overheating issues

[ed B]

After much searching I bought a 1969 1600 from the west coast and had it shipped (from vancouver wa). Even with all my requests for info and photos it appears the owner was less than generous with the truth. It had been sitting a while, but I had the owner send me a video showing it at least ran. The body was actually in pretty good shape but it needed everything else. Before it arrived (and armed with the owners info) I thought I would have it on the road in a week. Well I have been diligently working on it (and constantly viewing this site and asking questions) since May. I replaced the convertible top and frame, fixed the all the brakes, lines and bleeders and master cylinder and then started on the electrical. I was about to give up on that until Garth helped me out a few weeks ago (I had all kinds of issues with the turn signals and flashers, battery, as well as the running lights, horn, back up lights, dash lights etc.). I still have to redo the seats and interior and some body repairs, but decided to put that off until I got it on the road. I wanted to get all the electrical issues done before I began to work on the engine.
I finally had the engine running the other day and unfortunately it smokes, so more bad news. I did a compression test, but I'll save those results for another post.

Last weekend I got up early and drove the car around my block with no plates. I just wanted to make sure the were no major issues before I brought it in for my state inspection. It seemed to run ok but I noticed the temp guage was almost pegged so I shut it down.
Today I got home from work and took the thermostat out (that I had just replaced with a new 160 degree one) and put it in a pan of boiling water and it opened right up, so at least I know that is working. I replaced it and went to start it - nothing. Not enough in the battery to start - so I guess I'm not done with my electrical as I thought (but I am at my limit of knowledge in this area, so not sure to go with this next).

I read some posts on overheating issues and I replaced the coolant with new a 50/50 mix. I also loosened the fan belt and the fan/waterpump turned easily.
I decided to try and start the car and just crack the rad cap a bit to try and get any air out. I jumped the car and got it started and ran it a few minutes. I could see the temp gauge rising again and the coolant escaping from the rad cap and I shut it down again. For the heck of it I then took off the domed cap holding the thermostat on and started it again and ran it a minute or two. I expected to see coolant coming out of the area where the thermostat was. But I saw no coolant. It was dry, just a little steam coming out and I could see the temp rising again so I shut it down - see pix below. Is this normal? Should this be dry, does not seem like it should be?!

[msampsel]

Well these cars are not the easiest to fill with coolant.

Maybe you did not get it full? This might explain the overheating issue if there is not enough coolant.
Looks like yours fills from the radiator, mine fills from the top of the thermostat housing.

Take your time filling it, I raise and lower the front end and and squeeze hoses to get the air out and it works for me.
Once your sure you got it full you can start from there. There is the burping too but I find it is not needed if you take your time filling
and raise an lower and squeeze the hoses to get the air out.

Good luck ...

[ed B]

Thanks.
Are you doing all this filling with the engine off?
Should I fill mine from the radiator or the overflow tank for both?

[msampsel]

Thanks.
Are you doing all this filling with the engine off?
Should I fill mine from the radiator or the overflow tank for both?

I do my filling with the engine off. Fill it from the radiator ... I use a floor jack to raise and lower both ends of the car too and squeeze
hoses to get all the air out of the head and block.

Overflow tank about half full but it is not where you need to get all the air out ...

[Linda]

If it sat for a long time the radiator could be blocked and need to be rodded out.
What were the compression numbers?

Linda

[ed B]

Linda,

I don't have the comp readings handy, I can post them later after work. I am not sure what rodded out means, is this something I can do or a shop? I think i will flush the entire system when I get home and then try to get it full and all the air out and see where I go from there.

[msampsel]

Linda,

I don't have the comp readings handy, I can post them later after work. I am not sure what rodded out means, is this something I can do or a shop? I think i will flush the entire system when I get home and then try to get it full and all the air out and see where I go from there.

You typically need to remove the radiator then a radiator shop can tell you if it needs rodding based on the flow.

[Linda]

It was not that easy to find a radiator shop to check and clean out my car's radiator. A lot of modern radiators are plastic.
The Champion aluminum radiators for the Datsun seem to clear up a lot of cooling issues, so, many opt for those over extensive OE repairs.
If the heater core is rusty it can also cause some flow problems.
BTDT.
Linda

[greydog]

In the old days, radiator shops removed the tanks and forced rods tru the radiator core to clean them. Then the tanks were resoldered, the fins combed to straighten them and the radiator was pressure tested.
I don''t thank many shops do that anymore as the labor would be prohibitive.
Nowadays, if the core is shot, they'll just get a new core or, in many cases, throw it away and provide a new radiator.
Dan

[bakerjf]

In the old days, radiator shops removed the tanks and forced rods tru the radiator core to clean them. Then the tanks were resoldered, the fins combed to straighten them and the radiator was pressure tested.
I don''t thank many shops do that anymore as the labor would be prohibitive.
Nowadays, if the core is shot, they'll just get a new core or, in many cases, throw it away and provide a new radiator.
Dan

I think it depends on where you live. I'm in LA, and found a shop less than 5 miles away that did all the above (about $75 two years ago). I got back a brand new-looking radiator and haven't any overheating issues.

[Datsun.David]

But to answer your question - no. It should definitely not be dry. I would fill the therm housing with 50/50 and see how much coolant it takes. Then see if you get circulation with the engine running. The water pump turns constantly so you should always have some circulation in the block, the thermostat opens the circuit to increase coolant volume and surface area (radiator).

Good luck - it will be worth the effort!

[datsun1968]

I had my 1968 1600 overheat on me on labor day. I read some posts here on it. What worked the best for me to bleed the system was to raise the front of the car. Fill the system fully and then pressurize with a cooling system tester and then loosen the heater hose clamps in the engine bay. Guaranteed there is an air pocket in the heater core.

[JDeatsch]

Hey Ed, (howdy almost neighbor),

Take a read through this that I wrote lo those many years ago. It applies to our Roadsters and most anything else.

I do hope it helps.

http://www.thebriton.com/cool.htm

[ed B]

Thanks everyone, the overheating seems to be fixed, it runs now at about 160 degrees. Have a water pump issue that i need to fix now.

Thanks.
Are you doing all this filling with the engine off?
Should I fill mine from the radiator or the overflow tank for both?

I do my filling with the engine off. Fill it from the radiator ... I use a floor jack to raise and lower both ends of the car too and squeeze
hoses to get all the air out of the head and block.

Overflow tank about half full but it is not where you need to get all the air out ...

I took the hoses off below the thermostat and filled it there first and then the radiator, and jacked it front and back and squeezed the hoses and no issues now. There must have been a large air bubble in the engine blow, but not sure why it never drew coolant from the reservoir. The reservoir stayed half full all times.

[ed B]

If it sat for a long time the radiator could be blocked and need to be rodded out.
What were the compression numbers?

Linda

I flushed out the radiator and it seems to be ok. The compression numbers were 185, 190, 190, 180 - dry and 190, 190, 195, 180, wet (respectively). So it would seem it is not the rings or valves. My brother thinks it may be the valve guides or valve guide seals, for the smoking in the exhaust. Still looking into that.