Datsun Roadster Forum-311s.org

JDeatsch wrote: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

Howdy "neighbor", good the me another New Yorker, we are only 4 hours or so away. Thanks for the helpful hints. I was glad to see I was following most of them except for using water instead of the 50/50 mix. If I read that earlier I would have saved myself some coolant

Not sure what the problem is with my water pump. Originally everything was covered with oil and antifreeze, so I cleaned up the engine and replaced the valve cover gasket, the oil pan gasket and the oil pump gasket (with a home made one). It still seemed to be leaking so took it apart again and this time used a permatex form a gasket. It was now better but still leaked, appeared to leak out of the stud at the bottom of the water pump - so took it apart again. This time I noticed that the back plate gasket (between the plate and pump) did not look too good so I took that apart and added a form a gasket to that and then added form a gasket between the plate and the engine block. Well it still leaked from that lower stud (seems to be coming out the threads at the end of stud and the nut).
You are supposed to finger tighten the bolts and then wait an hour and then fully tighten down. I thought maybe the form a gasket was not cured enough after and hour and when I tightened it up that it squeezed the material out. So, took it apart again and finger tightened it but then waited 24 hours and then fully tightened and then added the fluids again. Even not running it is still leaking from the end of that lower stud. I had even put additional form a gasket material around the base of the stud and in the recess of the hole before I assembled it. Not sure what the issue is. It is dry at the front of the pump where the bearing is and also dry where the two bolts go into it on the top. I'm stumped at this point. Anyone ever have a similar issue?

Opps I meant water pump gasket (home made one) above, not oil pump gasket...

How rusty is it? Around that bottom bolt (on the block).

You could cut a gasket out of the usual cork based gasket material which coveres the whole surface. Then permatex that spot as well when you assemble. But I would seriously consider doing it up right and helicoiling it or something along those lines. Weld it all up, then redrill retap?

Oh, so you think it is leaking directly through the block at the base of the bolt. I had not thought of that. It would explain why no matter how well I form the gasket, it still leaks.
The bolt is a little pitted at the base. What is a helicoil?

ed B wrote:Oh, so you think it is leaking directly through the block at the base of the bolt. I had not thought of that. It would explain why no matter how well I form the gasket, it still leaks.
The bolt is a little pitted at the base. What is a helicoil?

I don't know about Datsuns but some engines have studs that go through the outer surface of the block and into the water jacket, necessitating the use of thread sealer when when putting those studs in. If this is the case with this stud, simply removing it will tell you. It is possible that the hole did not originally go through to the jacket but that sometime in the past a bolt that was too long was put in the hole, opening the bottom into the jacket. You will want to replace the stud any way but while it is out you can hopefully evaluate the hole to see if it has a crack leading away from it or is just rusted. As Andy B said you may need to drill it oversized and insert a Helicoil. Helicoils are sold in kits at any place that sells any amount of fasteners or bearing and such. You first need to evaluate the condition of the hole, then settle on how big you need to drill it to. Then, you go to the store and get the kit and correct drill for it, and the new stud. If the hole goes through to the water jacket you will of course need to seal both the coil and bolt. I would use a paste type of sealer.

After taking the water pump off and reinstalling (at least 7 times), I think I finally have the stud sealed (the one that goes through the block). However it now appears the pump is leaking through the weep hole on the bottom side of the pump (under the shaft I believe). I guessing this is supposed to be open for condensation or whatever to get out, but I can see my green anti freeze coming out drop by drop. Any idea why this would be and if sealing up the hole would cause issues?

I really, really don't want to take it off again as I finally got that stud to seal....

Sorry to say ed, but your water pump seal is leaking probably because it is failing. The weep hole is so that any coolant that comes past the seal weeps out and doesnt immediately kill the bearing. A new pump is probably in order but a weep like this should not cause an immediate over heat like you are describing, but the pump willl eventually give out. I have actually had a water pump where the impellor was not turning with the shaft as the press fit had failed. Wasnt a datsun, but worth looking at.

As far as filling the coolant a 1600 can be finiky to get the air out. However from your pic this one has a 2 liter style radiator and you described a 2 liter style thermostat outlet as well. These do make a lot of those issues easier but a closed thermostat still makes the filling a slow process. I drill a small 1/8" dia hole in the plate of the Tstat to allow the air to purge easier when filling and this doesnt cause any issues with engine temp control.

If after filling carefully then knowing you have circulation of coolant and there is still an overheat condition, then I hate to tell you a leaking head gasket should be suspected. Yes, you have some good compression numbers, but it is still possible. A leak down test or a combustion gas check of the cooling system is in order to see if this is happening.

After checking every other possibility with my 1600 I finally cured the overheat with a new head gasket and all the associated stuff of a head rebuild. Mine ran well but overheated after short runs. It also had good compressions and seemed fine otherwise. I hope your issue turns out to be something more simple. Good luck.

Sometimes a retorque can help. You might want to try the tests suggested though first.
Linda

DivinDave wrote:Sorry to say ed, but your water pump seal is leaking probably because it is failing. The weep hole is so that any coolant that comes past the seal weeps out and doesnt immediately kill the bearing. A new pump is probably in order but a weep like this should not cause an immediate over heat like you are describing, but the pump willl eventually give out. I have actually had a water pump where the impellor was not turning with the shaft as the press fit had failed. Wasnt a datsun, but worth looking at.

As far as filling the coolant a 1600 can be finiky to get the air out. However from your pic this one has a 2 liter style radiator and you described a 2 liter style thermostat outlet as well. These do make a lot of those issues easier but a closed thermostat still makes the filling a slow process. I drill a small 1/8" dia hole in the plate of the Tstat to allow the air to purge easier when filling and this doesnt cause any issues with engine temp control.

If after filling carefully then knowing you have circulation of coolant and there is still an overheat condition, then I hate to tell you a leaking head gasket should be suspected. Yes, you have some good compression numbers, but it is still possible. A leak down test or a combustion gas check of the cooling system is in order to see if this is happening.

After checking every other possibility with my 1600 I finally cured the overheat with a new head gasket and all the associated stuff of a head rebuild. Mine ran well but overheated after short runs. It also had good compressions and seemed fine otherwise. I hope your issue turns out to be something more simple. Good luck.

The overheating issue turned out to just be an air pocket in the system. I found leaving the main hose coming out of the water pump disconnected when filling the radiator, until the coolant comes out (and then connecting and continuing to fill), solved my air pocket issues.

I did not know this was a 2 liter system. I have found some other changes here and there that the PO has done, that were helpful, he must have been fairly knowledge on these cars.

Thanks for the note on the condition of the water pump, but not happy with the news, oh well, onward and upward.

Very glad to hear thats all it was. Now drive that car and enjoy it.

Thanks will do!

Good news Ed! Did you ever get your inspection passed?

jheck wrote:Good news Ed! Did you ever get your inspection passed?

Thanks Jason. I did, just in time for winter to come and then took it off the road. I have a few items I want to take care of before I put it on the road again. It appears I now need to replace the water pump and I also need to replace the valve guide seals (it is burning oil in the exhaust). The compression is good so it appears the rings and valves themselves are ok. My brother is going to help me sometime to do the job. We need to add compressed air into the cylinders to prevent the valves from falling into the cylinders when we replace the guides (that way we won't have to remove the head).
I also have the center console apart to replace the radio and the heater/defroster duct as well as redoing the wiring for the map light and cigarette lighter. I think I will replace the seat covers as well as the driver's side is ripped pretty well.
I would love to paint the car sometime. When I get a chance I will try to get some advice and pointers from the folks out there on how to go about doing that.

How is your project coming?