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Grinding Valve with head on engine
Topic Started: Aug 17 2014, 12:18 AM (1,907 Views)
cwatkin


DO NOT re-use the head gasket! You will be tearing the head off and replacing the gasket in the future if you do this.

Conor
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wanderingturtle
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ok I'll buy a new head gasket

but do I need to replace the valve guides if I replace the valves?
Edited by wanderingturtle, Aug 17 2014, 09:52 PM.
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rv93
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Hanuman
Aug 17 2014, 03:48 PM
rv93
Aug 17 2014, 12:44 AM
no. it wont. one, a burned valve is not just a slightly messed up sealing surface. burned is a bad term for it. cracked or broken are better. it happens when a chunk literally falls off the valve. second, everything else thats wrong with what youre doing. no, you cant grip the valve in any manner while the spring is still on. the retainer and keepers are more or less flush with the top of the valve stem (there is a trick with rope you could use to get past that particular obstacle, so well leave that alone for now). second, when grinding a valve, you need to use a grinding (or lapping) compound. this is what actually does the work. spinning the valve against the seat wont do anything. at all. listen to these good people. take the head off. if you wanna go cheap and reduce the chance of success, do it smart. number one, you can reuse the head gasket. no, its not a good idea, but if you coat it with copper sealant spray on both sides, and clean the mating surfaces of the head and block properly, id say you have a decent chance of being ok. second, you can reuse the head bolts. they are not torque to yield. clean up the threads on the bolts and the block when its all apart, and *lightly* coat the bolts with oil whhen you put them in. that last one i actually did. third, changing the rings is a separate job from messing with the head. whole different game. dont mess with them if they work fine now. you also wont have the replace the other valves, but the burnt one will have to be replaced. what i just told you would take you around a full day if youve never done it before and you have some mechanical ability and common sense. if you try to cut more corners than that, you will fail.
"third, changing the rings is a separate job from messing with the head. whole different game. dont mess with them if they work fine now. "

:banghead no! no! no! no! no!
if you do the head on a suzuki G-series engine you must change the rings!
for some reason when you do the head even if the rings are in great condition, the engine will pull oil past the rings.
unless, you enjoy replacing your valves on a regular bases!

ask me how i know. :D
ask many, many other members on the forum how they know. :D :D :D
:thumb
im sorry, but ill need a little more than "it happened to a few guys here" to believe that. i dont see how it makes any sense. what i suspect is that there was a reason the head was coming off. probably causing low compression. if your compression is crap, you usually wont produce much oil smoke. when i got my metro, the crank timing gear was bad, causing timing to be retarded by about a tooth. it ran bad, but it ran and no smoke. replaced the gear, got it timed, and hey, look at that! clouds everywhere! i replaced the rings and all that fun stuff, and its fine now, but without a better explanation, i dont see how taking off a head will cause the rings to magically go bad
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Woodie
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It won't, but the majority of the time, the rings and valves are both bad. And with the nice tight valves, the increase in compression (vacuum) pulls oil right past the worn rings. Then the burning oil burns the brand new valves and you're right back where you were before with all that labor and $100 of gaskets and head bolts to buy again.

If your G engine has over 100K on it, go ahead and do rings and hone as long as you have the head off anyway.
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myredvert
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myredvert

Quote:
 
"...changing the rings is a separate job from messing with the head. whole different game. don't mess with them if they work fine now."
It's one thing to say the words "if they work fine now," but that's a hollow statement if nothing specific is considered in order to make that determination. There has been nothing reported by the OP that indicates they actually do work "fine" now, but there has been a few things that may suggest they don't.
Quote:
 
My problem is a burnt exhaust valve on cylinder 3... (then after the head was off)
Funny thing is, cylinder 2 had better compression than 3.
Something had to cause #3 perform badly enough to make you think it had the burnt valve (lower compression?), and if it wasn't the valve, then what was it? :hmm Out of curiosity, what was the compression, particularly on the cylinders that didn't have big honkin' holes in them? And how did those cylinders respond to a wet test to determine if the rings were an issue?
Woodie
 
It won't, but the majority of the time, the rings and valves are both bad.
Which is why it seems like a good idea to not to get tunnel vision and focus on the really bad, obvious problem like a burnt valve and be in such a big hurry to get the head torn off that you don't do the best you can at the time to objectively measure and/or consider what kind of shape the rings actually were in. Or at least consider the probabilities. Especially when it seems that badly worn rings can lead to a burnt valve.

If it turns out that the rings actually weren't in decent shape, how will you feel about the amount of time and money you already spent if it has to come back apart soon?
Edited by myredvert, Aug 18 2014, 07:08 AM.
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wanderingturtle
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I posted this some time back. http://geometroforum.com/topic/5218030/1/ At the time my compression was 175 180 170 dry, 210 215 210 wet. I've known that it needs rings. Which is why if the head came off I planned to do rings.

Many months ago, compression in cylinder 3 had dropped considerably, to the point of running on two cylinders.I figured a burned valve on 3. It sat for some time. Then it sat for sometime, and I had to move it. It actually ran better. My nephew suggested rings reseated from sitting. Idk. I drove it home on two cylinders a few days ago. Now I see that a valve on 2 is chipped. From listening to the air hissing with compression as I turned it over by hand before taking the head off, I don't think 2 or 3 had compression worth a damn. I think I made the last few miles of the trip home on 1 cylinder. Yes, I am a badass high revving speed shifting fool.
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wanderingturtle
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Now that's all fine and dandy, BUT...

if I replace the valves do I need to replace valve guides? Come on guys, I'm literally waiting on this input before I order parts.
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Memphis metro


I have done valve jobs on several g10 engines and I have not had any problems reusing the guides. That being said, new guides is nothing but a plus but it is not likely you are capable of replacing the guides yourself and that would involve taking it to a shop for replacement. In other words if you want a machine shop to build your head, then replace the guides. If you are doing the work, forget the guides and just replace the valves.
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wanderingturtle
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Thank you!

I was thinking that I would take the head to a machine shop to do the valves, and that I would do the rings myself. But I might just do the valves myself too, if it isn't too difficult. I just don't want to have to but a spring compressor to use once.
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Memphis metro


Here is the answer to your spring compressor situation and it is worth the money even if you never use it but once.

http://geometroforum.com/topic/5269560/3/#new
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David95237


thanks Big Rhino. I was just looking for that. I have sold quite a few, might see if some one will loan you one.
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wanderingturtle
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most excellent! I've PMd the David fellow. Hopefully I can get one pretty quick; I'm anxious to get this little car back on the road!
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geogonfa
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yup that spring tool is one heck of a time saver :thumb , and has been used many times...
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rv93
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im not saying that doing the rings is a bad idea. considering how easy it is, i agree that its a good idea. but his original idea was to not even take the head off. i was trying to give him low budget and time idea.
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