manometer blowby test

[JOHNFAK]

So .... 

Going to comp test here next week or so once my mate sends me the kit. I have a q though .....

If compression shows lower somewhere ..... how isolate to either cylinder/rings or head/valves/gasket 

 

 

[Mopar1973Man]

Difficult to do in a diesel for a wet test because of the small hole and trying to get oil on the rings and not in the piston bowl. In any case the engine will have to be open up at least the head and inspected.

[JOHNFAK]

Ok. But let's say you pull the head ..... how do you diagnose the ring issue versus the valve issue etc....... visual inspection may  not show.

[TFaoro]

You should be able to see if something is immediately wrong with the head.... I'm assuming you're going to have it at least decked anyway right? You could have the machine shop go through the head while they have it.

 

What makes you think you have an issue in the first place? Just the blowby?

[Cowboy]

 

[JOHNFAK]

57 minutes ago, TFaoro said:

You should be able to see if something is immediately wrong with the head.... I'm assuming you're going to have it at least decked anyway right? You could have the machine shop go through the head while they have it.

 

What makes you think you have an issue in the first place? Just the blowby?

Actually blowby looks fine engine acts great.

Smoke at idle.

From what I have been told by builders this is not controlled by pump. Usually means injectors.... however changed out and 0 difference. 

I'm thinking most likely a valve or head issue ...... but really prefer to isolate as best as possible before tearing open.

Of course until I do the test ..... all just guesses. 

 

[JOHNFAK]

2 hours ago, Cowboy said:

http://www.youtube.com/watch?v=WgrfT0LFMhc

Only problem I see here is that compression happens at like 500 psi .... so if it's a ring/cylinder issue may not see it at 75psi shop air. 

[TFaoro]

Compression without fuel is just above 400psi, or somewhere in there. If you have a bad enough issue I think it'll show up in the compression test.

When I did a leakdown I  removed all the rockers (makes sure all valves are closed and sealed). You should be able to hear air coming through the intake , exhaust, or crankcase.

[JOHNFAK]

Why removal of rockers. 

Assuming just air into the compression adapter ....... or a leak down tester adapter ..... compression stroke and valves closed ? 

[TFaoro]

I checked all of the pushrods to see if they were bent...(Have you done that?) so they were already out. Just means you don't have to turn the engine over when you go to the next hole. It also seems a little safer than putting things down in the injector hole, and gives you a good excuse to adjust em up.

[JOHNFAK]

OK.

My mates snapon kit arrived today - will aim to do this saturday.

So assuming (steps)

Remove All injectors.
Disable fuel (remove airdog fuse as well as manually flip up FSS solenoid)
No need to remove exhaust rocker (SNAPON) - just plug in and bolt down.
Crank and Measure.
Move to next cylinder.

Anything else ?

 

Leakdown ..... remove guage and add compressed air. Listen for leaks.

 

[Mopar1973Man]

Count the beats. Typically I'll do 3 beats and stop. Check the measurement.

[Cowboy]

As far as the FSS,  just unplug it.

[JOHNFAK]

On November 5, 2015 at 5:00:45 PM, Mopar1973Man said:

Count the beats. Typically I'll do 3 beats and stop. Check the measurement.

How do you mean ..... Three cranks ? 

Im guessing you pull ALL injectors to reduce cranking force on the 5 not being measured for battery/starter etc ........ Do you typically plug the holes ..... Thinking oil getting in from head on cranking other cylinder

also even though  I will disable fueling via lift pump and FSS I'm expecting I'll see some fuel from the p7100 from what's left in the pump delivery cylinder ..... After that I guess it will be dry .... 

Instructions say say to do on operating temp engine ..... Wasn't really planning on this at least this go around ...... Not overly concerned on numbers being high ..... More concerned on variation in 1 cylinder .....as main reason for doing this is try to isolate if anything wrong with engine for smoke at idle ....... Any issues with this . Can always repeat later if had to ..... Don't fancy working on hot engine .....

[Mopar1973Man]

You'll know what I mean when you run the test. With the other 5 holes open you should here a free roiling engine till it hits the compression stroke and it will make a off beat sound. That would be 1 beat or one compression stroke. I typically stop after 3 times.

Also I've had a few test the theory on hot vs. cold compression test typical the hot test shows higher pressures. Rings seal up better.

Edited November 7, 2015 by Mopar1973Man

[JOHNFAK]

Gotcha.

 

other weird part .... No oring on the slug. Not sure if I'm meant to pull from the injector ...... Guess will become evident when I put it in.

 

so cover up the holes ? 

 

[Mopar1973Man]

You not going to run the test slug and there is no other injectors in the rail. There is no fuel there to seal out. So don't worry about the o-ring.

Edited November 7, 2015 by Mopar1973Man

[JOHNFAK]

On Sun Nov 01 2015 12:46:08 GMT-0500, TFaoro said:

 

Was only from perspective of not having compressed air run up side of slug and poor reading .....

Edited November 7, 2015 by JOHNFAK

[Mopar1973Man]

Shouldn't. The sealing copper washer is there for that purpose. No compression should make it past the copper washer on the tip.

[TFaoro]

John, do you have 2 profiles??

The copper washer should do exactly as Mike says. Trust me when I say it's not fun if those copper washers start leaking