IS THIS BAD? Compression Test Results - Using STE/ICE -R

[MuddWeiser]

Im giving some love back to my M1009 (daily driver) and thinking about having the IP and Injectors rebuilt - total cost would be around $450. My truck is a daily driver and still runs fine, but the idle is getting rough and its starting to bother me...

So - I bought a really nice STE/ICE-R from a member of another forum and ran the PSI test today.

I would like to know what the compression (psi) should be in the cylinders of my truck AND if the following readings are "bad". I had a look through TM -34 in the "compression testing" section and it states 380-400 psi. I got NOWHERE NEAR that in my M1009.

Below are my results (psi)

Passenger Side (Rear to Front)

244
232
231
229

Driver Side (Rear to Front)

209
199
204
215


Just wondering if that looks suspicious to anyone else? Not even close to the 380-400 psi the TM refers to. It even sates that NO reading should be less than 380psi and that no cylinder reading should be less than 80% of the highest reading.

Aside from them ALL being less than 380psi; They are all pretty consistent... 80% of 244 is about 195 - so that 199 reading is CLOSE to being out of spec...

So is it worth having the IP and Injectors rebuilt or is this motor pretty much end of life? It only has 120k miles on it and oil changed regularly. So I was surprised to see the cylinders this far out of spec?


EDIT:

Sine the STE/ICE-R "transducer kit" does NOT come with a proper 10mm x 1.00 pitch adapter, I fabricated my own length of hose that fits properly in the glow plug hole and runs directly to the "pressure sensor" of the ste/ice-r... The original compression test adapter that comes with the ste/ice-r had a "pressure release valve". My fabricated hose did NOT.

After posting and thinking about this for a while I realized that the original compression hose had a "pressure relief" button that probably means it "traps" the pressure in the hose - since I was NOT using that -- I wonder if my results were "inaccurate"? As I was getting the 200-244psi reading from a single stroke instead of a combined 6 strokes...

I suspect that every revolution dumps the pressure out the exhaust valve before compressing the NEXT revolution and therefore my test is inaccurate since I wasn't building pressure in the hose from 6 combined strokes but rather individual strokes before it released out the exhaust valve?

Any thoughts on this?

 

[12vctd]

Just my opinion but maybe find a rebuildable core, go thru it slowly and still enjoy your m1009 as you slowly work your core motor over IE go thru heads, rebuild and put everything back into specs to include inj pump and inj. Then just swap them over. Just seems more realistic to slowly get another motor up to where you want it as you enjoy your truck, and you can buy and spend as money comes.

 

[southdave]

If the reading is right, through a turbo on it sounds like the right comp. for a turboed motor

 

[MuddWeiser]

I thought about throwing a 6.5 turbo "kit" on it (using junkyard parts)...

I live at 6200ft elevation so the extra 10psi boost would help a lot; HOWEVER, I am not really complaining about a lack of "power"... I don't need it to be a racecar - I simply drive it to get from point A to B and it has been extremely reliable for me, as well as a GREAT winter vehicle...

I was almost wondering if being at elevation might pose an issue to the compression readings - I know the higher elevation = less oxygen, but the compression test is measuring the pressure in the cylinders and NOT the oxygen level.

I am almost thinking that I ran the test incorrectly? The STE/ICE-R kit does NOT include the proper adapter for the 6.2L glowplug holes - it comes with a a little 1/8" pipe thead adapter that threads 1 or 2 revolutions into the hole but then binds up -- so I just got a 2ft airhose with 1/4 pipe on both ends and added a 1/8" "nipple" that I tapped to 10mm 1.00 pitch.

I set the STE/ICE-R for "maximum" reading and cranked the motor over 6 revolutions per cylinder .

After posting and thinking about this for a while I realized that the original compression hose had a "pressure relief" button that probably means it "traps" the pressure in the hose - since I was NOT using that -- I wonder if my results were "inaccurate"? As I was getting the 200-244psi reading from a single stroke instead of a combined 6 strokes...

 

[12vctd]

that was my second part I forgot to write. I have only seen a few STE/ICE-R kits and no very little about them, But I think your results need to be confirmed with a standard compression tester. I will be willing to bet you will have better results.

 

[Chief_919]

Unless your STE-ICE is known to be in calibration, and you are using the exact length hose and the exact connectors called for, I wouldn't trust the numbers. The calibraioin can easily go out on them.

Before you go any further get a good mechanical guage and use it.

 

[coyotegray]

I agree on using a mechanical guage ...
Have you done the test "wet"?


Andy..

 

[Scarecrow1]

I would do like 12 vctd said if it means that you trust the numbers but don't want to throw in the towel with the truck the way it runs now ...This would give you the time to build it thru the winter and have a new one in the spring ...If the truck is running well now with plenty of power then why rush it ......

 

[MuddWeiser]

UPDATE:

$25 and trip to Harbor Freight -- I now get much better readings. It was DEFINITLEY the fact that I was missing the little "1 way check valve" in my test apparatus... I could clearly see pump 1 (200psi) pump 2(270 psi) etc... until pump 6 got me to 350psi...

STILL NOT AT THE 380PSI THE TM SAYS IS ACCEPTABLE.

HERE ARE THE RESULTS - DO THEY LOOK DECENT?

Passenger Side (rear to front)

365 psi
360 psi
360 psi
355 psi

Driver Side (rear to front)

330 psi
340 psi
340 psi
350 psi

EDIT : I live at 6,200ft. sea level -- so I just looked it up and you lose 24% of atmospheric pressure (4% for every 1000ft - can anyone else confirm this?) http://www.hotrodders.com/forum/1956-nailhead-322-compression-test-171339.html


So my lowest reading of 330psi + 24% adjustment for altitude SHOULD actually read around 410 psi at sea level?

 

[MuddWeiser]

I agree on using a mechanical guage ...
Have you done the test "wet"?


Andy..

I did NOT do the test "wet" as that would be cheating

I suppose there might be more lubrication about when the motor is running, but I had it warmed up pretty good when I ran the test (left it idling for 20 minutes just prior to testing).

 

[12vctd]

do your rebuild and run that puppy I think your results are fine