I need a new thermostat housing.

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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I need a new thermostat housing.


Post by indogwetrust88 »

Hello, everyone.

So, I have a 81 Datsun 720 diesel that I went to replace the thermostat on the other day, and in doing so the bolt holding it's top part (the dome shaped piece where the thermostat is held) snapped off inside the aluminum cast below.

I went and got an ez-out and commenced drilling a pilot hole for it and as I was cranking on it the ez-out snapped off in the bolt. I'm kinda screwed here... I cut the bolt with a dremel, filed it flat, and used a center punch to start a new pilot hole. And low and behold, I hit a piece of the remaining ez-out that I couldn't see and now I have no bolt to work with. And the drill bit I currently have wont drill through the ez-out's hardened steel.

Does anybody have a full thermostat housing set up they could sell me or any bright ideas? I need to leave Georgia for a farm job up north soon and I'm stranded.
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Re: I need a new thermostat housing.


Post by scrapman1077 »

I have a spare parts engine, I will try to remove the housing tomorrow and post again.
Posts: 869
Joined: 13 years ago
Location: Cochrane Alberta Canada

Re: I need a new thermostat housing.


Post by plenzen »

A bit late to this party but sometimes if you can get a torch on the bolt itself and heat it up, just concentrate the flame on the bolt and not the housing and then get a bit of a twist on it you can get them out.
Be careful with Oxy/Acet as you don't want to melt the aluminium.
I have had some pretty good luck with propane torch.
The "dissimilar" metals thing is whats seizing it in there. The heat will help.
You may have gone too far at this point but if you can get a little edge sticking up where you can tap at it with a small sharp chisel you may get lucky.
I usually try and get the tip of the blue cone in a propane torch just touching the broken part of the bolt.

If using oxy/acet then small tip and same thing but don't stay too long. Propane is a bit safer if it's your first time.

Good luck.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
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