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Hello all - I'm new so please don't laugh at my question as I'm only a novice repair guy. Certainly wouldn't call myself a mechanic. Not hardly. I'm in over my head and I know it. I can't seem to find anything on YOUTUBE or in any of the posts here about how to change out the heater core on my 2004 Xfire limited. The repair manual postings suggest that the entire HVAC system is pulled out and then it describes how to put a new heater core in. Other posts on the web suggest: Take out the glove compartment console and such so that you can get to the HVAC system and that you can do it from there without having to remove the entire HVAC assembly. Others' note you have to pull the entire dashboard out to do this (heater core replacement).
I do have the glove box and entire assembly out of the way so that at least I can see the entire HVAC system.
Again, I'm an engineer, but definitely NOT a mechanic.
Any help/support/assistance would be greatly appreciated. If there's a video out there? Something??
Hello all - I'm new so please don't laugh at my question as I'm only a novice repair guy. Certainly wouldn't call myself a mechanic. Not hardly. I'm in over my head and I know it. I can't seem to find anything on YOUTUBE or in any of the posts here about how to change out the heater core on my 2004 Xfire limited. The repair manual postings suggest that the entire HVAC system is pulled out and then it describes how to put a new heater core in. Other posts on the web suggest: Take out the glove compartment console and such so that you can get to the HVAC system and that you can do it from there without having to remove the entire HVAC assembly. Others' note you have to pull the entire dashboard out to do this (heater core replacement).
I do have the glove box and entire assembly out of the way so that at least I can see the entire HVAC system.
Again, I'm an engineer, but definitely NOT a mechanic.
Any help/support/assistance would be greatly appreciated. If there's a video out there? Something??
It is, and has been seriously plugged or broken. 6-months ago, on the way to work, I smelled antifreeze badly and when I turned on the heat it was even worse. Then I noticed that my temp gauge was up 1/2 a tick. Concerned? Yeah, but it wasn't overheating. Then I also noticed that the passenger side floor board was soaked with anti-freeze. When I followed up and read through web explanations and this particular site, I saw that it sounded pretty much like what had happened. Now move up in time to last month. I got clipped by a hit-n-run driver that just grazed my front bumper from the side, but enough to take my bumper off and crack my radiator. Put the new Radiator in (with some help) and within 5-minutes of running dark sludge and antifreeze started spilling out on the passenger side. Car overheated quickly and I shut it down. Yes, I know that there are many working parts, but with a new radiator? That's probably not it. And I knew that the heater core was already causing me grief. Should I try to flush it somehow first before I go to the extreme? I've got the new heater core unit in the garage. Any thoughts? Thanks for your interest. I'm trying believe me. thx, B
Don't know too much about replacement, but I do know that you can pinch off the single hose going to the duovalve ( just in front of the battery ) and stop any heater core leaks.
Unfortunately, this also stops any heat, but it's July - you have plenty of time to get it repaired. Duovalve
Don't know too much about replacement, but I do know that you can pinch off the single hose going to the duovalve ( just in front of the battery ) and stop any heater core leaks.
Unfortunately, this also stops any heat, but it's July - you have plenty of time to get it repaired.
Sorry George, but both the supply and return MUST be clamped off. If you just clamp the one, the fluid/water will just go through the coil from the other sidel. A partial draining must be done (when the coil is removed the fluid will drain to its lowest point so drain it to below that lowest point) bnelson1970, your going to have quite a job replacing the coil, good luck! Your on your way as it is, just take a lot of pictures so you can get it back together as reversed to how you got it apart.
Sorry George, but both the supply and return MUST be clamped off. If you just clamp the one, the fluid/water will just go through the coil from the other sidel. A partial draining must be done (when the coil is removed the fluid will drain to its lowest point so drain it to below that lowest point) bnelson1970, your going to have quite a job replacing the coil, good luck! Your on your way as it is, just take a lot of pictures so you can get it back together as reversed to how you got it apart.
Thank you for the help both George and ala_Xfire. Okay. Now I know I'm pushing my luck but I want to make sure that I understand. There are two nearly perpendicular hoses that go into the firewall and then into the Heater Coil. They are located in front of the silver engine heat shield and 1/2 a foot under the O2 sensor directly above (passenger side). Are you suggesting (George) that if I clamp both of these perpendicular hoses, that these are both the supply and return and this will be a somewhat legal bypass for now? OR that it will just go back around and come in on the other side?? I'm trying guys and I definitely don't want to hurt my engine.
thx again. what am I missing??
hey...if I can get around NOT doing the coil right now and still get the engine up and running and not hurt anything then I'd much rather do that as opposed to tackling something that will cause me to make up swear words...
According to the Student Reference Book, coolant enters the heater core halves via the two valves and exits via a common hose. The two hoses coming from the firewall are the in lines.
The Service Manual and the Student Reference Book differ in the direction of the coolant flow, should we be surprised?
The system is under pressure so both sides of the heater core have to be clamped off.
Okay. I've looked at the diagrams a few times already. I didn't understand that the two hoses going into the firewall and then the Heater Core were both supply lines. If I were to do a bypass, my guess would be that I cut the 2 tubes going into the firewall, put an adapter on the remaining hoses with a horseshoe U-tube. Then I find the exit/Return hose and clamp that off. This would cut the supply and it circles back into the Radiator and when it (the anti-freeze/water) tries to collect from the exit/Return from the Heater Core...it doesn't know where to go because it's clamped off so it to then circles back to the Radiator.
Is this correct?
This will temporarily still cause extra work on the engine and it will run a little hotter and I'll have no heat; however, it will work temporarily and I can get the thing up and running assuming nothing else is wrong. And there shouldn't be anything else as it sounded pretty good the last few times I've run it before the Radiator remove and replace.
Update: I've seen schematics of the whole VAC system but I don't see where the return hose comes out of the firewall.
Thanks everybody for the exceptional advice / input, etc.
Okay. I've looked at the diagrams a few times already. I didn't understand that the two hoses going into the firewall and then the Heater Core were both supply lines. If I were to do a bypass, my guess would be that I cut the 2 tubes going into the firewall, put an adapter on the remaining hoses with a horseshoe U-tube. Then I find the exit/Return hose and clamp that off. This would cut the supply and it circles back into the Radiator and when it (the anti-freeze/water) tries to collect from the exit/Return from the Heater Core...it doesn't know where to go because it's clamped off so it to then circles back to the Radiator.
Is this correct?
This will temporarily still cause extra work on the engine and it will run a little hotter and I'll have no heat; however, it will work temporarily and I can get the thing up and running assuming nothing else is wrong. And there shouldn't be anything else as it sounded pretty good the last few times I've run it before the Radiator remove and replace.
Update: I've seen schematics of the whole VAC system but I don't see where the return hose comes out of the firewall.
Thanks everybody for the exceptional advice / input, etc.
B.
If the heater core is leaking it has to be taken out of the system completely.
Aww George, gawsh… You give credit where none is due. There are just a few things I know a little about. And lately a few things I remember incorrectly!
Thank you for the help both George and ala_Xfire. Okay. Now I know I'm pushing my luck but I want to make sure that I understand. There are two nearly perpendicular hoses that go into the firewall and then into the Heater Coil. They are located in front of the silver engine heat shield and 1/2 a foot under the O2 sensor directly above (passenger side). Are you suggesting (George) that if I clamp both of these perpendicular hoses, that these are both the supply and return and this will be a somewhat legal bypass for now? OR that it will just go back around and come in on the other side?? I'm trying guys and I definitely don't want to hurt my engine.
thx again. what am I missing??
hey...if I can get around NOT doing the coil right now and still get the engine up and running and not hurt anything then I'd much rather do that as opposed to tackling something that will cause me to make up swear words...
thx,
Brian
Brian, those two hoses are the two ZONES (passenger and driver). The other line is on the firewall closer to the drivers side (if I remember correctly). If I am not mistaken, the SUPPLY line is the single line near the center on the drivers side and the two returns are the hoses on the passenger side. The duovalve controls the throttling on the two return sides (zones). The rest pump is forward of the duovalves below the passenger side headlight assembly (on the LHD cars). You should download the online service manual, look up the heating system piping, and use that while you do the repair (section 24, @ page 65 titled HEATER SYSTEM in my 2008 service manual). Good luck!
A SIMPLE TEST to know what way the coolant flow is, is to set ANY cold crossfire car A/C head to full cool, then start/warm up the car. After it is warm, have someone move the dials to all heat and feel which side gets hot first. The side (single line) should get hot first then it will travel over to the two duovalves coming out of the firewall on the passenger side (LHD). If I remembered correctly from years ago, the supply is the single line side, the return is the two going to the duovalves.
Okay. Here's the scenario and bear with me please. I know in the grand scheme of things and the Big Picture that the Heater Core NEEDS to be replaced. The job really is too big for me and I'm surprised that I've been able to get this far. For the next 3 or four months, I need to go approximately 10 miles a day and on back roads at roughly 35 to 40 miles an hour with zero freeway driving.
Can I bypass as I (and others) explained above (included note below as well) and get by for now until I can get it taken care of professionally. I know it's the wrong thing to do overall...but can I do it without destroying my engine? If I go easy, don't race the engine, monitor it daily (especially for hose leaks) and be extremely careful. Can I get away with it? And you seem to really know what you're talking about and I appreciate both your wisdom and sharing your obvious experience.
quote with extra revised additions in bold: "Okay. I've looked at the diagrams a few times already. I didn't understand that the two (perpendicular adjacent) hoses going into the firewall and then the Heater Core were both supply lines (there seems to be some differing opinions on this with some folks saying SUPPLY while others are saying RETURN). If I were to do a bypass, my guess would be that I cut the 2 tubes going into the firewall (again, perpendicular adjacent on the passenger side), put an adapter on the remaining hoses with a horseshoe U-tube (and 4 hose clamps to secure both lines 2 on each line). [and I've seen 20 videos on the web that suggest this course of action with the U-tube really works] Then I find the exit/Return hose and clamp that off (near the firewall on the driver side). This would cut both the supply and exit Return hose and completely bypass the Heater Core altogether as the supply anti-freeze/water circles back into the Radiator and (for the exit/Return) when it (the anti-freeze/water) tries to collect (not collect, but rather go back up the line on the exit/Return tube on the driver side) from the exit/Return from the Heater Core...it doesn't know where to go because it's clamped off so it to then circles back to the Radiator."
I mean, if it doesn't have a supply line nor a exit return line then nothing goes to it and it doesn't matter whether it's currently working or not. IT IS BASICALLY OUT OF THE SYSTEM.
In fact, all of the videos do not show doing anything other than the 2-supply lines on the passenger side. U-tube style bypass.
Okay. Here's the scenario and bear with me please. I know in the grand scheme of things and the Big Picture that the Heater Core NEEDS to be replaced. The job really is too big for me and I'm surprised that I've been able to get this far. For the next 3 or four months, I need to go approximately 10 miles a day and on back roads at roughly 35 to 40 miles an hour with zero freeway driving.
Can I bypass as I (and others) explained above (included note below as well) and get by for now until I can get it taken care of professionally. I know it's the wrong thing to do overall...but can I do it without destroying my engine? If I go easy, don't race the engine, monitor it daily (especially for hose leaks) and be extremely careful. Can I get away with it? And you seem to really know what you're talking about and I appreciate both your wisdom and sharing your obvious experience.
quote with extra revised additions in bold: "Okay. I've looked at the diagrams a few times already. I didn't understand that the two (perpendicular adjacent) hoses going into the firewall and then the Heater Core were both supply lines (there seems to be some differing opinions on this with some folks saying SUPPLY while others are saying RETURN). If I were to do a bypass, my guess would be that I cut the 2 tubes going into the firewall (again, perpendicular adjacent on the passenger side), put an adapter on the remaining hoses with a horseshoe U-tube (and 4 hose clamps to secure both lines 2 on each line). [[b]and I've seen 20 videos on the web that suggest this course of action with the U-tube really works] Then I find the exit/Return hose and clamp that off (near the firewall on the driver side). This would cut both the supply and exit Return hose and completely bypass the Heater Core altogether as the supply anti-freeze/water circles back into the Radiator and (for the exit/Return) when it (the anti-freeze/water) tries to collect (not collect, but rather go back up the line on the exit/Return tube on the driver side) from the exit/Return from the Heater Core...it doesn't know where to go because it's clamped off so it to then circles back to the Radiator."
I mean, if it doesn't have a supply line nor a exit return line then nothing goes to it and it doesn't matter whether it's currently working or not. IT IS BASICALLY OUT OF THE SYSTEM.
In fact, all of the videos do not show doing anything other than the 2-supply lines on the passenger side. U-tube style bypass.
This works right???
Thx all,
B.
YES, you CAN bypass the core. I would suggest you get a "Y" and install it rearward of the duovalves (leaving the two exiting the firewall loose/open), and then tying the final leg of the "Y" over to the supply line that goes from the engine TO the core (leaving that last single heater core line open at the firewall). Make sure the system is drained below the lowest open line before you try to bypass the core at this point or as soon as you cut into those lines, some coolant will leak out.This will isolate the three lines connected to the heater core (sealing the entire cooling system up). The alternative is just CAP all three, and stop all flow at the duovalves (returns) and the other side at that supply line. IF you just cap all three, remember to cap BOTH duovalves rearward side on both valves AND that supply line going to the core (single line) on the opposite side of the engine. You do not want to let the duovalves get dried out (keep them wet) because if those valves aren't left wet you might have trouble with them after the core is replaced.
I cannot see why you cannot plug and clamp the single hose going into the duo valves, it should be easy as you have over a foot of hose free to get at. and do the same to the hose coming from the firewall by the power brake booster also with ample hose to access. All this after lowering the coolant level below the open end of the hoses.
It may be a good time to drain and flush the coolant anyway as the wrong coolant could have been used at one time and caused the problem in the first place.
You could if you felt like it join the two ends of these hoses to each other, with a hose extension using two barbed fittings and four clamps. Plugging both ends would be simpler and act just like the valves were closed.
The duo valve could be opened, cleaned and stored indefinitely.
YES, you CAN bypass the core. I would suggest you get a "Y" and install it rearward of the duovalves (leaving the two exiting the firewall loose/open), and then tying the final leg of the "Y" over to the supply line that goes from the engine TO the core (leaving that last single heater core line open at the firewall). Make sure the system is drained below the lowest open line before you try to bypass the core at this point or as soon as you cut into those lines, some coolant will leak out.This will isolate the three lines connected to the heater core (sealing the entire cooling system up). The alternative is just CAP all three, and stop all flow at the duovalves (returns) and the other side at that supply line. IF you just cap all three, remember to cap BOTH duovalves rearward side on both valves AND that supply line going to the core (single line) on the opposite side of the engine. You do not want to let the duovalves get dried out (keep them wet) because if those valves aren't left wet you might have trouble with them after the core is replaced.
.
Originally Posted by onehundred80
I cannot see why you cannot plug and clamp the single hose going into the duo valves, it should be easy as you have over a foot of hose free to get at. and do the same to the hose coming from the firewall by the power brake booster also with ample hose to access. All this after lowering the coolant level below the open end of the hoses.
It may be a good time to drain and flush the coolant anyway as the wrong coolant could have been used at one time and caused the problem in the first place.
You could if you felt like it join the two ends of these hoses to each other, with a hose extension using two barbed fittings and four clamps. Plugging both ends would be simpler and act just like the valves were closed.
The duo valve could be opened, cleaned and stored indefinitely.
There you go, three choices already (there may even be more)! Only thing left is to choose one and go with it. You are involving more work with removing the duovalves though. Anyway, that's what I like about the forum. The diversity in various ways to handle the issues. Good luck!
Great information folks. I'm going to try it this weekend and will post the outcome. I'm getting some help as well by someone who worked in a Mercedes shop, so I'm hopeful we can do it!!!
Thanks again to everyone for ALL of the support!!!
Yes...I appreciated the analysis by all! Provided many different ways to handle the situation and look at things from different perspectives. I liked it and it helped me a great deal. I oh so badly want my beautiful little sporty car back up and running reasonably. My spare car is ugly and I have to wear a hat, a fake mustache and dark glasses so nobody recognizes me!!! LOL
Heater core replacement
Re: Heater core replacement
Sorry George, but both the supply and return MUST be clamped off. If you just clamp the one, the fluid/water will just go through the coil from the other sidel. A partial draining must be done (when the coil is removed the fluid will drain to its lowest point so drain it to below that lowest point) bnelson1970, your going to have quite a job replacing the coil, good luck! Your on your way as it is, just take a lot of pictures so you can get it back together as reversed to how you got it apart. 
