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compresion test

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Old May 5, 2011 | 03:06 PM
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compresion test

When doing a comp test on these eng do you take all the injectors out and put some adapter into injector hole or do you go through the glowplug hole
 
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Old May 5, 2011 | 03:28 PM
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You can do either. I couldn't find an adapter for an injector hole when I was looking. I was going to replace the injectors anyway, and didn't want to pull the glow plugs needlessly. I ended up making an adapter out of one of the old injectors...
 
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Old May 5, 2011 | 05:19 PM
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I have had the glowplugs out with know prob Wat I need to know is do I need to take all the injetors out to do a proper comp test ? I will be doing a pop test on the injectors on saterday and I am trying to get my hands on a comp tester I have a IP of my old eng and one head and 6 injectors the exhaust manifolds and water pump the rest is junk
 
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Old May 5, 2011 | 07:08 PM
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No, you can do a compression test with the injectors in using the glow plug hole.
 
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Old May 7, 2011 | 06:41 PM
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What should the comp be I havent found the psi for the 7.3 in my book yet went and tested all the ijectors today I got 8 that all squeek and dont drip they go off at about 1800 to 2000 psi
 
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Old May 8, 2011 | 12:24 AM
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I have made an adapter out of a injector it was easy I have a friend who is a Machienest now I just need to find a gage that goes to 500 psi and it would help to know wat kind of numbers I should be looking for That seems to be top secert LOL
 
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Old May 8, 2011 | 10:17 AM
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7.3L IDI Turbo Diesel Engine Performance Specifications

1,900 ± 75 psi
 
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Old May 8, 2011 | 11:27 AM
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Compression should be around 350. I was never able to find actual specs, but 350 is the best I could find on the forums. The actual number is less important than the consistancy. Ideally, all the cylinders should be within 10% of each other...
If you're building a test guage, you need to have a check valve so that the guage will stay at the highest reading, and a pressure release so you can zero it.
 
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Old May 8, 2011 | 11:33 AM
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I adapted one out of a tire pressure gauge, i put a gauge for a Oxygen Canister on it, goes up to 4k psi. worked great when i did my compression test, i had a consistent 352+/- 2-3. I did two readings and got an avg of 352 on the first and second one avg of 354 on the second.
 
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Old May 8, 2011 | 03:35 PM
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Thankyou for that I have all I need now even the gage but I would like to ket a better gage for a more accurate reading and I will post the numbers I am sure that some math wisard out the could figuer out wat the comp should be with bore and stroke
 
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Old May 8, 2011 | 04:46 PM
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260-440 psi on the compression.i thought it was within 20% of each other.i dunno,don't remember.
this is all posted here though.you tried a search right?
 
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Old May 8, 2011 | 05:51 PM
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You're right, FORDF250HDXLT, a 20% range. All cylinders should be within 10% of the average, higher or lower...
 
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Old May 9, 2011 | 06:30 PM
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Well sort of did a comp test could not get a gage to fit on ethier one of the test units the snapon only went to 250 the sun unit witch I think a way better unit went to 300 but the needel would go all the way to the zero pin wat would be about 390 or 400 psi we would stop cranking wen it got to pin hit it on them all except number 8 it was 265 I did not do a wet test will do tomoro hopeing its just a valve I am wondering if anyone here has done a wet test on there idi and wat oil did they use normal eng oil or something else I dont want it to fire while doing this as that would not be to much fun LOL
 
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Old May 10, 2011 | 08:21 PM
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I did the wet test today with new eng oil I put about a tespoon down the injector hole and let it sit for a min the roled it over to get it around in the cylinder and blow out ant exsess cause I did not want to hydualic the piston IT picked up 40 pisi but after I put it all back together it still smokes and has an intermitent miss like a valve
 
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Old May 14, 2011 | 12:34 PM
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Snapon sells a diesel engine compresion tester with all the adaptors. I believe I also saw one in Harbor Freight. The adaptor screws into the glow plug hole.
 
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