Anyone advise on cooling fan setup on the Chimaera?
Discussion
Hi all,
new to this site and fairly new as a Chimaera owner. Used to wrench on my own cars back in the UK, but not done anything for the last 20 years and certainly not since I moved to Japan. Now I have a Chimaera 500 (mid life crisis), and have limited resources to work on it over here and finding limited information on the mechanicals when I get stuck.
Current issue is the car overheated last week when stuck in traffic for about 20 minutes. Parked it for an hour and drove home with no further issues, but concerned it over heated in such a short time in stationary traffic in December weather of about 10 degrees. Was reading through my copy of Steve Heath's book on the Chimaera to see what could be the issue on the cooling and found a puzzle - at least to me.
In the book it mentions early cars had a single cooling fan, and later this was upgraded to 2 fans. But there is no mention of 3 fans in there which is what I have on my car. I have the normal 2 fans on the back of the radiator but a 3rd fan on the front of the radiator. Seems counter productive to me as all seem to be pulling air through the radiator, so 2 would cancel each other out?
Maybe I've been away from the tool chest for too long and making some fundamental error in what I'm looking at. Any advice?
new to this site and fairly new as a Chimaera owner. Used to wrench on my own cars back in the UK, but not done anything for the last 20 years and certainly not since I moved to Japan. Now I have a Chimaera 500 (mid life crisis), and have limited resources to work on it over here and finding limited information on the mechanicals when I get stuck.
Current issue is the car overheated last week when stuck in traffic for about 20 minutes. Parked it for an hour and drove home with no further issues, but concerned it over heated in such a short time in stationary traffic in December weather of about 10 degrees. Was reading through my copy of Steve Heath's book on the Chimaera to see what could be the issue on the cooling and found a puzzle - at least to me.
In the book it mentions early cars had a single cooling fan, and later this was upgraded to 2 fans. But there is no mention of 3 fans in there which is what I have on my car. I have the normal 2 fans on the back of the radiator but a 3rd fan on the front of the radiator. Seems counter productive to me as all seem to be pulling air through the radiator, so 2 would cancel each other out?
Maybe I've been away from the tool chest for too long and making some fundamental error in what I'm looking at. Any advice?
Photographs would be a big help. The Steve Heath bible is a good start, however, overheating could be a few things. Firstly, you need to ensure that both the fans at the back of the radiator are actually coming on. If not, check the fan connectors under the radiator as they corrode. A quick clean, a bit of Vaseline and a reseal should resolve the issue. If this fails, you need to check the otter switch in the base of the swirl pot. Also check the hose from the swirl pot to the expansion tank and ensure it isn't blocked, pinched or leaking.
The fact that the owner has added a third fan may suggest that the car has had unresolved overheating issues in the past and the third fan was an attempt to fix them.
I would also consider checking the thermostat and making sure that it isn't stuck in the 'closed' position. This would prevent the cooled water from the radiator from circulating. Fitting a lower temp thermostat would help.
IIRC (open to correction) you can check if the water is circulating by removing the thermostat and then replacing the thermostat cover back on the manifold. Then remove the lower radiator hose from the radiator and the hose that goes from the heater rail to the manifold near the coil. Attach a running hose to the small hose attached to the heater rail and you should get water circulating and running from the bottom radiator hose. If it doesn't it may indicate a blockage somewhere which will need investigating…
The fact that the owner has added a third fan may suggest that the car has had unresolved overheating issues in the past and the third fan was an attempt to fix them.
I would also consider checking the thermostat and making sure that it isn't stuck in the 'closed' position. This would prevent the cooled water from the radiator from circulating. Fitting a lower temp thermostat would help.
IIRC (open to correction) you can check if the water is circulating by removing the thermostat and then replacing the thermostat cover back on the manifold. Then remove the lower radiator hose from the radiator and the hose that goes from the heater rail to the manifold near the coil. Attach a running hose to the small hose attached to the heater rail and you should get water circulating and running from the bottom radiator hose. If it doesn't it may indicate a blockage somewhere which will need investigating…
QBee said:
One small additional comment to add to that excellent post - the otter switch on some cars is low down on the back of the radiator, passenger side.
Indeed, and as I also found out there is another otter switch on top of the cylinder head. Regarding the fans they would not cancel each other out if they are rotating in the correct direction. Step 1 check coolant level. You need to take the top of the swirl pot off . Coolant should be up to the brim. Dont rely on the level in the expansion tank
Step 2 check both fans are coming on when they should
Step 3 check both fans are blowing in the right direction its not uncommon for them to be plugged in the wrong way round
Step 4 thermostat is it stuck closed IME they fail open but worth checking
Step 5 any garage can check the cooling system preferably with an infra red sensor . Might be a blocked rad or an airlock
ETA check the dystem is holding pressure. Get it up to temp then switch off and leave for 20 minutes then put a towel over the expansion pot and undo the cap a half turn, this should give a good hiss of pressure release. Beware this can be dangerous and you can get burned if in doubt ask a garage to pressure check the cooling system.
Step 2 check both fans are coming on when they should
Step 3 check both fans are blowing in the right direction its not uncommon for them to be plugged in the wrong way round
Step 4 thermostat is it stuck closed IME they fail open but worth checking
Step 5 any garage can check the cooling system preferably with an infra red sensor . Might be a blocked rad or an airlock
ETA check the dystem is holding pressure. Get it up to temp then switch off and leave for 20 minutes then put a towel over the expansion pot and undo the cap a half turn, this should give a good hiss of pressure release. Beware this can be dangerous and you can get burned if in doubt ask a garage to pressure check the cooling system.
Edited by Dodsy on Saturday 28th December 21:26
Thanks guys for that comprehensive list. I will get out to the garage later today and check off what I can from the list. Car was a low mileage '99 that had just been sat neglected on an out of the way garage forecourt for years so have expected issues - many of which were resolved during it's first Japanese MOT. However since then I've had a pulley bolt sheer off that shredded belt and bounced the pulley around the engine bay. Then most recently had the HT coil blow and leave me stranded. Getting parts out here takes time as not much available locally. Even fewer garages that will even touch the car at all.
Will get the fans pics later when I get out there. For now here is my money pit for the next few years as I start to bring it back to the way I want the car.
Will get the fans pics later when I get out there. For now here is my money pit for the next few years as I start to bring it back to the way I want the car.
Hi,
apologies as I made a mistake. The fan on front on the radiator is in fact blowing air through it, so with the fans on the back of the radiator pulling the air through, I now assume this to be ok. Am blaming a loss of sensitivity in my hands as to why I could not tell the air direction without the aid of tissue paper
This shows the position of the fan in front of the radiator. Does not look to me like someone added later, seems like OEM to me. Also just in front of the fan on the lower right of the wing is a duct that this fan may be pulling air from. Will have to get the car up on the ramps later to see where this duct goes.
Running the engine up to speed now the fans all come on together to cool and then switch off after a while, keeping the temperature around the 80C mark. Seems to run as good as before she got hot, just the normal moans and groans from her that is on my list of to do's.
I believe I did look at the Japan TVR club sometime during the past year, but I got the impression it was mostly based around parts and service from Sanc Auto. While this is a great shop for TVR, it normally means them trailering my car from one side of Tokyo to the other, which can get expensive before even starting any work. One reason I've been trying to do more at home, or find a local garage that can work on it. Sanc has to import a lot of parts too, so when I find a good firm I always let the guys there know about it. Will give TVRCCJ another look, so thanks for that.
One more day of work then will have a couple of weeks off to relax and work in the garage!
apologies as I made a mistake. The fan on front on the radiator is in fact blowing air through it, so with the fans on the back of the radiator pulling the air through, I now assume this to be ok. Am blaming a loss of sensitivity in my hands as to why I could not tell the air direction without the aid of tissue paper
This shows the position of the fan in front of the radiator. Does not look to me like someone added later, seems like OEM to me. Also just in front of the fan on the lower right of the wing is a duct that this fan may be pulling air from. Will have to get the car up on the ramps later to see where this duct goes.
Running the engine up to speed now the fans all come on together to cool and then switch off after a while, keeping the temperature around the 80C mark. Seems to run as good as before she got hot, just the normal moans and groans from her that is on my list of to do's.
I believe I did look at the Japan TVR club sometime during the past year, but I got the impression it was mostly based around parts and service from Sanc Auto. While this is a great shop for TVR, it normally means them trailering my car from one side of Tokyo to the other, which can get expensive before even starting any work. One reason I've been trying to do more at home, or find a local garage that can work on it. Sanc has to import a lot of parts too, so when I find a good firm I always let the guys there know about it. Will give TVRCCJ another look, so thanks for that.
One more day of work then will have a couple of weeks off to relax and work in the garage!
dazee said:
It's certainly not standard, it should be a blue VW pressure cap.
If your aluminium header tank cap is not a pressure cap the car will not hold pressure, so it'll definitely overheat.
The correct pressure cap should look like this:
I'd be looking very closely at that aluminium header tank cap if I were you.
dazee said:
The cap looks like a Leven cover to me.
http://www.ppctvr.co.uk/products/engine-water-cap
The thing behind the number plate is a GoPro camera mount.
http://www.ppctvr.co.uk/products/engine-water-cap
The thing behind the number plate is a GoPro camera mount.
Trevor450 said:
The cap looks like a Leven cover to me.
http://www.ppctvr.co.uk/products/engine-water-cap
The thing behind the number plate is a GoPro camera mount.
Yep that's the cap on mine. Not sure if that's a good thing or not. From that link I would think if designed for Chimaera then shouldn't be an issue, although that may just be me being naïve. Certainly when the car did overheat it did vent coolant from here. http://www.ppctvr.co.uk/products/engine-water-cap
The thing behind the number plate is a GoPro camera mount.
And yes, GoPro mount. Had been playing over the summer trying to get some video but having an issue capturing good sound without wind noise. Using a separate sound recorder, just looking for the sweet spot to mount it.
I've not seen the fan on the front of the radiator before. I'd be interested to see how much it benefits the cooling. The intake duct you are referring to on the right hand side is likely to be the engine induction. You should have an air filter in there somewhere, which will be connected to the corrugated black hose that leads to the plenum??? Are you losing water? Any steam from the exhausts? Is the oil clear?
Edited by Chuffmeister on Sunday 29th December 09:39
dazee said:
Yep that's the cap on mine. Not sure if that's a good thing or not. From that link I would think if designed for Chimaera then shouldn't be an issue, although that may just be me being naïve. Certainly when the car did overheat it did vent coolant from here.
And yes, GoPro mount. Had been playing over the summer trying to get some video but having an issue capturing good sound without wind noise. Using a separate sound recorder, just looking for the sweet spot to mount it.
I'd still check to see the system is holding pressure.And yes, GoPro mount. Had been playing over the summer trying to get some video but having an issue capturing good sound without wind noise. Using a separate sound recorder, just looking for the sweet spot to mount it.
Do the hoses firm up once up to temp?
As you can see from the words of wisdom here you want to check on here before listening to a mechanic who's never laid eyes on such a car.
Surely a fan on the front of the radiator will hold up the flow of cool air.
Loving the car it looks great.
Good luck and I'd be doing all the above before taking the car more than a mile!
Surely a fan on the front of the radiator will hold up the flow of cool air.
Loving the car it looks great.
Good luck and I'd be doing all the above before taking the car more than a mile!
- Random ramblings whilst I'm having lunch..
First questions from me would be how high did the temperature get and how much water was in the tank to start with? My one doesn't like to be more than half full and will quickly get rid of it if I've overfilled it, I've heard that some of them like to be around a quarter full. Check all of the standard things that have been said above first. Take the screw off of the top of the swirl tank when its cold and start the engine, if there is water circulation the level should at least move a bit. All of the pipes should be hot and hold pressure, top left of the radiator should be hot and the bottom right should be colder. Cheap patent tank caps can be crap and not hold pressure too, so that could be something to look at if you can't find anything else.
Thanks all. She is up on the ramps now and won't be going anywhere until I've gone through that list and checked everything. Especially want to check if there is air trapped in the system. Do you think it worth replacing that cap with the standard one?
Japanese MOT is very strict and everything on the car has to be tested thoroughly. When I first got the car I did have Sanc auto do a full service and check on it and then put it through it's test. That was an expensive one! But worth it as they did a lot of work and replaced many parts I could not have done. Also generally means you won't get many surprises then when you are driving.
Body work is now good. I also had a new set of carpets fitted from Coverdale - was hard to tell what the original colour was as everywhere you looked it was a different colour. All hoses have been replaced, basically wanted everything replaced that could have weakened and perished over the years.
Best time saver I've had so far has been to replace every single fuse in that darn fuse panel with a smart fuse. Had they been in from the start I could have avoided an annoying hour in a dark car park and night trying to find the fuse for the lights to replace. Also highlighted an electrical short I did not know was there from a botched up relay.
Glad I've found this site, seems to be a wealth of invaluable information here from some knowledgeable people. Hope you'll forgive my stupid questions I'm bound to have. For example.... does anyone have the power steering option? Does it seem to lack "power"?
Japanese MOT is very strict and everything on the car has to be tested thoroughly. When I first got the car I did have Sanc auto do a full service and check on it and then put it through it's test. That was an expensive one! But worth it as they did a lot of work and replaced many parts I could not have done. Also generally means you won't get many surprises then when you are driving.
Body work is now good. I also had a new set of carpets fitted from Coverdale - was hard to tell what the original colour was as everywhere you looked it was a different colour. All hoses have been replaced, basically wanted everything replaced that could have weakened and perished over the years.
Best time saver I've had so far has been to replace every single fuse in that darn fuse panel with a smart fuse. Had they been in from the start I could have avoided an annoying hour in a dark car park and night trying to find the fuse for the lights to replace. Also highlighted an electrical short I did not know was there from a botched up relay.
Glad I've found this site, seems to be a wealth of invaluable information here from some knowledgeable people. Hope you'll forgive my stupid questions I'm bound to have. For example.... does anyone have the power steering option? Does it seem to lack "power"?
dazee said:
Yep that's the cap on mine. Not sure if that's a good thing or not. From that link I would think if designed for Chimaera then shouldn't be an issue, although that may just be me being naïve. Certainly when the car did overheat it did vent coolant from here.
And yes, GoPro mount. Had been playing over the summer trying to get some video but having an issue capturing good sound without wind noise. Using a separate sound recorder, just looking for the sweet spot to mount it.
Matt Poxon does a lot of GoPro recording. He often sticks the microphone around the rear number plate, getting a good rumble without wind noise.And yes, GoPro mount. Had been playing over the summer trying to get some video but having an issue capturing good sound without wind noise. Using a separate sound recorder, just looking for the sweet spot to mount it.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff