compression check '97 7.3l
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compression check '97 7.3l
What is the proper procedure to check the compression on this engine? People have written "take it to a shop, to get it done properly". What is so difficult? With the proper gauge/adapter, disable the fuel supply, what else is there? Remove all glow plugs before testing the 1st cylinder??
Thanks,
Tim
Thanks,
Tim
Cargo Master
Joined: Oct 2004
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From: Seneca, SC
well you're talking diesel here, shich uses compression to do the combustion. The glow plugs are only there if the fuel/motor is a litle too cold to ignite off of compression alone. This should geinv you some indication of how much compression we're talking here. Make sure that your tester is for diesels, then go at it.
There was a post a while back for a guy looking to restore an eighties ford. A guy wrote in on how to a wet and dry test, what you should look for and what not. Not sure if it's the same for diesels, so let another guy tell ya the specifics.
There was a post a while back for a guy looking to restore an eighties ford. A guy wrote in on how to a wet and dry test, what you should look for and what not. Not sure if it's the same for diesels, so let another guy tell ya the specifics.
Senior User
Joined: Oct 2004
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From: Ridgecrest, CA
I would NOT try a "wet" compression test unless you know what you are doing. I had a friend that was doing some top end cleaning of intake stuff (getting the oil residue off) and thought it was a good idea to pour some diesel fluid down the intake runners. It did crank over and start up, but he heard some baaaaad things in the process. I helped him rebuild the motor and showed him how he destroyed his motor. There's very little space in the combustion chamber.
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Originally Posted by timo2le
What is the proper procedure to check the compression on this engine? People have written "take it to a shop, to get it done properly". What is so difficult? With the proper gauge/adapter, disable the fuel supply, what else is there? Remove all glow plugs before testing the 1st cylinder??
Thanks,
Tim
Thanks,
Tim
Thanks in advance,
Tim
Post Fiend
Joined: Apr 2004
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From: Silver Lake Dunes, MI
well other than a special adapter and guage made specifically for diesel and since the PSD is much different than many over the road trucks the equipment needed will be pretty pricey. i would guess around 500 if you don't have any of the stuff you need.
are you doing this because you have a problem or just want to know?
are you doing this because you have a problem or just want to know?
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The 500 psi gauge and adapter are about $80 from ATD. The adapter is a 10mm x 1mm thread with a hydraulic quick connect. (About $20 worth of parts). Yes, I do have a problem, the thing runs rough/misses when cold, chugs, low on power, shakes/shudders at certain RPM until it is warm. If you run the truck at various RPM, without a load (trying to find where the miss occurs, you can feel it miss at 2000 rpm, at 2500, there is lots of white smoke, starts to clear at 3000, and then swings up to 3500 rpm like it should. The local diesel guy is pretty busy, but wants to start with a compression check. If I could get the numbers for him, before he started, that might save some time. I would rather have the numbers and tell him that I did it, rather than ask him how to do it.
Thanks,
Tim
Latest info is: this might be an engine that has had some gas in it. He sees intermittent misfires on most cylinders, similar to what he has seen on engines that have been known to have gas put in them. I can see a CUMMINS CONVERSION in my near future! vs. $2500 - $3000 worth of NEW injectors.
Thanks,
Tim
Latest info is: this might be an engine that has had some gas in it. He sees intermittent misfires on most cylinders, similar to what he has seen on engines that have been known to have gas put in them. I can see a CUMMINS CONVERSION in my near future! vs. $2500 - $3000 worth of NEW injectors.
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Fleet Mechanic
Joined: Oct 2003
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From: CentralEastern Utah
3000 grand for injectors.. You can get em cheaper than that. 650-750 will get you upgraded injectors from Bean or Swamp. Plus I would check into the valve cover harnesses and see if you have any melted or burned connections/wiring. Have you run any fuel treatment in the truck???
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Post Fiend
Joined: Apr 2004
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From: Silver Lake Dunes, MI
i stand corrected those are cheaper than i would have thought! random miss... fuel quality or pressure, or cam sensor come to mind. if there is no sensor codes then chase the fuel thing.
Cargo Master
Joined: Oct 2004
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From: Seneca, SC
yeah sounds like a fuel delivery problem, I thought that the gas thing burned up a diesel because the diesel needs the extra lubrication of the diesel fuel to run. If I'm right then this means new rings instead of new injectors, but from waht yu guys have said already I'm probably wrong on this one.
Posting Guru
Joined: May 2004
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From: China Grove, TX
Hey Tim, i can see where you are coming form in doing the compression test for your mechaninc. 1, its less labor cost for you to pay him, and 2, it does make it easier on him and he can get down n dirty with the truck faster. injectors from Swamps or Beans do run close to 1000 for the set, but htey are a high quality product from what i understand. personally, i'm thinkin abouta cummins swap when my motor blows (which hopefully isn't any time in the near future). good luck on that comp. test, and hopefully the motor isn't shot. try checkinthe fuel, CAM sensor, and injector harnesses like suggested. hopfully it will be an easy fix for ya. good luck.
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