Compression test

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Aug 25, 2020 | 09:13 PM

RA52025

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Compression test

Hello,

I have a 93 IDI and did a compression test and got most cyilnders 390 and one was 450 are these reading normal ?

Aug 26, 2020 | 11:49 AM

DarkOverCast

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Most say 350+ is desired so id say those are fine.

You can also compression test on a hot motor and the numbers will jump a bit, most of mine jumped roughly 80+- psi

Rings seat better when everything is all warmed up

Aug 27, 2020 | 10:06 AM

Olds64

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From: Edmond, OK

Quote:

Originally Posted by DarkOverCast

You can also compression test on a hot motor and the numbers will jump a bit

x2

If you do the compression test on your engine after it's hot and remove all of the GPs your numbers will go up.

Sep 4, 2020 | 11:56 PM

RA52025

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Awesome thats good to hear. What would cause excessive blow by ? It has one of those first gen banks turbo kit. And on the front of the pump houseing it has quite a bit of blow by coming out of the pipe

Sep 5, 2020 | 12:22 AM

DarkOverCast

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Quote:

Originally Posted by FordGuy1992

Just the way the motor was designed

6.9/7.3idi, 7.3/6.0/6.4/6.7 powerstroke all have positive crankcase pressure by design.

It does get worse with age but generally shouldn't get excessive until you start loosing compression below the desired threshold.

If you take your oil cap off does it throw oil droplets out while idling? If not I'd say it's just fine.

Sep 5, 2020 | 08:40 AM

tjc transport

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i wonder if your CDR valve is bad? when the diaphragm ruptures it lets oil past.

Sep 5, 2020 | 04:52 PM

DarkOverCast

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Quote:

Originally Posted by tjc transport

i wonder if your CDR valve is bad? when the diaphragm ruptures it lets oil past.

The cdr is normally in an open state, it's really just a runaway device incase the air filter is plugged. Weather it's intact or not it'll still pass oil into the intake

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Sep 5, 2020 | 06:43 PM

DarkOverCast

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Quote:

Originally Posted by tjc transport

when the diaphragm in my 88 ruptures, it dumps a whole lot more oil into the intake.

Interesting, when I replaced my cdr I noticed just as much oil getting to the intake.

Sep 5, 2020 | 07:12 PM

#10

lonewolf_

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the Victor valley pan has some baffles that help cut down on some of the oil... other Pans don't have the baffles, just open hole for the CDR

Sep 5, 2020 | 10:33 PM

#11

DarkOverCast

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Quote:

Originally Posted by lonewolf_

the Victor valley pan has some baffles that help cut down on some of the oil... other Pans don't have the baffles, just open hole for the CDR

Mine had the baffles because they wanted you to poke holes in it when I did my first turbo go with a banks kit but I skipped that step incase I wanted to go back, which I did.