Pre-cat Radiator Airflow
Discussion
Hello All,
Just getting used to my '92 pre-cat and all its 'characteristics' ;-)
I have a question for fellow pre-cat owners.
I believe my cooling system is spot-on. Thermostat fine, temp gauge steady as a rock 90-95, fans cut in, heater toasty warm, absolutely no airlocks.
So whats the problem then?
Well, I'm used to having a car that once up to speed (40mph +), the temp needle drops to whatever the thermostat regulates at. With mine, the temp needle stays at 90-95 and occasionally the cooling fans cut in whilst cruising. I know this because my headlamps and volt gauge take a hit when they cut in.
Why are my fans occasionally cutting in when driving along at speed? Is it a characteristic of the pre-cat nose with the little letterbox under the numberplate?
I have shone a torch through the rad and the fins are all in order, not bent or blocked. I don't believe the radiator to have blocked cores. Its the first time I have owned a car with a radiator lent over at such an angle - perhaps I'm worrying about nothing.
I have just purchased 'The Griffith Story' and there is a bit in there about struggling for air flow and different designs around the leading edge of the bonnet. Indeed, the front nose was modified for the 500.
Just seeking other peoples experiences before I declare 'faulty'.
Sincerest Regards,
Jay.
Just getting used to my '92 pre-cat and all its 'characteristics' ;-)
I have a question for fellow pre-cat owners.
I believe my cooling system is spot-on. Thermostat fine, temp gauge steady as a rock 90-95, fans cut in, heater toasty warm, absolutely no airlocks.
So whats the problem then?
Well, I'm used to having a car that once up to speed (40mph +), the temp needle drops to whatever the thermostat regulates at. With mine, the temp needle stays at 90-95 and occasionally the cooling fans cut in whilst cruising. I know this because my headlamps and volt gauge take a hit when they cut in.
Why are my fans occasionally cutting in when driving along at speed? Is it a characteristic of the pre-cat nose with the little letterbox under the numberplate?
I have shone a torch through the rad and the fins are all in order, not bent or blocked. I don't believe the radiator to have blocked cores. Its the first time I have owned a car with a radiator lent over at such an angle - perhaps I'm worrying about nothing.
I have just purchased 'The Griffith Story' and there is a bit in there about struggling for air flow and different designs around the leading edge of the bonnet. Indeed, the front nose was modified for the 500.
Just seeking other peoples experiences before I declare 'faulty'.
Sincerest Regards,
Jay.
I must admit I don't recall my car displaying the characteristics you describe with the fans....... every thing else sounds on the money though (jealous of toasty heater though)
I'd be half tempted to see if it's a dodgy temp switch first...... albeit a nice new radiator is always nice
(If you do change the rad, think very carefully weither you get an ali one or not)
I'd be half tempted to see if it's a dodgy temp switch first...... albeit a nice new radiator is always nice
(If you do change the rad, think very carefully weither you get an ali one or not)If you have access to an IR Thermometer you can test the coolant temperature in/out of the radiator, therefore determining if it's working.
Something like this;
http://www.ebay.co.uk/itm/Handheld-Non-Contact-IR-...
(no personal link to advertiser)
Something like this;
http://www.ebay.co.uk/itm/Handheld-Non-Contact-IR-...
(no personal link to advertiser)
Hi, I Have an early 500 preserp. i had the same problem a few years ago with the Fans constantly running on and off whilst driving. I had my rad recored but it didnt make much difference. I noticed on the later griffs they fitted a small metal Splitter. so i fitted one onto the bottom lip of the intake to the radiator. what a difference it made. My temp used to be at 90c when driving now its at 80c even when the weather is hot.
The rads do build up with sediment after time and mine was blocked up to about 6 inches from the bottom. thats why i had it recored and improved by going to a 4 core rad.
Alex
The rads do build up with sediment after time and mine was blocked up to about 6 inches from the bottom. thats why i had it recored and improved by going to a 4 core rad.
Alex
Dash gauge can be inaccurate and more so at speed as the sensor can get cooled by high speed airflow.
Sounds like it's right based on fan operation on yours though. If the fans are still coming in at speed, could be rad or stat as already mentioned - and do you have the ally lip spoiler under the nose - this can help push air through the rad?
My current 500-nosed car doesn't have the lip and runs ok - new stat here though, as mine was jammed open.
My precat ran 5-10 deg cooler at speed (from memory - a decade ago!) once I added the lip - I reckon the less open precat nose doesn't help cooling, but then underbonnet temps should be lower than 500s as no cats. Early precats only had one rad fan then they added a second fan at some point in 92 probably because one wasn't up to the job - sounds like you have a pair though?
Sounds like it's right based on fan operation on yours though. If the fans are still coming in at speed, could be rad or stat as already mentioned - and do you have the ally lip spoiler under the nose - this can help push air through the rad?
My current 500-nosed car doesn't have the lip and runs ok - new stat here though, as mine was jammed open.
My precat ran 5-10 deg cooler at speed (from memory - a decade ago!) once I added the lip - I reckon the less open precat nose doesn't help cooling, but then underbonnet temps should be lower than 500s as no cats. Early precats only had one rad fan then they added a second fan at some point in 92 probably because one wasn't up to the job - sounds like you have a pair though?
Thanks for all your replies.
My experience of a blocked radiator is that the cooling fans (I have the twin set up) would run and run to make up for the poor heat dispersal of a ineffective radiator. They have to 'suck for longer' to make up for the inefficiencies so to speak. As my fans run for the shortest, infrequent little bursts, that suggests to me the radiator is really efficient and doing its job well. I have no complaints with my cooling system whatsoever, I am just trying to eliminate those short fan bursts whilst cruising.
What does interest me, and it was the answer I was hoping for, Waggy and others have mentioned a little lip or something to assist airflow through the radiator when cruising. My nose cone has evidence of repair and there is no lip, channelling, ducting or flaps to provide any assistance. Perhaps this has been omitted in its history?
Thanks again.
My experience of a blocked radiator is that the cooling fans (I have the twin set up) would run and run to make up for the poor heat dispersal of a ineffective radiator. They have to 'suck for longer' to make up for the inefficiencies so to speak. As my fans run for the shortest, infrequent little bursts, that suggests to me the radiator is really efficient and doing its job well. I have no complaints with my cooling system whatsoever, I am just trying to eliminate those short fan bursts whilst cruising.
What does interest me, and it was the answer I was hoping for, Waggy and others have mentioned a little lip or something to assist airflow through the radiator when cruising. My nose cone has evidence of repair and there is no lip, channelling, ducting or flaps to provide any assistance. Perhaps this has been omitted in its history?
Thanks again.
jay-kay-em
Sound very familiar to when I first had my Precat. As Waggy suggests, do not under estimate the benefit the splitter has on airflow over the rad and it’s the cheapest option to start with. If the symptoms persist you could try a new alloy rad or vented bonnet from http://www.damagedtvrs.co.uk/products/part/16
Good Luck
Steve
Sound very familiar to when I first had my Precat. As Waggy suggests, do not under estimate the benefit the splitter has on airflow over the rad and it’s the cheapest option to start with. If the symptoms persist you could try a new alloy rad or vented bonnet from http://www.damagedtvrs.co.uk/products/part/16
Good Luck
Steve
Hi Frank - new coolant pump from Rimmer Bros, new genuine Land Rover thermostat. Block, heater matrix and rad flushed (including the inlet manifold valley pipes). Good condition (still blue) coolant ejected right from the start of the flushing procedure. New SAMCO hoses all round including heater matrix supply/return. Comma anti-freeze mixed 50/50 with distilled water. System bled out perfect with all bleed screws. Thermostat opens just fine. Brand new, twin SPAL fans operate as normal, for normal time intervals. Rock steady temp 90-95, heater matrix nice and toasty. Cogged V-belt correctly tensioned. Coolant level bob-on. Radiator in perfect visual condition. All the things you have asked me to check are bonafide overheating root-causes. Mine does not overheat. As far as I am aware, to the best of my knowledge, my cooling system is in top shape and has no faults. I just want to eliminate cooling fan operation whilst cruising.
Steve - thanks. I'm really interested in this splitter for a pre-cat nose. Was it factory fit? I don't appear to have one. Many people here have mentioned it. If it *is* factory, I will obviously have to make one. Does anyone have a picture of one, or is there a pre-cat in Cambridgeshire that I can compare with over a pint?
Thanks in advance,
Jay
Steve - thanks. I'm really interested in this splitter for a pre-cat nose. Was it factory fit? I don't appear to have one. Many people here have mentioned it. If it *is* factory, I will obviously have to make one. Does anyone have a picture of one, or is there a pre-cat in Cambridgeshire that I can compare with over a pint?
Thanks in advance,
Jay
jay-kay-em said:
Steve - thanks. I'm really interested in this splitter for a pre-cat nose. Was it factory fit? I don't appear to have one. Many people here have mentioned it. If it *is* factory, I will obviously have to make one. Does anyone have a picture of one, or is there a pre-cat in Cambridgeshire that I can compare with over a pint?
Thanks in advance,
Jay
Here's some very old pictures and info that will give you an idea of what we are talking about.Thanks in advance,
Jay
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Splitters are not unique to precats and were also fitted by the factory to Griff 500s. The factory splitters were made of fibreglass but I personally have an aluminium one so I can bend it up and down to suit the local speed bumps.
You may also find this thread interesting, in particular rad temperatures & two stage fan speeds.
http://www.pistonheads.com/gassing/topic.asp?h=5&a...
Well, thanks to you guys, I think that's my question answered. Nose cone airflow can be an issue.
I would imagine mine was torn off years ago...
More discussion here :
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Its actually a TVR listed part :
http://tvr-parts.com/tvr-parts/part-details/tvr-u0...
To quote the following website "Take a look under your car... If you can't see one, then you need one."
http://www.damagedtvrs.co.uk/products/part/18
That's me busy this weekend.
Regards,
Jay.
I would imagine mine was torn off years ago...
More discussion here :
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Its actually a TVR listed part :
http://tvr-parts.com/tvr-parts/part-details/tvr-u0...
To quote the following website "Take a look under your car... If you can't see one, then you need one."
http://www.damagedtvrs.co.uk/products/part/18
That's me busy this weekend.
Regards,
Jay.
I've found a rubber draught strip does the job, plus being mainly rubber it doesn't get ripped off so often:
http://www.diy.com/departments/stormguard-aluminiu...
http://www.diy.com/departments/stormguard-aluminiu...
jay-kay-em said:
Hi Frank - new coolant pump from Rimmer Bros, new genuine Land Rover thermostat. Block, heater matrix and rad flushed (including the inlet manifold valley pipes). Good condition (still blue) coolant ejected right from the start of the flushing procedure. New SAMCO hoses all round including heater matrix supply/return. Comma anti-freeze mixed 50/50 with distilled water. System bled out perfect with all bleed screws. Thermostat opens just fine. Brand new, twin SPAL fans operate as normal, for normal time intervals. Rock steady temp 90-95, heater matrix nice and toasty. Cogged V-belt correctly tensioned. Coolant level bob-on. Radiator in perfect visual condition. All the things you have asked me to check are bonafide overheating root-causes. Mine does not overheat. As far as I am aware, to the best of my knowledge, my cooling system is in top shape and has no faults. I just want to eliminate cooling fan operation whilst cruising.
Steve - thanks. I'm really interested in this splitter for a pre-cat nose. Was it factory fit? I don't appear to have one. Many people here have mentioned it. If it *is* factory, I will obviously have to make one. Does anyone have a picture of one, or is there a pre-cat in Cambridgeshire that I can compare with over a pint?
Thanks in advance,
Jay
Hi Jay, I had similar with my 430, but a lot worse - fans on most of the time and getting quite hot all the time. I ended up having Rad recored (locally done for about £175), changing the 'otter switch' (the thermostatic switch on swirl pot that activates the fans). This improved things considerably, fans hardly came on except in traffic, but she still ran hot when driving along, whatever the speed. So, I put this down to insufficient airflow into and through the rad and proceeded to design a small profile aluminium air splitter to mount at the back of the air intake grill. It made an amazing difference with temperature whilst driving along 80 to 85 ish! I made quite a few and supplied our local TVRCC group Griff & Chim owners. Send me a PM if you are interested in one as I still have a few in my workshop! All the best, PeteSteve - thanks. I'm really interested in this splitter for a pre-cat nose. Was it factory fit? I don't appear to have one. Many people here have mentioned it. If it *is* factory, I will obviously have to make one. Does anyone have a picture of one, or is there a pre-cat in Cambridgeshire that I can compare with over a pint?
Thanks in advance,
Jay
[quote=jay-kay-em]Hi Frank - new coolant pump from Rimmer Bros, new genuine Land Rover thermostat. Block, heater matrix and rad flushed (including the inlet manifold valley pipes). Good condition (still blue) coolant ejected right from the start of the flushing procedure. New SAMCO hoses all round including heater matrix supply/return. Comma anti-freeze mixed 50/50 with distilled water. System bled out perfect with all bleed screws. Thermostat opens just fine. Brand new, twin SPAL fans operate as normal, for normal time intervals. Rock steady temp 90-95, heater matrix nice and toasty. Cogged V-belt correctly tensioned. Coolant level bob-on. Radiator in perfect visual condition. All the things you have asked me to check are bonafide overheating root-causes. Mine does not overheat. As far as I am aware, to the best of my knowledge, my cooling system is in top shape and has no faults. I just want to eliminate cooling fan operation whilst cruising.
[quote]
You are thorough !
If installing an airdam/lipspoiler make sure its in the correct position, about 3" (ish) behind the rad/vent grille, you want an area of low pressure behind it, drawing air from the engine bay and hence air thru the rad
If need be, I've got the dims of the spoiler....
Frank
[quote]
You are thorough !
If installing an airdam/lipspoiler make sure its in the correct position, about 3" (ish) behind the rad/vent grille, you want an area of low pressure behind it, drawing air from the engine bay and hence air thru the rad
If need be, I've got the dims of the spoiler....
Frank
So, just a bit of an update. Firstly I followed the advice of Griffdude and purchased an IR thermometer from Machine Mart. I knew these existed but shocked at how much the price had come down. For £28 its just worth having in your toolbox I think. Temperatures across the radiator just fine, no cold spots.
On that basis, I then set about making these splitters. I purchased a length of semi-square section OSMA guttering and cut it down with a circular saw table.
I have owned many high performance cars over the years, but I have never visited a builders merchant quite so much for any of them!
I fitted two, one at the trailing edge of the air intake just making a little lip, and the other at the rear which matches the OE principle and causes an engine compartment depression.
I did a long run down to Stansted on the M11 and temperatures have been drastically reduced. My cooling fans no longer cut in when cruising. Difficult to quantify, but I would say 5mm lower needle height on the gauge. Quite incredible really. I would say that my coolant temperature when cruising is now regulated by the thermostat partially closing - which is just what I want.
Thanks for highlighting this issue.
Regards,
Jay.
On that basis, I then set about making these splitters. I purchased a length of semi-square section OSMA guttering and cut it down with a circular saw table.
I have owned many high performance cars over the years, but I have never visited a builders merchant quite so much for any of them!
I fitted two, one at the trailing edge of the air intake just making a little lip, and the other at the rear which matches the OE principle and causes an engine compartment depression.
I did a long run down to Stansted on the M11 and temperatures have been drastically reduced. My cooling fans no longer cut in when cruising. Difficult to quantify, but I would say 5mm lower needle height on the gauge. Quite incredible really. I would say that my coolant temperature when cruising is now regulated by the thermostat partially closing - which is just what I want.
Thanks for highlighting this issue.
Regards,
Jay.
Gassing Station | Griffith | Top of Page | What's New | My Stuff