Help-VERY POOR fuel economy on Peugot 106xnd-32.3mpg???!

DEBTMONKEY1A

Fuel...looking good guys (even with stop start driving-motorway speed 50-60 mph-occaisional 70!)-565 miles doe & still just under a 1/4 tank left!!!!!!!!!!!!!

'from cold, remove the radiator filler cap,start the engine and let it run,after a while you should be able to see the water in the rad top circulating,this may take a while depending on how cold a day it is,but if you feel the top and bottom hoses they should get warm,'

hartcjhart-is the above to test thermostat? Pretty sure my sisters B/F said ok but is that what you mean?.

'Hi yes thats what I mean

dont know how hard it is to get the matrix out, but if easy enough ,try pouring kettle descaler into it,use the descaler just like you would for a kettle '

SO...sorry to be thick but BOTH hoses (the ones going from water expansion filler tank to back of dashboard-big hoses) have to be the SAME warm temp (after runnig car for say 15 mins to warm up)...if one is cold & other is warm/hot is that a definate answer that the stat is knackered?

Please don't say take it out & test it-not that technical!! But I gather thermostats are cheap (any ideas anyone for part & fitting cost-fair price for a garage to ask???) ...if theres a 100% definate way to tell if its knackered I'll get it changed this w/end-any ideas?

Reason I now think its a sticky thermostat is that it sometimes does give warm air...(still nto fully warm!)

mikey72

Easy way to test the thermostat is to start the car, let it idle for 15 minutes, and the radiator should still be cold. If the top hose starts to warm up immediately, the thermostat is stuck open.
If it's cold, and you take it for a run, the radiator should be warm after 15 minutes or so of driving. (probably not very warm in this weather)

DEBTMONKEY1A

Mikey7-thanks so much for helping a motoring thickie (!)-so-if I start car up & within say 1-2 mins (no longer) top hose is warm/hot then its deffo the thermostat???? After say a 30 minute run the top hose is normally warm/hot & bottom hose is very cool/marginally warm.

So...most accurate way is to say sit in car & let it idle for 15 mins-if i feel the rad at front & its cold its definately the thermostat? Would any of the above hose symptoms indicate the thermostat is knackered?

Mikey72-I know the stats are cheap parts-any idea what a garage should charge to change it?

Sorry to be thick (!)-I'm on week 3 of my new job & training at the moment-head fit to burst!

mikey72

The thermostat stops water circulating in the radiator if the engine is cold. As the engine warms up, the thermostat opens, the water runs from the engine into the top of the radiator, passes through the raditor to cool down, then returns to the engine via the bottom hose, to the water pump.
If the thermostat is stuck open, the water circulates all the time, so the radiator and top hose will be hot (not very hot in this weather) all the time.
The 106 diesel doesn't get very hot on idle, it takes a long time for the thermostat to open, so even after 10 to 15 minutes the radiator shouldn't be warm. The top hose may feel hot, but that could just be from conduction from the block.
After a run the thermostat should open, the water will circulate, and the radiator will warm up (again, probably not much at the moment)
The heater matrix circulates all the time, dependant on the heater valve switch on the dashboard, at whatever temperature the engine is at..

DEBTMONKEY1A

So Mikey72...

Being ultra thick can you give me a yes or no to these...(sorry-you must really think I'm dumb!)

1)-If within say 2-4 minutes of starting top hose is hot & bottom is cold thermostat is stuck open?

2)-If after a 30-40 minute run top hose is hot/bottom hose is cold/cool/only slightly lukewarm then thermostat is stuck open?

3)-If radiator is warm after say a 30 or 40 minute run does this mean thermostat IS working ok?

Thanks & sorry again (my brain really is not working tonight!).

mikey72

1)-If within say 2-4 minutes of starting top hose is hot & bottom is cold thermostat is stuck open?

No, too soon to say

2)-If after a 30-40 minute run top hose is hot/bottom hose is cold/cool/only slightly lukewarm then thermostat is stuck open?

No, in this weather it's working ok, may be warm, or cold.

3)-If radiator is warm after say a 30 or 40 minute run does this mean thermostat IS working ok?

Yes, or maybe stuck open.


All the thermostat does is open if the engine gets hot, and the hot water will pass through the radiator to cool.
If the engine is cold, the thermostat should stay shut, and the radiator will be cold.

DEBTMONKEY1A

Thanks Mikey 72! Also read that if you start engine from cold & put your hand on the radiator it will get hot within a minute or so if stat stuck open-is this correct?

mikey72

Not really on a 106 diesel. They produce next to no heat when on idle. I doubt you'd notice the radiator warming up much.
You could wait all day with ours. I had to run it up and down the road in the end when I changed the radiator and filled with antifreeze before the engine got warm enough to open the thermostat.

DEBTMONKEY1A

Mikey72-any idea on cost of part+fitting for thermostat?

off too bed now-my head hurts (!)

mikey72

£20 for the thermostat and housing, antifreeze, an hours labour. £60 maybe at a cheaper garage, £80 at a dealer. £10 cheaper if you don't have a combined thermostat housing.