I don't know personally but a mechanic friend of mine believes that the heater core replacement on a RRC is more complicated. If there is any truth to that than perhaps that extends to Discovery 1? Again I'm not sure. Best of luck to you.

 

I decided to dig in and attempt following your instructions.

 

Awesome write up! Hope I never have to use it!
Can we get this added to the sticky?

 

Already is a sticky under the All D2 Sticky thread at the top of the Forum threads

 

hey, do you still want those measurements? I just replaces my heater core and have the original. Mine is a 99 D1 if that matters.

 

Nice write-up with pictures! I noticed in your pictures of the old & new heater cores, the old core has some foam strips around the perimeter--I would assume to keep the heater core from rattling in the plastic space in the housing--but the new core does not have that in the pictures. Is that included with the new core or should I get some weatherstripping from Lowe's or Home Depot? Or is it really necessary?

 

New core is a aftermarket brand so it did not come with foam straps or anything else for that matter. You get what you pay for. But with it installed and have driven several months since doing the heater core job, I dont notice any new noises or rattling. So not required.

 

Easy job until you get to the clamps to reattach new core.

This is a COMPLETE pain in the Biden.

Already gad to replace the tubes from wrestling with them so much.

AAaaaaaargggghhhhh

 

Fantastic Write-Up!

 

This references the comprehensive, thoroughly awesome heatercore replacement write-up from our friend TRIARII. Kudos to you, you saved me so much time, THANK YOU. Here's some supplementary information concerning the nitty-gritty of hooking up the pipes to the new heatercore.

The workflow is as follows:
A. open up the under-dash space so you can work, loosen pipes
B. seat the lower returnline
C. install the lower returnline pipe clamp
D. seat the the upper feedline
E. install the upper feedline pipe clamp.

Bottom line: you want to stabilize and secure each individual item before you move on to the next. This will make it easier as you go creating a virtuous cycle of ease and stability since these pipes, clamps, and screws are a crazy rebellious bunch each requiring special attention. You can't go caveman on this -- it will really test your patience. Follow these directions which worked very well. Take your time and secure each item while leaving the difficult part for last, which will then be easy since each item that comes before it will be nailed down righty tighty and not undermining you.


RAVE PDF -- use search term 'Heater Matrix'

A. Once the old core is out, use a ratchet strap around the front passenger seat etc. etc. to pull the dash area adjacent to the core straight back to give you a reasonably open working space. It's impossibly tight otherwise and you'll be fighting the dash repeatedly and become a miserable unhappy person unless you're TRIARII who did the original write-up and can leap tall buildings with a single bound.

Now you can fit your hands in to grab the feedline and returnline pipes and work them back and forth a bit so they're not so rigidly factory-frozen in place Doing this will give you much needed flexibility later in positioning these aluminum pipes (or 'lines') and seating them into the new core.

After having cleaned out the heatercore cavity, slide in the new unit -- don't worry about the feed/return lines. Just get the core seated properly with the lines doing whatever they want ...you should have loosened them a bit already so they should move out of the way.

With the new o-rings in place on the feed/return lines and a little petroleum jelly on these seals, work to get the lower returnline seated as follows (forget about the top connection for now, it's harder to get to ... get the bottom line secured first).

B. The bottom returnline can be roughed-in as needed. It's tight, but it's doable. Remember these are soft metals and will distort easily. Go slow, be patient, take breaks if you need to. I used a channel locks / large pliers against the insulated portion of the return line to move it around. Seat it roughly into the lower port on the heater core. Now, given the tight working space, you won't have any leverage to seat the o-ring into the heater core. So, to remedy this, I used a 2x4 rig wedged against a stiff plastic rotomolded box terminating rearward into the rear seats, terminating forward into a ball-peen hammer handle shaft wedged up against the heatercore's lowermost outermost corner. This should push the heater core forward into the o-ring fitting. Also, you'll probably need to push the heatercore laterally just a bit -- toward the driver's side -- to get everything to line up. Note that the heater core will move -- not too much but just enough -- since its housing compartment is plastic on all sides. It's a hard slog trying to pull pipe into the heater core since you simply don't have the leverage. Instead, push the heatercore forward and and also laterally to the driver's side to seat it into the pipe o-ring.


So now that the bottom returnline is lined-up, it's now ready to receive the circular clamp, ...

C. Since the 2x4 rig is holding everything in place, you can take your time and position the clamp on the returnline connection. As mentioned in the original thread, you need to work the clamp until it encloses over the heatercore-to-pipe connection interface. Rough it in at first, then position it properly over the interface to its install position, then squeeze it shut with needlenose pliers so it's more or less ready for its annoyingly tiny and short phillips screw... I used curved-end long pliers, large forceps, and needlenose pliers to manipulate the clamp and then finally give the ends of the clamp a good hard pinch to limit its travel around the pipe axis. Note that once you get the clamp worked into place and are ready to go with the screw, the clamp screw holes will no longer line-up since you've squeezed the clamp ends unevenly downward and inward. Put a small screwdriver shaft through the clamp screw holes and pry it a bit to get the holes to line-up once again. Once you've done that, then rotate the clamp end to a horizontal / parallel with the ground position, and insert the screw from underneath with the screw pointing up / vertical (a magnetized screwdriver or dab of RTV on the end of the driver is helpful). By 'going vertical' instead of horizontal with the securing screw, you a) have much more working area and b) you won't accidentally drop the screw into the carpet gap hole directly under the heater core. If the screw falls, it will instead land on the passenger footwell carpet, and you'll just try and try again. You may need to work it a bit since the holes may still not be lining up properly .... no big deal ... you'll need to work that out and try try try again without losing the clamp's hard-fought install position since earlier you gave it a good hard squeeze, so now, it should hold steady and not rotate out of position so easily.

You'll need to tweak the clamp a bit to get the holes to line up once you've squeezed it into place

Once you get the screw seated properly into the clamp and its beginning to snug up, you can rotate the clamp into its correct (final) position per RAVE pic above and give the screw its last few turns.

You may now ease up on the 2x4 rig that's been pushing the heater core forward this entire time. You're halfway there.

C. Now, with the lower pipe having been secured into the heatercore, you have a 'stable base' from which to work to get the upper feedline into place. Work it into place -- you'll have more wriggle room that you think, move the heater core as needed and the upper line with channel locks -- go easy -- just enough to get the upper line to roughed into place. With this upper pipe interfacing with the upper heatercore port, you can dial it in as follows...

Reestablish the 2x4 push rig, this time pressing into the uppermost corner of the heater core frame and thereby seating the heatercore into the upper feedline just as you did with the lower connection. Remember, you're pushing the heater core forward into the pipe rather than pulling the pipe rearward to the heater core since you simply have no leverage to do much of anything with the pipe itself. Moving the heatercore mostly forward and but also laterally toward the driver's side should get you where you need to be - the upper pipe seated into the upper heatercore port.

D. Fasten the upper clamp in the same way you did the lower clamp. Since the lower pipe is now secured, you'll have a much more stable base to work from which is necessary since the the upper pipe is less accessible. You need to reach up a bit and access it from under the dash, but its not too bad. Again, align the clamp holes horizontal with the ground, and put the screw in vertically since this upper connection is tucked away so you pretty much have no choice but to do it this way -- and you're an expert now having already done the lower connection.

You can fill with coolant from the engine bay into the upper feedline which is the hose closest to the engine. Test for leaks. Test under pressure by running the truck. Button everything back up per the TRIARII master template write-up to this supplement.

Peace. Hope this helps someone. Like his canine namesake, Rover is your friend, he's just demanding at times ... but aren't we all?

2004 Discovery 2 4.6L 144k -- 'Brutus'
@142k 2yr virushappyfuntime engine / susp. rebuild
crank polish, cyls honed, new pistons, rings, cam
om.emu 'lite' springs + t.firma front + bilstein rear
neither owner nor Brutus sneezed once (how dat?)
Both goin' real strong. Praise the Lord (yeah, dat).