306 XSi too hot after fixing misfire problem

Hi all
My '95 306 XSi has had a misfire/juddering acceleration problem
for more months than I'd care to admit to - from reading this
newsgroup & elsewhere I had been chasing down air leaks and other
possibles as causes of the problem. However after a casual comment
from a local garage I realised that the HT leads were sparking,
replaced the leads and - Bingo! My misfire is gone.

I report this here partly so others can know about this as a possible
caused. And I'm embarrassed for not trying the simpler things first.
However...

When the car was misfiring the engine would get hotter than I'd like -
up to around 110 or higher in town traffic - but I was able to keep
the temperature down by keeping in low gear & the revs outside the
misfire range. After I had the HT problem diagnosed I also replaced
the spark plugs, and reset the ECU, guessing that the misfire would
have 'miscalibrated' the ECU.

Now though, the engine is consistently running hot - 110 or greater,
and a couple of times it's hit the temperature at which the STOP light
comes on ;-(. My oil & water levels are good good and the engine seems
to be running well.

I'm guessing that fixing the misfire problem may be showing up this
temperature problem, or that they may be related. I was hoping that my
new sparkplugs & reset ECU approach would work, & now it hasn't I'm
wondering what to do next. Any suggestions?

Thanks
jon N

 

not wanting to ask the obvious but is the electric cooling fan cutting in
when it should,
Only ask this as I had a Vauxhall many moons ago and if you watched the
temperature gauge then as soon as you saw it pass a certain point you new
the fan would cut in, plus it had a battery gauge so you could see the power
drain. Occasionally the fan would not cut in and it was usually a dirty
connections, once it was the relay that had failed
Anyway, its a fine line between the fan coming on and the engine
overheating.


GGJ

 

Hi Gary

[...]

AFAIK the fan is cutting in - at least it's can hear it running for a
few minutes when I switch the engine off!

I'll see if I can hear it cutting in in normal operation.

Thanks for your thoughts.

jon

 

It hasn't got two fans has it and only one working? Seems to be quite a
common Pug problem to do with relays.

 

Hi Keith

seems to have one fan.

Some more experiments: I unclipped the connector from the radiator
thermostatic switch and shorted it; the fan started up fine. And it
runs for a few minutes after the engine has stopped. I've heard it
running whilst driving but haven't determined at what temperature it
cuts in.

I've just driven around 5miles/10 minutes (A roads mostly) from
'almost cold'. The temperature gauge has just hit 110. From feeling
around the radiator, the Right Hand Side (looking from the front) of
the radiator, including the hose, is pretty hot. The middle and LHS of
the radiator are cool.

I'm wondering if the thermostat is b*ggered?

Cheers
jon N

 

Does sound as if it is stuck in the closed position or not opening early
enough. I only know one way to test that. It involves removing it, a
cooker, a large saucepan and a cooks thermometer. The rest you can probably
work out for yourself. On my old Princess (the last time I had occasion
to test one) it was supposed to open as the water approached boiling,
bearing in mind it boils at a lower temperature than in the car because it
is not pressurised.

If the 306 is anything like the 406 watch out on refilling. On the 406,
because the water circulates higher than the filler cap, you have to
artificially raise the filling position. I believe plastic lemonade
bottles with their bottoms removed can be used provided that a good seal is
maintained where it enters the filler neck. You could, of course, also
stand the car on its tail ;o)

 

sounds like your thermostat is stuck closed as suggested. You could test it
using boiling water in a sauce pan , but to be honest I would just replace
it with a new one.
It could also be well worth it while you have the radiator pipes off to
blast a hose pipe through it from on side to the other and see if any crud
comes out of it, could find that half of the radiator is blocked with crud .
Best of luck, let us all know how you get on.
GGJ

 

Hi Guys
Thanks for the suggestions. I'm trying to locate a new thermostat
at the moment. Unfortunately the one for the 2L XSi seems to be hard
to come by ...

I had a look at the thermostat housing. On this model at least, on top
of the housing there's a small unscrewable knob, very like the top of
a toothpaste tube (though black plastic obviously). Any clues what
this is for?

Cheers
Jon N

 

Bleeding the cooling system

 

Hi Bob

Thanks - I was guessing this might be so, & now I've found the right
pages in the Haynes manual ;-)

I'm actually wondering if the problem has been an airlock in the
cooling system all along. Things have been significantly better after
I loosened and refitted the small 'toothpaste' knob. I also note that
the hose from the thermostat gets 'properly hot', indicating I think
that the thermostat is operating.

Anyway, since a new thermostat is only 12 quid or so, I think I'll get
one and drain & flush the whole system anyway. I'll let you know how I
get on.

Cheers
jon N

 

If your in the u.k dont forget the anti freeze.you might think i do it
later but you always forget and by then its too late.

 

I know it's 7 years ago since this thread but did you ever sort this problem on the pug306 xsi 2L? I have exactly the same car with the same problem. When the car gets hot, and only then, it gets really unhappy - idling rough, misfires etc. diagnostic light comes on and a funny smell comes through the heaters in the car; like unburnt petrol. Have checked the coolant system, flushed airlocks, replaced thermostat, checked fans - both kick in to cool overheating, replaced sparks, new exhaust sytstem etc but still cant pin the problem down. Wondered whether the HT leads might be worth checking - did this help? Cheers, Luke