Coolant leaking at plenum

[project 92z]

I had been smelling burning coolant when I parked and thought maybe it was from a pin hole in a hose or maybe a loose clamp until I pulled up at work today. It looked like my Z34 was breathing fire through the nostrils in the hood. After checking, I found that where the plenum O-ring is was leaking. I bought a new gasket set tonight and plan to replace it tomorrow but had a couple of questions. Do I need any gasket sealant? If I remember correctly, there is a stripped plenum bolt- perhaps on that side. Can I replace that bolt with a larger bolt in order to torque it down? Any other tips out there on doing it, (engine temp, special tools or procedures) Any help would be a big help....

[pocket-rocket]

Those bolts are kind of special bolts. I would helicoil the stripped hole.

I would also get a replacement piece of heater hose for that coolant line that plugs onto the nipple on the bottom of the throttle body. That thing likes to be a bear to come off if it hasn't been removed for a ling time.

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[project 92z]

OK, helicoil it is. Any idea what size that bolt is? Before I pull it apart, I wanna make sure I have everything and I'm not sure if my local O'Reilly's carries them in all sizes.

Also do you mean I should extend that nipple with hose or is there some hose inside the LIM that may be corroded or damaged?

[pocket-rocket]

M8 x 1.25

This is the hose I'm talking about. Unless it's been pulled apart recently it will not come off quietly. I usually just cut it between the nipple and the coolant tube to save some effort and plan on replacing it if the UIM has not been pulled off in a while. Sometimes a store will give you the section free because you don't need a full foot section and they charge by the foot. I also noticed you asked on engine conditions for doing this and all I can say when it comes to aluminum top ends, do this with the engine as cool as you can. If you can do this after it sits overnight before you go out for the day, all the better. Now if you have to move it first thing in the AM to do it, that's fine, but don't do it first thing when you get home from work or you will use up all the helicoils in the package.



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[project 92z]

Thanks for all the help! It took a few hours and a bucket of sweat but it's done. It must have been leaking coolant for a while. It had gooped and jellied all around that O-ring and the #3 cylinder. FUN FUN FUN. Again thanks. 50 bucks I had planned on using to change tranny fluid though....