Thor06
06-27-2006, 09:07 PM
A guide wont just bend, if it did, the valve would be stuck. I think I know whats going on in your case. If you ever just look at the bottom side of a guide (on our cars anyway), the hole wont be exactly in the middle. There is almost always some extra material on one side or the other. I heard this is because when the do this, they put the guides in THEN drill the holes. Well, when you break a guide and have new ones put in (like I am guessing you did), they put the holes throught the guide before they go into the head so the holes are right in the middle. See the problem? The valves will then be off center. Not to mention that the hole in the original guide might not be straight through the guide, it might be skewed a bit causing the valve to not fit in there right at all. Then the machinist would have to grind the shit out of the valve seat to get the valve to sit right. Yes, it is a good idea to check the other stuff out. Even on a bad fuck up, the worst that I have ever seen/heard of getting messed up during the actual bending is the tops of the pistons, vavles, and guides. All you have to do to check it out is look. Look for the guide to be cracked, chipped, or broken and look for the kisses on the pistons. I have never heard of pistons being fucked up to bad to not be useable just from bending valves. You can check the seat too, make sure its not messed up at all. Machining isnt necessary all the time but sometimes it is. If the valves werent seating very well anyway, might as well have the seats ground to fit the new valves. However, if the seats are still good, the new valves should just drop in and go.
You will know that a valve is possibly bent when there is no compression in that cylinder. Bent valves arent always the culprit to no compression, but they are the most common. Some times valves will be obviously bent. When I toasted my whole set, only 5 were obviously fucked up. To test to see which ones are bent, theres a couple methods. One, fill the port up with a liquid while the valves are closed and see which ones are leaking, those are the bent ones. The way I do it is turn off all the lights and shine a bright flashlight into the port. If its bent, you will be able to see light coming through around the valve.
Heres my story. I bought a '90 TSI AWD from Goat Blower over spring break with a blown headgasket. I tore off the head and sent the head to my dads friend for machining. It took me a couple weeks to get it off, I didnt have much time and I didnt know what the hell I was doing. He got it and had it for damn near 5 weeks, but he didnt charge me for the head planing (warped from overheating) or the valve job (ground the seats/original valves). Well, I got it all back together and was just driving out of the garage when it died. Uber shitty or no compression all the way across. I forgot to put that fucking washer back on before the bolt that holds the crank sprocket on. The sprocket walked away from the engine and the timing belt fell behind it. Thats when I trashed the full set. So then I had SBR 2 day air some new valves. I got them in, started the car and it ran like shit. Compression test showed no compression in cylinder 3. Both intake valves bent. So I ordered them yesterday, they were here today, got the bitch back together AGAIN and tried to start it. This time it wouldnt run, no compression in 1 and 25 psi in 4. So tomorrow after work I will go out and rip the fuckin head off AGAIN to see which valves I bent. I have bent about 20 valves and the car has been driven 10 feet since it was parked. At this rate, I will need another 17 billion hours of work time and 10,000 valves to get the bastard home! I know they arent bending due to bad timing or getting the head from the bench to on the car, I think its setting the timing that is killing me. I am going to have someone give me a hand next time. I think I have a lesser tolerance for fuck ups since the first time I put the head on, I got FP2's not too long ago.
You will know that a valve is possibly bent when there is no compression in that cylinder. Bent valves arent always the culprit to no compression, but they are the most common. Some times valves will be obviously bent. When I toasted my whole set, only 5 were obviously fucked up. To test to see which ones are bent, theres a couple methods. One, fill the port up with a liquid while the valves are closed and see which ones are leaking, those are the bent ones. The way I do it is turn off all the lights and shine a bright flashlight into the port. If its bent, you will be able to see light coming through around the valve.
Heres my story. I bought a '90 TSI AWD from Goat Blower over spring break with a blown headgasket. I tore off the head and sent the head to my dads friend for machining. It took me a couple weeks to get it off, I didnt have much time and I didnt know what the hell I was doing. He got it and had it for damn near 5 weeks, but he didnt charge me for the head planing (warped from overheating) or the valve job (ground the seats/original valves). Well, I got it all back together and was just driving out of the garage when it died. Uber shitty or no compression all the way across. I forgot to put that fucking washer back on before the bolt that holds the crank sprocket on. The sprocket walked away from the engine and the timing belt fell behind it. Thats when I trashed the full set. So then I had SBR 2 day air some new valves. I got them in, started the car and it ran like shit. Compression test showed no compression in cylinder 3. Both intake valves bent. So I ordered them yesterday, they were here today, got the bitch back together AGAIN and tried to start it. This time it wouldnt run, no compression in 1 and 25 psi in 4. So tomorrow after work I will go out and rip the fuckin head off AGAIN to see which valves I bent. I have bent about 20 valves and the car has been driven 10 feet since it was parked. At this rate, I will need another 17 billion hours of work time and 10,000 valves to get the bastard home! I know they arent bending due to bad timing or getting the head from the bench to on the car, I think its setting the timing that is killing me. I am going to have someone give me a hand next time. I think I have a lesser tolerance for fuck ups since the first time I put the head on, I got FP2's not too long ago.