Datsun Roadster Forum-311s.org

Me again with another issue.

While checking things on my 69 1600 I found that the coolant reserve tank was empty! (Luckily I haven't driven the car very much since I got it)

I also found that the passenger floor mat was SOAKED with coolant

I cleaned up the passenger side, bought some new coolant, and filled up the tank. I drove it around the block and sure enough I see a drip coming from the wiring on the right side. Here's some photos and I've circled where the drip was coming from: https://imgur.com/a/1JsdOQX

I found this post in a thread that is basically the same symptoms as what I'm seeing, and specifically some info about the brass switch after the second carb that I can use to bypass the heater: viewtopic.php?p=254954#p254954

Since I'm in California and plan to only drive this with the top off it doesn't matter much to me if the heat in the cabin works or not.

However, just like that thread says the valve is not wanting to turn at all.

Does anyone have tips on how to get that valve to turn? Is there anything else I can do to try and stop the leak inside the cabin?

I talked to the shop (Dando's in Freemont) that has done work on the car over the past couple years as it was in fact just in for service on the cooling system where the thermostat was replaced so I'm not really sure how this leak was missed as I have to imagine the system doesn't hold pressure very well... But they said they don't have an opening until October... I'm waiting for a callback from the owner to discuss it more but would but am open to and interested in fixing this myself if possible.

Thanks.

if you can tap on the end of the valve shaft opposite the handle, you might be able to get it free. I don’t remember if turning the valve will totally bypass the heater core, or just keep water from flowing through it who’ll still having it pressurized. Best bet is to disconnect both hoses from the core & temperature control valve & loop the lines back.

Peace, Pat

Ah! The loop back sounds like a good plan and within my skill set.



My assumption is that the hose on the top is the supply and the hose with the braided cover is the return. Is that correct?

Should I drain the coolant system first? I don't have a sense of how much pressure will be in the lines if the engine hasn't been running... I am wondering if I can: take the pressure cap off of the coolant reserve tank, remove the supply line and keep it elevated as much as possible, use a hand pump to force the fluid through the return line, then remove the return line and finally attach a new hose to make it a loop.

I assume that the best bet will be to buy a new piece of hose. Pardon my newbie-ness, but what is the type of hose I should be buying? Is there a special name/type of the clamps used to attach it?

Really appreciate all the help so far!

Just take off the overflow tank cap, then put it back on. That will release any pressure. Then by putting it back on before removing the hoses there will will be less coolant coming out in comparison to leaving the cap off.

I made the same decision to completely remove my heater system when I lived in So Cal. Core was bad. I now miss it in WA State but use the space for the core under the dash for other things I've done. I now use seat warmers and they help a lot when my wife gets chilly. You should be able to get the whole system out of the loop by locating and looping the in and out lines at the firewall.

Gregs672000 wrote: Tue Aug 08, 2023 11:37 am You should be able to get the whole system out of the loop by locating and looping the in and out lines at the firewall.

Thanks for chiming in, Greg! Do you mean creating the loop on the cabin side of the firewall?

Hard to say what will be the best and easier way to reroute the water... it's been like 30 years since I deleted mine, and mine is an early car. It's gonna take some digging I'm sure...

Oh wait... is the valve you're talking about the one in the engine bay? If you're able to get that one moving I think it cuts off water to the heater core... vise grips might give you a bite. Someone with more recent experience may need to chime in here... Otherwise I think you'll have to remove the heater core.

Success!

Bought a new 2 foot length of heater tube from auto zone. Disconnected the hoses going to and from the cabin and replaced it with the new hose. I had a little leak at first since I didn’t tighten the clamps enough. After a few more turns off the ratchet my little cruise around the block yielded no more leaks. I’ll take it for a longer drive tomorrow and see how it holds up but it’s looking good so far.

Thanks for all the input and suggestions!

Yeah! If you have mats they may need some washing as coolant doesn't evaporate like water.

Drove to and from work today (about 12 miles total) and the loop to bypass the heating block is working great!

Thanks for the note about cleaning the mats. I did a pretty decent job when I first pulled the mat from the passenger side but I should double check before I put it back in. I should also do some cleanup on the fabric that I can't remove from the car...