"Arfa Daily" wrote in
:
"Jim Yanik" wrote in message
4...
"Ian Field" wrote in
:
"Boris Mohar" wrote in message
...
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.
http://www.viatrack.ca/Misc/FP%20Relay/
I thought automotive was exempt - after all you wouldn't want the
solder falling off your FI relay half way through an overtake.
Honda fuel pump relays have the same solder problems,have had them
for many
years.
my 1994 Integra had it,I resoldered the PCB and it worked fine for
many years afterwards. I saved at least $50 for a few minutes work.
the relay failure mode was that on a hot day,the car would start
briefly,then die,and only crank for 15-20 minutes(no fuel
pressure),then the car would start and run normally(after the car's
interior cooled down).No further problem until it got another heat
soak. In the mornings,the car would start and run normally.
I think the solder crystallizes with age,then thermal cycling cracks
it.
the automotive environment is very tough,hard on electronics.
lots of thermal cycling,shock and vibration.
--
Jim Yanik
jyanik
at
localnet
dot com
Looking at the pictures, I think it is highly unlikely that the relay
is manufactured with lead-free solder. Although the joints have a
somewhat crystaline appearance, the surfaces of the individual
'grains' still appear too shiny to be lead-free. Also, if you look at
the shape of the joints, they are much more conventional solder than
lead-free solder. Whilst I would agree that there is rather a lot of
poor joints to be seen, again, I don't see any that are typically
consistent with a 'volcano' joint that you get with lead-free. Annular
cracks in the actual solder, rather than cracks around the component
lead where the solder has not taken to it, are far more common with
leaded solder. I would say that we are looking at a combination of
circumstances here, including age, temperature cycling and the
generally harsh automotive conditions that it lives in, relay hammer
from the relay operating many many thousands - if not millions - of
times in its life so far, and the possibility of the solder having
been 'over-cooked' in the first place. Smitty with his knowledge of
production soldering may be able to comment better than I on that.
Also, as Nigel says, the RoHS directive was not implemented with a
vengeance in most of Europe, until June 2006. That relay board is
fully 10 years older than that. Like him, I don't think that I have
seen any electronic design that old, that was implemented in lead-free
solder.
Just as a matter of interest, I had a 1985 VW Passat for about 10
years. It was the 2 litre version with the 5 cylinder Audi engine
fitted. It had a fuel pump actually inside the tank, and this was
controlled by a relay on the main board at the front of the car.
Towards the end of the time I had it, so probably around 1996, it
started to suffer intermittent engine stops - always in embarrassing
places like four-way junctions, of course. It would run for weeks
without so much as a cough, then it would just die without warning.
Not too bad if you were tooling along on a big highway. It just lost
power and slowed down, giving you time to get off onto the side
shoulder, before you had no power at all, but worst was when you
pulled away from a stop light, and it just died ...
I discovered that you had to wait exactly four minutes - not a second
less - before turning the key and trying a restart. Invariably, it
would then start and run as though nothing had happened. It took me a
long time to track the problem down, but it eventually turned out to
be bad joints in the fuel pump relay. As I recall, it looked in pretty
much the same state as the OP's one.
Arfa
interesting;
the Honda relay failure would not occur once the engine had started and was
running normally,possibly vibrations kept the solder joints "connected".
Others(on rec.autos.honda) have told me that smacking the relay would also
"get you going",until the next heat soak. Honda put their fuel relay("Main
relay") up under the dash on the drivers side. Not too bad to access for
removal/repair.
That Acura gave me a couple of "interesting" problems,the second was eroded
starter relay contacts,causing intermittent and unreliable cranking.
More than a couple of hundred bucks for a new starter(relay not
separate),but I found a "contact replacement kit" for $30 USD,and rebuilt
the relay myself.
--
Jim Yanik
jyanik
at
localnet
dot com