Datsun Roadster Forum-311s.org

Hi Everyone! I just bought my first Datsun roadster a few days ago! A 68 SPL311. Its very nice looking, new paint, rims, etc.. but it has some issues! It overheats very quickly! I keep adding more water/coolant to the overflow tank but, it keeps dissapearing! I've check for leaks from the hoses and or radiator and I can't find any! I can't figure out where all the water is going! I was going to take out the thermostat to see if its stuck but, HOW DO YOU GET THAT "BOX" OFF where the thermostat goes? I took the nuts off the top but, can't break it lose where the gasket is at the bottom! I don't want to break the box so, not sure how to get it lose?? CAN ANYONE GIVE ME A TIP HOW TO BREAK THAT BOX LOSE? THANKS SO MUCH! P.S. I'M IN FLORIDA SO I THINK I COULD RUN IT WITH NO THERMOSTAT, ITS ALWAYS SO HOT HERE!

Coolant has to be going somewhere, either leaking or going through the head gasket. Any steam or smoke from the tailpipe? Total capacity is 8 qts, If you added more than that, you have issues and need to get a cooling system tester.
You need a thermostat, it will overheat on the highway without it. Get a 160 or 180.
If you were to search Thermostat stuck, you would find most of this. this one prety much covers it. The desperation drill method is on page 2. If you're careful, you can save the housing, if not, they are available. You DON"T want to snap the stud off if at all possible, it's most likely corroded and stuck to the inside of the aluminum tower, not the threads in the head. Time and penetrant and patience..
http://www.311s.org/phpBB3/viewtopic.php?f=3&t=12383

First,
You fill a 1600 on the engine normally through a cap that is on top of that box.

The over flow just keeps it full by allowing the expanded water to be sucked back when the engine cools.

You need to burp the air from system.

If you can not fill the system at the highest point (on the engine) you can fill the over flow and the compress the lower radiator (engine off of course) and you should hear some bubbling. Keep repeating this until you do not hear any bubbling (keep the over flow 1/2-3/4 full during this operation)

It most likely will take 20-30 minutes....

Welcome! I hate to say it, but you likely have a head gasket leak... that is where the coolant is going. Smell your exhaust, or pull the plugs and look for the super clean one, or the one that looks different and you will likely find your leak. The exhaust may be white in color, or will smell like burned coolant assuming you're running antifreeze. Or, you can go to your local autoparts store and rent their tester that will sniff your radiator coolant for exhaust. You have to buy the chemical to test it, but it's not expensive.

Regarding "the box" be very very careful. The studs have bonded to the body of the box and it will likely take a lot of patience, penetrating oil and/or a propane torch to get it to come off w/o breaking it, and you really don't want to do that. Others who have been through this will chime in I'm sure. I would not mess with it at this point until you find out where the coolant is going and get the head gasket done or do it yourself if able.

I am facing a coolant leak at this moment. I recommend going to Advance auto parts and rent a coolant system pressure tester and a compression tester. this will tell you a lot. you don't want to end up like this other guy... http://www.311s.org/phpBB3/viewtopic.ph ... ak#p100447" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;.

Thanks for the the tips everyone. I spent a good 4 hours or so on it today and was not able to break the box free! Very frustrating! Used PB blaster, etc.. but, although I could get it to wiggle on one side (could see movement between the bolt and the body of the box), the other side just won't budge. Banged on it with a rubber mallet, smacked it with a block of wood, etc.. How much does a new one cost (I'm losing hope that I'll be able to get this one off with out destroying it) and WHERE can I order one? I've heard of Datsunparts.com in Ca. but, is there anywhere else to purchase stuff like this from?
The motor seems to sound good, other than the overheating issue. I'm hoping that it is just a sticky thermostat and possibly a dirty, clogged up radiator.

If you wait overnight, the penetrant might work Light taps with a metal hammer on the tower can jar things loose. If you can double nut the looser stud and remove it, it will let you move the tower a bit left and right. The drill method in the other post does work, if you're careful and drill where the housing is thick and keep it close to the stud, the tower can be re-used. They aren't cheap, one site lists $150.00+, so worth trying to save it.

Welcome cocoaed. Where in FL are you?

Dave, Do they sell the top of the box separately? The part that the radiator cap attaches to? I think I've already ruined that part. It was very corroded anyway. Hopefully I can save the box.
--Ed

You could put a post in the Wanted section, And try the vendors, some list the partsm, others may have them in a it. Worth calling around.
Verndors http://www.311s.org/vendors.html
Dann http://datsunroadster.com/SUB_SECTION_D ... ooling.htm
Dean http://www.datsunparts.com/Cooling
Ross http://www.sportsimports.ca/

Welcome Cocoaed -
All the advice above is sound. Time and patience will save you a lot of money - if you can get it off cleanly yourself.. Check with Ross at Sports Imports for used parts, and if you go to the vendor links section there are a few other well recommended places to try as well.

RobertAuclair wrote:Welcome cocoaed. Where in FL are you?

Thanks everyone for the advise. Robert, I'm in the Cocoa Beach, FL area, near Cape Canaveral.
I sure hope its not a head gasket leak! That would be beyond my abilities and tools, etc.. In my area it would probably run over $1,000 to have a new head gasket put on, head milled, etc... I did check the plugs and they all look the same, pretty black and a dry soot. I think the seller (on ebay) knew it had issues but, is pretending he had no idea. So tired of dishonest sellers. I couldn't a SPL311 locally so I had to go with this one, sight unseen, just based on the pics and description. Then pay to have it shipped all the way from WI to FL only to find this overheating issue within the first few minutes of owning it. ARGG!

Thanks everyone for the advise. I sure hope its not a head gasket leak! That would be beyond my abilities and tools, etc.. In my area it would probably run over $1,000 to have a new head gasket put on, head milled, etc... I did check the plugs and they all look the same, pretty black and a dry soot. I think the seller (on ebay) knew it had issues but, is pretending he had no idea. So tired of dishonest sellers. I couldn't a SPL311 locally so I had to go with this one, sight unseen, just based on the pics and description. Then pay to have it shipped all the way from WI to FL only to find this overheating issue within the first few minutes of owning it. ARGG!

cocoaed wrote: P.S. I'M IN FLORIDA SO I THINK I COULD RUN IT WITH NO THERMOSTAT, ITS ALWAYS SO HOT HERE!

Once you get to the thermostat, I would not remove it and then run without it. I am far from an expert but believe if you run w/out the thermostat, the coolant is allowed to free flow through the system and thus does not spend enough time in the radiator to dissipate its heat out of the system.

We get pretty hot here at times in WI (not like in FL). I run a 160 degree thermostat and my temp gauge, which works fine, very rarely goes above that mark.

tim

A head gasket on a 1600 is not very hard - and actually not too expensive.
If you have basic tools, and a torque wrench, it can be done! The machining, if required, shouldn't be too bad.
Don't panic yet, get the thermostat housing squared away first. Run a compression check, and if possible a leak-down test, and finally borrow the tool from advance and do a radiator pressure check.
Hopefully a thermostat and radiator cleaning will be all you need.