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[Mrtom73]

Hi my names Tom and i have owned my 05 plate cdi forfour for a couple of months now. I have a question regarding the engine. My car seems to be running rather cool. The engine temp gauge shows it running between 50 and 60. Now im sure this is way to cool and not what its supposed to be. Ive opened the bonnet and the top rad hosre and the top of the rad while not cold arent exactly boiling either. Im now thinking of changing my thermostat, water pump and temp sender. My question being where are they all on this engine? I think i know where the pump is but not the rest. Anyone can help please.

Tom

[Problemchild]

could be that your thermostat has failed open

if water pump had failed then water temp reading would be high

have you checked the levels? may not be high and have a bit of an airlock?

JJ

[Mrtom73]

Yeah im thinking thermostat. Levels look ok to be honest. Going to order a stat i think. Is the stat at the back of the engine?

Tom

[CrazyG]

The symptoms you describe are that of a thermostat that has failed
in the open position.  It is not a simple job as the thermostat is located
at the back of the engine in a very awkward area. Even I would baulk
at attempting to change it, so my advice is get if sorted by a good
Smart independant. (MB would charge you a fortune)

There is a Technical Guide that I created here:-
http://www.forfour.co.uk/forum/index.php?topic=4235.0

However, we are in an awkward position at the moment as
nearly all pictures in posts on the forum have been hosted
on Photobucket....and recently they have changed their
terms and conditions (with zero warning) that any images
that they host that are to be displayed on any other website
requires the owner of the images to pay them $399.99
before they will permit them to be displayed to a 3rd party...

I have just been advised by our forum technical 'guru' that
the forum can 'upload' images from members posts...providing
they are not more than 800x600 or 600x800 pixels.
So...it will now take some time for any member who has images
currently on Photobucket to resize them, download them, and then
change the link in their posts.  In the case of JJ and myself, we
have a mamoth task as we have many hundreds of images that we
loaded/have loaded since we started the forum back in 2010 !

So...please bear with us.

[Mrtom73]

Many thanks for that crazyg. I will attempt it myself as i usually do all my own repairs. It does sound like a rubbish job. Shame about the pics but will try and suss it out. Many thanks

Tom

[Mrtom73]

Just seen i can look at the pics by clicking on them.

Tom

[CrazyG]

Oh..good...
As fa doing it yourself...God help you is all I will say !
nodi who did his...and on whose info the Guide was written
took 38hrs to do
And his was a LHD car that has; in comparison to an RHD; loads
more space to work in to get to/at the thermostat.

I do know that a Smart indie took about 4 or so hours to do on an
RHD 454 CDI...and that was with the advantage of having the car
up on a hosit, with all the right tools, and a dam good idea of what
and how they were to do it.  And they still cursed and swore every
5 minutes while doing it...saying it was a real b'stard of a job.

[Mrtom73]

Yeah it looks a real crappy job but hey ho. I workedon black cabs for 15 years and they were a bloody swine to work on.

Tom

[darklord]

I would suggest simply installing an inline thermostat in the top hose if the original is is bad as that to replace.

The Rover 75 diesel has a similar problem, and the usual solution is to for a Renault 5 thermostat in the top hose - you can even buy a a ready made housing for it on eBay. The Renault thermostat is quite compact and opens at 88 degrees.

I did the the same trick on an Alfa Romeo 156 V6 that had the same problem - the original thermostat failed open. It too was a difficult repair. So £5 later, and  Renault 5 thermostat in the top hose, all was well...

As someone who likes to do jobs properly, it took me a while to not see this as a bodge, but rather an acceptable alternative, but I assure you it worked beautifully.

[CrazyG]

Darklord...
I've just searched on ebay for 'Renault 5 thermostat housing'
and got everything bar a Renault 5 thermostat housing...
I did find just the Renault 5 termostat though...loads of them

So please, as you say they can be found, and that they will
do the job, would you please be so kind as to post up a link
to one of those items on ebay...or the search parameter that
you used to find them, as I myself am in need of one for my
CDI with a similar low coolant temp issue.
(Or...if you are saying you fitted one into the hose, please
 explain how you went about that, for the benefit of other
 CDI owners who may have or get this issue with low temp) 

[darklord]

Sorry for not making myself clearer.

What I mean is you can buy a Rover 75 kit on eBay to fit a Renault 5 thermostat in the top hose. I don't see why it won't fit the top hose of any car - it's designed to be fitted in-line.  I don't know how to post links, but Ive just checked on eBay - just search for "Rover 75 inline thermostat". You can buy one kit for £14.99, or a fancier kit which includes a metal housing which you presumably fit inline in the hose for £58.99.

When I did the Alfa, I just inserted the thermostat down the hose...

Given the seeming difficulty on the Smart diesel, I'd be tempted to try if the opening temperature of the Renault thermostat is suitable for the Smart.

As for fitting it directly in the hose, well it will depend on the diameter of the hose. The Alfa was a struggle, so some washing up liquid came in handy...but at least I could be confident it was never going to move! The Renault 5 thermostat is often used though because it's quite small, opens at a normal temperature range, and is widely available.

I'm ready for the backlash from outraged owners...

[Mrtom73]

Thanks for the advice. Its certainly something worth bearing in mind i would say. I think a pic would help if at all possible.

Tom

[darklord]

Sorry it was several years ago so no pics.

You could either cut the top hose mid way and fit the housing available between the two ends, or do what I did on the Alfa - simply undid the hose at the radiator, pushed the thermostat part way down, and re secured the hose on the radiator.

[Problemchild]

i did this on the bmw 5 series

it was either replace the 2 thermostats for £100 or buy a £4.99 thermostat and feed it into the top hose.

this only works if its failed open (which it seems like it has)

need to know the diameter (internal) of the top hose and find a cased thermostat



JJ