Hi all,

My 1999 SL 1 was suffering from very lukewarm heat, and only seemed to even blow lukewarm thru the panel setting on the slider- from the defrost and the floor settings it was pretty much cold, maybe BARELY lukewarm.

Changed the thermostat - no luck. Changed ETCS and the wiring/electrical connector for same- no luck.

So I crawled under the car and unfastened the rubber hoses that lead to the heater core tube which come thru the firewall.

WARNING- this job is pretty much a miserable, miserable nightmare. The hoses are in a location that is hard to work on them, and there's no real choice but to work on them from under the car (I have ramps, but jack stands would work as well. The higher off the ground you can get the car, the easier it will be.

The larger diameter one of the two hoses which is on/connects to the passenger side heater core tube runs down from the intake manifold. There are held on with spring clamps that can be a real bear to get off- I used a largish pair of needle-nose vice grips to work them off.

BE VERY CAREFUL getting the rubber hoses off the aluminum tubes from the heater core. These are not very strong and if you break or damage these tubes its new core time! Don't yank or twist too hard- just go slow and take your time!

A trick I used is to take an "S-hook" off an old rubber bungee cord, and bend it slightly in a vice to make a sort of "hose hook"type tool. I then clamped the S- hook in pair of vice grips and used it to wriggle between the hose and the tube and gently "work" the hose off. It's a real pain, but be paitent- they will eventually come off.

Once both rubber hoses are off the heater core tubes, its flush time. Trouble is there isn't enough room to really get a garden hose on them, and if you work from the bottom you're gonna get SOAKED.

So I took some scrap 1/2 inch PVC pipe about 2.5 feet long, and put a female-threaded PVC elbow on one end, so that I could hook the pipe up to my regular garden hose. I put a regular 90 degree PVC elbow on the other end of the pipe. Now, you have a nice "wand" to flush the core from the TOP (i.e, with the hood up looking down at the engine lol). Position the elbow of the PVC pipe right over where the core tubes stick thru the firewall, and have a helper then turn on your water facuet and blast away! Flush thru both tubes until the water runs clear thru the core both ways.

Mine was pretty crudded up with tons of gunk and just crap. Once I was all done, I hooked the rubber hoses back up, refilled with anti-freeze, and took her for a drive.

I could now roast a turkey inside the car! It made a 1000% difference and completely cured my lack of heat. The car now heats up like a champ!

Flushing the core is a real miserable job, mostly because its a tight, hard space to work and the old hoses get so "welded" on to the metal pipes. But it is well worth it. If you can eliminate the thermostat and the ETCS as your problem (or being low on coolant period), try flushing the core and likely your problem will be solved. You don't need any cleaners or anything, just plain water does the trick under garden hose pressure.

 

Thanks for contributing that.

Others will surely find it helpful.

Go over to the new member section and introduce yourself

 

First thing I do is disconnect the lower radiator hose on a car and drain the radiator. Then I NEVER pull or twist on a hose on a heater core pipe. I use a box cutter and split them along the tube. I've never had one that didn't have enough slack in it to cut an inch off and reuse. Then, I flush the core, reattach the heater hoses and fill the radiator and bleed any air out of the system. Sounds to me like you did this the hard way.

 

Good tip, but on my car I think someone years ago already did that, because there was very little slack in the hoses. Believe me, I would've loved to have cut them off. The hose that runs down from the intake manifold to the heater core tube is larger diameter and would be pretty easy to just replace. The hardest part is unhooking the upper spring clamp where the hose is hooked to the manifold. Hardly any room to manuever up there.

A pair of these are REALLY helpful to the whole heater core job:

http://www.pjtool.com/15longnoselockingpliers.aspx

I borrowed a pair like this from my neighbor, but if I couldn't I'd surely make the $15 investment. Still way chepaer than a radiator shop.

I'll post/upload a pic later of the "PVC pipe hose wand" I made to flush the core. I forgot to mention that I used PVC glue to permanently fasten a 5/8 inch female (internal) threaded fitting to one end of the PVC pipe, so that a regular garden hose fitting would screw on that end. The other end with a plain 1/2 elbow I did not glue up, because there is enough friction to "hold" it if you shove it well onto the pipe, and also if you don't glue that one, you have the ability to "swivel" that end so you get a good, tight fit over the heater core tubes. All the PVC pipe and fittings to make the "flush wand" are available at Lowes or Home Depot for about $7. Now that I'm done with the core flush, my GF is going use the "wand" to wash the dog and water hanging plants LOL!

Without my "flush wand" rig, this would have been a really WET job, cause once the clog come out of the core the water really starts blasting out of it like a fire hydrant. You'll pretty much be laying on your back with filthy anti-freeze and sludge water blowing all over your face.

Oh one more thing- if you have a scrap section of garden hose or tubing, slide that over each heater core tube as you flush the other, and bend the hose downwards so the outlet water will blow out right to the ground, rather than splash all over the engine bay. You could even temporarily clamp that hose on with a screw hose clamp.

I don't think some of the connectors etc inside the engine bay like to get soaking wet, and without a hose on the outlet side tube it will get really wet.

 

Well written and incredible. It was like being there in person! Except I did not get soaked. I have not done that particular job, but have done similar.
It also made me think about mine, a car that has been owned since 1996. Despite the years and the repairs (completely re-upholstered, painted once and screwed up and now needs it again, ) something that has in general been trouble free, reliable and when desired? Fun to drive!!!!! It is still now 20 years old and I have never replaced a single hose in the thing! The only part in the cooling system replaced was the plastic over flow tank which is actually pressurized so it is the top of the radiator. Something rubbed on it wearing a hole in the side of the tank.

There is a tube running out of it that does act as an over flow drain. It wanders around towards the fire wall rather than pointing at the ground. Does anyone know where that goes? Things are so tight in there I can not trace it.