Cooling System Diagnosis

[DChaput]

I own a 2000 Explorer, V-6 SOHC. In what's best described as ridiculous stupidity, I ran water only, no antifreeze, in the coolant system. Somewhat predictably, it froze. The car's overheating badly now - enough so that she's parked until I find and fix what broke in the freeze.

I know the upper radiator hose is split, so that's one thing I need to fix. I've looked at the block and the radiator and I can't see any freeze plugs pushed out, but I'm not sure where the plugs are, so I'm not sure they aren't out. I also know I need to drain and flush the system to get out the rust and crap that's accumulated from me running just water in there. But I hate to do that before I figure out what all needs to be fixed; I don't want to have to drain it more than once.

If any of ya'll can help me, I need to know where the freeze plugs are, and what else I need to check. What's most likely to have broken in the freeze?

Thanks!

 

[my98nnj]

First thing to do is to pressure test the system to see if you blew a head gasket.
Leaks, freeze plug failures will all show up during the test.
If the system holds pressure, consider yourself lucky.
Flush it, refill with the correct 50/50 mix, purge any air and you should be OK.

 

[DChaput]

I don't THINK I blew a head gasket... The coolant water is brown with rust and crud, but it doesn't look oily and there's no water in the oil.

Is there any easy way to pressure test it myself? (I live on a college campus, so I can't do anything especially messy or that requires much equipment.) I have to take it to a mechanic for a flush anyways, so I can have them pressure test it, but I hate to pay for anything I don't have to.

Thanks for the advice!

 

[96eb96]

If you blew a freeze plug you would have coolant spew all over place.

 

[my98nnj]

Have the mechanic pressure test it before he does the flush just to make sure there are no other leaks. (you did say the upper hose was busted?)

 

[gijoecam]

Replace the upper hose, then see what it does. It's possible that the freeze (if it froze solid) damaged the thermostat and a simple $30 replacement will have it working fine. Until you replace the hose and test the system, there's no way to know where the other problems lie.

 

[DChaput]

First, thanks for ya'll's advice.

Second, new problems abound.

I replaced the upper hose and it still leaked, so I took it to a mechanic and had it pressure tested. He told me that it was leaking from the thermostat housing and he could fix it for me for a mere 800 bucks. My response to this is perhaps best left unprinted.

After poking around some here and elsewhere online, I learned how to replace the thermostat housing and did so. I put in a brand new housing, and a brand new gasket underneath the housing. But it still leaks. I think the leak is coming from the two sensors that screw into the housing - I have the pre-2001 model, so it still has the ones that screw into the housing, rather than push in.

Do ya'll have any thoughts on how to fix that leak, short of replacing the thermostat housing again? Is there anywhere I can get new screw-type sensors cheap?

 

[2000StreetRod]

Coolant temperature sensors

There is an engine coolant temperature (ECT) sensor (sends data to the PCM) and an engine coolant sender (drives the temperature gauge on the instrument cluster) that screw into the housing. I assume that you used your old sensors with the new housing. There is a metal O ring that fits between the sensor and the housing to prevent leaks. Many times it stays attached to the housing when you remove the sensor. Did you install the O rings with the sensors in the new housing? I don't trust relying strictly on the O rings since I'm afraid to torque the sensors tight in the housing. I apply high temperature thread sealant to the sensor threads in addition to the O ring when installing the sensors. If the threads in the housing have not been stripped then the thread sealer and O rings should prevent the leaks.

 

[DChaput]

Ah. I honestly didn't even notice the O-rings at the time - given the corrosion on the old piece I'm sure they're still there. In the morning I'll have to pick up some thread sealant and put it and the O-rings on there. Thanks!