Thermostat???

[renagade]

My car is a 2011 c5 1.6 e-hdi vtr+ egs6 and I have noticed that when starting from cold the engine oil heats up a lot quicker that the cooling system does. Now on my 2009 2ltr hdi vtr+
the water used to heat up a hell of a lot quicker than the oil but on this (new to me ) car it is the other way around. Is this normal ?????? By the way,I can't find the thermostat on this engine, any ideas guy's ????????

[RichardW]

On the earlier engines the stat is under the fuel filter on the NS of the engine - comes complete in a housing, expect these are the same. These have a small oil capacity, so not surprised if it heats up quickly. If the water temp is reasonably constant, then I wouldn't worry about it.

[dnsey]

I don't know about the 1.6, but the 2.0 has a bypass solenoid valve which effectively short-circuits the cooling system to assist with warming-up. There is a conventional stat, too, but the HDi is so efficient that there's little waste heat, so it would take ages to warm-up without help (hence the 'immersion heater' to assist with initial cabin heating).

[Old-Guy]

I've noticed the same thing with the 1.6HDi (DV6C) of our 'new' Picasso - takes twice as long as the XUD9 in the old Xantia, but then it powers a big MPV using significantly less fuel (memo to self to reset trip computer) so it shouldn't be surprising that it's slow to warm up. Unfortunately the GC4P in VTR+ trim doesn't boast a temperature gauge at all let alone an oil temp gauge!

[white exec]

Similar in our Toyota RAV4 2.0 D4D. If I leave home and turn left, it's 5km before the coolant temp gauge even gets off the ground, simply because it's nearly all downhill, when almost no fuel is being burnt. Turn right, and I climb uphill (steep for 500m), and the gauge is at Normal within 1.5km.

Fortunately, the cabin heater is equipped with three electrical PTC heaters, so warmth is available within 1-2 minutes of starting the engine.

The 2.5 diesel XM, without PTC heater, and now 20 years old, doesn't suffer this way, because the folk who designed it were clever with their pipework*. Both vehicles return the same average fuel usage, 32-34mpg mixed use.


* Warning: sit down before looking at this:

[elma]

Whats the water to air heat exchanger all about? Is it in the place of an intercooler?

[white exec]

It is the intercooler, James, by Valeo. Two large turbo air ducts, and a multi-finned coolant circuit radiator inside, and located vertically just behind the radiators.

[elma]

So somewhere between old fashioned water cooled turbos and an intercooler or just a very sophisticated intercooler? I didn't realise the XM had such an elaborate system compared to the Xantia.

[white exec]

Citroen documentation claims better cooling than can be achieved from air-cooled intercoolers.
Also has the advantage that, with a cold engine, immediately available and unwanted turbo heat can be transferred to the engine coolant, thus warming up the lump that much quicker.

A reliable bit of kit on the 2.5, unlike the dreadful Valeo aluminium oil-water heat exchanger that sits under the oil filter. The steel 'pancake' versions on XU and XUD etc were fine, but the bigger alu version used on DK5 and 605 were prone to internal perforation, which resulted in engine oil being suddenly injected into the cooling system. Not a lot of fun; happened to me twice, when even a new replacement failed. No longer on the car: a traditional Setrab radiator-type oil cooler has replaced it.

[elma]

That makes a lot of sense. Intercoolers are a big point of debate on racing cars, theres a fairly even split between they are good / bad. It'd be interesting to see what race engineers opinions are on the water cooled one, I wonder if they are aware they exist. I'll ask tomorrow and report back, just out of interest.

Oil coolers are not so good when the turn into mixers, I've been there and I didn't like it much either.

[white exec]

Re oil cooler (and for that matter failure of HGs, radiators, heater matrixes...) I think a good bit of this on the +/-10-20 year old cars that we drive could be down to coolant neglect, and probably inadequate coolant system bleeding.

Most coolant mixes should be changed at 2 year intervals (so-called long life mixes are a fairly recent invention), but I guess often aren't, but simply topped up instead - and possibly with water! I have run several company cars over the years, always serviced by main dealers, and never once was the coolant drained and replaced.

Few owners, and quite a few garages, know about the hazards of mixing coolant types, and in the absence of a definitive and up-to-date sticker in the engine bay, it can be anyone's guess what mix is in there, and when it was last replaced. There is no standardisation of coolant mix colours between manufacturers, and many garages just shrug if the subject is raised.

Many of us are better informed these days, partly because of forums like ours, but also having seen engine/cooling components disintegrate or fail. Mixed metal and delicate systems (especially where aluminium or copper are involved) do need looking after, but it's all too easy to get overlooked. Acquiring a secondhand vehicle can add further unknowns.

My own suspicion is that proper bleeding of a cooling system (particularly where it might involve the use of a temporary header bottle, and bringing the engine up to full working temperature) is something that commercial workshops will probably skip, on the grounds that it just takes too long to do. And how often, after coolant draining, is the owner asked to bring the car back for a level and bleed check? Perhaps I'm expecting too much of garages, and too little of owners!

It's bad enough having certain components built to marginal standards. The best we can do is protect them properly.

[renagade]

I was waiting 25min. at a funeral yesterday with my engine running for the heater and noticed that the temp for the water disappeared from 5 bars to none and the oil temp went from 5 bars to two.It was only 5deg outside temp.

[Kennyd90]

I have a late 2011 C5 Tourer with the 2.0hdi 163hp engine and mine does exactly the same. The oil temp increases before the coolant temperature. On my old Peugeot 206 2.0hdi dTurbo the coolant would always get warmer before the oil gauge would move.