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Skipping the coolant bypass valve.

47K views 32 replies 15 participants last post by  byastremski 
#1 ·
So, Eeuroparts has the euro-spec heater-core hoses, and I'm Going to go that route.
I had the upper hose pop yesterday when I downshifted to 3rd to pass someone, and ran up the revs.

anyways.
my bypass valve hasn't failed, but I'm a GIANT fan of removing over-complicated parts to make things more-reliable.

has anyone done it yet?

I'm going to do my best to get good photos, and post 'em up for y'all.
 
#2 · (Edited)
it's not the BEST pictoral, but here's what I got:

Here's the mess before I started tearing it apart. Nothing special, here:


this is the coolant bypass valve, and the mess of hoses that go along with it.
it's against the firewall, right under the brake master cylinder.
mine was only held up by a ziptie. this leads me to believe that it had been replaced once in it's lifetime.
here it is, mounted:

here it is.. on it's way to the trash.



and... the 2 simple hoses that replace the rat's nest of a bypass valve:


it turns out that mine WAS leaking. There was some coolant up around the cap. tossing it turned out to be a good idea.

I had to remove all of the crap on the driver's side.
all rad. hoses, the intake pipe, and the wiring harness for the inlet pres. sensor, DIC, and intake temp sensor.


when it's all removed, you can clearly see the inlet/outlet of the heater-core:


I don't have any pictures of it back together.
it's as simple as re-connecting hoses.
you also have to take a "T" off of the vacuum port for the BPV solenoid.
I would recommend getting hose clamps instead of re-using the spring clamps that saab put on from the factory. they work well, but there's no REALLY easy way to get in there.
you can NOT get to the valve/heater-core from underneath like you can on a 9-3.

Just take your time, and remove everything in your way.
 
#5 · (Edited)
not a bad idea if you want heat all the time. you a/c isnt going to blow as cold any more. that cuts the hot water to the heater box while that a/c is on. cause the 9-5 heater box doesn't have a door to cut off the air flow through the heater core like the 9-3's it uses that valve to PWM the coolant valve, witch controls the heat. id sugest you go dumpster diving for those hoses and replace the valve. they came for the factory with a zip tie on them if its been replaced the tie wouldn't be there any more. i guess the only thing that that would really affect is the a/c's performance

just a little note too.... i know its alittle late now but doing that job is 1000x easier if you take the wiring harness off the fire wall (like a ten minute job to replace the coolant bypass. two 10mm and a couple clips) instead of everything off the head
 
#6 ·
just a little note too.... i know its alittle late now but doing that job is 1000x easier if you take the wiring harness off the fire wall (like a ten minute job to replace the coolant bypass. two 10mm and a couple clips) instead of everything off the head
yeah I beleive that's what I did when I did mine, didn't take very long at all.
 
#7 ·
so, you're suggesting that the european cars don't have a/c? they just run heat all the time? I believe the blend door is what makes the "decision" between hot air off of the heater-core, or cool air from the a/c system. pulling this won't disturb the heat, and cool air functionality.

beyond that, I'm perfectly happy with how it came out... I was in there because one of the hoses burst. I was pulling that crap off, if I wanted to, or not. I had purchased both sets of hoses, and decided that removing the system was the best option for me...

all will be well, I'm sure....
 
#9 · (Edited)
that hose was probably for a euro non ACC spec HVAC. there are two verions listed in WIS 1) heating and ventilation system w/ a/c 2) heating and ventilation system w/ a/c and ACC. you may be fine but buy the looks of it it would have been better to just replace the valve as Saab intended


....ya they did make a MCC 9-5 that hose is listed in EPC for MCC 9-5's. but hey if its working for ya good for you! i just wouldn't do it
 
#12 ·
So, since I've removed most of the AC system (ie. Everything but the compressor; Because you need that pulley for belt routing; which is annoying), is this going to affect me in any way, aside from saving some money, and possible hose failures?

I just ordered the non bypass valve hoses, but I'm prettysure I can just cut on a bit shorter to replace the one that is hacked together at the moment; But when I do them tomorrow evening, I just want to know the pros/cons to removing that stinkin' valve.

Cheers!
Benjamin
 
#13 ·
raven is correct.
If you have blend door issues, this will exhaggerate them.
if your blend doors are fine, you'll be fine.

I don't miss the valve at all.
I was able to clean out the engine bay some, and make the car more reliable at the same time.
I'm thrilled with it.

I'd do it again, given the choicel
 
#14 ·
raven is correct.
If you have blend door issues, this will exhaggerate them.
if your blend doors are fine, you'll be fine.
Exactly. As far as I've been able to work out, the bypass valve only kicks in when you set the ACC to LO. It might also do it if it decides it can't make it cold enough, but that has not happened to me, I just got baked. Needless to say, I've been driving around since the beginning of june with my ACC set to LO. Damn swedish heater. :rolleyes:
 
#17 ·
Okay. A/C is a huge concern of mine now that I have a fully functioning ice cold car. It is crucial in the 90 degree traffic jams.

I almost wish I could pump just a little bit into the front of the car so it can be happy too.
 
#19 ·
Also , a quick question. My brain wants to believe that the top pipe on the heater core is the inlet, and the bottom, the outlet. I'm going to set it back up this way; as I've got everything removed.

is this correct? I figure I've got a 50/50 chance here, and outlet + gravity speaks to me...
 
#25 ·
It's been so long since i did it, but Im pretty sure i removed the solenoid, and the "t".
I now have the bov and fpr both running directly from the plastic vacuum tree on the manifold.
I skipped the bov solenoid, but left it plugged in, too.
 
#28 · (Edited)
S-K

Something like these, there are lots of different brands.

I really like the factory spring hose clamps, they don't strip, are infinitely reuseable, and apply pressure uniformly around the hose ends without cutting into the rubber like if you overtighten a worm gear clamp.

All the manufacturers are using spring clamps like this, the tool is really handy.
 
#31 ·
The only time when the valve is actuated is when the ACC is set to 'LO,' it stops coolant from flowing through the heater core. The 'cold' and 'hot' areas of the climate control mix box are fairly well separated, but if it's extremely hot outside it can make a few degrees of difference, that's probably about it.
 
#32 ·
My heat was working fine untill i developed a leak in the bypass valve. Against my better judgement because of time constrants I had someone change it for me. Now I have no leak but no heat. He swears he put the hoses on correctly. Any ideas what he might have done to cause this? This is a 2004 9-5 wagon.

Thanks,
kevin
 
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