cutlassman Posted July 7, 2010 Report Share Posted July 7, 2010 Well, I rebuilt the top end of my engine (3.1L) in my '92 Cutlass Convertible after it hydrolocked due to a blown head gasket. I had the heads tested and resurfaced and re-installed everything with new gaskets. I also put in new plugs. Upon completion and starting the car, it ran very rough. Lots of white smoke pouring out, which was from the residual coolant, I'm sure. That went away, but the idle is still very rough and the exhaust smells rich. If I rev the motor to 2000 RPM or higher it is smooth and strong, but if it does idle and not quit on me, it really shakes. It usually quits if I put it into gear. What could be wrong, what should I test? I've spent over $600 on new parts over the past couple months (which includes new water pump, power steering pump, radiator, along with all the rebuild costs), in addition to about 40 hours of my time! I don't want to have the car towed to a mechanic as I'd rather do the work myself. But my patience is running out! The car ran great before the overheating and hydrolocking. I checked the vacuum lines and don't see any problems. I'm almost positive I hooked everything up correctly, but I guess I should double-check the wires. I checked all the coil packs and they're good. I need to ohm test the injectors - could they just fail like that? I cleaned the EGR, but that didn't help. The only problem I had was the MAP sensor hose connection on the bottom broke, so I put in a used one from the J/Y. Could a bad MAP sensor cause the problems? I tested the IAC and it's okay. I need to check the coolant temperature sensor. I've had coil packs and the ICM fail in the past and it always turned the catalytic converter red hot, but that's not happening. Thoughts? Quote Link to comment Share on other sites More sharing options...
96oldsmobubble Posted July 7, 2010 Report Share Posted July 7, 2010 double check your spark plug wire order. sounds like your not firing on all 6 cylinders. Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 7, 2010 Author Report Share Posted July 7, 2010 I checked the wires and there was one problem up front - the 3/6 coil pack had the wires mixed up. I bet that happened when I tested the coil packs last week. Anyway, I fixed that but the rough idle is still present. If I rev and hold the idle between 2000 and 3000 RPM, all is good, (although there does appear to be a slight miss once in a while). If the car tries to idle, it just gets real throaty (sounds like a '72 Cutlass, not a '92!) and wants to die. Seems like it fades out cylinder-by-cylinder and dies. While I had the engine rotated forward, I swapped out the MAP sensor and put in the original back in as I had epoxied the broken connector. No luck. Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 10, 2010 Author Report Share Posted July 10, 2010 I broke down and talked to a mechanic and have plans to take the car in next week. They charge $65 for the scan and diagnosis, then apply that to the labor charge. I hate to do that, though. I swapped EGR valves, but no luck. Before I take the car in, I'm debating whether or not to pull the upper intake. During the tear down, one of the fuel injector plugs seemed to break or crack when I took it off. I pushed it back in during re-assembly and it seemed okay. Could that one connection be bad and now be the source of the rough idle? Would one bad injector cause a rough idle and want to stall the car, but yet allow the car to run good at 2000-3000 RPM? If there's a chance that's my problem, perhaps I can muster the mental toughness to see this thru... Quote Link to comment Share on other sites More sharing options...
jtwmechanic Posted July 11, 2010 Report Share Posted July 11, 2010 is the mil light on? you can pull the codes yourself and save the $65.you can take the fuel rail back off with the inj's on it ! and the harness hooked up and try cranking it over to see if all the injectors have a nice uniform umbrella like spray when they pulse. that injector could you stated could be causing a problem. is the plug on that cyl. fuel fouled? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 11, 2010 Report Share Posted July 11, 2010 that "throaty" noise sounds like what happens when you're idling, but not with a lot of vacuum... Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 20, 2010 Author Report Share Posted July 20, 2010 I spoke with the mechanic today and he did a compression test. Five of the cylinders are at 180 psi, but cylinder 1 is entirely dead - 0 psi. The car ran fine before blowing the rear head gasket and the machine shop did a pressure check on the cylinder heads and all was fine. The mechanic thinks I may have switched the intake and exhaust pushrods, causing the problem. Or a burnt valve. I was careful about the pushrod order and had them labeled in individual bags, but I'm far from perfect! Perhaps I messed that up - makes sense. I dread digging into the car again, but to pay a shop $65 an hour for a job I can do...I'll suck it up. Has anyone else mixed up the pushrods and had zero compression? Quote Link to comment Share on other sites More sharing options...
jtwmechanic Posted July 20, 2010 Report Share Posted July 20, 2010 (edited) intake pushrod lenght is 5.75" and the exhaust pushrod is 6.00" i think. not sure if it would cause a no compression issue but would probally have rocker arm rattle for sure. worst case would be that the intake valve collided with the piston and knocked a hole in it. i have never mixed them up or had to go behind someone who did so i can't say for sure. Edited July 20, 2010 by jtwmechanic Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 20, 2010 Author Report Share Posted July 20, 2010 Man, I hope there's no hole in the piston! The last thing I'm going to have the mechanic do is use the tool (I can't remember the name) that will let him see into the cylinder to check the piston (boroscope?). Hopefully that checks out. Best case is I messed up the pushrods. Quote Link to comment Share on other sites More sharing options...
AL Posted July 20, 2010 Report Share Posted July 20, 2010 I switched 2 pushrods on my GA 3400 and bent an intake valve and if you had the heads checked already then there has to be a problem with the piston Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 20, 2010 Author Report Share Posted July 20, 2010 Turns out the piston is okay, but the mechanic said there is some scoring of the cylinder. I'm not sure how bad...I just spoke with the office lady on the phone...I haven't picked up the car yet. I'm not sure how that would happen, either. Compression is zero, though, for that cylinder. If it's not a simple fix by switching pushrods, I may be screwed. May be time to part out a beautiful '92 Cutlass Convertible...or let it rot in my garage until I have $1000 to throw into a used motor and labor. I love/hate that damn car! Quote Link to comment Share on other sites More sharing options...
AL Posted July 21, 2010 Report Share Posted July 21, 2010 I dont believe that the heads are ok... Especially if the piston is good... One of the valves is bent I bet, which you could get with a used head Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 26, 2010 Author Report Share Posted July 26, 2010 Good news - I fixed the problem!!! I took off the rear valve cover and checked both the pushrods. They were in the right spots and not bent, so I put them back in and put the valve cover back on. I did a leak down test and to my surprise, found the cylinder was actually holding compression! I put the spark plug back in, re-installed the alternator, and started the car. It purrs now! The idle is super-steady with no misfires or problems. I took it for a test drive and it runs great (outside of a little rough downshifting of the trans, but I attribute that to sitting idle for three months). Obviously, the pushrod(s) for cylinder one were not seated properly, causing an open valve or two and the zero compression problem. Thanks for the help during this monster project. Hopefully I won't have any more issues for a while! Quote Link to comment Share on other sites More sharing options...
Crazy K Posted July 26, 2010 Report Share Posted July 26, 2010 ??? iirc on a 3.1, the pushrods are the same length??? on a 3100 they are different lengths.... Quote Link to comment Share on other sites More sharing options...
cutlassman Posted July 26, 2010 Author Report Share Posted July 26, 2010 On the 3.1, the exhaust pushrods are 6 3/8" and the intake are 6". Quote Link to comment Share on other sites More sharing options...
Luminator9c3 Posted August 2, 2010 Report Share Posted August 2, 2010 Wait... so the problem was what? Quote Link to comment Share on other sites More sharing options...
cutlassman Posted August 4, 2010 Author Report Share Posted August 4, 2010 I'm guessing the push rod for the intake or exhaust valve (or both) for cylinder 1 was not seated properly on the lifter, causing the valve to remain open, preventing compression. The re-assembly must have been correct. Or, the rocker arm was too tight, but that seems like a long shot. Quote Link to comment Share on other sites More sharing options...
ande_1994@yahoo.com Posted March 25, 2011 Report Share Posted March 25, 2011 I have a 1997 grand am se 3.1L. Just recently tore it down and did the intake gasket (which I took the push rods out with the tool i bought to lift up the rockers), plenum gasket, both vavle cover gaskets, and throttle body gasket. And one more i did with the exaust temp or w/e. Idk why i did but i pulled the plug wires w/o marking them also. I cleaned off the old gaskets well too. Mine idles rough at low rmps and kills, or it will kick it up to 2200 rpms by itself before it kills. If i rev it over 2000 it purs nice. At all times their is a loud air leak noise. Any ideas on my problems. It sounds kinda like ur problem not sure if u had the air leak. Cant afford not to fix this so any help would be appriciated. Thanks Quote Link to comment Share on other sites More sharing options...
AL Posted March 26, 2011 Report Share Posted March 26, 2011 Sounds like you have a vacuum leak... Check the EGR valve gasket and also, were all of the gasket surfaces cleaned correctly before reinstall? Quote Link to comment Share on other sites More sharing options...
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