740 Anti freeze leak

  • Thread starter Thread starter arnold
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arnold

Hi there !! My friend has a 1990 740 sedan and there is an antifreeze leak
(puddle on the ground) It drips from where the engine meets with the
transmisson, on the passenger side, but it could be squirted from a pinhole
somewhere, I cant really tell where it is coming from, but I suspect either
a freeze plug or the 2 hoses in the back that go to the heater core inside
the car though the firewall.

The question is, how dificult is it to replace the hoses, I can see one
clamp, the one that connects to the pipe that comes from the water pump, the
other one is under the intake manifold. Does the manifold have to come off?

Thanks

Arnold
 
arnold said:
Hi there !! My friend has a 1990 740 sedan and there is an antifreeze leak
(puddle on the ground) It drips from where the engine meets with the
transmisson, on the passenger side, but it could be squirted from a pinhole
somewhere, I cant really tell where it is coming from, but I suspect either
a freeze plug or the 2 hoses in the back that go to the heater core inside
the car though the firewall.

The question is, how dificult is it to replace the hoses, I can see one
clamp, the one that connects to the pipe that comes from the water pump, the
other one is under the intake manifold. Does the manifold have to come off?

Thanks

Arnold
Click to expand...

The hoses aren't too hard to replace, I've done it on the side of the road
in the middle of nowhere in Alberta in the winter, pays to replace them
pre-emptively when you have a nice warm garage. A trick I've used to track
down the leak is to unplug the overflow hose from the radiator, plug the
nipple on the radiator with a scrap of hose and a bolt or something, and
then use an air compressor connected to the hose to pressurize the cooling
system to about 5 psi. Don't go too high or you'll make a leak where there
isn't one, but this allows you to simulate operating pressure without having
the engine hot so you don't burn your hands on the exhaust manifold or get
sprayed with scaulding hot coolant. You'll probably see coolant dripping or
spraying from somewhere as soon as you pressurize it, should be a simple
matter to feel around and find out where it's coming from.
 
The manifold does not need to come off. If the pipe from the pump is metal
make sure that it is integral and not leaking due to rust from inside. It is
most likely a leak from the heater pipes before they enter the bulkhead.

Cheers, Peter.
 
Thanks for the sugestion, I will get the hoses from FCP Groton, and replace
them anyway. and will build some contraption to pressurize the cooling
system.

Thanks

Arnold
 
Arnold: Get a spare cap off a Volvo brake reservoir it will fit on the
radiator reservoir. Go to the parts store and get a screw type valve stem,
drill the proper sized hole in the cap and install the stem on the brake
cap. Use this to pressurize the cooling system. Use a bicycle hand pump, 5
to 7 lbs should be enough to check for leaks.

Harold
 
arnold said:
Thanks for the sugestion, I will get the hoses from FCP Groton, and replace
them anyway. and will build some contraption to pressurize the cooling
system.
Click to expand...


Another trick you can use for that is go to a scrapyard and get a coolant
resivoir cap, drill a hole in it and glue in a tire valve which you can get
anywhere that sells bicycle or car parts. Then you can pump it up with a
simple tire pump if you don't have an air compressor.
 
grtdane63 said:
Arnold: Get a spare cap off a Volvo brake reservoir it will fit on the
radiator reservoir. Go to the parts store and get a screw type valve stem,
drill the proper sized hole in the cap and install the stem on the brake
cap. Use this to pressurize the cooling system. Use a bicycle hand pump, 5
to 7 lbs should be enough to check for leaks.

Harold
Click to expand...


Oops, I should have read that post before I replied to the other.
 
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