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Symptoms of bad valves?

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Old 09-09-2009, 09:28 PM   #1
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Symptoms of bad valves?

Would a noisy valvetrain cause an engine to lack power? And if so, how much power could it lose from the valves?
Old 09-10-2009, 08:44 AM   #2
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Re: Symptoms of bad valves?

in some cases, yes. certainly not always.
i guess in theory, bent, burnt, or just severely worn
valves, or valve seats could cost an engine
practically all of its power. but this is exceptionally
rare on most modern engines.
a compression test would help detemine if the valves
are a problem.

what year?
Old 09-10-2009, 04:45 PM   #3
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Re: Symptoms of bad valves?

There is one cylinder making most of the noise, but there could be as many as 3 or 4, since I am just going by what I hear while driving, but one is VERY loud while idling, while the rest(if any more) are hardly noticeable at idle.
So would 1-3 bad sets of valves make a BIG difference?

Truck is '97.
Old 09-10-2009, 05:42 PM   #4
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Re: Symptoms of bad valves?

Could have a collapsed lifter also, what kind of noise is it?
Old 09-10-2009, 07:20 PM   #5
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Re: Symptoms of bad valves?

The exact same thing I was thinking.
AT IDLE, there is a very slight valvetrain racket coming from the engine, but the most noticeable noise is a very audible pecking, like metal to metal, that seems to come from the lower part of the engine on the left side, which also throws a misfire code from time to time. This pecking doesnt get louder with engine speed, but does get faster.
WHILE DRIVING, the pecking isnt noticeable because of the distance from the noise, but if I drive close to a wall or building on that side, it can then easily be heard. The main noise while driving is excessive valvetrain noise. I dont know if its only because of the lifter/valve problem at idle, or if some of the other valves are messed up too, but it is very noticeable, especially when the engine is cold, but it doesnt go away when warm either. When driving at slow speeds, it almost sounds like an exhaust leak, to the point where I actually checked the exhaust manifold, but it seemed intact, plus the sound doesnt get louder with rpms.
I can assume I will probably be needing some valve work done before resolving this problem, but was just wondering if this could be the reason the engine lacks power, sometimes being weaker than the 2.2, then a few min. later, it will accelerate strongly, but most of the time will run somewhere in between? The last thing I wanna do is shell out a few franklins on the valves/lifters only to find they were not the source of the problem.
Old 09-11-2009, 07:58 AM   #6
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Re: Symptoms of bad valves?

chances are, your valves are fine. most likely,
the noise is being caused by worn or dirty
lifters, allowing for excessive bleed down.
or possibly one or more rocker arm nuts
have loosened up.
Old 09-11-2009, 10:51 AM   #7
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Re: Symptoms of bad valves?

Yeah, I retorqued my rocker arms, took care of most of my noise in my valve train (wear I suppose has 227k on it), STP took care of most of the rest of the noise, pretty quiet now....
Old 09-11-2009, 01:38 PM   #8
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Re: Symptoms of bad valves?

So the questions i have are 1) would a few bad lifters causing valuetrain noise cause the big lack of power i described and 2) how far do they have to tear the engine down to replace the lifters? thanks for the info guys.
Old 09-11-2009, 02:39 PM   #9
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Re: Symptoms of bad valves?

1. If the lifters are collapsed and not opening the valves all the way then you arent getting the best ammount of air and you are choking the engine causing a lack of power. What is your oil pressure like also?

2. Pull intake out, pull valve covers, loosen rocker arms, pull pushrods, lifters are under where pushrods were.
Old 09-11-2009, 09:14 PM   #10
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Re: Symptoms of bad valves?

1) the oil pressure stays between about 43-65, depending on engine temp. And rpm. 2) so the lower metal intake will have to come off? Will the coolant have to be drained too?
Old 09-11-2009, 09:56 PM   #11
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Re: Symptoms of bad valves?

Yup and Yup...

Change the oil when you are done...
Old 09-12-2009, 12:24 AM   #12
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Re: Symptoms of bad valves?

One last thing, would a calapsed lifter like i probably have, affect the compression of the involved cylinders?
Old 09-12-2009, 09:42 PM   #13
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Re: Symptoms of bad valves?

Do you have some #'s? If the cyl is not taking a full intake charge into the cyl I guess it could be low...
Old 09-13-2009, 12:43 AM   #14
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Re: Symptoms of bad valves?

the cylinder that has the lifter noise has 100psi. This seems a little low, but not really low enough to point to a major leak. I was just wondering if the valves were not leaking, and the only problem was the lifter/s not letting enough air in, if that would affect compression just enough to lower it a little, such as down to 100 like it is?
Old 09-13-2009, 09:18 AM   #15
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Re: Symptoms of bad valves?

what do the others look like, a little variance will happen, how many compression cycles did it take?
Old 09-13-2009, 10:33 AM   #16
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Re: Symptoms of bad valves?

I had it checked at a shop and they only checked the one cylinder. I was going by what i had seen on the 2.2 i used to have and that in the haynes manual it says 100 psi MINIMUM.
Old 09-13-2009, 01:23 PM   #17
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Re: Symptoms of bad valves?

The lowest value has to be within 10% of the highest value, IIRC like 80PSI Min?
Old 09-13-2009, 08:11 PM   #18
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Re: Symptoms of bad valves?

My haynes repair manual says 100 psi minimum, but either way, that is a lot lower than most of the engines i've seen(around 120-140 psi), but is not really in what i would call the danger zone(<70 psi).
The only reason i was asking about the compression is that i didn't know if a valve not opening all the way/not at all, would cause it to be maybe a little low,like it is; or if it would still show good compression, meaning that i might wanna check the other cylinders to make sure they are close, because if not, it might actually be something more serious wrong with the missing cylinder.
So would a bad lifter not opening all the way/not at all affect compression, or should it still be as good as the others?
Old 09-18-2009, 01:59 AM   #19
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Re: Symptoms of bad valves?

when you drove it would it cut out after awhile??
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