Location Of Radiator Drain Plug

[rcecale]

Okay, I'm getting ready to change my thermostat in the hopes it will cure my over-heating issue. I have the front wheels up on ramps, dropped the belly pan and am ready to start draining the colling system.

I know there is a plug on the engine block, between 3rd and 4th cylinders. Looks like a pain to get to, so I think I'll be popping off the lower end of the lower radiator hose instead. (I've read that should do the trick as well as the engine block plug.)

My question is regarding the location of the radiator drain plug. Everything I've read indicates the plug is made of plastic and is located on the lower, driver's side of the radiator. (Lower-left side, if looking towards the front)

the only thing I've been able to locate that looks as though it could be the plug, on MY radiator, seems to be a 19mm plug that seems to be made of brass. Below is a drawing of where I'm seeing this "plug". Can anyone confirm this to be correct?




Thanks!

Randy

[Rasta Monsta]

On a '44 I believe the drain is covered by bodywork. . .even if you get it out it will go everywhere, you may be better off just pulling the hose.

Pics (click):

[rcecale]

Thanks! That appears to be the same location as the plug I'm looking at. I'll confirm when I get home this everning and will post an actual photo from the car.

Interestingly, there is "nothing" in front of this plug. Looks as though it will come right off and the coolant should flow right out, into a waiting bucket. Again, I'll confirm I'm looking at the correct item and will post a good pic of my own.

Thanks again!

Cheers!

Randy

[Techno Duck]

I would personally remove the lower radiator hose instead of the drain plug. Those plugs become pretty brittle and there is a good possibility it will break off. Atleast have a spare ready if you do use this method.

[Rasta Monsta]

Oh, and it would also be wise to pull the rad and have it flow tested. . .this is a common cause of overheating.

[Desert Fox]

and be careful with the bucket when you do this. I thought it would just come out pretty close to the radiator, but it went 6 feet clear across the floor under the car. not exactly what I intended to hit.

[rcecale]

Originally Posted by Desert Fox

and be careful with the bucket when you do this. I thought it would just come out pretty close to the radiator, but it went 6 feet clear across the floor under the car. not exactly what I intended to hit.

Good advice! I actually thought about cutting the bottom off a big soda bottle (At an angle) so that I could attempt to catch/direct the coolant down into a bucket.

Randy

[LowTechRedneck]

I'd leave it alone too, stock, those plugs are plastic, and will break easily. I drained my radiator that way to replace a faulty thermoswitch, and ended up snapping the head off the plug when I put it back in.

If it's not blue plastic, then someone just used a different (and probably sturdier) bolt in the hole after they broke the original.

[Slam]

^+1 Just pop the lower rad hose off.

[rcecale]

Originally Posted by LowTechRedneck

If it's not blue plastic, then someone just used a different (and probably sturdier) bolt in the hole after they broke the original.

I'm actually a little concerned about the idea that a dis-similar metal plug may have been used. From what I've read, this can be a really good source for corrosion throughout the radiator. Hmmmm...!

Randy

[Rasta Monsta]

Not just the rad, your aluminum engine parts can suffer from this as well.

[rcecale]

Okay, this is the best I can do with the pic. This is a view, from right in front of the driver's side front tire, looking forward, at the radiator. The plug is located in the lower left-hand corner, as indicated in my drawing above. Does this look about right?



Randy

[white944cup]

Randy:
The best way to drain the radiator is to remove the lower hose on the passenger side of the radiator. Are you sure the thermostat is causing the problem? What symptons are you seeing? I put a brand new thermostat in, along with a new German Laso water pump when I did the top end job. I also flushed out the radiator even though it was very clean. Have you checked the fan circuits and made sure there is absolutely no air in the system? What about the connections and grounds for the temp sender and temp gage? Did you tap on the face of the gage to make sure the needle is not sticking? Just some ideas before you start wrestling with that PITA thermosat retaining clip.

[rcecale]

Hey, Terry! Hope all is good. Things are pretty good here in Marietta. How's that 951 treating you?

As for the issue with the car, well, no, I'm not positive that the thermostat is the culprit. If you changed it recently, which I kinda figured was the case, when you did the water pump, I wasn't totally convinced. I really just planned to remove it and do the pot-of-water-on-the-oven test on it.

The issue, basically, is that it just runs way to hot during stop and go traffic. If I'm cruising steadily down the freeway, even in the recent high temps we've been having, she runs fairly cool. The needle on the gage stays pretty much straight-up, on the second indicator bar.

If I get caught in traffic, however, it's a completley different story. For instance, I get off work @ 5:30 and work fairly close to I-75 (with lots of rush-hour traffic). It's not uncommon for the gage to be practically into the solid yellow area, withing about 15 to 20 minutes. If traffic is really bad, I've seen it get practically pegged, to the point I've actually smelled coolant. Once traffic picks up again, it cools back down fairly quickly.

When I get home, I pull it into the garage and shut it off and can hear the fan(s) still blowing. can't confirm if it is one or both though.

I've tried reading up on it, both hear and on a few other boards I frequent,, but haven't been able to find anything that definitively tells me what my issue would be. I'm definitely open to suggestions. :-)

Regards,

Randy

edit: It's only 8:45, I think I'll take her for a quick little run and check out those fans...see if they're both spinning.

[rcecale]

Well, that was easy enough! Didn't even have to leave the garage.

Ran the car for 15 minutes, watching both fans and the temp gage on the dash. Immediately upon starting the engine, the driver's side fan turned on and never shut off during the entire 15 minutes.

The other fan, the one on the passenger side, never came on at all. Monitoring the gage inside the car, I was able to get the temp up to the third bar (the last bar before reaching solid yellow) and in spite of the increased temps, again, the fan on the passenger side never came on. Looks like this may be where I need to focus my efforts, (not the thermostat.) For some reason, this fan is not coming on.

Damn, I HATE electrical issues...

Randy

[white944cup]

Randy:
The 951 is treating me great so far. I think you are on the right track......if it runs cool at speed and then overheats in traffic, my first guess is that the fans are not working as they should. I can't remember exactly which one, but one fan should come on and stay on whenever the A/C is on ( I think it's the driver's side fan). The other should come on when the coolant gets up to temperature, run for usually a couple of minutes, and then it will shut off when it cools down below a certain temp. I believe that fan also has a low and high speed. It runs on low when the car is turned off, but runs on high when the engine is running. If this is not what you are seeing, check the fuses, all the electrical connections to the fans, and the relay. I think there is a good checkout procedure on Clark's garage. Good luck.....keep us posted.

[rcecale]

Ya know, Terry, they say great minds think alike.

I've been to Clark's Garage and was following the procedures for checking out the fans. You were right in that the driver's side stays on and the passenger side works as directed by temps.

according to the troubleshooting guide there, it says that the #5 fuse on the aux panel should be checked first. Checked that and the fuse seems fine.

The next step is to check out the relay, the directions are located also at Clark's. Will maybe get to that either tomorrow or this weekend.

Glad to hear the 951 is being good to you. I have to admit, while not a 911, this 944 you sold me has really turned out to be a really great car. She really is a lot of fun to drive, she really has a nice top end, and with the price of gas nowadays, 25+ MPG on the highway is so much nicer than my 12 MPG truck!

Keep me in mind if/when you decide to swap out the 951 for something else. You do a really good job of sorting them out!

Randy

[white944cup]

Randy: After reading the Clark's writeup, I realized I was slightly mistaken in what I told you about the fans......I'm pretty sure that both fans are supposed to come on and stay on when the A/C is running. The next thing to check is to make sure that both fan motors are still good by applying direct power to each fan using a jumper wire from a hot 12V source. Motor failures are pretty common. If you have to replace one, see if you can get one with the updated 6 blade fan.....they pull more air. Thanks for the kind words about the car....I'm glad she's still treating you well. Keep up with the timing belt and you will be rewarded with many years of good service.

[hpservertech]

Both fans should come on when the AC is on. If the dont then follow the troubleshooting steps on claks.

Could be the wiring (not as likely), could be the fan motor (more likely) or the termoswitch (most likely)

[rcecale]

Did a bit more troubleshooting last night by following the steps laid out in the Haynes manual.

I applied small jumpers to both sides of the electric socket on the fan, one jumper to each of the two blades. One jumper was then connected to ground and the other jumper was applied to the + side of the battery, providing direct battery power to the fan motor. Long story short: I got nothing! No movement at all from the fan/motor. Looks like my next step is to locate a replacement fan.

Here's a description of operation from Clark's:

On early 944s equipped with air conditioning, there are two electric cooling fans. The driver's side cooling fan is supplied via a parallel circuit. One leg of the parallel circuit has a resistor which causes the fan to run in slow speed. The other leg of the parallel circuit consists of a contact in the cooling fan relay. The passenger's side fan is supplied via a contact in the cooling fan relay.

When the coolant temperature reaches a preset value (normally 92 °C or 198 °F), the temperature switch (normally referred to as the thermofan switch) closes and cause the driver's side fan to run. We'll refer to it as the primary fan. Since the resistor in series with the fan is still in the circuit at this point, the fan runs in slow speed. The fan will run as long the temperature remains above the setpoint, regardless of whether the ignition is turned on. This is a common problem area which will be discussed later.

When the ignition is on and the air conditioning is turned on, the air conditioning relay picks up. This causes the cooling fan relay to energize, closing two contacts. One contact causes the secondary cooling fan to run. The other is a contact that is in parallel with the "slow speed" resistor for the primary fan motor. This shorts out the resistor and causes the primary fan to run in fast speed. The second fan has no "slow speed" resistor so when it starts, it always runs in fast speed. Also, when the air conditioning is turned on (with the ignition on), the primary fan will run regardless of coolant temperature.

When the ignition is turned on, if a high temperature condition is sensed by the thermofan switch, a contact closes in the thermofan switch circuit which energizes the cooling fan relay and causes both fans to run in fast speed.

Randy