radiator size - auxiliary fan

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Guest

Guest
Hi Guys,
I just returned from Algeria when I spent entire month traveling in
southern parts.
My kzj95 survived the trip without any problems although the driving was
really tough. The only problem I had was related to temperature rise on
long dunes while pushing the engine close to red for some time. But I
managed to avoid any overheating.
When I came back I tested the viscous coupling and it turned out that it
was the reason for problem. The guys who tested the visco told me that
it is very important that the radiator size (amount of coolant)
shouldn't differ too much in size from the original radiator (I replaced
original 2 cell aluminum with 3 cell cooper approx 0.5 l more coolant).
When I think about that it not clear to me why this might be a problem
since bigger radiator should provide bigger convective surface. If I
understood correctly it has something to do with temperature related to
bi-metal in visco which might be to low and consequently the fan is
spinning at lower speed - but on the other hand if the temperature is
lower why would it be a problem ...(of course I'm taking about
overheating problem) Nevertheless I replaced the visco with original
one ... and I hope that the problem is solved.
Can anybody explain me why the size difference might be an issue ? Let
say 1 l of coolant more ...
My second question is related to auxiliary fans since I think that on
one hand they might be helpful (long dunes at low speed in hot weather)
but on the other hand they are also a barrier for the engine air flow.
Has anybody tried to install some auxiliary cooling fans (pusher type)
in front of the radiator (or A/C unit) ?
Thanks in advance for your help & regards,
Tomaz
 
G

Guest

Guest
Hello Tomaz,
- Who did you go with? Any chance for the route, waypoints, roadbooks,
pictures .... please!
- How did you manage to go off-piste in Alg? According to most
sources, in the south you are only allowed to travel on tarmac. Has
anything changed?
- Is your LC manual or auto?
- The theory about interaction between the size of the radiator and
the operation of the fan viscous coupling sounds a bit strange to me,
too. In hot climates many cars have the coupling locked for good,
either deliberately or because it is broken. All it does is making the
fan spin faster when the engine is cold, but it definitely doesn't
make it spin slower when it's hot. Perhaps someone could present the
maths behind one litre of coolant upsetting the engine heat balance?
- Second fan: it might help for slow speed climbs if the main fan was
found wanting, which I can't say about the 1hd-t engine fan in such
situations. Because auxiliary fans are fitted to work in an open
space (unlike the primary fan which sucks air through a funnel) the
cooling effect is always limited. I suppose their advantage could
become evident when the main fan were damaged beyond repair. But by
then the radiator would have been probably shot, too.
According to my personal experience, a well maintained stock land
cruiser cooling system should not need a second fan. Long slow climbs
on soft sand put a greater strain on the automatic gearbox than the
engine.
--
Rgds,
Roman (London, UK)
'92 HDJ80
On 6/1/07, Tomaz Sustar <[Email address removed]> wrote:
 
G

Guest

Guest
Tomaz,
When you replaced your radiator did you retain the shroud around the engine
driven fan? If this was left out overheating would be very likely.
If the shroud is still in the correct position perhaps the thicker radiator
is more resistant to air being sucked through it - there by reducing cooling
capacity? Sounds unlikely you never know.
The engine driven fan should be more than adequate. An auxiliary fan will be
fixing the symptom not the cause, and may itself cause other problems.
A decent quality auxiliary temperature gauge might be a better investment.
The gauge on many 80 series has a logic circuit built in which keeps it at
the halfway mark until a major variation in engine temperature takes place.
This means that when the gauge does move it looks pretty dramatic. You may
find an indication of the actual temperature more useful.
All the best,
Toby
1990 HDJ80 UK
 
G

Guest

Guest
Hello Roman,
thank you for your replay ....
we were three cars : Arab guide with his own vehicle (hilux), a friend
of mine who has plenty of experience since he is driving as asistance
vehicle on paris-dakar with his hdj80 (three times already) and me.
Regarding the route - it is presented on the web site
(www.go-adventure.si (the page is unfortunately in slovene only))
although far from exact. there are some pictures there as well (under
"fotogalerija" - "2007 Alzirija"). I hope I will put my pictures on the
web in next week. Roadbooks - i don't have any, waypoints - no problem
... i just have to download them from gps to my computer (i'm planning
to put them on web as well).
Off-road driving is not really a problem as long as you are with guide
which is anyway obligatory. While we were crossing plateaus we were
driving from one piste to another off-road as also locals do. But of
course there are some areas, pistes which are closed for tourists and
some even for locals. On the other hand you have to be aware that the
distances are huge and that you have to be quite careful all the time
since the tarmac roads are fare from ideal ... also some of the pistes
are really tough for driver and car .... and when you come to the south
you might become less enthusiastic about off-road driving.
technical issues - my lc is manual. This thing with the radiator size is
also quite strange to me and that is the reason why I posted it here ...
to me it does not make much sense. I agree with you regarding the second
fan - I also think that well maintained lc cooling system should be
enough. searching the net i found that the auxiliary fans are quite
popular in the states - but not on toyotas...
regards,
Tomaz
 
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G

Guest

Guest
Hi Toby,
what do you mean by shroud ? - are you referring to the plastic part
with the hole where the fan is spinning ? If this is what you mean then
- yes it is still there but I think it is not really a player in this
game ...
What I'm thinking is that the radiator (even with shroud ) has done a
good job since the engine was not overheating even with a weak visco -
while we were testing visco you can really see the huge difference in
air flow with weak visco and new one.
I agree that with auxiliary fan you are fixing the symptoms - but before
I figured out the visco problem I was looking for every posible
solution. The problem was that my mechanic and a guy who is repairing
radiators were teling me that visco is ok but it was not ... maybe it
was ok for european climate but in for the desert definitely not.
auxiliary temperature gauge sounds like a very good idea. Can you
recommend one ? I just hope they not to difficult to mount.... (no
modifications ..)
regards,
Tomaz
 
G

Guest

Guest
Hi All,
After getting stuck in a muddy hole a long time ago and seeing what happened
to the inside of my engine compartment, most of the mud is still there, I
decided an electric fan I could switch off when entering mud or water would
be a good idea, so I installed a Kenlowe sucker fan, the shroud has been
removed, from memory I think the fan couldn't be fitted with it still in
place.
Since then the temp has never reached even halfway on the gauge and the fan
has never come into operation, and therefore has never needed to be switched
off, this is only on normal road driving and the occasional excursion
off-road, as no sand dunes were available in Surrey to test it further, is
this to be expected? I would have thought even normal driving would have
heated the engine up more than it seems to have.
TTFN
Chas
----- Original Message -----
From: "Tomaz Sustar" <[Email address removed]>
To: <[Email address removed]>
Sent: Friday, June 01, 2007 5:20 PM
Subject: Re: [ELCO] radiator size - auxiliary fan
 
G

Guest

Guest
More coolant can only be good, with one condition, there must be adequate
expansion space for the coolant when hot. In thermodynamic terms the system
is no different once in a steady state, equations for heat transfer are
based on flow and temperature differences etc, not radiator capacity.
Your logic regarding the operation of the viscous coupling is correct the
operation of the coupling is dependant on temperature around the coupling
and can't be affected by a larger radiator.
Malcolm Bagley
Stafford UK
FJ45 '75 & FJ45 '76
-----Original Message-----
From: [Email address removed] [mailto:[Email address removed]] On
Behalf Of Tomaz Sustar
Sent: 01 June 2007 15:14
To: [Email address removed]
Subject: [ELCO] radiator size - auxiliary fan
Hi Guys,
I just returned from Algeria when I spent entire month traveling in
southern parts.
The guys who tested the visco told me that
it is very important that the radiator size (amount of coolant)
shouldn't differ too much in size from the original radiator (I replaced
original 2 cell aluminum with 3 cell cooper approx 0.5 l more coolant).
When I think about that it not clear to me why this might be a problem
since bigger radiator should provide bigger convective surface. If I
understood correctly it has something to do with temperature related to
bi-metal in visco which might be to low and consequently the fan is
spinning at lower speed - but on the other hand if the temperature is
lower why would it be a problem ...(of course I'm taking about
overheating problem) Nevertheless I replaced the visco with original
one ... and I hope that the problem is solved.
Can anybody explain me why the size difference might be an issue ? Let
say 1 l of coolant more ...
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.472 / Virus Database: 269.8.5/826 - Release Date: 31/05/2007
16:51
 
G

Guest

Guest
Hi Chas,
If your moving along the air movement will be sufficient, its just when your
stationary, traffic jams, or not moving quick enough you need the fan, hence
the viscous coupling. I take it you have been able to check the fan does
switch in.
I have to say, some cars I have had seem to hardly ever have the fan on,
other cars the fan is on regularly around town in the summer.
Malcolm Bagley
Stafford UK
FJ45 '75 & FJ45 '76
-----Original Message-----
From: [Email address removed] [mailto:[Email address removed]] On
Behalf Of Chas
Sent: 01 June 2007 18:08
To: [Email address removed]
Subject: Re: [ELCO] radiator size - auxiliary fan
Hi All,
After getting stuck in a muddy hole a long time ago and seeing what happened
to the inside of my engine compartment, most of the mud is still there, I
decided an electric fan I could switch off when entering mud or water would
be a good idea, so I installed a Kenlowe sucker fan, the shroud has been
removed, from memory I think the fan couldn't be fitted with it still in
place.
Since then the temp has never reached even halfway on the gauge and the fan
has never come into operation, and therefore has never needed to be switched
off, this is only on normal road driving and the occasional excursion
off-road, as no sand dunes were available in Surrey to test it further, is
this to be expected? I would have thought even normal driving would have
heated the engine up more than it seems to have.
TTFN
Chas
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.472 / Virus Database: 269.8.5/826 - Release Date: 31/05/2007
16:51
 
G

Guest

Guest
Hi Malcolm,
Yes, I did let it run on tickover until the fan cut in, so I know it does
work.
TTFN
Chas
London UK 1HDT 80 Safari snorkel, Custom Winch bumper and Rear bumper
with spare wheel carrier.
----- Original Message -----
From: "Malcolm Bagley" <[Email address removed]>
To: <[Email address removed]>
Sent: Friday, June 01, 2007 7:43 PM
Subject: RE: [ELCO] radiator size - auxiliary fan
 
G

Guest

Guest
Having said that Malcolm, I went to Biggin Hill airshow yesterday, and stuck
in a traffic jam going up a hill I watched the needle climbing, got out
checked and found the fan wasn't working, but once I was back on the move
the needle dropped. The fuse has blown before so I will check that later
today.
TTFN
Chas
London UK 1HDT 80 Safari snorkel, Custom Winch bumper and Rear bumper
with spare wheel carrier.
----- Original Message -----
From: "Chas" <[Email address removed]>
To: <[Email address removed]>
Sent: Sunday, June 03, 2007 8:56 AM
Subject: Re: [ELCO] radiator size - auxiliary fan
I have to say, some cars I have had seem to hardly ever have the fan on,
 
G

Guest

Guest
Hi,
just another thing related to visco - it is interesting that the problem
for its malfunction is not in the mechanics of visco but is mostly
caused by oxidation of bimetal which is triggering it.
I'm very interested in getting an auxiliary temperature - Can somone
recommend one ?
regards,
Tomaz
 
G

Guest

Guest
Tomaz
| just another thing related to visco - it is interesting that the
problem
| for its malfunction is not in the mechanics of visco but is mostly
| caused by oxidation of bimetal which is triggering it.
Could you explain this a bit more?
I thought the viscosity of the silicone fluid increased with
temperature, but if it is done by a bi-metallic method that might
explain why some people have found that replacing the fluid does not fix
the problem.
Christopher Bell
Devon, UK
1996 1HD-FT
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
 
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Guest

Guest
Yes it was the fuse.
Chas
----- Original Message -----
From: "Chas" <[Email address removed]>
To: <[Email address removed]>
Sent: Monday, June 04, 2007 10:18 AM
Subject: Re: [ELCO] radiator size - auxiliary fan
 
G

Guest

Guest
Hi Christian,
the toyotoa visco has a bimetal spiral spring which becomes less
responsive due to oxide layer (changed thermal and mechanical properties).
The bimetal spring regulates the amount of silicon entering into clutch
and if it is now working properly even new fluid can't help.
At least that is how I see it ....
regards,
Tomaz
 
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