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We've got a 1990 GTZ with a quad 4.  It is leaking antifreeze under what looks like what you would say the maft or map sensor or whatever you call it.  The small line that comes out of the thermostat housing that goes into the what looks like a black plastic connection underneath that sensor where the line goes into the black plastic is leaking out of there pretty steady.  I went ahead and replaced the thermostat thinking it was sticking, but it still leaks.  What is the black plastic thing underneath that sensor and what do I need to replace to get rid of the leak?  


Thanks for your help.

1990QuadGTZ

Hey, I'd appreciate any help on this leak problem......
that sensor I'm talking about is where the hose connects when it comes out of the air box with the air filter in it.  It has some electrical connections to it.  That black plastic on the bottom of it looks like an elbow that has that antifreeze line that comes from the thermostat cover to it.  That's where it's leaking.  Maybe the sensor is the wrong term on the quad four.  It's probably the throttle body.  I'd appreciate any help tracking this down or finding out what that is or how to get it to stop leaking.

Thanks alot.

1990quadgtz

Would you be able to post a picture or maybe edit a picture of a Quad 4?  I can't seem to find any good pictures of this area (and my Quad's currently in storage).  The thermostat housing is on the side of the engine, and the throttlebody is on the front corner (where the airbox hose enters).  The MAP sensor is center-front of the engine on the intake manifold.

Ok here is my best guess without pictures and you giving names to items that are incorrect.

I'm going to guess that these metal lines that are leaking are under the throttle body.  The 93-94 engines did not even have them and many of us took them off the older cars and capped off the holes near the thermostat with pipe plugs of the correct size.

If you want to fix them the lines have rubber o-rings on them where they insert into the throttlebody.

thanks, i just got home from work and saw your post...if i block it off will it effect the running of it. and what about the place where it goes in under throttlebody... leave it alone.... what was it for??

         thanks alot          1990quadgtz

hey, still need help.. i plugged the place where the tube came out of the thermostate housing but i took the tube all the way out and antifreeze is pouring  from under the throttlebody from the black plasticthing where the tube went.... how do i stop it and what was it for..


                  thanks.....1990 quadgtz

There are two lines.  You need to remove both and block them off at the Thermostat housing.  One may come from the back of the block.

If these are 1/2 inch rubber hoses, then you are messing with heater hoses and not the TB lines.  The TB lines are small steel lines.

The TB heat was to keep the TB from icing up under extreme conditions.  I guess GM decided they were not necessary and removed them.

hey i got your post on friday am. that fixed it. i thank you alot for your help...

                                               thanks   1990 quadgtz

What a idea gm had a???   something abought warming the tb would warm the air gowing in to the engine making it run better better fuel combustion  or some crap.
though air planes with carbs do have heaters in them so they dont freeze up..

Mr Goodwrench

It would also increase NOX emissions on an engine that does not have EGR, so perhaps that is why they removed the lines on the newer engines.

I have never heard on any quad4 with a TB icing problem anywhere.  There is no vaporizing liquid near the TB like a TB injection or carb.  Yes it could be possible under EXTREME conditions, but again, I've never heard of it happening to one of these cars in over 15 year.