I should have gone with OEM replacement rather than the billet aluminum. I'm sure another plastic tank will outlast my ownership of the '02.

As for the solution now, I don't have the original cap. Suggestions?

 

 

^^
https://www.ecstuning.com/Search/SiteSearch/17107515499/

 

Thanks to everyone for their advice and input. These forums are priceless. So, here's an update on my situation. Changed the thermostat, installed brand new valve cover, shop said it repaired /replaced the fan relay. Also changed the expansion tank to a new one (plastic, not aluminum). Car running great EXCEPT the coolant level has been dropping daily. One day it was down a couple of inches, two days later it was almost empty. I can't find any leaks anywhere. Shop said they pressure tested the system before I got it back so I don't think there could have been such a large air pocket in it. I haven't done the open bleeder cap thing when I've added coolant so I'm going to try that today. Also, I haven't heard the fan come on at all, even after I've driven for a while.
I haven't seen white smoke out of the exhaust either.
Maybe we haven't thoroughly air bled the system but I can't figure out where the coolant is going. Not sure if it's the heater core, as I get great heat in the car when I turn the heat on.
Suggestions??
Thanks

 

Firstly. Tell us where you are. If you are in S California vs Northeast makes a big different for us to understand the operating condition of the car. If you are in the Northeast the fan may hardly need to come on at all in the dead of winter.

Since you have been driving your car any air in the system would have been purged and refilled by the expansion tank. Did your shop verify you cooling fan is functioning on both speeds? If you fan failed on both speeds, you can have the symptom of losing coolant that you are experiencing. The reason is the coolant boils over and forces the expansion tank cap to release the steam along with coolant, which I hope it is the case or else you might have a cracked head again. Boiling coolant is not a good thing for your engine.

BTW. With modern cars, clogged radiator is almost the thing of the past. It rarely happen.

If you turn on the AC and let the car idle long enough, the radiator fan should run after a while. If not your fan low speed may have failed. Then the question is if the high speed also failed. Low speed failure is typically caused by the resistor, while high speed failure is likely that the fan has gone kaputt.

So far my impression is you are not exactly the home mechanic type so I am reluctant to provide instructions on how to use a DMM to debug further.

 

Thanks pnwr53s for the feedback. I am in Northern NJ where it's been extremely cold the last couple of weeks. I understand that when its this cold out the fan may not come on, but I got the car back from the mechanic a few weeks ago when it wasn't so cold and didn't hear the fan come on at all then either. I'm probably not as well versed as you on mechanics but can get by if pointed in the right direction and am a quick learner. I have a multi meter and if you have some suggestions can troubleshoot further. I have a feeling that either the fan has failed or the relay is shot. The mechanic had originally jumped the fan and it was coming on when I parked after I drove for a while but that was before I discovered I had a cracked expansion tank and cracked valve cover. After he made those repairs he told me "his guy fixed the fan". Never came on after I took back the car, so not sure what they supposedly fixed. I need to take it back to him so he can make sure the fan is working properly. But I can troubleshoot if you have some suggestions.
Thanks!

 

​How to test the fan using a continuity meter or multimeter:

Disconnect fan plug from harness

Put multimeter into continuity mode and connect negative lead to the brown ground wire on the fan plug

Attach positive lead to the thinner red wire (low speed fan) on the fan plug
If functioning properly, multimeter should beep
If no beep on low speed wire, the low speed resistor has failed.

Attach positive lead to the thicker red wire (high speed fan) on the fan plug
If functioning properly, multimeter should beep
If no beep on high speed wire, the entire fan has failed.

 

^

I cannot write one better. If your DMM don't have a continuity setting, just set it to read the lowest resistance - like 200 ohm. They should both measure almost a dead short.

 

Here is the wiring diagram for the radiator fan circuit (as always, model years may vary). It also offers the insights to the PS fan relationship to that of the radiator fan. You can see there are 3 fuses and two relays for the radiator fan. The best way to test the fan full functionality is to use a software tool that can turn on/off the fans at will, but most people don't have access to one.

 

Haven't had a chance to check fan with DMM, but had maybe a stupid question. Would the fan still make a difference if the outside temps here have been around 10-20 degrees the last couple of weeks? Wouldn't the low temp prevent the coolant from evaporating?

 

Rebuilt or not, sure sounds like you have a warped head and the coolant is being blown out the exhaust. I would put some dye in the coolant and check things with a black light including pulling all the spark plugs.

 

Checked fan with DMM. On both the low speed and high speed wires, the resistance was 44ohms. Looks like my fan is dead.
So my questions are:
1) in cold Temps such as the ones I mentioned, wouldn't that help keep the coolant temp low even if the fan was shot?
2) OR as one of the replies mentioned, could this all be a result of my head being slightly warped enough that coolant is getting into the engine and that would explain the daily loss?

 

1) in cold Temps such as the ones I mentioned, wouldn't that help keep the coolant temp low even if the fan was shot?
The engine will reach it's max temperature based on the thermostat rating not the temp outside. In your situation where you have a overheating problem, I would suspect that the only way the outside temp would make a difference is when you're first starting the car, or if you're coasting down hill with no load on the engine, air cooling.

Did you do a Pressure Test to see if your cooling system is holding pressure? Did you do a Block Test to see if you have exhaust gases in your cooling system? This would answer your 2nd question.

 

If your measurement of ~44-ohms is correct your fan has likely failed. Did you do a sanity check of the DMM by seeing the resistance by shorting the two test leads? If you read from 0 to a few ohms consistently you are good. The fan should read no more than a few ohms on both hi and lo contacts, which is in the same ballpark as most cheap DMM lead in a novice hands.

1) You clearly do not understand the basics of how ICE cooling system, and heat transfer work but that is ok. Your engine can generate a lot of heat depends on if it's just idling or under heavy load. Typically under heavy load the car is at speed. With the car at speed, the cooling fan may not need to come on at all. But at low speed or sitting in traffic, even at the current Bomb Freeze in NE the fan may have to come in at times to prevent the engine from overheating.

You cooling system is can be simplified as a pressure cooker. Like a pressure cooker, one of the radiator cap's function is to raise the boiling point of the coolant, and the other is to release dangerous excessive pressure like in your case - when the coolant reaches excessive temperature, thus excessive pressure. When the pressure exceeds the expansion cap release pressure the steam, along with coolant will be expelled and that is likely why you lose coolant.

One important thing to verify is if your water pump is functioning. If you are getting cabin heat then your pump is OK.

For all you reported so far, in all likelihood your problem is the radiator fan, not working in both low and high speed, which points to the fan being bad.

 

Fan ordered and will be installed this week.
I am curious however....is it normal under the conditions I've described for the expansion tank to lose almost all of the coolant because the fan isn't working? Seems like a lot of coolant to evaporate?

 

Yes, absolutely, if your engine in the process of overheating.

 

OK, so new fan is installed. Was checked and is working correctly. HOWEVER....after 2 days of driving, the coolant level in the expansion tank has gone down. My temp Guage on the dash is within range, def not approaching overheating. Also, I have not heard the fan come on after driving to work (50 miles) when I park. I guess this is normal if the engine temp hasn't exceeded the high temp point for it to come on??

 

It has been suggested a few times in this thread (Posts 20, 22, 38) that you perform a block test to check for exhaust gasses in your coolant, which could account for your coolant loss.

You have not indicated that you have performed the test. The answer to your coolant loss dilemma might well be revealed as a result of that test. It will also serve to rule out certain criteria.

Have you done the block test as suggested?

 

What temperature is your MCS running at when it loses coolant?

If you don't have a temp gauge installed, you can use the OBC (on board computer) to diagnose.
My 53 never exceeds 88 degrees C in normal operation. On a hot day in Arizona traffic, I've seen it go up to ~98 degrees max, and when I was troubleshooting cooling issues last year, I would turn it off to cool down around 102 degrees C. Never add cold coolant to a hot motor, it's very easy to crack a cylinder head like that.

Good luck and let us know how it goes! Probably not a bad idea to block test either, if exhaust gases are entering the cooling system (early stages of head gasket), they will overpressurize the coolant, causing it to overflow.

 

Beside the block test that everyone has been advocating, how about something so simple as a coolant pressure test to ensure the integrity of the system? Pump up to 15 psi at the recovery tank and be sure it holds steady for an hour or two.

 

Along with the block test, a coolant pressure test was also suggested by gumbedamit back in post #38...

The coolant is going somewhere . . .

 

Before suggesting the tests the OP would be challenged to perform, I question if he is aware that the expansion tank should only be filled to the max mark (with the engine cold).

 

Which should be noted is halfway up the reservoir.

 

...but has the OP done the coolant pressure and block tests yet? As for the coolant level in the recovery tank, I've found that the optimum level should be no higher than the top of the S-shaped baffles in the bottom of the tank. Any higher and my system wants to "burp" excess coolant.

 

Block test performed as suggested and there are no signs of a cracked head or blown head gasket. Block test fluid stayed solid blue the whole time.
So the mystery continues. It doesn't look like the radiator is leaking and yet the coolant level continues to drop. Also, fan stages are coming on correctly, and the car is not overheating or even approaching overheating as I drive in traffic, etc.
Where can the coolant be going?