mwspera

Flushed out the heater core last winter a couple of times but that only fixed the "no heat" problem temporarily. So, I decided to do it right and replace the core. As I mentioned in other posts, this particular chassis (B6) has the core easily replaceable - no instrument panel removal required. I know of some shops who try to screw customers and charge them for an IP R&R. Shameful but true.

Sorry, no pictures. The repair manual does have pics and this one is pretty easy without pictures anyway.

Before you start:
YOU NEED TO GET NEW SEALS AND CLAMPS!!!! They DO NOT come with the core. The kit costs $32 from the dealer but YOU REALLY NEED THEM. The old seals will be trashed.

Following the manual, it is about a 4-5 hour job for the moderately experienced wrench. Pull the battery. It will save you a lot of pain when working the heater core hoses off. You pull the heater core hoses and blow out the core with compressed air. I got super **** because I did not want a flood in the interior. So, I blew it out for about 8-10 minutes alternating short bursts with long ones. Once done you remove the driver's side lower dash panel/cover (the panel that holds the owner's manual). 2 bolts on the bottom and one in the left side (once you pull off the fuse cover). The panel needs to be pulled back to release the clips after the bolts are off. With the cover off, you disconnect the accelerator module connector and take out the 3 allen bolts to the module. The top ones are a bite because of the cramped location.

With the accel pedal out you look to the right of where the pedal was and see a smooth plastic panel with 2 silver water pipes running behind it. This is the core cover. Take out the 2 screws (one up way high) and remove it. Observe the position of the pipe/hose clamps and draw a picture so you can get the new ones on the same way. Next you remove the clamps on the water pipes and core and then wiggle the pipes off. I used a flat head screwdriver to pry them apart but you need to be careful that you don't bung up the mating surfaces. They are flared AND they are soft aluminum. Turns out I blew out ALL the coolant so that I only got about 3 drops once the pipes were disconnected. I looked pretty silly with 4 bath towels and half a roll of paper towels spread all over!!! The core will slide right out. You need to wiggle past a few obstacles but it will slide out.

Before you reinstall - one more time:
YOU NEED TO GET NEW SEALS AND CLAMPS!!!! They DO NOT come with the core. The kit costs $32 from the dealer but YOU REALLY NEED THEM. The old seals will be trashed.

Before you put in the core, you should slide the new clamps onto the pipes and push them back out of the way. I recommend you DO NOT open the clamp up and wrap it around/put it on later. Look at the picture you drew and orient them on the pipe the right way. Now slide in the new core. Lube the seals with coolant and slide them into place on the pipes. Now comes the hard part. You must wiggle the pipes back onto the core so that the flared mating surfaces are almost touching (10 thousands or less - preferrably actually touching). Pushing, pulling, twisting, and swearing will not make them come together AND STAY PUT. And, CLOSE WILL NOT DO IT!!! The trick - You need to use a pliers and squeeze the lips of the pipe seal and the core seal together GENTLY so that the surfaces actually touch. THEN they will stay together. You need them to stay put in order to put on the clamps. Again, don't bung up the aluminum pipes/lips or you are screwed (new pipes and new core will be needed because it will forever leak). You need to slide the clamps into place one at a time in a way as to NOT disturb the pipe-core connection. Once in place and absolutely in the correct position (perpendicular to the pipe - not on an angle), you use a pliers to squeeze the clamp shut just enough for it to "click" closed on the catch. If the clamp will easily twist, you did it right. If it binds, then the connection came apart and you DO NOT have it sealed right. Once both are clicked in, screw in the tightening screws. If you did this right, you should be able to tighten up the screws about halfway and still twist the clamp around. Twist the clamps to position them like the old ones were by looking at the picture that you drew.

Reinstall everything and bleed the core. I bleed it by sliding the top hose back to expose the bleed hole with the engine running. When coolant and no air comes out, I slide it on and tighten the clamp. Take it out for a ride checking with a flashlight every now and then to make sure the core is not leaking on the inside floor by your right foot. Bleed it again and top off the coolant if necessary. Then drive it for 15-20 miles. Check the level and button everything back up. From then on you should have heat.

Good Luck,
Mike

Pete@ECSTuning

Great read! Very helpful. Bookmarked for sure.

stolnheartdealr

This was the only heater core DIY I stumbled on so I thought I'd share what made this install easier for me.

I found the heater core connections to the inlet/outlet pipes tough for two reasons:

1. There was some rough deposits left from the old coolant on my pipes that impeded the seals from sliding into position easily. Taking 600 grit sandpaper and wet sanding this surface smooth helped tremendously. Next I sprayed some white lithium lube on a paper towel and wiped the pipe ends and the inside of each seal. Proceed at your own risk using white lithium or other lubes on your seal unless you're positive about compatibility, I wasn't sure so I used the least amount possible.

2. Getting the seals seated if you start them on the pipes first is very difficult. I would suggest starting them in seated in the core. Reason for this is there a small ridge on the seal's core side surface and when you try to slide the core onto it with it sitting on the pipe already that ridge is very tough to clear. Start the seals in the core and if you followed Tip 1 you will be able to easily slide the pipes into position. Just make sure the edge of the pipes don't catch a side of the seal and try to push it inside the core however the pipe ends are tapered to help you avoid that if you're careful.


I used a channel lock wrench at it's largest setting to press them together, against the flare of the pipe and the opposite side of the core body a couple times per pipe and after these two steps I got them seated and clamped in minutes.

My core came with the seals (and two o-rings I didn't find a need for???) but like the OP suggested it's better to order them anyway just in case if your part doesn't say it's included.

j.mayer4@gmail.com

Thanks for the info, any idea how much coolant I should expect to replace from blowing out the heater core hoses?

GRUPPE M

After attaching the new heater core and using new seals and old clamps the bottom inlet to the core leaks. what should i do ?