compression numbers... help

[Guffey6]

Alright guys, i finally tested compression. Shes low on power. Hardly any white smoke at all. A little bit of blow by from checking the oil fill. uses 2 qts of oil every 2500 miles or so.



2= 350 1= 390
4=340 3=320
6= 330 5=300
8= 290 7= 330


All checked using 6-7 compression strokes. Is it time for a rebuild? Are the numbers acceptable? should i look further like maybe injectors? Thanks!

 

[ifrythings]

If the engine was cold those numbers look acceptable to me, also depending on what order you tested each cylinder and if you had a battery charger attached or not can skew your results as it cranks over slower. Did you pull all the glowplugs before testing or just one at a time?

 

[Guffey6]

just one at a time and it was a warm engine. I started with # 7 and worked counter clockwise. ill hook a charger up tomorrow and pull all plugs and try it again. but the batteries were pretty hot, i didnt hear an audible change from start to finish.

the numbers would be better, im guessing if i had of done it a different way?

 

[79jasper]

Yeah, you want all glowplugs out.
Even then, those numbers wouldn't scare me.
What oil are you running?

Sent from my SM-G892A using Tapatalk

 

[Guffey6]

What oil are you running?

Delo 15/40. It was using rotella like crazy.

so am i looking at injectors/ IP issues? the injectors to my knowledge are originals. and the original pump went out last year. i put a used one i had from a parts truck back in it.

 

[79jasper]

Or even timing.

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[no mufflers]

Those numbers look pretty good. The 290 and 300 are a little low.

 

[no mufflers]

This is from one of my threads.


results...
#1-350
#2-380
#3-360
#4-360
#5-380
#6-360
#7-360
#8-380

that's an average of 366 psi vs the old engine had an average of 317 psi.

The more worn out motor.


#1-340
#2-320
#3-340
#4-320
#5-300
#6-300
#7-300
#8-320

 

[Guffey6]

that's an average of 366 psi vs the old engine had an average of 317 psi.

yeah, i wanted to see more consistent numbers on mine, but i will play with the pump tomorrow and see if i can get a little more power out of her. It does fine with just the truck weight but when i have any weight in it especially a trailer im just super sluggish, pedal to the floor and nothing, no more RPMS and loosing speed till it flattens back out. Down hill is balls out tho! lol

 

[no mufflers]

I did mine with all glow plugs out.

Timing makes a big difference.

 

[Macrobb]

Timing, fuel, air. All three make a big difference.
What I've found is a worn engine(not sure on PSI, but it had a bore taper of .020") will run fine, but be more sluggish at the lower revs where more leaks out past the rings.
At higher RPMs(and especially with a turbo at higher RPMs), there isn't much difference from a 'fresh' motor to a 'worn' one - shove enough air and fuel in there and it'll make power.

 

[Thewespaul]

You’ve got plenty of life left in that engine.

 

[Guffey6]

Alright guys, i didnt get around to redoing a compression check, however i did slightly advance my timing. i advanced it around a 96th, just ever so slightly, to start with and it seemed to have a little more power than normal. i wont be able to test it with a load for a little bit, things are just too busy around here this time of year. I will continue to play with the timing to get it right. as for the injectors. would it make a difference is one is stuck open or even not spraying a good enough pattern? whats those symptoms? i have a set i pulled from a parts engine that i dont know if they good of not. should i swap them and see? they've just been laying on a shelf about a year of so.

 

[IDIBRONCO]

Maybe you should just stick to the timing for now. If you make several changes at once, it can be hard to tell what you actually got the improvement from.

 

[Macrobb]

Someday, you might want to get an injector pressure tester. You can then see what each does etc.
I believe they were around $150 or so.