Datsun Roadster Forum-311s.org

Couple of questions.
I want to remove the two bolts that hold the thermostat housing. But don't want to mess up my head. Any pointers?
I'm also replacing the temperature sensor. Any advice on what type of product to use so that the nut and the sensor don't get stuck like the one I just removed.

If the bolts are stuck fast and won't succumb to penetrating oil, CUT OFF THEIR HEADS

Unless you go to a mechanical gauge and appropriate sender, what you see is what you get with the temperature sender technology

The fasteners holding the t stat housing on should be studs not bolts. If you have the housing off, penetrating oil and patience. If they are bolts, sometimes tightening a bit before trying to back out works. It really is a task that sometimes doesn't end well with broken off studs, etc. Just use lots of patience, oil and time for it to work is the ticket. The last 1600 t stat housing I did ended up being cut off with a Dremel and then destroyed piece by piece to get it apart. The one before that came off intact with lots of tapping and gentle prying.

Upon reassembly of the temp guage and collar nut use some anti seize paste and that will help ensure the new one doesn't seize into the housing like the old one did. Same goes for the tstat housing onto the studs.

I made stainless studs from some bolts and used lots of anti-seize. I tried to make some studs using stainless rod but just couldn't get the die started straight. I think perhaps the material was wrong for hand cutting threads. Bought some bolts longer than needed and cut the one end off. No problem with threading it.

[I am there where I need to cut mine off, the stud seems fussed to the housing, I don’t have a dremel only an oscillating saw. Just paranoid of hitting threads or head, if anyone has any tricks or strategies to avoid this I am all ears

Treat all those bits as disposable. (the studs are done and the tower/housing too probably.)
I would cut horizontal about 15-20mm above the head to tower mating surface.
That should enable you to ease off the remaining portion relatively safely.
I don't see any way out but new bits

I now use Kroil for penetrating oil. Being a 2000 head tread carefully. $$$

Were it mine repeated doses of oil and a just enough heat not to warp things between doses. I've found a putty knife to be useful to tap in-between the two surfaces. if that works then I go to a thicker putty knife.

Have you tried loosening them with a stud removal tool, or double nutting them and using some heat, penetrating oil to break them free?

Thanks I will try to double nut it with heat. I didn’t think about pulling the stud,I was more focused on trying to get the housing to slide off the studs like the thermostat housing did.
I have a new temp sensor housing so don’t mind that getting hacked just was scared about damaging the studs and obviously the head. Are the studs easily sourced?

Side note looks like my engine issue(s) are more the rings and maybe less the valves. I did manage a smokey 200 miles this weekend going up to SF to have Mike Young give it a once over. Had a nice rip down skyline on the way back and ran into an old friend in Pescadero at my favorite bread stop. He knew Duncan whose car it was so it was a nice reunion. I will update and thanks all for the tips.

It's one of those locations where you go in expecting that something will probably go wrong, lol.
I mean, we're dealing with two different metal types, countless heat cycles, coolant leaks, etc. So, lots of penetrating fluid multiple times and praying for the best.

We got one out, but the second one wasn’t so lucky.


we started by drilling trough the stud to remove some pressure


then welded a nut to gain leverage to get it out



All done and new studs in

Nice illustration and pics. I do believe the middle section is installed upside down though. Mine always had the sender on the bottom and pointed towards the firewall. I did drill and tap the other end for my GM temp sensor for the EFI... worked great.

Regarding ol smokey, what was the compression? Did you/he do a leak down test? I've been reading really great results in modern cars using Valvoline Restore and Protect oil to free sticking rings and slowly remove sludge/build-up. May be a completely unrelated issue resulting from direct injection fuel systems, but you have nothing to lose. You may also try Ametech- Restore Engine Restorer & Lubricant... I've seen some before and afters with this stuff (I THINK Project Farm on YouTube tested it on his own high mileage rig) and it helped... improved compression and reduced oil consumption on his farm tractor. Might keep you happy enough until you're ready to tear into it. Here's the link, assuming I did it right... maybe you can do your own before and after video...

https://www.google.com/url?sa=t&source= ... pUat1KKsKr

I got one of those $150 amazon induction heaters to get off broken studs from a couple 1600's I had. Wasn't sure if it would be worth it, but the amount of rusty / nasty bolts on these old cars... That + vice grips as low on the stud as you can, less likely to shear and also preserves the threads if you want to double nut them. Probably paid for itself on the second stud via the headache that would have occurred if it hadn't worked. I'm really surprised how well it heats, its the first thing I grab after letting a stud soak in penetrant. Plus, if it doesn't work (try heating it again for several more ~8-10 sec intervals) you can then move on to the scary drilling knowing even a torch would have found it hard to pull

Welcome vckstrm, we appreciate your input and experience!

I don't think you mentioned what kind of heat your applying, but if it's a torch, you might try a Harbor Freight or similar brand heat gun, to provide controlled and even heating, all around the housing, while tapping on it from all sides, and also using the tightening technique. It worked for me....YMMV.
Mike