possible burnt valve?????? - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 04-10-2002, 07:15 AM Thread Starter
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possible burnt valve??????

my exhaust has been popping realy loud durring decelration and when Im idleing and jab it ounce real quick. it makes a realy lound pop cackle almost like black cat fire work.

so yesterday I pulled it in my freinds shop and lifted it on his hoist. what I did was weld all my clamped exhaust joints. I fifgured the clamps where letting the exhaust system suck cold air in somewhere makeing it cackle. hmmmm it sure wasnt its now all welded except for one clamp thats on the crossover of the manifolds.

heres what Im thinking. I think Ive got a exhaust valve that is burned (wore out) and is no longer sealing completly. I guess it could even be an intake not sealing on the exhaust stroke. or the other way around.

sooooo now looks like I gota figure out whats wrong and decide depending on whats wrong what Ill do about it[img]images/icons/tongue.gif[/img]

I just felt like giveing you engine guys/gals something to think about

thankx
Evan
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post #2 of (permalink) Old 04-10-2002, 01:57 PM
 
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Re: possible burnt valve??????

Hmm, a valve job is not that difficult if you have the right touch with a grinding stone. In my overhaul class this semester I have done like 120 something seats so far[img]images/icons/crazy.gif[/img]. You could always just pull your heads off, pop the valve springs off and get some lapping compound and see how the contact patch looks on the valves.

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post #3 of (permalink) Old 04-10-2002, 02:44 PM
 
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Re: possible burnt valve??????

I"ve ground a few in my day. pretty easy to do. you might eb able to get away with just lapping them though.
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post #4 of (permalink) Old 04-10-2002, 07:30 PM Thread Starter
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Re: possible burnt valve??????

ummmmhmmm Id think that if its gone this long it better keep going atleast untill I unload it on someone. Ive also done valve[img]images/icons/tongue.gif[/img] well on dang road bikes but its pretty much the same, dang it, Ill bet theres 16 dang valves that need done on my truck, lol why do just one. well heck Ill bet I cant even find the ones thats causeing the problem. dang tobad its not fresh motor cause this is prolly when Id toss a set of vortec heads and intake or maybe edlebrocks on it, but its running on borrwed time so Im wont be doing that.[img]images/icons/tongue.gif[/img].

you come to think of it I bet I can find the bad valve[img]images/icons/wink.gif[/img]

noones got any ideas on what else it might be, I realy dont feel like pulling the heads, dist, and intake off, without putting somthing better back on.

I wish I had a motor sitting on a stand I could toss in

Evan
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post #5 of (permalink) Old 04-10-2002, 07:47 PM
 
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Re: possible burnt valve??????

With the characteristics that you mention, it sounds to me like you have a lose manifold to exhaust connection, or maybe a blown donut. However, since you were under your truck welding up the exhaust connections, I guess that you checked the manifold connections. That being said, my next suggestion would be to do a compression check. Couldnt you do a compression check to see if you have a bad valve. If its burnt and popping, then wouldnt it also be losing compression. I would probably pull the plugs and do a compression check. That may narrow things down for ya.
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post #6 of (permalink) Old 04-10-2002, 07:56 PM Thread Starter
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Re: possible burnt valve??????

yup a compression check should so wich one is leaking, or if its leaking. well that would tell me wich hole its in.

didnt notice any black where the exhaust would be blowing, from the conections the donuts are hammerd from when I did my clutch, funny thing is they dont leak, that blows my mind.

I think I broke more stuff than I fixed when I did my clutch lol I was so close to flying off the handle.

thankx for the advice.
Evan
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post #7 of (permalink) Old 04-10-2002, 09:14 PM
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Re: possible burnt valve??????

Sounds more like a stuck lifter or sticky valve to me!!! Usually they will make this popping noise and you won't really notice that much loss in power over all. I just had a stuck lifter....actually it was a %ucked lifter (6.5L diesels run roller lifters) anyway the seat that the push rod sits on was turn sideways keeping the valve up 1/8". On mine though it was an intake valve so it made the poping noise in the intake. On a gas motor is the intake valve is stuck you will get flames shooting back up the intake but because its a diesel that wasn't happening because the fuel is burnt by compression.

Anyway, it could be a wrecked valve but I will put my money on a sticky valve or lifter.

If you want to see if it will lossen up try running a quart of ATF thru with your motor oil and drive 60Miles. You can also add a bottle of Mystery Oil to the oil too....that $hit does wonders. Last but not least if the noise is still there try a 50/50 ratio of ATF but don't let it run for more than 25 minutes and don't run it at high RPM's or on the road. If there is anything stuck or a oil build up the ATF will take care of it. I usually run a quart thru the motor a few days before I change the oil about every 3 or 4 oil changes. It cleans up the motor great. On my diesel when I run it thru it actally keeps the new oil golden a few days instead of turning black after the first 5 minutes or the engine running like after a normal oil change.

Good luck...Ryan
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post #8 of (permalink) Old 04-11-2002, 10:52 PM Thread Starter
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Re: possible burnt valve??????

Ryan
thankx for the info.

what kind of sound was yours makiing with the stuck lifter.????? popping throught he exhaust.
Ill definatly run some atf in the motor tomorrow, its time to change the oil anyways. it even just so happens I will drive about 50 niles out of town. Ill just dump some in on my way back and change the oil when I get home.

thankx again
Evan
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post #9 of (permalink) Old 04-12-2002, 06:43 AM
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Re: possible burnt valve??????

Well, it was an intake lifter that was stuck. But the noise it would make sounded alot like an air compressor pumping up. It was very loud and noticable. Funny thing was when you would restrict the air at the intake(a turbo diesel really sucks, if you don't watch your self it will suck your whole hand in!!!!!!) it would stop making the noise. It took us 2 weeks to figure out what the problem was and when I took the top off the 2 piece intake manifold I could hear it even better and if I put my hand up to the port where the lifter was damaged I could feel the hair pulzating back up.

Good luck with yours...Ryan
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