Blue S2

Thermofanswitch and fan relays and switches all been checked? Mine did this months til i went through everything. Even my guage was off!!!

kennycoulter

i did all the tests as written on clarks, but there is a fusible link or something for the drivers side fan on the fire wall under the dash.....i havent gottren to that, BUT everyhting else checks out...the fans work, but according to the gauge, they arent pulling the heat out of my engine.

RedlineMan

You should be seeing two switches in close proximity, in the head, close to the front. One is the temp sender for the gauge, and one sends that info to the DME. I always get them mixed up, but if you throw some voltage into them you'll see which one fires the gauge easily enough.

Yes & yes.

Water temp gauges fluxuating wildly are either bad electronics or air pockets in the system. Occasionally this can be caused by a sticking thermostat, but the action at the gauge is usually then confined to getting real hot, then cooling suddenly. I've even had them come unstuck audibly!

I urge you to eliminate the electronics from this by measuring the water temp externally. One time when I replaced my thermostat, my OE gauge read 1 line hotter than before (???). I redid everything 3 times with no result. It turned out the sending unit had decided right then to F$@% with my head! After I got my blood pressure back down I ditched the electric gauge for a mechanical one and have had no further troubles!

Matt

I wouldn't rule out the radiator, the replacement probably looks good and probably wasn't plugged severely, but it may or may not be flowing enough coolant. No way to know without pulling it and having it flow tested.

A few years ago I had an overheating issue and decided to replace the radiator. I emailed George B (944Ecology.com) to see if he had a used one. George impressed me by responding that he had plenty, but that I should buy a new one, they're pretty cheap and, here's the important part, these radiators are known to lose effectiveness over time. I didn't have a history with George yet at that time and he could have easily sold me a used one, but he did a very stand up thing.

I installed a new one (got it from Paragon) and the overheating was fixed.

Matt

Bill

Did you pressure test the system?

I have seen many instances, where a coolant leak will not surface until the system is under pressure (actually lack of pressure, see below). Usually what happens is this:

1. Cold start up/idle in driveway, system cold, no pressure, no leaks.
2. Drive down the road, system heats up, system attempts to pressurize but can not, coolant boils, system leaks onto street or steams into atmosphere.
3. Slow down at driveway, low coolant in system, idle into garage, no pressure, no coolant, no leak.

Water boils at 210 degrees F. For every 1 psi of pressure added to the system, the boiling point of water increases 2 degrees F. Anti-freeze (glycol) mix also increases boiling point temp. The 944 cooling system is designed to run at 7 psi of pressure. That would put the boiling point at 224 degrees F (plus whatever anti-freeze adds). The cooling system is designed to run at 190 degrees F. Fans turn on around 210 degrees F. If the cooling system does not hold pressure, it will not be long before you have a problem. And as stated above, it will occur only when you are driving and will not be able to see the leak. You can look for water stains/trails, but pressure test is best.

Also remember, once you have lost the coolant from the system, other issues will arise. Your temp gauge will read low, because it needs to be in contact with the coolant to obtain a reading. The fan switch will not turn on the fans because it needs to contact coolant to get a reading. Temp sensors will not read air or steam, only liquids. The heater will not work, because it needs coolant flowing through it to exchange heat.

Bill

By the way, I am currently looking into getting Griffin radiators interested in making an all aluminum direct replacement radiator, to replace the crappy plastic 944 unit. Go to their website, they make quality stuff. Sent them my radiator to use as a template and for pricing. It will arrive at Griffin tomorrow (tuesday 3/1). They will give me a quote and have stated that the more we purchase, the lower the cost.

Interested in a group buy on a superior unit that will last longer, cool better and carry a year warranty?

Yes, my car is also in the garage with no radiator. Factory one died, and I for one am not interested in saving a couple of pennies now, but then have to do the repair again later (or should I say sooner?). When you buy used, you usually just by someone else's problem. New will save time, money and frustration.

nine-44

aftermarket radiator caps are known to cause overheating, ask Pete, he went round and round only to figure the aftermarket cap was the problem. He went OE ans instantly fixxed it.

Mark944na86

So: you never said. What procedure are you using the "burp" the system? (You can replace every component three times over with new ones, but if the system isn't properly bled of air, then all bets are off...)

-Mark

kennycoulter

i guess by burping you mean letting the air out of the system... i was unscrewing the 12mm bolt on the tod of the waterneck.....(where american cars wouldve had their easy to replace thermostat)....thats why i said, i was unscrewing that, and letting the steam or whatever out, and then the radiator cap wasnt hissing or relieving pressure when i took it off.
redlineman, so if i take some jumpers, and apply them to the "switch" or "sender" whatever it is, the gauge will probably go to full hot with 12v battery? i was only seeing one sender, but ill check again. is it only supposed to have one wire?
andy, did pete have the problem because the cap wasnt holding the same amount of pressure?
bill, what would i do to test the pressure? can i hook up a mity vac that measures both vacuum and pressure, and hook it to a certain place? any special tools needed to hook it up to a certain place? how about the tiny tube (white nylon screw in) above the fan switch and below the upper hose location? would that just be sucking coolant?

Mark944na86

OK, from your response I'd say that whatever else is up with your system, you almost certainly have air in it. You need to get the air out -- not difficult, but absolutely necessary.

Here is the simple method (called the "Heger Burp") I've used many times with success:

Ok, The EASY way to bleed...

1) Make sure that the car is on a level surface.
2) Open the bleed screw
3) pour in the coolant/distilled water mix until it comes out of the bleed screw (yes, it will be well over the "full" mark on the reservoir)
4) close bleed screw, leave the cap off of the reservoir
5) start car
6) turn the heater control to FULL HEAT, turn the fan on to 4.
7) let the car heat up, the coolant in the reservoir will burp and go down as this is happening
8) you may rev the engine to get the engine to heat up faster and to get it to open the thermostat
9) Once the thermostat opens (the reservoir will burp and the coolant level will decrease) add more coolant
10) let the engine continue to run to fully warm up. Keep adding coolant as needed.
11) You can rev it a little to move the coolant/any remaining air out of the system as needed.
12) once the radiator fans have cycled at least twice (on-off, on-off) and the reservoir is not burping air anymore, fill to the full line or above and put the radiator cap back on.
13) you're done.

Use a good (no silicate/no phosphate) antifreeze and distilled water in a 50/50 mix.

I've done this many times and it works well. Be sure to wash down the area with water to make sure no animals lick up any spilled coolant. You WILL spill coolant.

As with any scalding hot liquid, be careful.

(above copied and pasted from an earlier post by Dal Heger -- you might want to do a search and read some of the cooling related threads.)

-Mark

porschefig

don't all other resources say to park with the nose up hill....or to jack up the front end?

Mark944na86

There are certainly other methods and approaches that may or may not work as well. This one is the simplest one I've found that works reliably for me. The only downside is that the system really does "burp", and you may end up with about a litre of coolant being spilled in total -- a bit messy, but no big deal. Just need to make sure its cleaned up so animals don't ingest it, etc.

-Mark

Bill

A mity vac is not the correct tool. Stant makes the pressure testing tool. It is a pump with a gauge on it and has several attachments to fit different radiators. It connects in place of the radiator cap. Then you pump up the system to the required pressure (944 is 7psi). Then you look for leaks and/or watch the pressure gauge. A proper functioning system will hold a steady pressure. The tool costs around $100. If you do not want to purchase this tool, most shops have it and can do the test.

Ken D

Are the fans rotating in the proper direction? Should be counterclockwise when looking forward.

RedlineMan

Hmmm...

I can't remember how many wires there are, but both of the senders have 2 terminals. The front sender has a plastic shield around the spades for a plug to slip on, while the rear spades are exposed for two female spades to attach. If you run some voltage to wire set, you will see which one fires the gauge.

As for air bleeding, I'm going to give you a far different procedure in one respect: The bleed screw is the LAST thing you should close.

- Open the bleed screw, rad cap off.
- Fill with coolant.
- I do this in stages while I do other things (like pick up the shop). Air/fluid will work through the system by gravity.
- I squeeze all the hoses periodically - like milking a Cow - which makes air erupt into the tank. Keep refilling as necessary.
- When fluid comes out the bleed screw, start the engine. I tape the throttle open to about 2000rpm. Crank the heat and defrost up full. Let it run. Nothing will happen for some time.
- When the T-stat opens, you will start getting very sporadic bubbles from the bleed screw. This progresses to constant large bubbles, getting finer, ocassionally spitting, to eventually frothing. It progresses still to a point where some solid fluid is still interupted by bubbles.
- Leave it running with the cap open until you get a solid jetstream of fluid coming out of the bleed screw. LEAVE it open until this happens, and only then tighten it.
- You are REALLY done now.

Closing the bleed screw before the fluid runs clear out the bleed screw hole means there WILL be air in the system. Any other method WILL NOT clear all the air from the system. If you don't like the spillage, put a pan under the car. Hose the floor and driveway down afterwards. Drizzle a little water around on the engine block to rinse it off. DON'T flood a hot engine with cold water!!!!! Let it run and get nice and warm to boil off the excess water on the block. I use compressed air to hasten this.

Another tip you might find useful is to place a 12mm wrench on the bleed screw and position it such that the spray from the bleeder does NOT point toward the distributor cap or belt casing. I let it run down on the head. Use a piece of tape to hold the wrench if you must.