defflepp1 Posted November 9, 2013 Report Share Posted November 9, 2013 i am seriously out of ideas here, i need some expert advice. i have a 1994 lumina with LQ1 i recently replaced UIM, LIM, Thermostat, CTS. after all that work i now have a coolant leak from some where. i dont really notice it on the ground, however if i drive it it will start to smoke/ steam from under the hood. the smoke/steam has a very sweet smell to it. to try and solve this i have replaced the rubber coolant hose going to the plenum, the quick disconnect for the heater line, and resealed the thermostat housing. i tried using a pressure tester but i still cant see anything. I'm just so lost right now, any help would be greatly appreciated Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted November 9, 2013 Report Share Posted November 9, 2013 Sweet smell would indicate it's burning on the exhaust... Two possibilities I can think of...the "o" ring that sits in the LIM that the plenum seals against, or possibly, though I doubt it, a coolant leak at the LIM gaskets. i am seriously out of ideas here, i need some expert advice. i have a 1994 lumina with LQ1 i recently replaced UIM, LIM, Thermostat, CTS. after all that work i now have a coolant leak from some where. i dont really notice it on the ground, however if i drive it it will start to smoke/ steam from under the hood. the smoke/steam has a very sweet smell to it. to try and solve this i have replaced the rubber coolant hose going to the plenum, the quick disconnect for the heater line, and resealed the thermostat housing. i tried using a pressure tester but i still cant see anything. I'm just so lost right now, any help would be greatly appreciated Quote Link to comment Share on other sites More sharing options...
deftonesrocker Posted November 10, 2013 Report Share Posted November 10, 2013 if you replaced the intake manifold gaskets it is possible that it may not be seated correctly. The only other thing that could be leaking other than some random hose would be the head gasket ---in my mind at least. is it correct that the car is not overheating but just smoking. how much coolant are you losing after a 1/2 hour drive? I just did the lower/upper Intake manifold, plenum, TB, gaskets and threw a K&N on my 96 GTP I used to have the same exact problem you are having. Could it be the heater pipe that goes in to the thermostat housing is not popped in all the way? Also there is another heater core hose that links up to the throttle body which then continues into the thermostat housing directly behind the pipe i just described. are those hose clamped off correctly because if it was leaking from there it would be dripping directly onto your exhuast manifold pipe. Quote Link to comment Share on other sites More sharing options...
deftonesrocker Posted November 10, 2013 Report Share Posted November 10, 2013 There is also the coolant temperature sensor on the bottom side of the intake manifold beneath the thermostat. If you took that out when you did the intake manifold gaskets you would definately need to put that teflon tape around the threads when replacing. Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted November 10, 2013 Report Share Posted November 10, 2013 (edited) I know that on a 3100 there is a coolant passage in the timing cover and mine was leaking coolant from it. You need to put a pressure gauge on your radiator cap, add pressure and then see where your leak is coming from. The more pressure you add by pumping up the gauge the more evident your coolant leak will be. Any autoparts store should rent them out and if not just go ask a neighbor with a garage, it should be a common tool in any auto repair shop and would only take up about 10 minutes of your time. Edited November 10, 2013 by rich_e777 Quote Link to comment Share on other sites More sharing options...
defflepp1 Posted November 11, 2013 Author Report Share Posted November 11, 2013 so i tried the pressure test and i couldnt see anything leaking, but the pressure was going down. so I'm really lost now, i did have one other thought though. i used to have a cadillac and the head gasket went(go figure) and heard about these sealant tabs you can add to the coolant and its suppose to stop leaks, would it be safe to use those on this? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted November 11, 2013 Report Share Posted November 11, 2013 Others might disagree, but the only thing I would recommend using those tabs for is throwing them in the trash. Often, they create far more problems than they solve. so i tried the pressure test and i couldnt see anything leaking, but the pressure was going down. so I'm really lost now, i did have one other thought though. i used to have a cadillac and the head gasket went(go figure) and heard about these sealant tabs you can add to the coolant and its suppose to stop leaks, would it be safe to use those on this? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 11, 2013 Report Share Posted November 11, 2013 so i tried the pressure test and i couldnt see anything leaking, but the pressure was going down. so I'm really lost now, i did have one other thought though. i used to have a cadillac and the head gasket went(go figure) and heard about these sealant tabs you can add to the coolant and its suppose to stop leaks, would it be safe to use those on this? Stopping seepage where usable parts are not entirely sealed by a gasket in decent condition is one thing. Sealing a leak caused by a DEFECTIVE gasket is quite another. Others might disagree, but the only thing I would recommend using those tabs for is throwing them in the trash. Often, they create far more problems than they solve. GM installed those "tabs" in millions upon millions of engines, particularly those using a mix of iron and aluminum main components. How many problems did those cause? Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted November 12, 2013 Report Share Posted November 12, 2013 Losing coolant pressure and no external leaks? Internal lower intake manifold gasket failure. Might find missing coolant hanging out with the oil. Never use any kind of stop leak on a vehicle, new gasket/seal is a sure fix, stop leak is a gamble. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted November 12, 2013 Report Share Posted November 12, 2013 (edited) Schurkey: You bring up a valid point, GM DID use those tablets on millions of NEW cars. No corrosion present. No deposits in the coolant passages. No major cracks, or coolant passages nearly plugged with rust, corrosion, and minerals. In other words, they had a consistent set of circumstances to work with, and as such, the tablets worked in a predictable manner. This is not true of old engines/cooling systems that have been in use for perhaps decades, and as such, the results of using those tablets become unpredictable, because the conditions found in each of those old systems are necessarily going to be quite different. Stopping seepage where usable parts are not entirely sealed by a gasket in decent condition is one thing. Sealing a leak caused by a DEFECTIVE gasket is quite another. GM installed those "tabs" in millions upon millions of engines, particularly those using a mix of iron and aluminum main components. How many problems did those cause? Edited November 12, 2013 by Galaxie500XL Quote Link to comment Share on other sites More sharing options...
defflepp1 Posted November 12, 2013 Author Report Share Posted November 12, 2013 ok so after further investigation i believe it is either the front head is cracked or the gasket is bad. now if circumstances were different i might have considered fixing it the right way, however, being time is a factor and the cold weather is coming i need this fixed now on the cheap. i know this is not the prefered method but, what is the best way to seal it up? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 13, 2013 Report Share Posted November 13, 2013 (edited) ok so after further investigation i believe You believe??? Either you know, or you haven't done enough investigation. it is either the front head is cracked or the gasket is bad. now if circumstances were different i might have considered fixing it the right way, however, being time is a factor and the cold weather is coming i need this fixed now on the cheap. i know this is not the prefered method but, what is the best way to seal it up? The way I see it, you have two options. 1. Shut the hood, buy another car. 2. Order a head gasket set and (maybe) a timing belt kit. $250 in parts. Another $50 to plane the heads. Take it apart, fix what's wrong. Might want to have the exhaust valves ground. I bet the intake valves, and all the valve seats, are just fine. These threads should help: http://60degreev6.com/forum/showthread.php/49657-Losing-coolant-into-2 http://60degreev6.com/forum/showthread.php/49680-1993-3-4-DOHC-quot-Lifters-quot (Optional: ) http://60degreev6.com/forum/showthread.php/49738-LQ1-Service-Bulletin-57-61-09-Lifter-tick-%28cold%29 http://60degreev6.com/forum/showthread.php/49839-3-4-VIN-X-LQ1-Engine-Block-Heater-Warning Edited November 13, 2013 by Schurkey Quote Link to comment Share on other sites More sharing options...
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