Cooling Problem

[SolarSteve]

After swapping out the head on my 1.6 N/A and hooking up all the conections, I began to refill the cooling system.  I pulled the top radiator hose off and poured coolant in there until it was just about full and re-installed the hose.  I also filled the expansion bottle.  I took the car for a short drive and it quickly needed to be shut down due to nearly overheating.  I shut down, let it cool enough to be in the safe zone, re-started and tried to get home stopping and cooling down 1 more time.  During this time my V/C was leaking so I parked the car in the garage and went to work.

Last night I replaced the V/C gasket and topped off the expansion bottle (cold engine) and went for a drive.  I was able to go further than last time, but the needle, which normal sits at center for normal operating temps, was heading for the next line hotter.  It past that line and was approaching the last line when I got back home and shut it off.

I got up this morning checked the expansion bottle, it did not need any coolant and I went for a drive.  I have a Frybrid system that taps off of the coolant system for heat.  It comes from the hose off of the side of the head, goes through the Frybrid system then enters the heater core and then back to the engine through the normal return for the heater core.  During this drive I was able to switch over to VO.  This told me that the air was purged out of that part of the system.  Also the heat exchangers and hoses for the Frybrid were hot.  However the temp slowly but surley kept climbing.  By the time I got into town I had to shut down to cool off.  Had to stop twice more on the way home as well.  I had the fan on the entire time too.

When I got home, I checked the hoses.  The top radiator hose was very hot but the lower radiator hose was not.  I could keep my hand on it.  I figured the brand new thermostat that I installed during the head swap must not be opening.  So I removed it and installed my old t-stat.  Now I am back to trying to get all of the coolant back into the engine.  I collected everything that came out when I opened the system and after filling the bottle (I did not pull the radiator hose and fill it this time) and running the engine until it reached the first line after normal operating temp I shut the engine off.  It took some more coolant from the bottle but not enough to refill it and I did not open the bottle.  I still have about 1/3 to 1/2 of the coolant that I collected that still needs to go back in.

Tonight when I get home I will check the bottle to see if it needs more, but I can't help wondering what is the best way to get coolant back into this car?

Also, I don't really understand what went on with the drive into town.  I would have thought that while I was driving the 10 miles or so that it would have been regulating the temp and that if the T-stat was not opening I would have had to stop much earlier...

Any help would really be appreciated.  If you need more info, let me know.

Thanks

[8v-of-fury]

Best way to add coolant IMO is to fill it by the expansion bottle, and after it tops off run it without the cap on until running temp, filling it up as needed. The water pump should aid in pushing any bubbles out of the system. The expansion bottle is the top of the system.. so air should naturally rise to that part.

Good luck hope you fixed it.

[maxfax]

I pretty much do the same thing 8V menationed..    Pouring the coolant in the bottle will fill the engine but not necessarily the radiator.. After it's started I raise the idle (to about 1500 ish) and just keep topping the bottle till it takes no more, and there is a steady stream of coolant squirting out of the small return line to the bottle...

I also have the extra plumbing of heat exchangers and tank heater so the higher idle helps get the coolant pumped through...    I did recently (this past winter) as an aux electric water pump in the lines to the WVO tank heater and heat exchangers..   At idle the coolant didn;t flow real fast, heat would suck and the exchangers woudl start to cool down..    With the aux pump I don;t even have to raise the idle anymore when filling...

[SolarSteve]

OK thanks.  Tonight I will remove the cap, top it off and start it and continue to fill as needed.

Also, there is a plastic piece on the front drivers side of the head that 2 coolant lines hook up to.  It has 2 electrical connection for temp sensors.  Both have 2 wires, 1 has a tan wire and a yellow wire with a red trace and the other has a tan wire and a blue wire with a red trace.  Does it matter where these go?  I know 1 of them controls the temp gauge but it funtions on both places.

Thanks

[92EcoDiesel Jetta]

If your temp gauge moves normally, it is connected to the right sender, if they were swapped, the gauge won't move correctly. The other sender controls the glow plug relay. The color code for the wires is in the Bently if you want to double check. Cold lower rad hose is not normal. Possible causes are: air, T-stat not opening, blockage in radiator. You are having some strange problems dude- first, disappearing oil, now coolant. Why did you not also fill it from the upper radiator hose the last time? That is a known good way to fill the system in conjunction with filling from the exp tank. Did you get the cyl head pressure tested?

[SolarSteve]

When I got home last night I opened the expansion bottle and the coolant in it got sucked into the motor and I re-filled the bottle.  Next I squeezed the top radiator hose and it felt empty so I removed it from the rad and it was empty.  I filled the head/block from that hose and used a spare hose to fill the rad.  Between the 2 it took a little over a gallon.  Next I left the cap off the bottle and started the engine.  Once it got close to operating temp I kept a close eye on the coolant in the bottle.  I got some bubbles out and as I revved it, the coolant went down and when I let off the coolant rose.  I yo-yo'ed it for a while and got more bubbles out and squeeezed hoses.  I had to rev it to get the fluid level down and I installed the cap.  When I let off it overflowed a little, but that's ok.  I took it out for a drive and nearby is a mountain that the hightway goes over.  I drove up, down and back over it again with the needle just a smidge over halfway!

This morning I checked the bottle again and it took a little more and this afternoon I drove it the 40 miles to work at 70 MPH no problems!

The disappearing oil thing has completely blown my mind.  I have done head swaps before and I have never seen this.  I had to run the engine 5 times for a bout 5 minutes each time before I ever got any oil on the stick and that was pretty scary, but I knew I had plenty of oil in it.  When I finally did get oil on the stick I had to drain at least 3 quarts to get it down to the proper level.

I needed to get his car going again and I did not have access to the tools to pressure test the head, so no, I did not pressure test it, nor did I perform a compression test.  The car is running fine now, or at least as well as it was before I pulled the head.  The problems with the coolant were all due to air trapped in the system and I now know how to fix that.

I consider myself pretty lucky that during the times I drove the car to try to get the air out of the cooling system that I did not damage anything.  I always shut it off before it got too hot, but without the proper amount of coolant I realize that it could have been hotter in other areas of the motor than where the sensor is...

Thank you all for your help.

[92EcoDiesel Jetta]

..................
The disappearing oil thing has completely blown my mind.  I have done head swaps before and I have never seen this.  I had to run the engine 5 times for a bout 5 minutes each time before I ever got any oil on the stick and that was pretty scary, but I knew I had plenty of oil in it.  When I finally did get oil on the stick I had to drain at least 3 quarts to get it down to the proper level...............

Is it possible you left the dipstick tube mounting nut off of the IP mount bracket and the tube got pulled up which gave you a false reading?

[SolarSteve]

Nope.  I never removed it.

[SolarSteve]

If your temp gauge moves normally, it is connected to the right sender, if they were swapped, the gauge won't move correctly. The other sender controls the glow plug relay. The color code for the wires is in the Bently if you want to double check.

I put the connetors in both locations and the gauge seems to operate normally in both.  I have been pretty busy lately and have not had time to get into the book.  If you know which goes where could you please let me know?

Thanks

[92EcoDiesel Jetta]

Yours may be different. On mine the red and yel wire connector goes to the temp sender at 12 o'clock on the flange, the blue and white wire connector goes to the sender at 3 o'clock (for the glow plug relay). If they operate the same on either sender, then it is possible that both senders are the same  but afaik they are different, so one of the senders may be the wrong one.

[SolarSteve]

Thank you.

I don't know off hand how I have them right now.  When I get a chance, in a few houors, I will go see how I have it and change it if it is necessary.

Since I got the car going again, the temp needle sits about 1 needles width hotter than it used to.  I think I have all of the air out of the system, but once the engine is stone cold I will check the bottle again.

92, didn't your needle ride a little high at normal operating temps?  Did you do something to get it to drop down a little?

Thanks

[92EcoDiesel Jetta]

1 needle width is not much and may be due to a new T-stat, higher ambient temp, or timing. If I swap the connectors my temp gauge barely moves when it's hot. That's because the resistance reading of the temp sender is more than 10 times lower than glow plug relay sender.

 When my engine was running hot (about 25F higher than normal),. it was due to a T-stat that was 98% stuck closed..

[SolarSteve]

I took a look and I have the connectors on as you do.

I'm not too concerned about the slight rise in temp but it ALWAYS rode right in the middle so this just happen to catch my eye.  It has been about 3 weeks since I drove the car and since I did major work to it I have been overly cautious of the gauges.

Thanks again.