Duratec (CSR) over cooling

[Darren Harrold]

Took the car out for its last time before I take it of the road for the winter. Decided to venture south and watch/join the London to Brighton.

 

Stamford to Brighton is over a 300 mile round trip so given the daylight hours available I had little choice but to take the motorways.

 

During the steady speed driving I noticed that my water temperature sometimes only read 60 deg C. Now throughout the summer it has maintained a steady 80 deg. Even on the hottest days.

 

On the return journey, whilst on the motorway, I discovered a correlation between RPM and TEMP. Above 4000 rpm the temperature would quickly drop. I was driving for most of the time at 5000 rpm = 60deg. But slow down to 3500 rpm and the temp soon goes back to 80deg (normal).

 

This was very consistent, anyone any idea what’s going on?

 

Darren

 

[CharlesElliott]

Does the cooling system still have it's thermostat fitted? If so, it could be stuck.

 

Charles

---

My SuperGraduates 2006 diary

My SuperGraduates 2005 diary, My Caterham Academy 2004 build and race diary

[Delberts Wallet]

Geez, you CSR owner are new happy. One minute its too hot and too cold the next.

 

Should of bought a car with a proper engine

 

Gareth

 

Blue and Carbon 6 Speed Supersport with new wheels

[sonicsaab]

Hi Darren

 

As they say TADTS. AS Iwas told, the engine when it was in a truck cooled perfectly. However, as the revs used are higher it means that the water is being forced through the cooling system at a higher pressure. First scenario was a diffferent pulley wheel to slow the pump but understand that has gone by the board. Next the thermostat was to be fitted with something to strengthen the spring. Heard nothing from CC on this. So it runs cool as the revs go up !!!!

[I.Mupferit]

The Duratec in my SV wouldn't get up to temperature either, when driving down to Sossiges yesterday. It was hovering below 60 most of the time and that despite the fact 60% of the rad was blanked off. Better on the way home though when the ambient temperature had risen to a more confortable level.

 

Perversely I decided against using the heater on the way down as that would only have made it worse so it was a tad chilly in the nether regions.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Darren Harrold]

Water pressure! Ok that makes sense. I would presume that a constant 5,000rpm on a motorway is not much work for the engine, so if water is being forced by the thermostat then on the cool day would it mean that the radiator efficiency improves and hence why its never happened until now.

 

Brent, i am presuming that the pump/pulley and stat setup is the same on yours and the cosworth version.

 

Is this a problem?. What is an accceptable range for water temp? Having in mind that on a cooler day its going to run cooler. btw oil temp was unaffected and was around its normal 90deg (no oil cooler on CSR200 yet!)

 

Darren

 

PS.. Gareth. I was nice and warm !

 

Edited by - Darren Harrold on 6 Nov 2006 08:12:37

[DohNut]

 

I would have thought that opening the flow to the heater circuit would have helped as it would be reducing the pressure head accross the pump

A small flow of air through the heater should keep your toes warm and take relatively little heat out of the engine (compared to 80mph through the rad)

 

N

 

Time for an electric pump?

[Rob Walker]

Are you using the ECU controlled themostat or the fixed mechanical Mazda type?

 

Rob

[I.Mupferit]

I can't really see how opening the heater circuit would help as that effectively just gives more surface area to be cooled, rather like introducing another radiator into the flow circuit in the same way that putting the heater on in the summer can help reduce overheating.

 

Mine is a mechanical thermostat btw.

 

I did find yesterday that when the car is stopped with the engine running, the temperature will slowly creep up towards normal (as you would expect) and won't drop as much when you are moving again almost as though pre-warming to normal temperature first would help keep the temperature up in the right band.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Rob Walker]

The Duratec water pump is capable of producing quite high flow within the block when the engine is revving I have seen it blow the hoses off . Cosworth then started fitting the oversized drive pulley, has this now been dropped? I wonder If the pressure/flow generated is so high that it is preventing the thermostat from closing once it has opened.

[paul jacobs]

It does seem to be an acknowledged problem, even when accelerating, when the revs get to around 4k, if you've got time to watch the water temp. you can see it dropping from 85-90 down to about 70, probably less this weather.

 

On my old Vauxhall, it was recomended that we drill a small hole or two in the flange of the thermostat itself, I guess that if there is high pressure in the pipes, this will release it a bit and allow the thermostat to close easier, but then, I'm sure that CC have already thought of this and discounted the idea

 

It might be worth playing around with though, after all it'll only be the cost of a new thermostat,if it doesn't work. Let us know if it works, and if it does, I'm sure that we'll all chip in to help with the development costs 😬

 

Paul J.

Loud pipes save lives, but quiet ones save your hearing.

 

Edited by - Paul Jacobs on 6 Nov 2006 10:43:57

[Rob Walker]

Paul,

 

The 3mm hole in VX thermostat was to reduce the overall temp that the engine ran at as the stock thermostat was rated too high and a proper replacement cost £90 ish from Swindon. Not sure it would help on the duratec.

 

Rob

 

Edited by - Rob Walker on 6 Nov 2006 10:59:11

[I.Mupferit]

I know it isn't a Cosworth engine but my Duratec already has a 2mm hole in the thermostat plate. I was surprised that even with the rad blanked off by 60% it was still not getting up to temp.

 

Sorry to butt in on Darrens thread btw but I thought it might be relevant since they are essentially the same engines.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

 

Edited by - Brent Chiswick on 6 Nov 2006 11:16:34

[Rob Walker]

Paul,

 

You may be surprised that the mechanical thermostat cannot be purchased as a simple thermostat its an integral part of the housing and hose take off spouts. Not a cheap item.

 

Rob.

 

Edited by - Rob Walker on 6 Nov 2006 11:07:19

[dazula]

I thought the idea behind having a hole in the thermostat is to prevent overheating by allowing some water to circulate to allow the thermostat to detect water temp. Otherwise if the water did not circulate a bit – how’s the thermostat to know.

 

I don't believe that such a hole in the thermostat will have any significant part on over-cooling. However, over pressure sounds very feasible.

 

Whilst it was fun for a very short time to watch the temp gauge do the opposite to the tacho!. My main concern here is if it is OK to run an engine with a water temp of 50-60 deg C alright for the engine in the long-term ?

 

btw - i looked at some electric pumps - not cheap !!!

 

Darren

 

[I.Mupferit]

The hole in the 'stat in mine is there for the purpose you state Darren since I have the Raceline water rail which sites the 'stat remotely from the head so it doesn't normally see the actual temperature within the engine until it opens to allow water to flow over it. The hole just allows a small flow of water over the bulb so that the 'stat can read the temperature sooner. This works quite well under most circumstances but clearly it was just too cold for it early yesterday morning.

 

Despite the issues of heat soak into the cockpit on the CSR Duratecs, generally, do seem to run quite cool I believe although yesterdays experience was quite extreme.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[DohNut]

Brent

I stand by the fact that opening the heater circuit will reduce the pressure accross the pump.

This will reduce the volume of water getting pushed past the thermostat and through the radiator.

If you then close off the air flowing through the heater then no heat will be removed from the system.

If you turn on the heater fan to Max then yes you have introduced another radiator to the circuit but you have reduced the flow through the main radiator (which would not happen in the summer)

 

A better engineering solution would be to get a pressure relief valve to vent excess water pump pressure from the pump outlet back to the pump inlet.

This would limit the peak pressure on the thermostat yet continue to ensure that there was full water flow around the engine when it returned to idle. Ensuring complete coolant flow at idle may be the reason why the oversize pulley is no longer used by cosworth.

N

 

 

[dannylt]

My car was built by Mick Attree and don't have the raceline water rail, but I haven't noticed the temperature move from 80 degrees at all once warm whatever the outside temperature and revs? It could be the location of my sender (on the back of the head)? I have no heater. Just to add another example.

 

I thought Cosworth were fitting oversize pulleys to save the pump vanes at 8000rpm, or to save power?

 

 

[I.Mupferit]

But don't forget, the heater has a bypass circuit anyway so closing off the heater simply flows the water through a different circuit rather than stopping it flowing completely so it can't affect the pressure across the pump by that much.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Mark w]

Not a duratec but my R400 used to do this . It was eventually solved by changing the thermostat to unit of better quality i.e. one with a spring that was strong enough to close against the high water flow.The stat i use does have a small hole in it so when its very cold the water circulates a bit more than it might need to but i have always felt this a safer bet in the hot summer when the car gets most use.

 

FWIW i went down to Handycross yesterday and going down the temp sat at 73 degrees on the motorway coming back it was more like 76 degrees

 

 

PS what was your oil temp ??

[RWHomer]

It is a well known problem with a factory retrofit solution being a larger pulley on the water pump to slow down the water flow , and a stronger spring on the thermostat . Does not now overcool to the same degree.

[RWHomer]

Well known problem. Factory solution is a bigger pulley on water pump to slow down the flow and and a stronger spring on the thermostat. Seems to have stopped the overcooling to some degree

[Darren Harrold]

I found that with the heater on or off there was no change in the water temp. only the revs made a difference.

 

..... so is running a petrol engine at 60degC bad for the engine ?

 

Darren

[ELV15]

FWIW, I use the stock thermostat, which has an electric override. I have this triggered by the radiator fan pin of my ECU. I have noticed that the water temp will vary according to rpm - ie: a quick burst of high rpms will drop the temp - but it quickly returns to normal (80'C) when the rpms drop, or if you sustain high rpms.

 

Mine has been quite reliable (touch wood). However, I know other folks who have switched out to the mechanical verison for reliablity reasons!

 

ELV15 - Tom in California -

200hp duratec powered 2003 Clubsport Build pics here: here

[Lennie]

Has anybody tried an electric pump? This would give a controlled constant temp, may save a bit of power and would also allow for a much simpler fan belt route.