Here's my tech tips page. Right now it looks like crap, but give it a while and it'll look a bit nicer. This info is taken directly from my posts on the Founders region PCA bulletin board. Enjoy!
Okay,
I have had several people write to me regarding overheating in 924s and 944s. here's how we fixed our overheating problems for good!
first of all some background:
when we purchased our 924, the heat used to sit between 1/4 and 7/8... it was always
seeming like it was ready to blow a head gasket if I ran it hard. sitting in traffic, or
going up a big hill, we'd cross our fingers. then, one day while stuck behind the world's
slowest Jeep Cherokee, we pulled into a parking lot outside of our insurance agent's
office.
when we got back outside, the car was spewing forth coolant like there was a fountain under the hood. we decided not to put off the situation for any longer, had the car towed home, and began to diagnose... what follows is basically a dirt-cheap way to id your car of overheating problems FOREVER!
here's what you will need:
...a flat-head screwdriver with at least a 12" shaft.
...a good set of channel-lock pliers.
...a good set of metric sockets and a nice adjustable-head socket wrench.
...a crapload of rags, towels, and maybe some gloves to touch hot metal parts with.
...three gallons of purified water, and three gallons of antifreeze.
...a bottle of "coolant system flush"
...a garden hose, and access to water.
...a coolant system flush-and-fill kit (about $3 from Wal-Mart or K-Mart).
...really tough scissors (tough enough to cut a coolant hose).
...a LONG Saturday afternoon.
the process:
first we have to figure out why the car is overheating. there can be several reasons:
the radiator is blocked by the air-conditioner, and it can't get enough cool air into
the engine.
if this is the case, then clean out this area THOROUGHLY, you might want to invest in a
special radiator-fin straightening "comb" and clean out the radiator and air
conditioning equipment.
the radiator fins are bent, and the radiator is dirt and full of bugs. if this is the
case, do the same as above.
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the cooling system is blocked, or full of deposits.
if this is the case, then we're going to need to flush out the coolant system. while we're
at it, replace the thermostat AND fan switch.
your thermostat is not functioning, or your fan is not coming on when it should.
if this is the case, then we'll need to replace the thermostat AND fan switch.
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in the first two scenarios, the answers are the same, clean out the radiator, in the second two scenarios, the answer is also the same... clean out the cooling system, replace the thermostat, AND the fan switch.
as a source for these parts, I highly recommend Performance Products. these guys have a lot of experience dealing with overheating Porsches. rather than hunting down an obscure part, you simply need to tell them what year 924/944 you have, and they will supply you with the thermostat and fan switch that will be matched FOR YOUR CAR!
it is very important that you get a switch and thermostat matched for the same temperature. mis-matching them even by 3degrees centigrade will cause just as much of a problem as it solved.
here's how you do the whole sh-bang. the instructions are pretty similar for the 924 and for the 944.
first, we must get to the back of your engine in a place that most human body parts can't access (but Porsche factory workers could, of course...) this part is a pain in the butt, but it'll NEED to be replaced.
way back in your engine, right between the firewall and the back of the last cylinder, is a "pigtail hose". it is only about 6" long and it is coiled up like a "curly Q". this is the hose that takes heat out of the engine and feeds it into the heater core.
on the 924, it is part number 477.819.723.
on the 944, it is part number 944.572.589.00.
in both situations, you can find these hoses for less than $15 or so. you should get 2 new clamps with them, which should cost another $2 or so. order them and have them ready, because you'll be replacing them. also, purchase about two feet of similar diameter generic coolant hose form an auto-parts store. we'll need it later.
CUT the hose (don't bleed the system yet) right in the middle. hopefully, you should get a blast of greenish coolant rushing out of it. if not, then we may have found your problem (air bubbles in the system). in our 924's case, this pigtail-hose was full of SAND!!! I blew it out with air pressure, and it was caked solid!
now, hook up your coolant flush system. the "t-valve" part will go in the middle of your two feet of extra rubber hose. connect the ends of the foot long sections to the original points of where the "pigtail hose" connected to.
now, replace your thermostat and fan switch. believe me, this is the best time. if you don't, you'll be doing it later and wasting your time. some coolant will leak out. this is okay.
now, get under your car and drain the rest of the coolant from it. dispose of it safely! it smells sweet to animals, so take care that cats or dogs don't drink it.
also, take the overflow-tank cap off. the extra yellow hose that came with the flush-and-fill kit will connect to the filler port of the overflow tank (the place where you fill in antifreeze).
now, hook up your hose and turn it on full blast. make sure that your heater controls are set to "hot" or your system won't be completely flushed.
after a minute or so, you will see only clear water coming out of the radiator drain and the overflow tank. during all of this process, take care to make sure that electrical components and ignition systems won't get wet. this is VERY important!!!
now, check to make sure that no water is leaking from the area that you attached the makeshift flush hoses to. this is very important also.
now, turn on your car. let it idle for about 15 minutes or so, watching the temperature all the time. it should stay really cool, usually under 1/4. you can feel the water from the radiator and overflow tank getting warmer. while this is happening, you'll also have time to check for sounds in the engine, sounds that may indicate a bad water pump, or other problems.
after 15 minutes of idling. turn the car off. keep the hose ON. then, plug the radiator drain so that all the system will fill up. take the overflow hose out of the overflow tank, and put the cap back on (not tightly, just a 1/4 turn). this would also be a good time to add "coolant flush" of you bought it, because we'll be flushing the system again for good measure. make sure that the system isn't too overfull (it will shoot out the extra water anyway if it is).
if you if a clean installation in the temporary pigtail hose, then remove the garden hose and block off the "t-valve" that you used to flush the system through.
now, start the car up and let the coolant flush do it's thing. this usually means another 15 minutes of idling. keep track of the heat this time. you should notice your car running SIGNIFICANTLY cooler than it ever did. it should not be ready to bust it's gaskets.
now after the engine cools down a bit, reconnect the garden hose, and take off the overflow tank cap. now flush out the cooling system cleaner, and drain the radiator. hopefully it should be a little discolored from cleaning the insides of the cooling system and the heater system.
flush the engine again with the engine on for another 15 minutes and the hose on full blast. this will really clean out all the crud for good.
after the last purge. let the engine cool for a while (like an hour or so). get something to eat, watch a bit of TV, or something. then return, and remove all the cooling system flush stuff. replace the pigtail-hose, and fill the coolant system with the recommended amounts of antifreeze and water. a little red-line "water wetter" won't hurt too. check all the hose connections, and make sure everything is at the right tightness. put the overflow tank cap on.
drive around for a bit, you should notice the car running a LOT cooler. with the new thermostat, fan switch, and clean cooling system, I'd be surprised if the heat gets above 1/3 when cruising. personally I went for the coolest fan switch and thermostat I could find. I didn't want to risk anything!
DISCLAIMER!!!
I am kind of tired, and I have to run. I wrote this in a little bit of a rush, please proof-read this for me, and run this scenario in your head. it seems right to me, but I'm stretching back about 18 months.
I neglected posting other reasons that would cause your car to overheat... because if you do the above tasks, you will, in effect be doing those other things (such as replacing your antifreeze, checking for air bubbles, checking for bad fan switch connections, and checking for clogged thermostats).
please try this and tell me if you need any more info.