Couple of theories on the diesel cool running problem?

[Mike Noc]

Originally Posted by Elliott

Diesels have never enriched the mixture just altered the injection timing to advance for cold start.

Just to clarify this diesels don't run on a mixture full stop. The incoming air isn't throttled so the maximum mass of air enters the engine each cycle irrespective of how much fuel is injected.

The actual mass of air will vary depending on atmospheric conditions and how hard the turbo is working, but there is no mixture as you get with a petrol engine - the fuel ignites as it is injected. At idle there is loads of air left over, and this can also have a cooling effect.

Drive it like you stole it and the M47R will get hot enough.

[clf]

Well it's been a couple of months since I fitted the new 'stat, and commented, so after a thread tonight, I thought I should update with my observations of how the Wahler 'stat has performed.

(all observations, are from my daily commute to maintain some form of continuity) It is still reaching 75 degrees within 2-3 miles, not that I doubted it, from how well engineered it was. This is where the best of the previously fitted ones began to let themselves down, with the lack of watertightness, resulting in a (too) long amount of time to reach 82-88 degrees. It would take a further 7-8 miles, 4 of which were m/way speeds.

Now what happens, is that after a further 2 miles, ie before I reach the m/way, it has reached 88 degrees. This was my target, to be fully at the accepted operating temperature, before I started driving at m/way speeds. Onto the m/way, and it rises still to 90 before the stat opens, and cycles between 86 and 90.

On the way home, I am only about 1/2 a mile from the m/way, but after about 3 miles of m/way speeds, the temp has reach 90 degrees, and cycles through 86-90 on the way home.

So far I havent noticed any differences caused by ambient temps rising, although I would have to assume it will though, when it gets warmer still. I do not think it will make a huge difference, considering it is at around 35-40 degrees within a quarter to half a mile from leaving home.

Fuel economy has leapt up to roughly 82 mpg based on brim to brim fills, I jest of course, the fuel economy brim to brim has raised very little by 1-2 mpg, but I wasnt expecting much if any. I wanted to hopefully to restrict unnecessary wear and tear because of the low operating temps.

My overall impression is, the Wahler stat is a beautifully made stat , but it is unnecessary. It is 15 quid! The issue as previously observed and discussed (many times, and not just this thread - I thank you all for your patience with me). Simply making sure the stat is watertight prior to fitting is all that will be required, and rejecting any that leak when cold. Mat and Jules have both selected samples from their stocks to check this.

[First_damned]

Originally Posted by Jules

Just checked a sample of my Firstline stock and they are 100% water tight.
Never had a leakage problem with these.

However just noticed one of them (top left is too large and never going to fit in top hose so that one will be returned!)

Also sometimes we are supplied these with external bulbs or the integral design.
We prefer the external bulb as they are easier to fit and don't have to be pushed so far into hose.

What are the part numbers for these first line stats please?


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[ceedy]

My CDti never gets to anything above 83-84 max , and that is only after giving a bit of a thrash otherwise its 80-81 tops .

C

[T-Cut]

Originally Posted by First_damned

What are the part numbers for these first line stats please?

You need an 89-90C, Renault 5 stat made either by Firstline, Wahler or Gates. I'm sure their thermostat webpages will tell you.

Originally Posted by ceedy

My CDti never gets to anything above 83-84 max and that is only after giving a bit of a thrash otherwise its 80-81 tops.

Cool running Renault 5 stats are due to coolant bypassing when closed. Some brands do, some don't.

TC

[First_damned]

Originally Posted by ceedy

My CDti never gets to anything above 83-84 max , and that is only after giving a bit of a thrash otherwise its 80-81 tops .

C

This is what mine does. Second thermostat that's been in there. Strange though as it got up to 86 when I first installed it


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[ceedy]

My Dizzle has the 89 stat from DMGRS and a new Sender and a new cap
so not a lot more to do

C.



Cool running Renault 5 stats are due to coolant bypassing when closed. Some brands do, some don't.

TC[/QUOTE]

[First_damned]

Originally Posted by ceedy

My Dizzle has the 89 stat from DMGRS and a new Sender and a new cap
so not a lot more to do

C.



Cool running Renault 5 stats are due to coolant bypassing when closed. Some brands do, some don't.

TC

[/QUOTE]



Same as what I've got, Renault 5 thermostat from DMGRS. I can only presume they open early / leak water past them when closed.

Mpg figures still seem ok though, so not sure it's worth the hassle to just gain about 6 degrees in temperature.

Unless putting one in that will actually open at 89 increases mpg a bit more?


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[ceedy]

TBH Worrying about a couple of degrees ? .or a couple of Mpg's .

Personally never found that much difference in Mpg's with temps of my original 78 deg or 88 .

And if you got to thrash the car to get up to the " recommended " Temps. seems to rather defeat the temps objective of scraping a couple of extra miles out of the mpg .

I'll have to stick with my Auto's 35ish mpg for general running about locally

Chris


PS Did actually get up to 98 ish once this year stuck in Traffic for a long time on a very hot day , so it can get there , but at 1-2 mph the MPG didnt seem that great

[Jules]

Many of my customers report MPG improvements of 3 - 5 mpg after their engines were running in the 70's so I'm not sure what went wrong in your case