost. Make up your mind.

 

No, don't touch them !

Just leave it all alone, and replace the headgasket *if* it pops. There's
only a small chance of it busting - they don't all do it !

Erm, don't do that either !
Your chances of head-gasket failure will increase many times over with a
power increase (higher boost = hotter intake air = hotter engine =
overworked cooling system).

If you want a faster car, then buy one. Tuning old, high-mileage Turbo cars
is a bad idea for obvious reasons. You need to be looking at a 406 Estate
2.2 HDi 130 - they'll happily make a *reliable* 160bhp or so with a bit of
fettling.

 

I've just spoken to our race mechanic who is a long established (20year)
Citroen/Peugeot specialist, he's never heard this.

Change your coolant, but first check with a hot engine that you have even
heat right across the radiator, that is most important. While it is empty,
give it a good flush with running water, try and run the water both ways
throught the radiator to get rid of any sludge.
Don't fill with distilled water as correctly pointed out by other poster,
it's agressively corrosive, if you want to be fussy consider buying
pre-mixed anti-freeze from Peugeot/Citroen, but it's expensive and
uneccesary.

Noooo... These are stretch bolts, don't mess with them, they are already
tightened beyond their elsasticity. DO NOT DISTURB!!! When/if you change you
timing belt, change the water pump. A lot of the sludge in these engines is
minute bits of alloy corroded off of the water pump vanes.

Up the boost by 40%? That will increase the charge and put more pressure on
the head gasket, I wouldn't, certainley not on an engine that I had worries
about the head gasket.

 

When/if you change you

Does that mean I should replace it because the metal worn away means
the pump wont work as effectively? Or it's likely to wear a lot more
metal off? Is it possible to inspect / service them? If not its a new
pump which would be $$$ (£££) from Peugeot.

Is there a way to check the water is flowing OK? (the radiator check?)

Thanks

Ian