Cracked My LIM [Archive] - Forum


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01-16-2013, 02:41 AM
So after buying a lemon and doing a complete head gasket and UIM/LIM job, replacing the thermostat twice (failsafe wouldn't fit), and unsuccessfully trying to aim headlights only to discover they are broken I've cracked my LIM while replacing the coolant sensor where I had detected a leak. I was installing it last night and heard a loud pop and sure enough, a nice half inch crack running from the thread holes toward the thermostat cover. Why does this car hate me?

I've got a trip to make to the salvage yard, I was hoping to see if any of you would know the torque specs for the sensor? (my snapped way before even shoring up for tightening but I couldn't find it listed it the book).

01-16-2013, 03:58 AM
well you bought a lemon. theres going to be problems.

idk the TQ spec on the coolant temp sensor but i put mine in pretty tight just guessing and it did fine.

01-16-2013, 06:21 PM
There is no torque spec for that. You don't need to "shore it up" either. It's a brass NPT fitting (pipe thread) so it's not like a normal bolt. It doesn't getting tightened until it's all the way in. NPT threads are an angled pitch (sort of cone shaped) that get larger the further you turn it in. You are supposed use teflon thread sealant paste on then and just turn them in until they are tight but not "white knuckle force" tight.

Sounds like you forced it in too far to me. The further you turn it, the bigger the thread gets and the more force it will put on the outside of the hole, and eventually it will crack.

01-22-2013, 12:05 AM
You would be correct good sir. They sure don't sell idiot proof auto parts. I felt resistance while driving it but nothing overly great. Not realizing that it was a different style fitting than 99 percent of bolts/fasteners i've ever dealt with I naturally felt inclined to tighten it till it replicated the depth of the original sensor.

Its fun having to buy a part so crappily manufactured that the oe company (Pontiac/GM) doesn't even stock or sell them anymore. Found a LIM a junkyard no bigger than than a tennis court though so it's not all bad.

After pressure test, clean up and install I seem to be leak free but as with a lemon a couple new problems have now sprung up lol.

So with a new temperature sensor, which was working, the coolant temp is now flatlined and the low coolant light has come on.

I recently installed a new overflow tank for good measure and the thermostat is a month old. The heat blows nice and hot and I don't seem to be losing or mixing any fluids. Any ideas gurus?

Your 97 GT is one beautiful car btw GTR.

01-22-2013, 03:03 PM
Yeah, that engine is getting older now. It's not that it was really poorly manufactured though. There are just a lot of them out there already though, and they don't actually fail that often and need to be replaced, so it doesn't make much sense for GM to stock them forever. They are easy enough to find used, and cheaper that way anyway. :)

For your sensor problems, it could be several problems. Electrical gremlins can be hard to track down. There is an actual sensor for coolant level built into the surge tank, so that is unrelated to the coolant temp sensor issue. If there wasn't anything wrong with the old surge tank you might have been better off leaving it alone. Do you still have the old one? Try putting some water in it and plugging the level sensor harness lead into it and see if your low coolant light goes off. If it does, the problem is the switch in the new bottle. If not, you might have a bad connector, a break in the wire, or some other kind of problem with the electrical connection.

Same thing with the coolant temp sensor. The new one could be bad (rare but it happens sometimes), or could be the wrong one. Or it could be a bad plug, wire break, etc. Sometimes when those wire harnesses get old they get brittle, and too much unplugging and plugging/moving them around will cause them to fail. Only way to find the problem sometimes is to get out the multi-tester and start checking for continuity on the wires.

And btw, mine is a 2000 GT1, not a '97. ;)

01-22-2013, 06:02 PM
A firm knock on the side seems to have freed the float on the coolant level sensor. Upon closer inspection I found a nick in the wire leading to the temperature sensor. I'm hoping some klein tools and electrical tape will fix it but if not I think i can get a pigtail for pretty cheap at the local parts store.

Thanks for y'alls help :-) . My old lady greatly appreciates it, as do I since I usually am turning the wrenches lol.