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Where to get compression test done?

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Old Jun 15, 2006 | 11:52 PM
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Default Where to get compression test done?

Is there a tool or something that I can rent from Autozone or am I going to have to take my truck to a shop? Will the dealers do it or is a speed shop a better place?
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Old Jun 16, 2006 | 12:07 AM
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Originally Posted by thunder550
Is there a tool or something that I can rent from Autozone or am I going to have to take my truck to a shop? Will the dealers do it or is a speed shop a better place?
very easy tool to use and not terribly expensive, just do it on a warm motor
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Old Jun 16, 2006 | 09:54 AM
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Don't tell me you got a problem with your new engine already.
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Old Jun 16, 2006 | 10:06 AM
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Originally Posted by Zick
Don't tell me you got a problem with your new engine already.

I don't think there's a problem with the engine, I'm thinking that I may have a valve hanging open cause I tightened the rockers up too much. I am running lean on bank 2 under vacuum, but not boost (started another thread about this) - swapped O2's, replaced intake manifold gaskets, doesn't sound like there's an exhaust leak, although I'm going to R&R the passenger side header in the morning to be sure. My airflow is messed up again, I had it all set where I wanted awhile ago, nothing has changed since then, but now it tries to stall on me when I shift from P/N to D. I was also real close to having my spark tables set where I needed, almost got rid of the part throttle KR under light-to-moderate acceleration, now I am getting a lot again. It sometimes fires right up when I crank it, sometimes I have to crank it for a few seconds. Last night I had to crank it for about 5 seconds, kept sounding like it was trying to catch, finally did and tried to die on me for a few seconds before it really caught. Fuel pressure is fine. When I unplug the coil packs and crank the engine it isn't a consistent crank, hard to explain but it sounds like it compresses a few strokes then has one that doesn't compress as well (starter sounds like it speeds up for a sec then goes back to normal, then speeds up, back to normal, etc etc). I'll try to get a vid or sound clip up.

Anyway, I thought a compression test would be a quick and easy way to tell me if I have a problem with a hanging valve.
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Old Jun 16, 2006 | 03:40 PM
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Sears has compression testers, they are easy to use and like previously mentioned do so on a warm motor.
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Old Jun 16, 2006 | 03:47 PM
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Originally Posted by thunder550
I don't think there's a problem with the engine, I'm thinking that I may have a valve hanging open cause I tightened the rockers up too much. I am running lean on bank 2 under vacuum, but not boost (started another thread about this) - swapped O2's, replaced intake manifold gaskets, doesn't sound like there's an exhaust leak, although I'm going to R&R the passenger side header in the morning to be sure. My airflow is messed up again, I had it all set where I wanted awhile ago, nothing has changed since then, but now it tries to stall on me when I shift from P/N to D. I was also real close to having my spark tables set where I needed, almost got rid of the part throttle KR under light-to-moderate acceleration, now I am getting a lot again. It sometimes fires right up when I crank it, sometimes I have to crank it for a few seconds. Last night I had to crank it for about 5 seconds, kept sounding like it was trying to catch, finally did and tried to die on me for a few seconds before it really caught. Fuel pressure is fine. When I unplug the coil packs and crank the engine it isn't a consistent crank, hard to explain but it sounds like it compresses a few strokes then has one that doesn't compress as well (starter sounds like it speeds up for a sec then goes back to normal, then speeds up, back to normal, etc etc). I'll try to get a vid or sound clip up.

Anyway, I thought a compression test would be a quick and easy way to tell me if I have a problem with a hanging valve.

Maybe I'm thinking this wrong, but I'm not sure you could possible tighten a rocker bolt tight enought that it would cause a valve to stay open. Your only suppose to tighten them to about 25ft lbs and even if you went beyond that I don't think that the bolt would put enough pressure on the valve spring to hold the valve open.
Like I said maybe I an thinking about it wrong. What the hell did you put the bolt in with, a impact gun.
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Old Jun 16, 2006 | 03:52 PM
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Originally Posted by Zick
Maybe I'm thinking this wrong, but I'm not sure you could possible tighten a rocker bolt tight enought that it would cause a valve to stay open. Your only suppose to tighten them to about 25ft lbs and even if you went beyond that I don't think that the bolt would put enough pressure on the valve spring to hold the valve open.
Like I said maybe I an thinking about it wrong. What the hell did you put the bolt in with, a impact gun.
I have the Crane adjustables, and when I installed them on the 5.3 the first time I tightened them too much and when I cranked the engine over the starter just spun freely, none of the cylinders were building compression. I was careful when I put them on the 6.0, but I still think that I might have tightened one or two too far....just want to check to make sure....

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Old Jun 16, 2006 | 03:54 PM
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Originally Posted by thunder550
I have the Crane adjustables, and when I installed them on the 5.3 the first time I tightened them too much and when I cranked the engine over the starter just spun freely, none of the cylinders were building compression. I was careful when I put them on the 6.0, but I still think that I might have tightened one or two too far....just want to check to make sure....


Ahhh, didn't realize you had adjustable rockers. Well your on your own with that one since I have never messed with adjustable rockers yet.

Good luck
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Old Jun 16, 2006 | 03:56 PM
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Originally Posted by Zick
Ahhh, didn't realize you had adjustable rockers. Well your on your own with that one since I have never messed with adjustable rockers yet.

Good luck
I really really really really do not want to re-do all of the rockers, but if I can do a compression test and find one or two that need to be re-done that's not so bad. I know where to go looking now, thanks guys! I'll update with results after I do it.
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Old Jun 16, 2006 | 04:10 PM
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So you're not coming down this weekend? We can figure that ish out at mi casa...assuming your truck can make it. I've messed with adj. rockers more times than a care to remember.
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