Hi

My 1.6 16v is now up and running again after burning a couple of valves. The car has been run for over a week now and I am pleased - all seems well (touches wood)

However I have noticed since the engine was rebuilt the car occasionally stalls at low revs such as when slowing down at a junction - its really strange one minute its running then it just cuts out.

I have used the search tool and found references to cleaning the inlet valve which I have done which has not cured the problem.
I have also cleaned the MAP sensor - again this has not cured the problem.

I am now thinking it may be the thermostat based on Deckchairs post. I am yet to do the test ne has suggested however I have noticed the engine does not get to the temperature it used too. By this I mean the needle used to always point straight up (North) no matter the weather. However recently - last 2 years or so it has only got to north west (maybe) say between 10 - 11 on a clock face.

Could this be the problem and will it definately cause stalling probs on the stilo? why since the engine (top end) rebulid could this have started to happen? are there any other sensors that may have been disturbed that could cause these syptoms?

Also where is the engine thermostat? and does the coolant need to be replaced to change it?

Many Thanks in advance

If your engine isn't getting the dash temp gauge up to the middle then that points to a weak thermostat that needs replacing. However, if the engine IS getting up to temp and it's the eng temp sensor that is causing an inaccurate gauge indication then it's NOT the thermostat that's causing the problem

How can you tell which? Go by feel
With heater fan turned off and engine started from cold, the heater pipes going into the cabin shouldn't take too long to be too hot to keep your hand on. The large pipe going from thermostat to radiator should be cold at this time as the thermostat should be closed and then when the thermostat opens there should be a sudden rush of very hot water going through it as the thermostat opens. Again this should be too hot to keep your hand on it for more than a few secs. In this weather your cabin heater would have very poor output if thermostat wasn't working properly ie opening only when it should


Where is the thermostat?
Follow the top large pipe from the radiator back to the engine and the thermostat will be at the end of that. Thermostat is replaced as a whole body unit and is therefore quite expensive so check and be certain it is faulty before replacing. The eng temp sensor (item 1) is installed in the same unit

So with a weak thermostat expect poor heater output, dash gauge never getting to N, heater cooling off even more and engine dying at idle after long fast stretch of road, heater pipes to cabin very warm but not scolding hot

It's not essential to replace coolant. I wouldn't drain the coolant out, I would just remove the thermostat and allow for spillage then there's very little to top up again

Thanks Decks (again) you really ave been a great help recently.

I will go and try the procedure in a minute.

So just to clarify - If I do get the rush of hot water your describing it will be the engine temperature sensor rather than the thermostat itself - is that correct? can this be repaced on ts own or cleaned atall to fix?

You have described the symptoms of my car perfectly:

So with a weak thermostat expect poor heater output, - YES
dash gauge never getting to N, - YES
heater cooling off even more and engine dying at idle after long fast stretch of road,
- YES (aghhhhhhhh)
heater pipes to cabin very warm but not scolding hot - Going to confirm in a while.

Will let you know the results.

Any ideas as to why this would suddenly start happening?

Many Thanks again Decks

If I do get the rush of hot water your describing it will be the engine temperature sensor rather than the thermostat itself - is that correct?
The rush of hot water is when the thermostat opens. If there is no rush at all and the pipe just gradually gets warm from square one then the thermostat is definitely goosed. If there is a rush but the pipe doesn't get too hot to hold then thermostat is opening at too low a temp.

If you have poor heater output already, you didn't mention that before, then the problem will almost certainly be thermostat as you can already feel the coolant temp isn't hot enough

Can eng temp sensor be replaced on its own or cleaned to fix?
Yes it's pretty cheap and a straight unscrew, put your finger in to stop spillage and replace. If you look at diagram above then it's very straightforward replacement although access isn't wonderful

Any ideas as to why this would suddenly start happening?
Thermostat is an extremely basic bit of kit working on caveman principles of wax warming up expanding and fighting a spring so it gets tired and leaks. But it's more reliable than electrics and electronics in water

NB If you change the thermostat then do an ECU reset afterwards so it relearns the new best settings

With valves recently blowing and a total misfiring engine then there will have been a lot of fuel/oil thrown down through your cat which will take a while to burn off totally during which time your O2 sensors will be a bit cheesed off at all this mess passing their way so it may take 1000 miles or so to get really clean steady tickover again.

Decks - assuming I have done this correctly the pipe does get hot quite quickly however it does not get to scalding - in fact I could quite comfortably hold on to it. It is showing 0° as the temp outside this morning. Car got to its usual temperature 10 'O' clockish on the dial.

Am I correct in saying it is the top pipe that leads to the RHS of the rad as looking at it from front of car and is closest to you, running from the thermostat to the front of the car. (not the pipe at the back that leads to the cabin)

Anyway the pipe did not get scalding so I assume this points to the thermostat being on its way out.

Will this get worse over time and what problems can I expect if I leave changing this component for the short term?

Thanks again Decks.

Regardless of the outside air temp, when the thermostat opens it should hurt to keep your hand on the pipe (yes you have the correct one) so that points to a weak thermostat.

It will do no harm to leave it for a while apart from burning a bit more fuel and all the symptoms you are already experiencing. If it gets worse then the heater will become very weak in this weather. Use the recycle switch often to keep the heat inside.

Decks,

Just been on a short trip approx 3 miles and noticed temp guage go up to nearly the halfway mark! anyway on checking the pipe to see if t was hot I noticed that the actual Thermostat itself was scalding hot - now I know its metal so naturally will conduct the heat as opposed to the rubber hose but does this signify anything to you?

Ive also read about a discount code for shop4parts on here but have been unable to find a code for it. Any ideas? as they seem the best place to buy the thermostat from at £53.00 ish.

Now I know that is not alot on its own but added to the engine rebuid bill its all adding up!

i did 12 months with a stilo with a bust thermostat. just took bloody ages to get warm, didnt cause cutting out issues though

Shminky
Yes it's difficult to judge if you're moving when outside temps are so cold. If your dash gauge is getting up to N then that's good, if it takes ages to get there even when stationary then something's up. You could put your air con on to keep your tickover up until you have time to sort it. Heat will always win over cooling so you wont be cold in the cabin

Shop4parts discount code
Go to https://www.fiatforum.com/member-offers/


Hey BBS nice to see you again
Its kinda weird but if the themostat is stuck wide open then it takes ages to warm up as you've said but ECU doesn't get confused by that so it doesn't lose tickover. When the engine is simply running cool through a weak thermostat then the engine gets up to a reasonable temp but then cools off after a high speed run and seems to have trouble with that

Deckchair5 said:

Hey BBS nice to see you again
Its kinda weird but if the themostat is stuck wide open then it takes ages to warm up as you've said but ECU doesn't get confused by that so it doesn't lose tickover. When the engine is simply running cool through a weak thermostat then the engine gets up to a reasonable temp but then cools off after a high speed run and seems to have trouble with that

Click to expand...

Still, bit wierd not being able to cope with that. I bet fiat only ever thought it would get hot and cool itself to normal!!

Yes I guess that's the plan, engines warm up and don't normally cool right off again.
Had any more broken gearboxes?

na. not in the bravo- got the sport so its not the smoothest of boxes! infact when its cold, best leave second alone till its warm.

not really had many problems with the bravo on the scale of the stilo. i think the worst i have had is a bust radiator that spray boiling hot water into my aircon condensor and ruined the lot.

all on warranty though!

as well as a bravo, i have a 2001 306HDi now as well (got rid of the saxo chav rocket). that has some intersting faults every now and then! that keeps me busier than any fiat has done!!!

My 1.8 16v stilo does the same thing so I will have it checked out, and it seems to fit the bill as the cabin heating is noticeably poor. Luckily I just bought the car and its under warranty so I shall get onto the garage I bought it from and get them to sort it out!

hi. my stilo seems to have the same problem of stalling all the time. it's in at fiat for a diagnostic tomorrow morning, will this pick up if it's the thermostat. Thanks