Engine over-cooling

[taylormj4]

All,
In these low temperatures, the Chimaera typically never reaches even 60deg when running. My understanding is that low temperature running is not good for the engine - crud build up and lower efficiency. Plus the heater output is poor.

Modern cars seem to reach 90deg and sit there quite happily regardless of road speed or ambient temperatures.

Is the problem on the Chimaera that the thermostat doesn't have enough control over the cooling system or is it that the engine bay has too much inherent cooling via the bonnet vents ?

Anyone managed to get better control over the engine temperature ?

Cheer, Matt

[bobfather]

You are most likely getting a false indication on your dash gauge. I assume you haven't carried out the Rover temperature sender mod. TVR foolishly chose to fit their own sender in the front of the engine in a place where the coolant doesn't flow well. In winter the area can become very much cooler than the rest of the engine. The best way to know is by feeling the rad after a run, it should be very hot and this will tell you that the true engine coolant temperature is more than hot enough to open the thermostat.

If you have access to RoverGauge you can read the coolant temperature from the ECU sender which is better positioned. The Rover sender mod picks up an unused sender sitting close to the ECU sender

[bobfather]

Further info here

http://www.pistonheads.com/gassing/topic.asp?t=118...

There are dozens of other threads discussing this problem

[TV8]

assuming you are still running the 14cux lucas system, get a rover gauge lead (£35) and that will tell you what the other sender is telling the engine about how much fuel etc it needs. I was surprised how quickly the engine warms up, at least on my car.

[QBee]

Have you not noticed how your Audi, BMW, Mercedes, Saab, Lexus, whatever goes up to 90 degrees almost straight away and stays exactly there whether it be 3 degrees or 30 outside, and motorway or traffic jam?
A 21st century car's temperature gauge has only got three positions - off, fine or fked.
It's only purpose is to tell you that much.

[PhilH42]

Even in this cold weather mine still runs as always (well since I sorted out the cooling system) which is 70-90 dependant on driving conditions/traffic. It may take a little longer to warm up but no real difference, so it sounds like something's not quite right. I'm presuming the gauge and sender have worked - at least as accurately as can be expected in the warmer weather and theres no overfueling? Well no more than on warm up.

[taylormj4]

QBee said:

Have you not noticed how your Audi, BMW, Mercedes, Saab, Lexus, whatever goes up to 90 degrees almost straight away and stays exactly there whether it be 3 degrees or 30 outside, and motorway or traffic jam?
A 21st century car's temperature gauge has only got three positions - off, fine or fked.
It's only purpose is to tell you that much.

Well, I thought this too on our Audi A4 and assumed the same. However, it started showing lower temperatures and the temperature dropped at motorway speeds, much like the TVR. When this was investigated, the thermostat was found to be faulty and after it was replaced, the temp comes gradually up to 90 and then stays there. So I think it is accurately reading the temperature, the system is just better at controlling the temp. I think modern heater systems probably need a more consistent hot water input for these climate control systems.

[ClassiChimi]

QBee said:

Have you not noticed how your Audi, BMW, Mercedes, Saab, Lexus, whatever goes up to 90 degrees almost straight away and stays exactly there whether it be 3 degrees or 30 outside, and motorway or traffic jam?
A 21st century car's temperature gauge has only got three positions - off, fine or fked.
It's only purpose is to tell you that much.

That's what I was going to say but you said it with more humour

[taylormj4]

PhilH42 said:

Even in this cold weather mine still runs as always (well since I sorted out the cooling system) which is 70-90 dependant on driving conditions/traffic. It may take a little longer to warm up but no real difference, so it sounds like something's not quite right. I'm presuming the gauge and sender have worked - at least as accurately as can be expected in the warmer weather and theres no overfueling? Well no more than on warm up.

Think everything is working correctly, yes. At least, it's always behaved like this. In the Summer, the temp comes up to 70-80 whilst moving and go up to 90-95 in traffic with the fans cutting in/out correctly.

In Winter, the temp will come up to around 60-65 but when moving it drops to 50-60.

The heater output temperature matches the gauge so when the gauge reads lower, the output heat from the blower vents is cooler, so I think the gauge is accurately showing the coolant temperature.

The only time this hasn't happened is when I had a minor un-noticed coolant leak and the level had dropped significantly. The coolant temperature was a lot higher for the time of year and eventually the heater output went completely cold, even though the gauge was showing hot.

So I am confident that the gauges are reading accurately.

My first thought was that the thermostat was stuck open but others were reporting the same behaviour from their cars so I thought this was just normal.

[ClassiChimi]

It is pretty normal
Mine will run slightly cooler if in cold weather I start and drive,
I tend to think ahead slightly and start her up and idle at about 1100 revs for a minute or so then turn it off, finsh locking up the house etc (another minute or so) then when I fire it again some heat soak has already taken place, it normally warms up to about 60/70 quickly after that, only takes a couple of minutes more and I've got warm air from the heater
Get into traffic and it will rise to 90 ish, get going again and it drops to around 70 on the run.

I like to get it over 50/60 degrees before getting onto open roads or it stays cool for to long.
Hope that gibberish helps

[QBee]

That makes perfect sense Alun, and what I will be doing this Spring to avoid fristbite of the tootsies.

[bobfather]

You sound like you're the first person to have this problem, you are not. Your dash gauge is not reading correctly and the fix is simple. I've done the Rover sender mod on 4 PH members cars to date, all of them suffering the same symptoms that you describe. All those gauges read correctly now, you'll also be amazed how quickly the engine reaches full temperature.

The TVR sender is in a very poor location and suffers from poor coolant flow and massive air cooling. Sometimes my gauge wouldn't rise at all until I stopped or slowed down. The RoverGauge reading showed me that the engine was heating up quickly and stably winter and summer. The ECU sender is well located, the TVR sender is poorly located. Many owners have seen precisely what you observe, the solution is very simple, carry out the Rover sender mod then thank me for being persistent

[BeastMaster]

taylormj4 said:

Think everything is working correctly, yes. At least, it's always behaved like this. In the Summer, the temp comes up to 70-80 whilst moving and go up to 90-95 in traffic with the fans cutting in/out correctly.

In Winter, the temp will come up to around 60-65 but when moving it drops to 50-60.

The heater output temperature matches the gauge so when the gauge reads lower, the output heat from the blower vents is cooler, so I think the gauge is accurately showing the coolant temperature.

The only time this hasn't happened is when I had a minor un-noticed coolant leak and the level had dropped significantly. The coolant temperature was a lot higher for the time of year and eventually the heater output went completely cold, even though the gauge was showing hot.

So I am confident that the gauges are reading accurately.

My first thought was that the thermostat was stuck open but others were reporting the same behaviour from their cars so I thought this was just normal.

Mine is exactly the same.

During the very cold months I insert a blanking panel in the middle of the rad, which covers a portion of each fan to cut down the cold air blast. This allows the temp to be similar to summer months and increases the heater output. In traffic the temp is the same as summer, less air is sucked through the rad but it is colder.

Very high performance cars have this type of thing auto operated, mainly to decrease drag, did think of making a mechanical operator, or even an electrical system running off water temp, but sticking a blanking piece in seemed much more TVR.

Andy.

[ClassiChimi]

I used to own a series 3 XJ6
That had rubber flaps on the rear of the rad housing, over a given speed the wind would push them away and allow the air through

[ClassiChimi]

QBee said:

That makes perfect sense Alun, and what I will be doing this Spring to avoid fristbite of the tootsies.

Spring,,,,, I sniff something going on

[PhilH42]

taylormj4 said:

Think everything is working correctly, yes. At least, it's always behaved like this. In the Summer, the temp comes up to 70-80 whilst moving and go up to 90-95 in traffic with the fans cutting in/out correctly.

In Winter, the temp will come up to around 60-65 but when moving it drops to 50-60.

The heater output temperature matches the gauge so when the gauge reads lower, the output heat from the blower vents is cooler, so I think the gauge is accurately showing the coolant temperature.

The only time this hasn't happened is when I had a minor un-noticed coolant leak and the level had dropped significantly. The coolant temperature was a lot higher for the time of year and eventually the heater output went completely cold, even though the gauge was showing hot.

So I am confident that the gauges are reading accurately.

My first thought was that the thermostat was stuck open but others were reporting the same behaviour from their cars so I thought this was just normal.

Sounds like mines the exception rather than the rule hey

As I said it does take a bit longer to reach temperature but mine is not acting much different once its there. Same as yours in summer really will go up to 90-95 in traffic. It Will run a few degrees less on a longer run in the cold but it's still over 70 at all times.

The only modifications I have is an ally rad, silicon hoses and a 75 deg stat (I think its 75) . I found in the early days mine ran cold at about where you say yours is now but would get hot bloody quickly in traffic....it was pretty blocked on inspection! Once everything was changed and cleaned all fine. The only other time it showed very cold was when the AFM was shot and it badly over-fuelled. To be fair though mine did that at any ambient
and yours is fine when a slightly warmer climate.

I'm sure positioning of senders as others have pointed out is quite likely a solution...make a little jacket

[PhilH42]

taylormj4 said:

Think everything is working correctly, yes. At least, it's always behaved like this. In the Summer, the temp comes up to 70-80 whilst moving and go up to 90-95 in traffic with the fans cutting in/out correctly.

In Winter, the temp will come up to around 60-65 but when moving it drops to 50-60.

The heater output temperature matches the gauge so when the gauge reads lower, the output heat from the blower vents is cooler, so I think the gauge is accurately showing the coolant temperature.

The only time this hasn't happened is when I had a minor un-noticed coolant leak and the level had dropped significantly. The coolant temperature was a lot higher for the time of year and eventually the heater output went completely cold, even though the gauge was showing hot.

So I am confident that the gauges are reading accurately.

My first thought was that the thermostat was stuck open but others were reporting the same behaviour from their cars so I thought this was just normal.

Sounds like mines the exception rather than the rule hey

As I said it does take a bit longer to reach temperature but mine is not acting much different once its there. Same as yours in summer really will go up to 90-95 in traffic. It Will run a few degrees less on a longer run in the cold but it's still over 70 at all times.

The only modifications I have is an ally rad, silicon hoses and a 75 deg stat (I think its 75) . I found in the early days mine ran cold at about where you say yours is now but would get hot bloody quickly in traffic....it was pretty blocked on inspection! Once everything was changed and cleaned all fine. The only other time it showed very cold was when the AFM was shot and it badly over-fuelled. To be fair though mine did that at any ambient
and yours is fine when a slightly warmer climate.

I'm sure positioning of senders as others have pointed out is quite likely a solution...make a little jacket

[blitzracing]

The stat should not allow water to even reach the rad until at least 75'C in your case, but it will still flow water around the heater all the time, but Id be surprised if it could pull that much heat out of the engine to keep it running so cool. A 75'c stat is a little on the cool side anyway as you are very close to the region of fuel enrichment (ie Choke) still, but it may be stuck open as well. Id be running at least an 82' Stat.

[rev-erend]

There are several thermostats available : 82 and 88 .. fit the 88 for winter.

It will help.

Another old trick people used to do was to partly cover part of the rad with cardboard .. but
you need to remove it if the weather turns warmer.

[taylormj4]

bobfather said:

You sound like you're the first person to have this problem, you are not. Your dash gauge is not reading correctly and the fix is simple. I've done the Rover sender mod on 4 PH members cars to date, all of them suffering the same symptoms that you describe. All those gauges read correctly now, you'll also be amazed how quickly the engine reaches full temperature.

The TVR sender is in a very poor location and suffers from poor coolant flow and massive air cooling. Sometimes my gauge wouldn't rise at all until I stopped or slowed down. The RoverGauge reading showed me that the engine was heating up quickly and stably winter and summer. The ECU sender is well located, the TVR sender is poorly located. Many owners have seen precisely what you observe, the solution is very simple, carry out the Rover sender mod then thank me for being persistent

Bobfather, I understand what you're saying and agree that the gauge could be sited poorly and exhibit those conditions but my point is this: if the gauge is reading incorrectly low and the coolant is actually at a much higher temperature, why does the temperature of the air output from the heater go cooler when the gauge drops ? Surely if the coolant was actually hot (as you suggest), the heater output would remain high. My experience is that the heater output temperature (which is linked to coolant temperature) matches the temperature gauge. That suggests the gauge is reading correctly.