HEATER CONTROL VALVE

Just found the coolant leak on my 960 turbo, it's been loosing water
slowly since I bought it 2 years ago. I was told that it was probably a
head gasket but over the last two weeks it's got to the point where I
need to top it up every 40 miles, looking under the bonnet tonight I
tried revving the engine and above about 4 thousand revs water is
spraying out of a crack in the vacuum operated heater control valve.

What will happen if I replace this temporarily with a short piece of
copper pipe? Our local Volvo pattern part dealer can't get one so it
looks like main dealer after the holidays. Will this just make the
heater operate flat out(Car has climate control) or do I risk any damage?

Steve H

 

Your heat will be on full, it won't hurt anything though. I did this on
my friend's 940 a few years ago and it worked fine, in fact the
temperature control still worked due to the climate control operating
the AC. Not very efficient, but ok for temporary use.

 

Just ordered a replacement on line from Euro Car Parts, a call to the
local main dealer sounded like it was a major job to replace and they
wanted to book it in for repair rather than sell me the part. Looks
like a couple of hose clamps and a push on vacuum pipe to me. I will
bodge it tomorrow as we need to do a few hundred miles the day after
Christmas, nice to find the problem now rather than on the motorway.

Steve H

 

Yeah it only takes about 10 minutes to change, and you can even do it
without spilling a lot of coolant. On a 240 it's a much bigger job, but
still not too bad.

 

Steve,

My 'bodge' for this same failed valve on my '86 740 frankencar, was to
replace it with a short length of 15mm copper plumbing pipe held in
place with hose clips, 4 years later, the 'bodge' is still doing its
duty, more trustworthy in my opinion than the dodgy split plastic valve
that it replaced.
The heater still works well, blowing both cool, hot and everything in
between (aircon is knackered), with the heat output well controlled by
its air flaps.
I've never really noticed the fact, that without the coolant flow
control valve installed, the heater matrix is always hot, but, thanks to
your research I can now replace my valve (after a short motorbike ride
to Preston), and make the heater work as it was originally intended to.

Merry Christmas,
Ken Phillips

 

Fitted it today, the old one fell apart when I removed it. The plastic
body had become very soft and brittle. Total cost 18.89 GBP. and about
half an hour.

Steve H

 

Glad the replacement went well, just out of interest how much coolant
did you loose? I often wonder how many times that a failure of this
valve has actually killed the engine by unnoticed or otherwise overheating.
I once got an entire 740 turbo sedan, from a scrap dealer for 50 GBP,
got all sorts off it before taking it back for crushing, including the
entire heating system (to upgrade my manual gle estate), the gearbox
(auto, now dead, my fault, oops! So cars a manual again lol), the
steering rack (still working very well, the 100A alternator (still
working and bloody brilliant!), the electric seats, etc. ......,
however, the only thing I actually found obviously wrong with the car,
was that wretched valve!
Split open, obviously, the car had bled all it's coolant.
Whatever possessed them to make it out of plastic? The earlier
thermostatic ones in the 84ish 240's were metal, so why not now? It's
almost as if some apparently insignificant parts are designed to fail,
with catastrophic results.

Happy new year! Don't waste that leap second.
TTFN,
Ken Phillips

 

I think I'll replace mine as a preventative measure, I don't like having
something as vital as engine coolant circulating through anything made
of plastic. It all becomes brittle and fails eventually, and unlike
metal, when plastic fails, it fails catastrophically.

 

Yeesh, converted *to* an automatic? If only you saw all the effort I've
gone through to replace several perfectly working (and a couple wonky)
auto boxes with manual! Fuel economy improvement of several mpg alone
makes the job worthwhile, even if the manual wasn't so much nicer to drive.

 

I don't think it ever ran dry, I noticed the coolant level was low when
I topped up the windscreen washers. The heater never failed to work and
I kept it toped up but if the failure had happened in the summer then i
think it would have damaged the engine. The new valve is plastic and a
made in Sweden pattern part but looks to be a lot stronger than the
original. The car is 18 years old next week so probably past the end of
it's design life but still going strong after 2 years of daily use, I've
done 37,000 miles in it and it only cost me 245.00 GBP, over here in
England second hand cars are very cheap.

Steve H

 

I've always wondered why. New cars aren't particularly cheap are they?
User cars here cost about 5x what they do there, and even still the
choice is a no-brainer for anyone with a decent understanding of basic
math. IMO the only reasons to buy brand new cars are unavailability of
used models, or a status symbol for those with so much extra money that
it doesn't matter.

 

I have just seen a 3 1/2 year old VW passat estate oil burner go on ebay
for 3400 GBP, it would have cost 24K new. Most new cars are sold on
credit at 30% interest to people who must have a better car than the guy
next door. Quality older cars can be more reliable than cheaper new
cars, I'm looking for a newer Volvo oil burner (V70) to replace the 965
as I do a lot of miles and petrol is about $8 a gallon over here.

Steve H

 

His percentages are a little optimistic but the concept is valid...
<http://www.daveramsey.com/etc/lms/drive_free/player.cfm>

 

Hi there,

You'll be pleased to know then, that it's a manual again, lol, I
actually did the change because I fancied a change; and the manual box
was misbehaving a bit, so I embraced an opportunity. However, the auto
box subsequently suffered the dreaded seal failure of doom, due to my
ignorance of the type and what not ever to do; lost forward drive,
etc...., but, not before the car served very well as my 'wheelchair'
after I broke my left foot. So the work was somewhat fortuitously done.
It's got the slightly wonky manual box re-installed, no syncromesh on
first, jumps out of second when 'goosed' (great fun!), but, hey it works
well apart from that.

TTFN, Ken

 

I wonder if it's the same thing that happened to one of mine? Apparently
a snap ring broke, the end result was that the face of 1st gear became a
thrust bearing on the syncro hub and ground up the synchro, the gear,
and the hub. When I replaced it, there was a big ball of metal shavings
on the magnetic drain plug. Easy to find good used gearboxes though.

 

No, it was the zf 4hp problem (didn't know of this when I did the
conversion) caused by a worn 'o' ring allowing bleed through of
hydraulic pressure when not in drive, thereby making the forward drive
clutch just 'kiss' the driven plates, even when in neutral or park, this
essentially eats the clutch friction material, because, it's not really
disengaged, or engaged, just wearing out. It had always given me a bit a
grief when cold, but, the straw that broke the camels' back, was all the
revving and stuff I did when converting from carb to fuel injection.
I priced up the bits from somewhere in Devon, to fix and upgrade the
auto box, the price was good at approx 80 UKP, and, the job seemed easy
enough, but, it was physically easier to just revert back to a manual
especially as my clutch foot was now in nominal working order :-0.

Bye for now.
KP

 

Oops, I just realised what you meant, Duh!
Well, that sounds credible, one more thing to dread. The symptoms are
that I have to be driving at less than 3 Mph, or to de clutch for about
5 seconds or more (by which time I'm usually at <3Mph anyway), I have
attempted double de clutching, but, I'm either doing it wrong
(probable), or it just won't work. Would the slip ring thing explain
jumping out of second? I thought that would be just a worn out detent
ball or something.

TTFN again,
KP

 

I meant the problem with your manual box, my own car never had an auto,
but I did break one M46 manual.

 

That is break an M46.

I have 2 in 740's and one of them is behind a turbo.

happy new year!

jimB

ps and maybe jimb will remember how to reply to a thread