JDBob62

Today I put some fire to the ol' gal after a long winter hibernation and some needed work. Among the work done was rebuilding the water pump, cleaning, flushing and pressure testing the radiator. Block was NOT drained of coolant below the lowest inlet/outlet to the water pump.

Prior to starting today I had done the following:

1. Double checked position of all 4 water pump gaskets. (Block to engine mount and engine mount to water pump)
2. Added coolant through top radiator hose into radiator until coolant ran out thermostat housing. (Top 20% of radiator is above the thermostat housing and since liquid will find its own level, runs out of thermostat housing before radiator is full.
3. Mounted top radiator hose to thermostat housing and added more coolant hoping to fill the radiator. I got a little trickle of coolant out the radiator and connected the hose.
4. Added coolant to expansion tank up to 1/2 full.

Within 1 to 2 minutes of starting and letting engine only idle, temp gauge is reading 220+ and I shut it down.

Coolant in expansion tank is same level, at room tempature and no pressure build up.

Radiator is room temp.

Top of engine is only warm to touch. No where close to causing a burn on hand.

When I squeeze the top hose between the radiator and thermostat housing, I do not hear any sloushing or gurgalling of coolant.

Questions:

1. What is the proper procedue to fill cooling system?

2. How do I test the water pump to insure that it is pumping and not blocked?

3. Do I have to open the heater valve?

4. Should the coolant completely fill the radiator?

5. If cooling system is a closed loop system should there be any air in the system? If answer is NO, where do I bleed off the air


Thanks for all your help

Please remember to say THANK YOU to a uniformed veteran

Bob

Plasticman

Bob,

Running 1-2 minutes at idle will not cause it to reach 220 F in that short period of time. Recommend you get an infared temp "gun", and measure actual temperature at the thermostat housing and elsewhere (heads, intake, etc.).

My thoughts are that you have a faulty gauge or sender. Especially since you say the top of the engine only feels "warm".

1/2 filled in the expansion tank is correct, and I don't see anything else in your post that raises a red flag. It does not hurt to open the heater valve to circulate the coolant.

I am assuming you installed the thermostat with the thermo "pellet" facing down, and the valve facing up.

Plasticman

Frankie the Fink

Not to step on Plasticman's response but I just found this little treatise on temp sending units: http://www.corvettespecialtiesofmd.com/faq/faq1.html

The interesting part is that they claim to sell 'calibrated' units for our vettes (expensive, but then I haven't seen the 'calibrated' claim before)...

JDBob62

Thanks to both for input.

Prior to putting the original sending unit back in I used teflon sealant tape on the threads to insure no leaks. Since the metal to metal contact between the sending unit and block is part of the electrical circuit, could the teflon tape cause a weak connection?

I will check the installation of the thermostat. I am not sure I understand the term 'pellet'. As I recall the coil spring extends farther to one side than the other. Should the spring side be down into the manifold or up towards the upper radiator hose?

Finally, is there some way to check pumping action of the water pump, short of pulling a hose and turing engine over with starter to see flow.

Thanks again.

Bob

Plasticman

Yes, I have heard of the teflon tape causing that type of issue. I never use the tape, but prefer the teflon paste for automotive pipe fitting applications.

The "pellet" is the thermostat portion that probably has the temp stamped on it. It is the portion of the thermostat that senses the temperature of the coolant and expands to open the valve. Most thermostats I have seen have a "hoop" over the valve, and that should be pointing up, and the coil facing downward.

Take a look at the below website. All the thermostats are pointing up (as they should be installed): http://www.summitracing.com/search/?...ermostat&dds=1

For testing the pump, remove the thermostat temporarily (and reinstall the housing) and feel the flow through the radiator hoses (when the engine is running).
Make sure you put the thermostat back in later!

Plasticman

1snake

Teflon tape will cause the gauge to read low or not at all but it won't cause it to read high.
The sending unit referenced above has been reported by others to be no more accurate than any others that are available. Several people(myself included) have had good luck with a Wells TU-5 sending unit and they are only $5 at your local AutoZone parts store.
To facilitate filling, drill a 1/8" hole in the outside rim of the thermostat.

Jim

Frankie the Fink

The write-up for this 'calibrated' temp sending unit sounded a little pretentious...

Yes, the Wells item is oft quoted here as being as good as it gets, commonly available and cheap...

I never put ANYthing on the threads of a temp sending unit. The connection is part of the electrical circuit needed for proper operation.

I am also mystified by all the trapped air, air bubbles and other problems cited in, filling coolant systems. I've never done anything special on the dozens of cars I've owned and never had a problem. A bucket or so of distilled water/anti-freeze mix through the cap opening and I'm back on the road.

Plasticman

Frank,

I also have never had to do anything "special" in filling the anti-freeze mix on most vehicles. Like I said earlier, it does not hurt to open the heater valve, but that is it.

Now the 87 Vette I had, was "special", but still was not a big issue if you followed the directions in the manual: Fast idle with the cap off, watch for the thermostat to open when the coolant level in the radiator dropped all of a sudden, top off the radiator immediately, put the cap back on, and fill the expansion tank to the cold fill line.

Plasticman

JDBob62

Thanks to all. I removed the thermostat and reinstalled. There was an arrow on the side indicating direction towards the radiator. This is a stock radiator (flat top) and no cap on the core. I refilled through the top hose into thermostat housing, letting it drain down into block until I had a trickle out the top radiator outlet (highest point in system). Upon starting engine and ideling for 2 or 3 minutes, temp was back up to 220+ and heading to 240.

I did NOT replace the sending unit. I will get a new one tomorrow and install without tape but using the white teflon paste.

I'll report back on Friday.

Thanks again,

Bob