AdamR
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| posted on 16/1/11 at 11:56 AM |
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Rover V8 coolant temperatures
What sort of coolant temperature typically constitutes overheating for Rover V8 engines?
My 3.9 will happy sit at 95 deg C all day long when at rest and idling, but if I rev the engine this can rise to just over 100. This is all based on
running in the garage, as I've not got the car on the road yet. I see this as a worst case scenario as there is no airflow over the radiator
other than provided by the electric fan, which is switched on at 95 degrees. Temperatures when moving should be the same or lower.
Are these sorts of temperatures acceptable? How hot does the engine need to get for me to worry about damage? System is pressurised so will not boil
until something greater than 100 degrees, though I've not yet worked out exactly what that temperature is.
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RazMan
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| posted on 16/1/11 at 12:15 PM |
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Sounds about right to me - my V6 runs at similar temps but in the colder weather it struggles to get above 70 deg or so. I have since fitted a
thermostat to help the electric water pump in getting warmer, quicker so I will see what happens next month when it comes off SORN.
Your boiling temp is probably around 110-115 deg C (with 50/50 antifreeze added) if mine is anything to go by, and with a pressurised system it will
be significantly more - 120 degrees is not unusual. I still get a bit twitchy when sitting in traffic, waiting for the fan to kick in as the temp
rises above 100 though 
[Edited on 16-1-11 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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wilkingj
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| posted on 16/1/11 at 12:40 PM |
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As its a 3.9 and they are prone to water problems with the liners slipping / leaking, have you done a block pressure check?
Also check to see if there is water in the oil, or oil or other (Combustion?) contaminants in the water.
Is it losing water?
I got an 82 degree thermostat in my Rover V8 (3.5Litre).
Rover SD1 Manual says 82 Degrees C and 1 Bar (15psi) pressure for the cap. This is for engines up to 1982.
IMHO I think 95 degrees is a tiny bit high...
How Big is your Radiator?
I also had to fit an overflow tank, as I always ended up using the same amount of water regardless of the journey length.
I was not getting any oil in the water, or water in then oil, and had checked the head gaskets as well. 3.5's do not suffer from the water
issues that the 3.9's 4.0's or 4.6 engines.
I since fitted a bottle to the overflow outlet, and changed the rad cap to one with the extra seal that seals the top of the cap to the top ring of
the radiator.
Then the expanded water exits via the overflow into the bottle, and is then sucked back into the rad when it all cools. (Needs the pipe to go to the
bottom of the expansion bottle so it can syphon the water back into the rad).
This has been a very successful mod for me.
I got this idea from the Series LandRover, which also used this method of retaining water.
Dont know if this is of any help to you.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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britishtrident
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| posted on 16/1/11 at 01:48 PM |
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At 1bar (gauge) radiator pressure your coolant won't boil until it reaches over 120c and if you use 60% antifreeze solution you can add 10
degrees onto top of that. When using high concentrations of antifreeze make 100% sure you have suffient by-pass flow.
If you have a conventional old fashioned thermostat one trick is to drill a couple of small holes in the thermostat valve plate to allow a little
extra water circulation around the thermostat valve plate which makes the thermostat respond faster to changes in temperature.
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AdamR
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| posted on 16/1/11 at 02:17 PM |
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OK, thanks all.
Radiator is the usual Polo item. I know it is small but there are plenty of examples of people using it to cool effectively much higher-output engines
than mine - Rover V8s included.
Thermostat has been drilled and my air bleed plumbing seems to be working well and preventing any airlocks - though would be interetsed to hear if
there is a way I can check for these to be absolutely sure.
The two variables items I can play with if these temps are too hot are the thermostat and the fan switch, which from memory at 87 degress and 92
degrees respectively. My concern is that the engine temp should be regulated by the thermostat, and therefore anything >87 is abnormal, even if
it's not dangerous? Suppose I could try a lower temp fan switch.
@Wilkingj - When you say block pressure check, do you mean compression tests on the cylinders, or something else? Was planning to do a compression
test at some point just as a matter of course - though I'm not too worried about any serious issues at the moment as engine runs well with no
mayo in oil or water.
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PAUL FISHER
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| posted on 16/1/11 at 02:53 PM |
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On my 5 litre Rover V8 TVR, it runs at between 75 and 80 deg C when driving, if I leave it ticking over on the drive Ive never seen it over 90 deg C,
the fans cut in at 90 deg C taking the temp back down to below 80 within a couple of minutes, the Chimaera's do have a very large radiator
though and 2 big fans, so I would advise just getting your fan to cut in at around 85/90 for now, and then see how you get on when your car is on the
road, you may find you need a larger radiator in the future.
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marcjagman
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| posted on 16/1/11 at 02:59 PM |
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You need an 82 degree thermostat, have your fan cut in at 87-90. Not a good idea to run a Rover V8 hot, they dont like it.
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rusty nuts
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| posted on 16/1/11 at 04:30 PM |
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Water wetter will drop the temperature by as much as 20 degrees, worth thinking about if your cooling system is a bit marginal? As said Rover V8s
don't like running too hot
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AdamR
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| posted on 17/1/11 at 03:56 PM |
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quote:
Originally posted by marcjagman
Not a good idea to run a Rover V8 hot, they dont like it.
quote:
Originally posted by rusty nuts
As said Rover V8s don't like running too hot
What sort of issues am I likely to see if I run too hot then?
BTW, I've since resolved a separate issue I was having with oil pressure and this seems to have decreased the running temps slightly. I've
not seen anything >95 since, even when revving. That suggests that the temperature is being successfully regulated by the fan, so a lower temp fan
switch should help if 95 really is considered too high.
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PAUL FISHER
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| posted on 17/1/11 at 06:50 PM |
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Yes 95 deg C is considered too high, but is not going to cause you any imminent problems, although rover V8 engines prefer less than 85 degrees for
maximum engine reliability and preservation, running the engine in the garage in the winter is no real test as to whether its going to overheat on the
road, these are big engines and produce alot of heat, on a hot sunny day under load or pulling up a big hill, and then standing in traffic you may
have problems, Rover V8 engines are mostly aluminum with some steel and iron components. Aluminum engines are very susceptible to damage from
overheating, problems can be warped heads, cracked blocks, slipped liners, another common overheating problem on the v8's causes the oil
pressure relief valve to stick causing loss of oil pressure, just see how go when you get it on the road, but I suspect in the long run, you may have
to fit a larger radiator.You could try a 74 deg c thermostat, they are only cheap so could be worth a try to see if it improves things.
http://www.rimmerbros.co.uk/Item--i-ETC4761P
[Edited on 19/05/04 by PAUL FISHER]
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