Fiat Coupe Club UK

Coolant Temperature issue

Posted By: Vinnytgm

Coolant Temperature issue - 09/05/2018 16:54

Hi all,

I'm having some issues with my Coupe, a 1998 20VT in blue. The issue is as follows; when driving the car at motorway speeds the temperature doesnt rise from the minimum value!

If I keep the car stationary whilst running (ie stuck in traffic) the temperature creeps upward past 90. If I start driving again it falls.

I am thinking that the thermostat is responsible for this.

Has anyone experienced this before or able to shed some light on it?

Thanks

Vinny
Posted By: Anonymous

Re: Coolant Temperature issue - 09/05/2018 17:30

Sounds like the thermostat may be stuck open.

Incidentally , does the radiator fan cut in when it creeps upward past 90 ?
Posted By: Vinnytgm

Re: Coolant Temperature issue - 09/05/2018 17:42

No the fan doesn't kick in I just did some digging around there and discovered that the second, lower connector on the fan is not connected I'm going to wait until the engine cools before I connect it. Hopefully that gets the fan operational.
Posted By: Blueboyracer

Re: Coolant Temperature issue - 09/05/2018 19:05

Sounds very much like the thermostat for sure
Posted By: Master_Mariner

Re: Coolant Temperature issue - 14/05/2018 14:35

Yep sounds identical to when my thermostat needing replacing.

It will also cause your car to run rich until its sorted.

Nice and easy fix for the 20vt.

Regards

MM
Posted By: X19_pilot

Re: Coolant Temperature issue - 15/05/2018 13:24

Just replaced my thermostat today, temperature was sticking at 70 degrees unless in heavy traffic, when it went up to 90 and the fans kicked in fine when it crept over.
Just got to check and bleed it one last time if nessessary when I get home.
The How To guide was a big help and it only takes about an hour if you are handy with a set of spanners. Worth just getting some liquid gasket before you start the job.
Posted By: Vinnytgm

Re: Coolant Temperature issue - 15/05/2018 20:40

Thanks for the advice I have a new thermostat ordered should have it tomorrow or Thursday! My fan isnt kicking in as it should I guess thats a seperate issue probably a relay, fuse or connector

Edit: I just tested the fan now and it works. Happy days. Going to swap out the thermostat with fresh coolant when it lands and all should be good!
Posted By: Vinnytgm

Re: Coolant Temperature issue - 19/05/2018 14:14

So I got a new thermostat and tried fitting it only to discover that the new thermostat has an extra pipe on it.

I've spoken to the supplier who said all the thermostats on the system are showing the extra pipe.

I've attached pictures below its the brass pipe on the front of the unit beside the black pipe. Has anyone any ideas? Is this the wrong part, I was thinking of putting on a blank plug?!

https://preview.ibb.co/n2FfrT/20180519_160554.jpg

https://preview.ibb.co/koz6WT/20180519_160549.jpg

https://preview.ibb.co/cL0wWT/20180519_160541.jpg
Posted By: X19_pilot

Re: Coolant Temperature issue - 20/05/2018 08:36

I threw my old one out yesterday so I cant say for sure where I inserted a blanking plug into, but mine did come with a grub screw for this purpose.
It didnt come with the extra pipe though, just a threaded hole.

Sorry for the vague reply, I will have a look in the skip shortly and see if it is still kicking around within reach...
Posted By: dante giacosa

Re: Coolant Temperature issue - 22/05/2018 07:31

this is a classic scenario, I think

you have to find a way to blank that off
Posted By: Vinnytgm

Re: Coolant Temperature issue - 22/05/2018 09:22

A few phone calls and a call in to the supplier this morning resulted in me returning the new thermostat. I've found a Mehle stat on ebay which has the correct pipes on it. Will have to wait a few days until delivery. Hoping it fits!

On a seperate issue the oil temperature gauge isn't reading. I suspect that this is the sensor itself, would anyone have a part number for ths sensor?
Posted By: X19_pilot

Re: Coolant Temperature issue - 22/05/2018 13:10

There are 2 numbers listed as OEM on this site

https://www.buycarparts.co.uk/fiat/coupe-fa-175/7760/10578/oil-pressure-switch-sender-unit-valve

Although I am sure someone will be along shortly to confirm. thumb
Posted By: DaveG

Re: Coolant Temperature issue - 22/05/2018 13:38

Wrong part number, that's the switch for the low oil pressure light, for the temperature gauge you need this one instead (7588856 is the Fiat part number, or you can use Valeo 700007 for example):

https://www.buycarparts.co.uk/oen/7588856
Posted By: Vinnytgm

Re: Coolant Temperature issue - 22/05/2018 16:14

Thanks for the help lads! I had a quick look for a how to, or the location of the sensor on the engine would you know where it is? I imagine it is easy enough to change.
Posted By: bockers

Re: Coolant Temperature issue - 23/05/2018 08:52

the ECU coolant sensor is on the thermostat.

Is all on the FAQ
https://www.fiatcoupeclub.org/forum/ubbthreads.php?ubb=showflat&Number=330845#Post330845
Posted By: bockers

Re: Coolant Temperature issue - 23/05/2018 08:53

My advice would be to replace the sensor too.
Posted By: DaveG

Re: Coolant Temperature issue - 23/05/2018 09:53

There's two coolant temperature sensors on the engine: one for the instrument panel gauge (located on early cars to the rear of the cylinder head behind the thermostat, and on later cars located in the thermostat) and another for the ECU (on the thermostat). That's why some thermostats have space for two sensors.

The oil temperature sensor is located at the bottom of the sump, on the offside/driver's side (RHD cars) below the crank pulley and drive belts.
Posted By: Vinnytgm

Re: Coolant Temperature issue - 24/05/2018 13:39

Are these the correct coolant sensors to get?

https://m.buycarparts.co.uk/eps/8744315

https://m.buycarparts.co.uk/metzger/1811241
Posted By: Vinnytgm

Re: Coolant Temperature issue - 11/06/2018 14:57

Well folks just an update the third thermostat unit I got was finally correct. Fitted it and the engine is now running as it should.

I proceeded to do a small service on the car; oil and filters and plugs.

The car drove for about 10 minutes afterwards until it left me stranded on the roadside. Turns out its an electrical short preventing the fuel pump from working! Mechanic says he is looking for the fault but could take him a while!
Posted By: barnacle

Re: Coolant Temperature issue - 11/06/2018 17:04

Yellow connector of death? By the fuel cutoff switch, driver's knee department.
Posted By: Vinnytgm

Re: Coolant Temperature issue - 12/06/2018 08:18

I'll check it out Barnacle. Is it a case of reconnecting it or does it have to replaced?
Posted By: mr_nobut

Re: Coolant Temperature issue - 13/06/2018 21:18

I cut my yellow connector out and soldered wires and shrink wrapped and the intermittent non starting has disappeared forever!!! Just search yellow connector, it’s a well known issue. Hope it’s that simple!!!
Posted By: Vinnytgm

Re: Coolant Temperature issue - 20/06/2018 08:39

Found the problem and sorted it. I accidentally pinched one of the wires on the 5th coil pack when I put the cover back on causing the wire to break, the fuse for the fuel pump blew. A new fuse and a used coilpack later and she's running again!

Dropped the Coupe off this morning at an Alfa specialist for the timing belt/water pump. To fit a set of Viper coolant hoses and to sort a small gearbox leak.
Posted By: Vinnytgm

Re: Coolant Temperature issue - 20/06/2018 08:44

Here's a quick picture of the Coupe, realised I haven't uploaded an image of it yet!

https://preview.ibb.co/d0RwEd/20180620_104156.jpg

https://thumb.ibb.co/bCz3cy/20180620_104906.jpg
Posted By: Master_Mariner

Re: Coolant Temperature issue - 20/06/2018 12:43

She looks very nice!

Glad you traced and resolved the broken coil pack wire- what a pita!

Here's to her flying through her timing belt (and ancillary belts?) water pump and other bits and pieces.

And being back in good form asap!

Regards

MM
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