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Discussion Starter · #1 ·
I need help trying to figure two things out. The first is what might be the most likely part that is causing my compression to leak. My number 6 cylinder is leaking it jumps up compression like all the other cylinders except for while you see it getting compression between cranks it's leaking pressure. When I stop the test I'm losing 5psi every second. I did a compression test with all of the glow plugs out (got the meltdown kit from accuratediesel) . I'm not loosing allot of oil between changes (have very little leaking from the pedestal. So what I was thinking because I'm not loosing much oil that it might be one of the valve heads might need to be reseated. Any help would be appreciated.
The second I have done countless searches on the here and the internet on what good compression for our trucks and I live in hesperia California I believe the elevation is over 4,000ft so I don't know how to do the conversion. The truck runs strong (can't compare to others) as far as I know except when start the truck and leave and that only last for when I barely step on the gas hardly has any power but goes away quickly.
My compression is averaging around 302 psi on all cylinders. Don't know anything about the truck except for what I have done. Thanks for the help in advance
 

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Kinda hard to follow


First, meltdown kit? That harness kit they sell? and while in there, you decided to check compression?

How are you seeing it drop with a gauge? The gauge should hold highest reading.
If you do a running dynamic compression test, it will take a the valves into account. Put glow plugs into the cylinders except on testing, unplug injector and start. You can also buy a cylinder leak down test kit.

As far as 302, I don't know the factor for your elavation deal but at sea level, that would be two low.
 

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The main thing to look at is balance percentage. Depending on the quality of your tester the actual number may not be accurate. If all of your cylinders are reading +- 302 then I think you are fine. This advice is of course for a known good/running engine. If I was looking at something from Joe blow that showed up in a box... I'd be more picky.
 

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Discussion Starter · #4 ·
Maryland dieselnick- the meltdown kit that I put on has the gasket,harness,glow plugs and glow plug relay. I decided to do a compression test on the truck was because I figure since I was taking the glow plugs out I was curious to know how my compression was. The #6 cylinder went to 300 psi but when the compression test was done it was leaking 5psi a second. I did a compression test with all the glow plugs off and injectors unplugged one head at a time and the compression was 280 psi. I did research on compression testing on our trucks and everyone was saying to take all of the glow plugs off so when I did the pressure went up to 300 psi and there were to that was at 305 & 308 psi. As far as cylinder leak down test I bought one from harbor freight I don't have it set up for the truck and also haven't figured out how to use it just yet. The compression tester that I used was the small kit. (had to go through 2 before one worked). This is the information I looked up to make my compression tester work and formula factoring elevation change. Homemade Compression Adapter - PowerStrokeNation : Ford Powerstroke Diesel Forum
gator5713- the percentage of compression is surprisingly almost straight across except for the only two. Normally on other vehicles I would see variable within a couple psi on a good engine.
 

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If you used the harbor freight kit and made an adapter hose then 300 is just fine. The extra hose involved will affect total compression and I don't trust the calibration of the HF guage... so if you had consistent #s call it good. The leak down on the other hand is concerning.
Only one cylinder showed leak?
 

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Question. If you haven't made the leak down tester to work on your truck yes how are you seeing the 5psi/min leak?
 

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Hi, compression is only there for a split second buddy. Your saying five seconds later it leaks down so you have completely lost me there. Now if the engine is not cranking or running and you are using a leak down tester, that is a different story.
How you use your spiffy new tester is to adapt the fittings down to screw into glow plug hole after finding top dead center on the compression stroke and then back off just a little bit so the piston goes back a little a creates a little bigger testing chamber. Run the air in stuff flow off with valve and watch your gauge.
 

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Discussion Starter · #8 ·
Gator5713- yes only #6 was leaking all the other pressure stayed the same until I released the pressure on the valve. I agree with some of the harbor freight stuff is crap hence had to go through two one wouldn't release the pressure and the other wouldn't hold pressure(leaking release valve). The adapter that screws on to the glow plug head does not have a valve to lock the pressure (is that pretty much how a leak tester work)? so that is how I am able to see how the pressure drops during the test.
Marylanddieselnick- I think that might help answer your question as far as how I am able to tell how I can see the pressure drop. Hope this helps out some thanks.
 

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That compression beat and compression is only their for a split second and then the piston is off in other cycles, so if your needle is showing that it drops from the highest reading, you have a defective set up.There should be a valve that holds the highest reading, so I'm at a loss.
Set up your leak tester and test as described.
 

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Discussion Starter · #10 ·
Maryland dieselnick I sent you a pm
 

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Discussion Starter · #11 ·
Maryland dieselnick- the compression tester kit has the valve that locks the pressure in is eliminated with the adapter that I had to use in order for it to fit, so if the release valve was defective it would drop on all the other cylinders. I took the tester off and screwed it back on thinking that I didn't have a good seal but had the same result.
 

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The shader valve should still be in place, just further up the line if you did the grease hose mod to make it work... give me a couple minutes to dig out mine and I'll post a picture.
 

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The first picture is the complete HF kit with my homemade adapter.
Second picture is the ends of the adapter.
3rd picture is the quick connect end with shader valve used from the HF kit. If you aren't using this then I'm not sure how you are holding pressure on any of the cylinders.
 

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He has a defective valve or a valve in his test rig with carbon on it.

A leaky cylinder is still going to make X pressure but the pressure does not stay there. Once at top dead center it's off to the Powerstroke cycle ect. If a needle stays up its because of one or more valves.
 

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Yes. I was thinking valve. But figured we needed to make sure the test was good first!
 

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I'm hip!
Yeah whatever pressure the cylinder is capable of making, it makes but after TDC there is no pressure so the needle drops falling away as pressure goes away. It only says up there because of one or more valves in the test rig.

Can't quite concentrate watching these terrorist attacks in France on TV.

Those people have a rude awakening coming when they find out it's not 90 virgins that is awaiting them.

French tv says our media is wrong, it's 7 locations
 

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you need a cylinder leak down test to really get to where you know what is happening. You can alway squirt a little oil into your cylinder After your first test. Crank it over a few times work the oil around the rings then test compression. If it comes up considerably youo may have weak ring on that cylinder.
 

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Discussion Starter · #19 ·
thank you guys for all your help. I do have the valve and I'm going to do the dynamic test as Maryland dieselnick suggest and go from there.
 

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300 lbs. is low, not wanting to be a thorn in your side but I would hope for 400 up.
 
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