Can someone point me out how to do a heater core flush.. i have looked all in the engine bay and cant seem to find the heater core hoses. What am I looking for?

I also cant find a thread about how to do it although there are plenty stating that when one side of the vehicle wont heat up its probably a clogged heater core..

04 XJ8 driver side heat does not work.

 

The heater core lines are aluminum lines on the passenger side and you will find hose connections that can be removed close to the front near the radiator. The top line is the return line back to the overflow tank. To back flush you can disconnect the rubber connections and clamp on 3/4" heater hoses and install a plastic ball valve and connect to water hose and try to back flush and then have bottom line empty into pail. I back flushed about 5 - 5 gallon pail fulls, until grit stopped coming and water looked clear. It helped and I now have heat on the drivers side, but still not as good as passenger side. Will probably redo in the summer when I can do it outside and perhaps circulation some scale remover. Hope this helps.

 

I would add here that when I backflush, I do not make a solid connection, but hold them together loosely with my hands. The reason is that most public water systems operate around 50-60 psi and the heater core cannot take this pressure. If it is really blocked, the pressure could blow it out. If you are holding it, you can feel the backpressure and let it loose.

 

Good call, oldmots!

 

What about an old auxiliary pump with two 5 gallon buckets to back flush instead?

 

QUOTE=kthrash;317531]Can someone point me out how to do a heater core flush.. i have looked all in the engine bay and cant seem to find the heater core hoses. What am I looking for?

I also cant find a thread about how to do it although there are plenty stating that when one side of the vehicle wont heat up its probably a clogged heater core..

04 XJ8 driver side heat does not work.[/QUOTE]

ktrash

As thorsfar wrote the heater core inlet and outlet lines run along inside the engine bay attached to the passenger side wheel well. I grabbed a picture that was being used to show the position of a fluid line connecter but also shows the heater core lines location pretty clearly. In the attached picture look to the left for a red arrow that points to a junction in a fluid line. The arrow itself is sitting right on the heater core's outlet line which is aluminum. The inlet line is located just below it on the inner fender well and they both go back towards the firewall where they make a right hand turn to connect to the heater core which itself is hidden behind the engine and attached to the firewall.

The metal lines are connected to the cooling system by two metal 'hairpin' type clips at the junction with a pair of rubber hoses. Don't lose the clips as they can't be replaced individually (don't ask me how I know this either). They don't work by pressure but rather act as a 'locking' clip that keeps the junction from pulling apart so they only have to be pulled back about 1/4 -3/8ths of an inch and left on the line. As a caution you might think about putting a largish towel or piece of paper under that area to catch any clip that gets away from you. Certainly easier to find than in the dirt or grass<G>

The upper line if the core's outlet and the lower is it's inlet. Since the core is rated for no more than 14 psi as others have posted DO NOT turn your garden hose on full force as nominal house water pressure is 40-50 lbs.

To loosen scale and accumulated mineral deposits first fill the heater core and lines with 'distilled white vinegar' and cap the lines so it can soak over night then back flush for several minutes. Some also recommend back flushing with hot water but that might be difficult to do given the space you have to work with. You might have to do this a couple of times to really get the crud out and as thorsfar wrote he did it 5 times so be patient and don't expect some miracle. There's also a chance that the build-up of silicates is just to great and at best you'll only get back partial function.

 

This is just a heads up for those (like me) who are discovering the joys of winter season heater issues. If a heater core back flush doesn't work or the problem is actually your auxiliary coolant pump here's a link to a site I use often for both of my Jags. I like doing business with our sponsors but sometimes the cost differential is just to damn much to overlook so I always double or triple check.

This is a link to one of those 'other' sites and is one that I've used quite a bit over the last 5+ years. They have several aux. coolant pumps to choose from all designed as direct replacements and I'm pretty sure that several of them are identical with the only difference being the jobber that's selling them.

Anyway they have aux. pumps from as low as $90 + shipping which in my case is under $10 and I generally get whatever I order in 2-3 days.

https://www.partsgeek.com/catalog/20...ater_pump.html