[xj40] A Flap About (Radiator) Flaps

XJ40
1

I happened to run across something very interesting in the ‘‘New
Zealand’’ Jag repair manual (IIRC, or perhaps it was in the Haynes
manual)last week and it got me a little confused, I think …

Soon after I bought Layla, I noticed upon inspecting her radiator
that she did not seem to have the rubber ‘‘flaps’’ built into her
shroud that I had heard discussed before on the XJ40 forum. These
are the flaps that raise (via ram effect) when the car is up to
speed, to provide additional air flow for cooling through the
radiator. Rather, Layla’s shroud contained instead what appeared
to be black plastic pieces akin to ‘‘blanking plugs’’ in the area
where the flaps should have been based on what I read on here.

I mentioned this discovery some time back on the forum, and a few
members suggested that what appeared to be plastic bits were really
indeed the original rubber flaps that had likely ‘‘petrified’’ over
time and heat. I thought this odd and, further, was disinclined to
believe that explanation after I attempted to ‘‘lift’’ a couple of
these petrified flaps, snapping and breaking same cleanly off of
the shroud, after some sharp pulls, in the process.

The mentioned passage I ran across in the manual stated that ‘‘the
U.K. version of the XJ40 was fitted with rubber flaps for
additional cooling’’, or some such … This particular statement
would seem to indicate that, conversely, NON-U.K. versions were NOT
fitted with such flaps.

If so, the thing with Layla’s plastic bits now makes sense.
Being a N.A. version, the area where the flaps would have been were
instead filled with plastic blanking pieces. (not sure why that
would be, since I would think many places in the U.S. get hotter -
much hotter even - than in the U.K.) …

What do ya’ll think about this?–
&:slight_smile: Paul '88 XJ6 VDP 138k (black), '96 XJ6 110K (black)
Garland, Texas, United States
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2

In reply to a message from AttyDallas sent Tue 3 Nov 2009:

Paul…Those plastic pieces you’re talking about were once called
‘‘rubber’’!

About 6 months ago I noticed the same thing on my 89XJ40. When I
tried to move one … SNAP. After removing the fan shroud I
drilled out the rivets on each metal bar holding each flap. I then
cut out new flaps from sheet rubber and pop riveted them back in
place.

They are designed to blow open about the time your fan clutch starts
free-wheeling your fan so the natural airflow through your radiator
has an unobstructive path. If any of those little rascals are
missing you’ll have a serious lack of cooling at low speeds when
your fan is doing all the work and can’t create a vacuum inside the
shroud.

I wasn’t sure how critical the actual thickness of these things were
so I went to Texas Rubber Supply which is on Irving Blvd just off of
N. Hampton. These people are great (I live in Arlington and it was
worth the trip just to meet them) and they came up with a perfect
match out of their Gajillion pieces of rubber. Good luck.–
Groove
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3

In reply to a message from Grooveman sent Tue 3 Nov 2009:

Dang, sounds like they really ARE ‘‘petrified’’ rubber than,
Grooveman.

How much work was involved in replacing them, as far as r/ring the
shroud? Does the radiator or clutch fan also have to be
removed? If so, I guess it would just be simpler to snap all the
remains of the flaps off and leave it at that (better the engine
risk being a bit ‘‘too cool’’ then ‘‘too hot’’, if that is possible,
right?)

btw, is your '89 a Texas cat too? It might be just our super
hot summers here that have that effect on the rubber. My X-300
Scrapper’s (from NJ originally) flaps are still perfectly soft, and
she’s 13 years old / 120K+ miles …–
The original message included these comments:

Paul…Those plastic pieces you’re talking about were once called
‘‘rubber’’!
About 6 months ago I noticed the same thing on my 89XJ40. When I
tried to move one … SNAP. After removing the fan shroud I
drilled out the rivets on each metal bar holding each flap. I then

–
&:slight_smile: Paul '88 XJ6 VDP 138k (black), '96 XJ6 110K (black)
Garland, Texas, United States
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4

Hi Paul.
Not a good idea to leave the flaps off. When the car is stationary the fan will not move air
through the radiator as it was designed to do.
With the flaps in place the fan pulls air through almost all the rad matrix, without them it will
be air from the diametre.
Yes the fan has to be removed to take out the fan shroud but that is not to difficult.
I just use a long screw driver ladged between the boss and one of the nuts to stop the boss
rotating as I ‘break’ each nut in turn. After they are free you have to undo them in turn as the
boss has to move forward to allow sufficient clearance to get the nut and washers out.
Once the fan is out just release the two clips and the shroud lifts out.
I did my old '88 about 8 years ago. From memory I used some 2.5 or 3mm neoprene rubber sourced
from a pool shop or rubber supplies.
Regards
Robin & Maureen
Auckland NZ
XJ40 '92 Sov.

On Thu 05/11/09 06:50 , “AttyDallas” attydallas3@aol.com sent:

In reply to a message from Grooveman sent Tue 3 Nov 2009:

Dang, sounds like they really ARE ‘‘petrified’’ rubber than,
Grooveman.

How much work was involved in replacing them, as far as r/ring the
shroud? Does the radiator or clutch fan also have to be
removed? If so, I guess it would just be simpler to snap all the
remains of the flaps off and leave it at that (better the engine
risk being a bit ‘‘too cool’’ then ‘‘too hot’’, if that is possible,
right?)

btw, is your '89 a Texas cat too? It might be just our super
hot summers here that have that effect on the rubber. My X-300
Scrapper’s (from NJ originally) flaps are still perfectly soft, and
she’s 13 years old / 120K+ miles …

–
The original message included these comments:

Paul…Those plastic pieces you’re talking
about were once called> ‘‘rubber’’!
About 6 months ago I noticed the same thing on
my 89XJ40. When I > tried to move one … SNAP. After removing the
fan shroud I > drilled out the rivets on each metal bar holding
each flap. I then
–
&:slight_smile: Paul '88 XJ6 VDP 138k (black), '96 XJ6 110K (black)
Garland, Texas, United States
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resources including Photo Albums, Event Diary / Calendar, On Line Books and
more !

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5

In reply to a message from AttyDallas sent Wed 4 Nov 2009:

Paul…I think you’ll find the shroud flapper fix very easy.

The shroud comes off by just unsnapping the 2 aluminum clips on the
top and then manuevering it around the fan. Nothing else to
disconnect. When you have the shroud out you’ll see a narrow metal
bar riveted to it above each of the 4 flaps. Drill out the rivets
and save the metal strips to reuse with the new flaps. Use the old
flaps as a guide or just measure the size you’ll need to cut out
you new ones (I believe the top flap is larger than the bottom 3
which are the same size) Pop rivet everything back in place and
awa-y-y you go. Not having the flaps operating (or worst yet
missing) will definitely affect your engine cooling and A/C ops at
low speed.

Actually one of the easiest fixes I’ve done on the car. Yup, my
89XJ40 has lived here in texas it’s whole life. Even on the hottest
Dallas day the A/C (God bless R-12) still can freeze me out!

Good luck on the project and E-me if you have any problems–
Groove
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6

In reply to a message from Grooveman sent Wed 4 Nov 2009:

Dennis,

Your car must be different to mine then in respect of the
fan shroud removal. I have to remove the fan and the shroud
together in the manner outlined by Robin earlier - no way
can the shroud be manoeuvred around the fan with it still
bolted in place - it fouls the radiator core.–
The original message included these comments:

The shroud comes off by just unsnapping the 2 aluminum clips on the
top and then manuevering it around the fan. Nothing else to

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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7

In reply to a message from AttyDallas sent Tue 3 Nov 2009:

Paul:
Both of my 88s had petrified rubber flaps when I bought them.
You have to remove the fan to get the shroud off – 4 thirteen
millimeter nuts with star washers – then drill out the 1/8 inch
pop rivets that hold the small metal channel to the shroud. Your
local hardware store will have sheet rubber and new pop rivets to
put it all back together again.
The only fiddly thing is the nuts holding the fan on. You have
to loosen them all about half-way off, then go around again to
finish the job. There’s not enough gap do remove the nuts in one
go-round. If you have a strap wrench, you can turn the fan pulley
by had in the opposite-from-normal direction without loosening a
belt.
If the flaps are missing, the fan will pull air in without it
having passed through the radiator and the engine will run hotter
than it should, which is not what you want to do in the dallas
summertime. While your there, get a diode from Radio Shack and
wire the aux fan relay to come on with the air conditioning
compressor clutch. Otherwise, the aux fan only runs when coolant
temperatures reach a high limit.–
The original message included these comments:

I mentioned this discovery some time back on the forum, and a few
members suggested that what appeared to be plastic bits were really
indeed the original rubber flaps that had likely ‘‘petrified’’ over
time and heat. I thought this odd and, further, was disinclined to
believe that explanation after I attempted to ‘‘lift’’ a couple of
these petrified flaps, snapping and breaking same cleanly off of
the shroud, after some sharp pulls, in the process.

–
Pete Peterson 70E(193K) 88XJ40s(253K & 242K) 94XJ40 (122K)
Severna Park, Maryland, United States
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8

In reply to a message from Jaguarpete sent Wed 4 Nov 2009:

OUCH…busted!

I did in fact remove my fan when I redid my shroud flaps, but it
was in association with replacing my fan clutch and I forgot that I
did the flap thing at the same time. Sorry 'bout that.

It’s like President Reagan said ‘‘Trust, but verification!’’–
Groove
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9

In reply to a message from Jaguarpete sent Wed 4 Nov 2009:

Thanks, everyone … !–
&:slight_smile: Paul '88 XJ6 VDP 138k (black), '96 XJ6 110K (black)
Garland, Texas, United States
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