406 HDI 90 Running Cooler than before

[pfusi1]

Hi, I tried to see if this question was answered elsewhere but I wasn't certain so please forgive me if this is repetitive.

Anyhow, I have a Peugeot 406 HDI 90 which used to run at a solid 90 degrees on the temp gauge. However, recently the temperature has been very slow to build up and it never seems to get any higher than about 75 degrees. I have stopped the car and checked to see if the fans are cutting in early but they aren't running. Coupled with this is an increased appetite for diesel, and rather than close on 50mpg I'm getting 38-39mpg which is enough to bring tears to my wallet.

I think there are fuel/oil smells coming in to the cabin but these seem to be intermittent and may just be other traffic in front of me on the road (and my paranoia). Anyway, reading around on this excellent forum and elsewhere on the web I can't find an answer as to why this is happening and wondered if anyone more experienced had any proper ideas!

For reference the car had oil, air and fuel filters replaced approx. 6,000 miles ago (by me). It's currently on 205,000 miles and I do hope that this isn't the sign of something terminal as I think my 406 is an absolutely fantastic car.
Any help will be much appreciated,
Phil

[mjb]

My guess would be your thermostat's stuck open and needs replacing

[Welly]

Sounds like a new thermostat and coolant flush/change will help.

The HDi is so efficient it does take an age to warm up and you will notice this more when the weather's really cold. The engines 'cold start enrichment programme' will also knock about 5 mpg off your usual economy in very cold weather - again it won't help economy if the engine won't warm up with dodgy stat etc.

A smell in the cabin will usually be a hole in the exhaust flexible downpipe section (really hard to see from above, and behind the engine - it drops in front of the bulkhead).

[Doggy]

this excellent forum

Flattery will get you everywhere

I'd go for thermostat too.

Welcome, Phil BTW

[EvilTwin]

Like they said, probably the stat, and the weather going colder, so the engine temps will take a lot longer to get warm.

[turbolag]

Aye lad, my 90 took a goodly while longer in the cold to get some heat into it.

[pfusi1]

Ok, that sounds like bearable news. Will change thermostat and report back!

I hope there isn't a hole in the exahust as it's not even a year old yet - but just lately everything on the car does seem to be furring up. New door locks last week, thermostat this week, brake pads as well. Why do I always find time to work in the freezing cold?!

On a slightly different note, anyone ever tried to get the tailgate lock out? I broke one side of the boot handle because it was all so corroded behind there and didn't dare to try the otherside otherwise I'd be minus a handle! Also, noticed today that the 306 estate seems to have the same handle - are they interchangeable?

Jobs for this week/weekend:
1. Brake pads front rear and clean discs and calipers.
2. New thermostat and coolant flush and new coolant.
3. Oil and filter change (thought I'd shorten the interval seeing as I'm getting good quality oil for 'free' from work).
4. General run round with the WD40 trying to counteract all the furring up - see if I can't get the bonnet release to 'pop' properly, same goes for the fuel cap (both seem to have got very tired with all the rain and cold - know how they feel!)

Oh well, I'm on the Kawasaki for the rest of the week - watch it absolutely p*** down.

[pfusi1]

Well I've started to drain the coolant and got a fair amount out of the radiator. (Very diluted orangey stuff that looks a lot like p*ss)

Just a few questions which I can't find answers to on the forum:

1. Where exactly is the mystery Cylinder Block coolant drain plug that the Haynes manual mentions but fails to provide a photo of?
2. My thermostat housing doesn't have one of those bleed valves that look like tyre caps - it's got what might be the remnants of one - it's bronzey coloured with what looks like a hex fitting in the end, has the plastic grippy cover fallen off it?

I never thought changing the coolant would be this difficult and it's not helped by -1 degree temperatures. Any help would be much appreciated before I start tearing out what is left of my hair and buring the useless Haynes manual.


Cheers as always, Phil

[pfusi1]

Oh b*gger. Now I've gone and snapped one of the thermostat housing bolts. The whole point of Diy mechanics is to fix faults, not create more of them! Oh well, with the new thermostat the car seems to be getting up to temperature and maintaining it which is a good sign. Now to wait for the whole thing to cool down, get the thermostat housing off again and remedy this bolt.

[steve_earwig]

Doo-doo happens, I hope you manage to get it out. I've not found the block drain on either car, I get a feeling I won't 'cos they're not there. The bleed should just be a Schrader valve cap covering a hole, maybe someone lost it and jammed the first thing that came to hand in the hole.

[pfusi1]

Ok, well new bolts and new coolant later I've finally got the thermostat changed and the car running at the right temperature. Top tip is to jack up the side of the car with the header tank in as it is easier than using an extra 'header tank'.

Now I've got to work out why my car has started to rev in first and not go anywhere fast. All other gears seem fine but I suppose it's a sign that the clutch is on the way out.

[mjb]

Top tip is to jack up the side of the car with the header tank in as it is easier than using an extra 'header tank'.

Better tip is to stick the wheel on a kerb