Is .020" ~ .026" clearance on an exhaust valve going to cause damage on a wrx if I keep running it? They're shimless buckets. I know it's out of spec, just wondering how soon I need to get it corrected... I don't have a feeler gauge between those two sizes, .020 goes in loose, .026 doesn't go in. Thanks.
Ah screw it, that's more than double the factory spec, it can't be good. I'm gonna tear into it. If anyone's bored tonight or tomorrow and wants to help... let me know.
Yeah a little much on the clearance. On another note I have some extra shimless buckets laying around. Let me know what you need for sizes.
Thanks, that would be very helpful. I'll let you know what sizes I'll need. Well, I just got the timing covers off and broke the bolts loose on all four cam gears. Now to take off the valve covers and measure the exact clearance on each valve.
I got further than I thought I would tonight. Both valve covers off and all clearances checked, timing belt and driver's side cam gears off. Driver's side, front to rear intake .006 .006 .008 .008 exhaust .021 .015 .009 .010 Pass side, front to rear intake .007 .006 .007 .007 exhaust .008 .009 .010 .010 (all number in inches) My plan is to just get two new buckets for the driver's side front exhaust, those are the only two really out of spec I think. So, tomorrow I just need to pull one cam and measure two buckets. I'll probably need help when I get ready to put things back together. It's nice to have the valve covers off, but I'm still paranoid about getting the cam gears lined back up without crashing valves...
Ok, I think I need the following buckets 475 480 487 or 488 482 or 483 It's kinda tricky because I can't get a good measurement of the current thickness of the bucket.. pics coming soon.
Ok, here are the four buckets from the driver's side exhaust. These were all ground to get extra clearance. From what I can tell, three out of the four are showing premature wear and might explain the extra clearance. Now, this is not a complaint against the person who adjusted my valve clearance and ground the buckets. He asked me what I wanted to do, I said he could grind them and from what I can measure the clearances would be correct if they weren't wearing. It just appears the hardening doesn't go all the way through the bucket. If anyone has opinions on what the pictures are showing, please let me know. It's tricky to measure exactly what I need since the micrometer doesn't measure the thinnest point where the wear is. For example, the 506 measures between .180 and .189, I measure about .184" in the middle which means I need .189 (480) to get the right clearance.
Yeah, I used a paint pen to find out where the contact is between the valve stem and the bucket and it matches perfectly with the wear points. The third pic above (one of the 494s) has a high point of contact in the middle of the bucket, the others are all contacting on the edge of the stem.
Where did those chunks go? Those things look like they were ground out with a dremel. Doesn't look pretty For buckets I have the following: 481 476 486 478 483 489
It does appear they were ground at one point to gain some clearance. They probably ground through the case hardening leading you to the excessive wear you have now. Also happens when people grind valve stems to get the clearance, they will be fine for a few thousand miles then open up rapidly. I used to see many motorcycle shops in the area do both, 5K later the customer was back going WTF. As for measuring to get the right size replacement bucket. I would swap in one of a known size that has not been ground, measure and do the math for the replacement. Saves you from finding out your guess work was off.
Ok, I tried to get as precise as I could to measure at the contact points. I think you have four that would work. Although, I think I need to take the rest of the cams out and preemptively replace any that have been ground. I think if I made the trip to pick them up I'd just take them all if that's ok. Here's my math if anyone cares to double check. .177 measured bucket + .021 measured clearance = .198 total -.010 target clearance = .188 desired bucket (4.775 mm) 476 is .1874, would give me .0106 clearance 478 is .1882, would give me .0098 clearance .1845 measured bucket + .015 measured clearance = .1995 total - .010 target clearance = .1895 desired bucket (4.813 mm) 481 is .1894, would give me .0101 clearance .193 measured bucket + .009 measured clearance = .202 total - .010 target clearance = .192 desired bucket (4.876 mm) 489 is .1925, would give me .0095 clearance .190 measured bucket + .010 measured clearance = .200 total -.010 target clearance = .190 desired bucket (4.826 mm) 483 is .1901, would give me .0099 clearance Yes, it was a dremel to grind them. And I knew it was going to be done with a dremel, again I'm not blaming the mechanic at all. I agreed to having it done this way and it didn't work out. I know there's another car in the area that had the same thing done and as far as I know it's still ok. I think the metal is deforming creating the low points. The deformation is probably due to non-parallel contact between the two surfaces as well as possibly grinding through the hardened surface of the bucket contact point.
Ah yeah, good idea. That sounds like more work but it does sound like a good way to get it right. Since I should double check the other buckets I'll go ahead and do this.
Ok, all the rest of the buckets are fine, they haven't been ground. So I just need to replace four. I double checked the clearances on those four with unground buckets. Here are the measuremetns for the four exhaust valves with different buckets. the buckets were not modified, but they measured slightly undersize from their labeled value. I used the measured size for my calculations. Code: [FONT=Lucida Console]labeled size: 491 495 496 490 --------------------------------------------------- measured size: .1928 .1944 .1946 .1926 clearance: .005 .005 .008 .005 total: .1978 .1994 .2026 .1976 --------------------------------------------------- target clearance: .010 .010 .010 .010 --------------------------------------------------- req bucket size: .1878 .1894 .1926 .1876 mm: 4.770 4.810 4.892 4.765 #: 477 481 489 476 [/FONT](+/- 1 is probably fine) Part numbers. .1878 == 13228 AB191 .1894 == 13228 AB231 .1926 ~= 13228 AB311 .1876 ~= 13228 AB181 OR 13228 AB191 (link)
$7 each whichever ones you need, If you take all of them $5 each. Thats if you come and pick them up.
Ok, started to reassemble tonight. Got four buckets, threw them in and put the cam back in, torqued the two main caps on the cam to 14ft/lbs and checked the clearance. Perfect. .010" fits with just a slight drag on the feeler. So, I go to put the front cap on (the one that holds the cam seal in as well). By now I've already taken out and reinstalled the other three cams with no problem. This last one, I go to torque the front cam cap bolts, 5ft/lbs first pass, good. Second pass at 7ft/lbs and it just doesn't feel right, so I back the bolts back out and they're stretching, probably would have broke off before 7 ft/lbs. The three other cams all torqued to 7 or 8 ft/lbs on the front no problem. aargh... So, now I need to get two new bolts before I can get the engine back together...
Bummer. I know it's a huge let down when you are just a few steps from the end when something else goes wrong. Murphy's law... When I did my Center Diff, I was missing exhaust gaskets and had to run to the dealer across town to pickup a $5 gasket before I could drive. Frustrating. Glad to hear you caught the issue before they snapped!
Usually I enjoy working on my car, but yeah, it's tough to wait for little things. I was really paying attention on these specific bolts on all the cams because I had read about people breaking them off, but usually it was people who were torquing them to 14 instead of 7 (there was an error in the service manual a while back I guess).
It runs! And it's so quiet now... The injectors are the loudest thing under the hood now. I hope I got everything together ok. The timing belt was tricky with just one person, but doable. I'm just doing an oil change now and trying to get all the air out of the cooling system.
