Heater does not work and 32 degrees outside....

Hi, I just put my 996 back together after replacing oil cooler, coolant, AOS and some other stuff. And my heat does not work! So I am thinking; air in heater core (because of replaced coolant), crud in heater core (since I had intermix, oil in coolant) or just broken heater core? My problem is that I havent really tried the heat before I started working on it, so I dont know where to start. Any suggestions on where to start? Thanks, Johan

Personally I would start by draining the coolant, removing some of the hoses at the front of the car both for the engine/radiator cooling loop and heater core loop, and checking their condition inside. If you see any intermix gunk in there then the radiators, hoses, and heater core must be cleaned of all intermix residue. Guessing by the pics you posted earlier there is still gunk in there. In some cases if the intermix is really bad these parts have to come out and be flushed or replaced. Some have luck power flushing the system with shop vacs, flushing agents, garden hoses, etc. And/or putting a flushing agent (prestone power flush/dawn/etc.) in the system with clean water, run engine until it gets warm, drain again, fill with flushing agent again, run engine again, drain again, fill again... until it is clean.

When I had my intermix I had the engine out with the heads off, water pump off/replaced all the hoses off to get the pudding out of the engine (both the coolant side and the oil side). Flushed the oil cooler. I also took all the hoses off the cooling system other than those feeding the cooling system. Cleaned all the hoses. For the tubes ( there are several long tubes in the cooling system running to the front of the car) I pulled rags through them to get out the gunk. I also took the radiators offhand had them hot flushed at a shop. Then I ran distilled water through the system to operating temps. Changed the water two times. Then ran coolant for a few hundred miles, then changed it. Also changed the oil at 500 and 1,000 miles. If you tested my coolant there would still probably be contamination . So cleaning the system after an intermix is pretty involved. For much of what I did I think you have to have the engine out.

The odds are pretty good that the system is still contaminated .The heater core is always on-heat is regulated by flaps which I doubt have failed .THere are several issues to contend with :just draining the system from the engine does not drain the radiators -which is over a gallon if I rember closer to two ;next issue is that the contaminated coolant is a mess and toxic to animals so draining it in the drieway is not a good idea . The solution I used was the shop vac in wet mode .I started with the heater core and worked thru all lines attached to the engine .By my bucket count I got almost all out .This was followed up by two containers of Prestone Supoer flush and distilled water .Runnig the car for the better part of a week and then draining .I used the shop vac to make sure I had an empty system .Refilled the system with two more containers of Prestone super flush and distilled water .Ran the car for a full week and drained again using the shop vac to clean all residual .Final fill was real antifreeze . That was 5000 miles ago and the system is clean . There are probaly easier ways but this technique worked for me Dave

Hi guys, I spoke to the shop mechanic again yesterday, and he claimed he had flushed the heater core. He s sure there either is air bubbles or something else wrong with it. He said that there was almost no oil in there, and the little left in the heater is gone now. My intermix was not that bad, nothing like dharn55's goo. I had the old coolant in a bucket for two months, and now when it has cleared up there is no more than 50 ml of oil in there. Where should I look next? Thanks, Johan

Somewhere in an earlier post someone in replaing thrir heater core recommended that you fill it first before putting it back in. I'm not sure how you do that,no pictures were available of what it looked like or where it was. If mounted higher that other cooling system parts it would retain air.

Well if you think it's air in the core you should try to vacuum the system down and get the air out... -Shawn

If you need to access the heater core, a good thread here: http://www.renntech.org/forums/topic...val-996-99-c2/

That is a good resource. Great Pictures

Two ideas-jack the car up and see if the lines going to the heater core are both hot .If only one line is hot lift the bail on the valve on the coolant tank .There have been several posts on renntech stating that it is ok to drive it with the valve open- apparently the system will self burp( to some extent ).If there is an air pocket it should work it's way out .Obviously need to watch the coolant level . If both lines are hot then the heater flaps may not be working properly . Dave

Thanks Dave, that is excellent advice! I will check the hoses. Are they the ones around 1" size located under the car, near the radiator pipes, about 3' to the front of the transmission? I have just read up on the bleeding process, and apparently I need to open some fill valve under the engine, since my is a tiptronic. Anyone familiar with the process? Thanks, Johan

Remember that the heater core is a "high Point" in the system, so if air pockets are in there is can be hard to get them out. A vacuum machine is probably the best bet.

Logray, excellent link! I think it might be possible to bleed the core from there. Thanks, Johan

If you go to www.pedrosgarage.com , in his diy section he has complete bleeding instructions .They are for a boxster but it's the same procedure The vacum tool is easier but it can be done without it .

One of the better Franklins I've spent... If you have a 5gal or larger air compressor it really is one of the better investments you can make if you plan to do your own regular coolant changes. No better way to refill the cooling system. Amazon link here: Amazon Amazon

Hi, I took a closer look today while I was putting on the snow tires. There seems to be some foam in the side vents. While searching that I realized it could be what is causing my heat problem. I have been searching both here and Renntech but cant find the DIY thatsupposedly exist. Could this be my problem? Anyone that know where to find the DIY? Thanks, Johan

Found the DIY but the pics was relly small. I will dig into that once the garage space is free. On another note; it seems like the car doesnt warm up as fast as before. I can practically drive 10 miles before the engine temp approaces 180 degrees. Is that really normal? Johan

Hi, I pulled the heater core today, and the heater flap was totally disintegrated. AND There were old green coolant in here, which to me points towards air pocket and no circulation in heater core. I am gong to fix this tomorrow, and I hope that it is what's wrong! There was no sign of intermix in the core, which was a relief. Thanks, Johan

Quotes source post: 9137254

I'm not sure where the coolant is fed from to the heater but going upstream would be a very good idea. The dealers service manager told me the best way to flush oil out of the cooling system is the laundry stain remover called Shout. You know, the one advertised on TV saying "Shout it out"? Anyway......he says it strips all the oil gunky stuff and all.

Johan, on renntech, click on the pictures and they get MUCH bigger. Pac996, heater core is a loop, goes back to the engine in a long pipe/hose.

Hi guys, This is going to crack you up: I know why I didnt have any heat! The heater core was bypassed.... I removed the heater core yesterday, but did not look that closely. Today, after removing the battery, I realised the hoses connected to the core was just hanging there. No wonder I didnt have any new red coolant in the core, or any heat! I cant understand why someone would do that. It is basically the same job to fix it properly, and heater cores are really cheap. I would guess you still could use the heat to demist even in Florida where I bought the car. So, I found a used one from a 2500 mile wrecked car, which should be like new. I would have it back together tomorrow, if I wouldnt have dropped the bushing holding the flap somewhere in the car.... Now I have to figure that one out too. Two steps forward, one step back. Regards, Johan

Just drive with no heat and pretend you have an air-cooled 911.

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/images/smilies/biggrin.gif https://rennlist.com/forums/images/smilies/biggrin.gif https://rennlist.com/forums/images/smilies/biggrin.gif https://rennlist.com/forums/images/smilies/biggrin.gif https://rennlist.com/forums/images/smilies/biggrin.gif

And there was heat! Got the new core in today (looked like new for $200), taped up the flap and it worked great! Still, I decided to buy the flap and bushing from the same wrecked car, since I got the entire heat package for $150 shipped. I should have it all back together tomorrow, if I get a few hours of spare time. Thanks all for your support and help! Thanks, Johan

I'm glad to hear you not only found the problem, but also remedied the fix.

Cool! I mean hot!

Just for future reference if someone decide to replace or repair the heater flap; here are some pictures of how it SHOULD look: This is the factory covered heat/cold flap from a 3k miles car. This flap regulate the amount of heat from the heater core or cold air from the AC that should be distributed: And the bearing holding the flap in place looks like this: The idea is to only shave of 2 mm of the plastic on top, and then gently lift out the bushing. Underneath the dashboard on the passenger side there is a 7 mm bolt that holds the other bushing. When that one is removed the flap can be lifted out from the hole where the heater core is mounted. Another big problem is that there is a total of 4 (FOUR) different flaps in the ventilation system. All of these will lose the foam eventually! I know the other 3 are not that critical, but still they will leak through making the ventilation less effective. For example, when you want to defrost the windshield, some air will seep through to the floor vents. The door distributing that should look like this: And then there is the flap for re-circulating the air, that also has foam on it..... So basically the heater flap problem is more complex than just reparing one flap. Just for future reference! Thanks, Johan