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: