Galaxie500XL Posted January 20, 2010 Report Share Posted January 20, 2010 I have a '95 Cutlass convertible with the DOHC 3.4...I noticed the "low coolant" light was on a couple of days ago, found the overflow empty, and the radiator about a half inch low. The "low coolant" light kept coming on, at odd times, particularly at closed throttle deceleration. I just came home from work, all seemed normal enough except for the "low coolant" light. I waited for the car to cool, then checked the coolant level. It looked normal, but I started smelling antifreeze. I couldn't find any on the ground, but shined my flashlight under the throttle body, and looked under the plenum. Looks like I'm loosing antifreeze from somewhere, and it's collecting in the valley area under the plenum. A couple of questions: Is this likely a lower intake manifold gasket failure, or do I need to look somewhere else for the source of the leak? I'm fairly experienced in working on cars, but have never disassembled an LQ1...how much time should the job take, and what besides the intake manifold gasket should I plan on having on hand? I'm going on a business trip Sunday, and need to know if I can likely fix the problem before I leave, since the wife will want to drive the car while I'm gone. Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted January 20, 2010 Report Share Posted January 20, 2010 That definitely sounds like your LIM is shot. In all honesty it is not a bad job. There are a few excellent write ups on here on how to do it but in a nutshell once you remove the upper intake your job is easy. Expect to spend about 3-4 hours doing it if it is your first time doing it. Good luck to you, but it isn't really all that bad. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 20, 2010 Author Report Share Posted January 20, 2010 I found one of the stickys...it doesn't look too bad. It's leaked enough that antifreeze is sitting in the depression in the oil pump drive. I'm debating whether the car needs to sit in the driveway until I address the leak...the last thing I'd want is a catastrophic failure of the gasket, and a fried LQ1... Thanks for the info! Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 20, 2010 Author Report Share Posted January 20, 2010 A quick question; Saw a pic of the LIM gasket, I'm fairly sure it is designed that gasket sealer is NOT to be used... But what about the plenum gasket? Quote Link to comment Share on other sites More sharing options...
mra32 Posted January 20, 2010 Report Share Posted January 20, 2010 this thread is BORING! I need pretty pictures to tell me whos talking and to keep my attention going. you need avatars and sig pics. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted January 20, 2010 Report Share Posted January 20, 2010 I've come to the habit of coating gasket surfaces (that use rubberized or paper gaskets) with dielectric grease, because it is inert and lasts to 392 degrees... and anything I have done that to still has good gaskets when I pull it apart again later. A few other thing to do: (problem areas!) The feed line coming out of the drivers side of the lower intake should probably have the fitting replaced, as the o-ring in it gets old and fails. (more dielectric grease here!) Oil drive o-ring: In the FAQ section I threw up an excellent how to post on double gasketing an LQ1 without pulling the head, with pics. read it and do it. Injector inspection. Ohm check all injectors, they should be in the near 12ohm range (post what you find if you have doubts) Since you are disturbing them, you should also expect to replace the O-rings. I like the brown silicone ones Advance Auto Parts carries BWD #274573 Dare I suggest inspecting the timing belt? the intake must come off to do it. Good luck! Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 20, 2010 Author Report Share Posted January 20, 2010 Exactly the sort of stuff I was looking for, thanks! The factory service manual also mentioned checking the filter screen on the fuel pressure regulator, it said to chuck it if it's clogged, and to reassemble WITHOUT the screen. That sounds wrong to me on several levels. What's your take? I've come to the habit of coating gasket surfaces (that use rubberized or paper gaskets) with dielectric grease, because it is inert and lasts to 392 degrees... and anything I have done that to still has good gaskets when I pull it apart again later. A few other thing to do: (problem areas!) The feed line coming out of the drivers side of the lower intake should probably have the fitting replaced, as the o-ring in it gets old and fails. (more dielectric grease here!) Oil drive o-ring: In the FAQ section I threw up an excellent how to post on double gasketing an LQ1 without pulling the head, with pics. read it and do it. Injector inspection. Ohm check all injectors, they should be in the near 12ohm range (post what you find if you have doubts) Since you are disturbing them, you should also expect to replace the O-rings. I like the brown silicone ones Advance Auto Parts carries BWD #274573 Dare I suggest inspecting the timing belt? the intake must come off to do it. Good luck! Quote Link to comment Share on other sites More sharing options...
Crazy K Posted January 20, 2010 Report Share Posted January 20, 2010 I clean the screen with carb cleaner... when I do pull it off... usually i don't. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 21, 2010 Author Report Share Posted January 21, 2010 Would the O2 sensor be easier to get to on a LQ1 with the plenum removed? Not sure how old the one on the car is...if it's easier, might be a good time to replace it. I clean the screen with carb cleaner... when I do pull it off... usually i don't. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted January 22, 2010 Report Share Posted January 22, 2010 Would the O2 sensor be easier to get to on a LQ1 with the plenum removed? Not sure how old the one on the car is...if it's easier, might be a good time to replace it. It might not be as hard, but I doubt that it would be easy. That sucker is buried in there, and the massive heads and cam carriers don't make it easy to get at. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted January 22, 2010 Report Share Posted January 22, 2010 Would the O2 sensor be easier to get to on a LQ1 with the plenum removed? Not sure how old the one on the car is...if it's easier, might be a good time to replace it. It might not be as hard, but I doubt that it would be easy. That sucker is buried in there, and the massive heads and cam carriers don't make it easy to get at. It is doable with the plenum removed. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted January 22, 2010 Report Share Posted January 22, 2010 It is doable with the plenum removed. Oh I'm sure it is! Imagine if it was designed so that you had to remove the cam carrier to get to it! I was just saying that it still won't be the easiest thing in the world to do. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 22, 2010 Author Report Share Posted January 22, 2010 That's sort of what I was getting at...I wasn't sure if it made it easier with the plenum removed...as bad as it's located, if it's easier, now would be the time. Thanks! It is doable with the plenum removed. Oh I'm sure it is! Imagine if it was designed so that you had to remove the cam carrier to get to it! I was just saying that it still won't be the easiest thing in the world to do. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted January 24, 2010 Report Share Posted January 24, 2010 If you are used to working on older cars a 3.4 intake gasket job should be cake. No sealer is needed on any of the mating surfaces. be sure to replace the coolant O ring where the upper intake meets the lower. I don't see the merits of adding dielectric grease to mating surfaces, I have NEVER seen that recommended in any service procedure for any car. In fact I can't even think of what in the world it is supposed to accomplish. Keep dielectric where it belongs spark plug wires and electrical connections. But like Ken also said count on replacing that coolant fitting in the lower intake. and don't forget to put a small dab of grease or oil on the fuel injector O rings when re-installing, that prevents destroyed O rings and ease of re-assembly. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 25, 2010 Author Report Share Posted January 25, 2010 Thanks for all the tips..I've parked the car temporarily, though since the weather has warmed to the 40's rather than the teens, the leak seems to be stopped. Far better to wait until it's fixed, than to have a catastrophic failure that fries the engine. The work will have to wait until I get back home, right now I'm in El Paso. I'm ordering an o2 sensor, and a thermostat as well..I decided to buy the OEM o2 sensor from Rockauto. I've had bad experiences with Bosch o2 sensors, figured I may as well buy the one GM put on it when new. BTW, for "O" rings, I always use ATF. It's got good lubricity, and pretty much guaranteed it won't attack the "O" ring. Thanks for all the help! This forum is great! Daniel in Knoxville If you are used to working on older cars a 3.4 intake gasket job should be cake. No sealer is needed on any of the mating surfaces. be sure to replace the coolant O ring where the upper intake meets the lower. I don't see the merits of adding dielectric grease to mating surfaces, I have NEVER seen that recommended in any service procedure for any car. In fact I can't even think of what in the world it is supposed to accomplish. Keep dielectric where it belongs spark plug wires and electrical connections. But like Ken also said count on replacing that coolant fitting in the lower intake. and don't forget to put a small dab of grease or oil on the fuel injector O rings when re-installing, that prevents destroyed O rings and ease of re-assembly. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted January 26, 2010 Report Share Posted January 26, 2010 Thanks for all the tips..I've parked the car temporarily, though since the weather has warmed to the 40's rather than the teens, the leak seems to be stopped... That sounds like the behavior of mine... Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 8, 2010 Author Report Share Posted February 8, 2010 OK...I'm getting this thing taken apart today. First problem I've found...the upper intake manifold gasket was CROOKED on the manifold, and the gasket torn where the pin should hold the gasket in place. The problem was someone managed to drive the retaining pin up into the plenum. It's bent badly, and needs to come out. Suggestions on how to remove it, and where to find a replacement? Would the dealership have the pin? Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 8, 2010 Report Share Posted February 8, 2010 pic? I could send you a used one... use a vice grip to break the old one out. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 8, 2010 Author Report Share Posted February 8, 2010 Managed to get the pin out of the plenum without making too much of a mess. I think I can reuse it in the lower intake manifold. One new fly in the ointment, broke the plastic line that sits in the valley under the LIM...I think it's the PVC line... Looks too like someone used at LEAST 50 ft pounds to install the lower intake...spec is for 20. They're Fel-Pro gaskets, and I've found two rounded bolt heads, so it's for sure someone has bee in there before..and made a mess. Additionally, there is a round rubber piece in the LIM, it doesn't appear like it seals well to the plenum. What is it, and where do I find a new one? Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted February 8, 2010 Report Share Posted February 8, 2010 I believe that round rubber piece you mention comes with the Fel-Pro intake gasket kit. Something else worth mentioning is that I have a leaky LIM, and I did torque it properly on assembly. I'd suspect that in your case someone thought they could solve a leak by simply tightening everything. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 9, 2010 Author Report Share Posted February 9, 2010 Well, I've got it back together, but seem to have a vacuum leak somewhere, not sure where. Idle is around 1100 RPM, and when it does drop below that, I've got a miss. I've missed something, just not sure what. Suggestions? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 9, 2010 Author Report Share Posted February 9, 2010 Tried the carb cleaner trick, idle picks up around the EGR...and it sounds like a vacuum leak somewhere around that area. I did replace the EGR gaskets with new ones...any suggestions are appreciated. The scantool reports Bank 1 lean, which would make sense if I'm throwing extra air into the system.. Any suggestions are very much appreciated. It appears I've fixed the leak, but now have created a hopefully minor new problem. Quote Link to comment Share on other sites More sharing options...
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