sewebster Posted November 17, 2010 Share Posted November 17, 2010 (edited) So, trying to fire up my rebuilt engine (VG30E) and it's not so happy. Initially I had the ignition timing totally wrong, but once I got that closer, it was idling too high, then used a light to get it to 15 deg BTDC and it was approximately the right rpm, but running super rough and then it stalled out. Poking around I removed the right side valve cover and unfortunately an exhaust valve was stuck down. It's a new valve, so I don't see how it could be sticking due to buildup. Possibly the cylinders firing at the totally wrong time when I had the timing screwed (edit: note only ignition timing was messed, timing belt is on correctly) initially didn't help, but I'm not sure I'd expect this. Anyway, now what? I tapped it with a hammer and it popped back up, but who knows what has happened. I guess I need to pull the plenum and look in the other valve cover to see if any are sticking over there... but I guess I need to pull the heads to see what if any damage has occured to the pistons, and figure out what is up with the valve(s). Is there anything I should do before I pull it apart? Compression test? Sigh. I don't have time for this! I've had the worst luck with this rebuild. Any thoughts on causes, tests or fixes appreaciated. Edited November 17, 2010 by sewebster Link to comment Share on other sites More sharing options...
Tungsten Posted November 17, 2010 Share Posted November 17, 2010 chances are the valve that got stuck down was bent you will have to get a screwdriver in there and pry the valve back straight or take it out and straighten in it out other than that, pray Link to comment Share on other sites More sharing options...
sewebster Posted November 17, 2010 Author Share Posted November 17, 2010 Can't be too bend since when I tapped it with a hammer it popped back up... if it's bent I think I'll just put another new valve in. I guess my real questions are: Do I absolutely have to remove the heads? (I think so, but one could imagine looking though the manifolds or plug holes to try to check things out) Should I do any tests before I tear things down? (things that would be impossible once the heads are off) I'm wondering if some other valves have possibly been occasionally sticking, and just weren't stuck when I looked. Engine has only been run for a few minutes or less, so hopefully things aren't too boned on this totally rebuilt engine! Could the engine machine shop that cut my valve seats and lapped the valves have screwed something up? Could the botched ignition timing have caused this? Link to comment Share on other sites More sharing options...
madhornet Posted November 17, 2010 Share Posted November 17, 2010 only thing to do is a compression test if the valve is moving freely, if it is still tight then remove the head and have a machine shop ream the valve guide properly Link to comment Share on other sites More sharing options...
frozenrotors Posted November 17, 2010 Share Posted November 17, 2010 This raises a number of questions. Did you clean the heads throughly after you got them from the machine shop? Did you bother to squirt some oil on the valve stems (through the springs) before start up? Ideally, your valves should move up and down freely (with out the springs in place). Since it sounds like the heads were reassymbled at the machine shop prior to you putting them on the engine. It is possible the valve stems may have had some valve lapping compound on them. This may have caused them to stick. Before I'd pull the heads off, do a leak down test on all 6 cylinders. If you have a bent valve, it will show up there. If you have zero to min leakdown, then lube all the stems up with some break in oil. Pull all six spark plugs out, disconnect the coil wire, pull the fuel pump relay, and crank the engine over with the starter. If you still have sticking valves, it should be obvious by looking at them. Hope this helps. My link Link to comment Share on other sites More sharing options...
sewebster Posted November 17, 2010 Author Share Posted November 17, 2010 Yeah, leak down test sounds like a decent idea. I guess if the leak down is good, and I can get all the valves moving properly while cranking as you describe, then things "should" be ok... I need to remove the plenum to get at the left head... do you think there are any complications with cranking things over to watch for sticking valves with some of that electrical stuff disconnected? Presumably not, it will just turn the starter... Link to comment Share on other sites More sharing options...
frozenrotors Posted November 17, 2010 Share Posted November 17, 2010 Yeah, leak down test sounds like a decent idea. I guess if the leak down is good, and I can get all the valves moving properly while cranking as you describe, then things "should" be ok... I need to remove the plenum to get at the left head... do you think there are any complications with cranking things over to watch for sticking valves with some of that electrical stuff disconnected? Presumably not, it will just turn the starter... No..., that's exactly why you don't want any fuel being delivered to the combustion chambers and no spark being generated. All you want, is for the engine to freely turn over and create compression. Since your removing the plenum, I would hope all fuel delivery is disconnected. Otherwise you could wind up with quite a mess. Add some spark to the equation, and a sticking valve will be the LEAST of your concerns! Link to comment Share on other sites More sharing options...
sewebster Posted November 20, 2010 Author Share Posted November 20, 2010 I did the leakdown... so some of my valves are leaking, especially on the passenger side. I get leakages from 7-15%. But the engine was cold and the rings aren't fully seated yet. I assume that even with a cold and not broken in engine you expect the valves to fully seal? Some of them did... Guess I'm pulling the heads today. Link to comment Share on other sites More sharing options...
sewebster Posted November 21, 2010 Author Share Posted November 21, 2010 Well, the valves were all rusted. The one that was stuck was pretty terrible. Had to drive it out with a hammer (and some wood). Apparently the shop that did the valves did not lube them, and I didn't either. Cool. Likely it wouldn't have actually been a problem if I hadn't ruined the cams right after and then let the engine sit for weeks. Anyway, thankfully, based on my experience and some measurements, the engine is only interference on the intake side, so there were no big problems. Cleaned up all the rust and re-lapped and I'll hopefully put it all back together tomorrow. Link to comment Share on other sites More sharing options...
frozenrotors Posted November 21, 2010 Share Posted November 21, 2010 Well, the valves were all rusted. The one that was stuck was pretty terrible. Had to drive it out with a hammer (and some wood). Apparently the shop that did the valves did not lube them, and I didn't either. Cool. Likely it wouldn't have actually been a problem if I hadn't ruined the cams right after and then let the engine sit for weeks. Anyway, thankfully, based on my experience and some measurements, the engine is only interference on the intake side, so there were no big problems. Cleaned up all the rust and re-lapped and I'll hopefully put it all back together tomorrow. The valves should be sealing without any break-in. The rings on the other hand, will require some run in time to seat properly. If you had to drive out the valves with a hammer and piece of wood, it makes me wonder how long those heads sat, and where? Did the machine shop use stock valve guides? If so, what are they made of? Normally, you would get some surface rust to on un oiled exposed parts. And I'm wondering why they didn't use bronze valve guides? They don't rust, and the bronze wears better, offering a little less friction to the valve stems. It still sounds like your machine shop needed to ream the guides out so there wasn't so much sticking. I'd go back to them and bring up that point! When I've done valve jobs, I always reamed the guides just enough to allow the valve to move up and down by hand (with out the spring obviously) but not so much, that it creates side play. You can tell by moving the valve about half way through it's travel, and wiggling it side to side. Again, little to NO side play. Just free movement up and down. If your not going to be working on the heads or motor for an extended period of time. Spray everything down with WD-40, and cover the heads (if there not installed) in a plastic garbage bag. Spray the cylinder bores down the WD-40 as well. Keep the rust off of the rings and cylinder walls! Hope this helps, Keith Link to comment Share on other sites More sharing options...
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