GP1138 Posted March 27, 2008 Report Share Posted March 27, 2008 I like not having to pull the engine to do the head gaskets. I'm not sure if the LX5 has this issue, but the V8 4.0L needs the engine pulled to change the headgaskets. Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted March 27, 2008 Report Share Posted March 27, 2008 You can do the head gaskets in the car I just choose to pull the motor and replace it because I have a free running engine whereas dumping almost $500 in seals into the one in the silver car to repair it. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted March 27, 2008 Report Share Posted March 27, 2008 yeah i know it has a timing chain, comparing apples and oranges here, a timing belt is a wear part, and it is expected to be replaced every 60k, look at just about ANY import up until recently same deal, except if their belt let go it smashed all the valves. the oil pump drive, thats a 60* thing, not just a lq1 thing, so I hardly see how that is making a point, that job is easy if you aren't stupid about it anyhow. but i am done hijacking this guys thread, call me if you want to bitch about it more! Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted March 27, 2008 Report Share Posted March 27, 2008 I was referring to the chains, the intake manifold, the tensioner on top, the injectors, and the rocker arms. Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted March 27, 2008 Report Share Posted March 27, 2008 "my motor is better than your motor" is kind of like saying “McDonalds is better than Burger king†It’s a preference thing. I like McDonalds as John like burger king. McDonalds is cheaper but burger king taste better. It’s never going to be proven. Nor can it be proven. Some people like Yamaha’s as I like Honda K? anyways lets go back to the Nightmare thread.. (btw L67 owns them all) lol!!! Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted March 27, 2008 Report Share Posted March 27, 2008 "my motor is better than your motor" is kind of like saying “McDonalds is better than Burger king†It’s a preference thing. I like McDonalds as John like burger king. McDonalds is cheaper but burger king taste better. It’s never going to be proven. Nor can it be proven. Some people like Yamaha’s as I like Honda K? anyways lets go back to the Nightmare thread.. (btw L67 owns them all) lol!!! It can be proven and has, several hundred times over, you all just fail to realize it. Anthony when you have worked on either engine you can have permission to talk to us about it. Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted March 27, 2008 Report Share Posted March 27, 2008 ok sorry...jezz Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted March 27, 2008 Report Share Posted March 27, 2008 I see Chris's point though, neither engine is exactly the best engine of the century, its a GM motor for gods sake not a formula one motor. And I do have an axe to grind with the LQ-1. Sorry about your valves bud get with Dinunzio he is a pro at taking them apart. I am a pro at dismantling the LX-5 and an amateur at the whole reassembly process. LOL Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 27, 2008 Author Report Share Posted March 27, 2008 OK, so I talked with the shop today, and what they did was a leakdown test. Basically, you close the valves on one cylinder, remove the spark plug, pressurize the cylinder with air, and see if/where it leaks out. Air out the dipstick, and you have bad rings. Air out the radiator or an adjacent cylinder, and you have a bad head gasket, Air out the exhaust, and you have bad exhaust valves. Air out the intake, and you have bad intake valves, and this is what I've got on cylinder 1. I was also told that there was a little leakage ont he front bank as well, but not enough to indicate bad valves, possibly just carbon buildup. So a top end job is in the immediate future for this car. I've gotten the alternator question answered; anyone else care to take a crack at the other questions? When it comes to the "that engine sucks, this one is better" argument, everyone has thier opinion. But as someone has already pointed out, this LX5 vs. LQ1 argument is stupid. Niether engine is the be-all and end-all of engine design. They both have their good points as well as bad, and quite honestly, neither one is anything to white home about! Personally, I prefer a 60* V6 over a 90* any day because of better balance, but whatever. To each their own, and right now I really just wish I had my LS1 (2004 GTO) back. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted March 27, 2008 Report Share Posted March 27, 2008 You have beautiful car there....good luck fixing it. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 28, 2008 Author Report Share Posted March 28, 2008 You have beautiful car there....good luck fixing it. Yeah, it does look nice, but as I mentioned before, it is now just a good looking paperweight. I'm gonna get it fixed, 'cause I refuse to get beaten by it. That and is sure isn't worth much as it is. But barring some sort of epiphany or miracle to make me change my mind, I'm done with this thing. I'm gonna fix it, sell it, and replace it with something that doesn't leave me stranded every other week and then try to bleed me dry. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted March 28, 2008 Report Share Posted March 28, 2008 how many miles does it have again? personally i am still wondering about that compression check, did they give you and specs from it, such as the PSI per cyl? Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 28, 2008 Author Report Share Posted March 28, 2008 It's got about 43.5k on it I just did a quick search and came up with this: http://autos.yahoo.com/maintain/repairqa/engine/ques057_1.html According to that, you don't get a pressure reading, but a percentage of loss. I was mistaken about cylinder 3, apparently it is just cylinder 1 that is really bad; it came with a reading of 78%. Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted March 28, 2008 Report Share Posted March 28, 2008 that doesnt seem bad but im not expert Quote Link to comment Share on other sites More sharing options...
Pontiac6KSTEAWD Posted March 28, 2008 Report Share Posted March 28, 2008 To do the test that they claimed they did, they would have to take the intake plenum off, and the exhaust manifold, plug the exhaust port with pressure guage, and the intake runner for that cylinder, and also do the same on the cooling system. If they didnt do each of those things, then they got a false test. Not to mention, a leak down test isnt exactly accurate. The rings, and, and, the other thing in there (name escapes me at the moment). Since these rings, and that other thing, spin freely during engine rotation, and they are slotted, that your engine will give you a diferent leak down at diferent locations within its rotation, because at diferent points, the rings, and that other thing, will seal diferently.. Any rate, a leak down test is a guage to tell the mechanic in what direction to go in. It isnt definitive. Also, since these are non-interference motors, and you would have had to put some diferent valves in for a bent valve to have taken place. In my humble opinion, 78% on a leakdown test, assuming they are talking about a 22% loss, is borderline on good/bad. My humble opinion, put a timing belt on it. If you have a bad valve, you will know pretty quick from its running condition. If it doesnt, you save yourself the teardown of the motor that wasnt needed. Saving money, and time. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted March 28, 2008 Report Share Posted March 28, 2008 Not to mention, a leak down test isnt exactly accurate. The rings, and, and, the other thing in there (name escapes me at the moment). are you thinking valve seals? My humble opinion, put a timing belt on it. If you have a bad valve, you will know pretty quick from its running condition. If it doesnt, you save yourself the teardown of the motor that wasnt needed. Saving money, and time. I'm with this guy! Also, if you have ever free rotated a LQ1s cams with the timing belt off, it is moderately difficult to do it smoothly enough to be 100% sure that you have all the valves in the position that you want them in. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 28, 2008 Author Report Share Posted March 28, 2008 They DID pull the plenum off, and from what I was reading, it is ok to test with the exhaust still on the car. Also, 78% means that 78% of the pressure was lost, so the cylinder was only able to maintain 22% pressure. In addition, since the leakage was detected on the intake side and the plenum was indeed off, it almost wouldn't matter if the exhaust manifold was on or not. I agree it is certainly possible for the intake valves to have been open somewhat during the test, but then I have no reason NOT to believe that the shop knew what they were doing. They used to specialize in older British cars, so they've got a lot of experience with t-belts. Regarding the non-interference nature of the engine, my understanding was that it was VERY close to contact, something like .01", is that correct? If so, wouldn't it be possible that slight differences in manfacturing tolerances could make it an interferance motor? Honestly, I'd really like to believe that I don't have bent valves, but my gut tells me otherwise. Thinking back to when the car died, I remembered one key event after I was told I had bent valves. I was cranking the thing to try to start it, not knowing the belt was toast, and at one point the cranking slowed to an almost stop for one revolution, and then continued on again. Happened only once, and didn't think anything of it at the time. Knowing that the motor was supposed to be non-interference, I didn't even think of it when I saw the belt. It didn't come to mind until I get the news on the valves, and I started thinking back. Quote Link to comment Share on other sites More sharing options...
Pontiac6KSTEAWD Posted March 29, 2008 Report Share Posted March 29, 2008 Well, you could do a tear down, pull the old timing belt, install a new belt, and only install enuf to see it run. Which means, the cam carreirs, the T-Belt guides, and T-belt Tensioner, and the harmonic balancer. Start it up, if she runs good, you will know. If she dont, you will still know. And can make a educated decision on what you wanna do from there. And I say this, I hate the LQ1 (points to sig), but the math of how this engine was made, what GM designed, and what is wrong with it, add up to a diferent scenario of whats going on internally compared to the shop you took it too. Brittish cars are inherently known to all be interfernece motors, and if they are stuck in this logic, of what most timing belt cars are, then the beleive falsly. Quote Link to comment Share on other sites More sharing options...
GM Guy Posted March 29, 2008 Report Share Posted March 29, 2008 I would try putting the belt on and give it a shot. Remember what I said about these engines and heat. That combined with cheap gas and if you haven't run any cleaner on a very regular basis you will get a ton of carbon built up on these engines. Yours is MPFI, same as mine. That means that the front or the rear bank of injectors fire all three at the same time no matter what cylinder is firing which means you get fuel puddling on the valves. This usually leads to more rock like carbon build up than that on SFI engines thus you could have one of the intake valves hanging the slightest amount. You can spray some intake cleaner in the runners and let it sit while you put the belt on. If you had a bent valve with that much leak down you would have had it backfiring like crazy. You mentioned when you cranked it over it got slow on a revolution. Since your belt was still catching slightly it was still spinning the cams although no where near what it should have and was slipping like crazy. You ended up with two cylinders acting like they were on a compression stroke and created that much more strain on the starter. Nothing you have said so far would lead to a bent valve. Only thing I can think of that could cause a bent valve is if your springs are severly weak and you are running it at high rpm. This scenario of smaking the valves is not due to the valve hanging open but rather rod stretch. If you are running around 6k rpm or higher it is rare but a very slight possibility and I have seen this happen. One last word of advice...ASK THEM HOW MANY GM 3.4 DOHC THEY HAVE REPLACED THE BELT ON and make sure you emphasize GM 3.4 DOHC. If they say none, GET YOUR RIDE OUT OF THERE. DONT LET THEM LEARN ON YOUR CAR OR YOU WILL BE BACK TO THEIR SHOP AGAIN...and AGAIN, and AGAIN. You may not have enought time to sell it before you have to go back several times. If you want to keep your sanity do it yourself or find someone that has done it several times. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 29, 2008 Author Report Share Posted March 29, 2008 OK, so If I just throw it back together not pulling the head, and it doesn't run right, I'm not out anything other than a couple gaskets and my time, correct? If so, then I might as well try it. On the flip side though, how much more to pull the head once it's torn down to the point where I'd be reinstalling the t-belt? Not having the car to look at right now, the only things that come to mind are the intake/exhaust manifolds... Given the extremely low mile usage of the car it certainly makes sense that carbon buildup could be the culprit here. One other thing though, and that is that NO shop in my area knows squat about the TDC, but this shop is by far the most competant shop I've dealt with in a long time. Could they have possibly made a mistake? Sure. Do I think that just cause they've not worked on a TDC often, they'll royally muck it up? After my past experiences with them, not a chance. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted March 29, 2008 Report Share Posted March 29, 2008 To do the test that they claimed they did, they would have to take the intake plenum off, and the exhaust manifold, plug the exhaust port with pressure guage, and the intake runner for that cylinder, and also do the same on the cooling system. If they didnt do each of those things, then they got a false test. Not to mention, a leak down test isnt exactly accurate. The rings, and, and, the other thing in there (name escapes me at the moment). Since these rings, and that other thing, spin freely during engine rotation, and they are slotted, that your engine will give you a diferent leak down at diferent locations within its rotation, because at diferent points, the rings, and that other thing, will seal diferently.. Any rate, a leak down test is a guage to tell the mechanic in what direction to go in. It isnt definitive. Also, since these are non-interference motors, and you would have had to put some diferent valves in for a bent valve to have taken place. In my humble opinion, 78% on a leakdown test, assuming they are talking about a 22% loss, is borderline on good/bad. My humble opinion, put a timing belt on it. If you have a bad valve, you will know pretty quick from its running condition. If it doesnt, you save yourself the teardown of the motor that wasnt needed. Saving money, and time. I can't tell you how many 151/2.5 "Iron Duke" Pontiac 4-poppers I've seen that ran with one cylinder indicating 80% leakage. (No, they didn't run "good"; and they had piss-poor power. But then, I consider the Iron Duke to be one of the WORST engines to come out of GM--ever. I'd rather have a Vega 2.3.) Remember that "indicated" leakage is AS MUCH a function of the leakdown tester you're using as it is of the actual cylinder leakage. A leakdown tester has a built-in restriction (orifice) and the larger that orifice is, the "better" the engine is going to test. A small orifice will make the tester show exaggerated leakdown results. My Snap-On single gauge tester must have a small orifice; I rarely get a reading better than 20% leakage; and the instructions state that 50% leakage on a cylinder of 50 cubic inches is the bottom edge of "normal". (Larger cylinders will tend to have more leakage than smaller cylinders.) So: yes, that cylinder is probably weak. I'd expect a bent valve to have 100% leakage though. It wouldn't hold in a fart. The air pressure would just whistle past the non-sealing part of the valve. First Guess: It's not bent, maybe there's a fleck of carbon on the valve/valve seat that's preventing total closure of the valve, or maybe it just needs a valve job--or the shop was sloppy about assuring that the valve was closed ('cause the cams would have to be turned manually to assure closure) and --maybe-- the valve was just on the verge of being lifted off the seat. If it were mine; and time/money/effort/enthusiasm were low--I'd throw a belt on it and drive it. You can make plans to do the extensive work--if in fact it needs the head pulled--and then do the work more-or-less at your convenience. Quote Link to comment Share on other sites More sharing options...
ismellrealbad Posted March 29, 2008 Report Share Posted March 29, 2008 Yanno I was positive you should just throw a belt on it and go, but when you mentioned the part about cranking it over and it stopping - really sounded like you got hung up on a valve. How I don't know. Maybe whats left of the belt caught some teeth for a split second and one of the cams turned. I'd still just put a belt on it. All you've got to lose is the extra time. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted March 29, 2008 Report Share Posted March 29, 2008 If you were to put a belt on it, you would be out the cost of the timing belt parts and time, if you did need valve work, you would still of needed to buy the timing belt parts anyhow, so in reality all you have to loose is time. like i said before, if you were to freely rotate a LQ1s cams with just a 15mm wrench or socket on the end of the cam cog, you would know that their movement is anything but fluid, so i could see it being easy to not be sure that the valves are open or closed. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted March 29, 2008 Author Report Share Posted March 29, 2008 Well, as everyone has said, the worst I'd be out is time to just put a new timing kit on and try it, so that s what I'm gonna do. If it works, great. If not, tear into it again, replace valves as needed, and get it to run. As I said before, I'm not gonna get beaten by this. I'm not likely to keep the car after all this, but I refuse to get beaten by it. Edit: Almost forgot to ask... where do I get the tools needed to do the timing on this car? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted March 30, 2008 Report Share Posted March 30, 2008 honestly, you don't need much, I think a standard gear puller can work, and all you *really* need to hold down the cams is a strong flat piece of metal with a hole in the middle and a bolt of the proper thread pitch... unfortunately I do not know what that is off hand. I myself have the entire Kent-Moore tool set for the job, however it tool a long time for me to dig that up. http://www.60degreev6.com has some good write ups about it, but the first time is a HUGE learning curve, thats for sure Quote Link to comment Share on other sites More sharing options...
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