Compression Test Results!

[ffgb]

Well, I just completed a compression test on my 84 rabbit with 1.6na.  Looking at the engine from the front of the car, and from left to right, here are the compression results:
1) 500psi
2) 480psi
3) 420psi
4) 320psi

I did the compression test as fast as possible after normal operating temperature from left to right.  I wonder if the time from cylinder #1 to cylinder #4, if the engine cooled too much and gave a much lower reading than normal.  I put a little oil in cylinder #4 for a second test, and the reading was about 350psi, not that much of an increase.

So, my engine does burn oil, about 3/4 of a qt to 1qt every 30 miles, but it starts up fine, drives great on the streets and freeway.
I don't know for sure if it is the piston rings, because the compression results from the left to right are from high to low, I just wonder if the headgasket is leaking more on the right side, thus giving those compression results.

Has anyone encountered anything like this?

[drrtybyl]

my engine does burn oil, about 3/4 of a qt to 1qt every 30 miles

Geez!  Do you notice oil on the ground after being parked?  That seems like quite a bit of lost oil.  Maybe #4 has slightly coked rings and the oil is making its way past gaskets?

[ffgb]

There is no oil on the ground what so ever.  I am at a loss for words, because the compression results seem decent.  The only thing I can think of are the valve stem seals, but that is a lot oil loss!!!

[Possum79]

I would say valves for the crompression loss on the one cylinder but as far as loosing the oil I'm at loss. The oil in the cylinder should have raised the comprssion more then that I would think.

[burn_your_money]

You removed all 4 injectors before doing any compression tests?

If you thought that the engine had cooled significantly you should have gone back and did cylinder #1 again to see if it changed much.

[ffgb]

Yeah, I had all four injectors removed.  I have to rebuild my injector pump because it is leaking.  I will redo the compression test and start from the right side to the left.  I am also tempted to do a piston soak while I am resealing my injection pump.  I have seen people use MMO or Seafoam as a piston soak.  I wonder if I pour this stuff in through the injector hole and let it sit for a couple of hours while I disassemble and reassemble my injection pump, if my piston rings would free up a little and possibly consume less oil.

[rabbitman]

I thought wet compression tests weren't a good idea with a diesel since the oil could light and blow the gauge up?

How long did the whole test take?

I did a compression test a while back, probly took 1/2 hour and all were within 20 psi.......

[maxfax]

Did you have a battery charger hooked up while you did the test??   

[ffgb]

Yes, the test took about 1/2 hour, and I did have a charger on the whole time.  I would switch the amp rating from 10amps when moving the injection/gauge fitting over, to the 50amp starting rating when starting for about 5sec.

[wolf_walker]

It really ought to be smoking visably at some point if it's eating that much oil.
Most of the dramatic oil usage like that I've seen has been valve related FWIW.
That being said they will run a long time, and well, eating oil and even with bum
compression if one is inclined to.  So don't despair.

[ffgb]

It does smoke, only when initially accelerating, not on idle, not on deceleration, and not when maintaining speed.
You said it could be a valve issue, as in what? Valve seals, valve guides, etc...?
I would rather just take the head off and get it rebuilt rather than do the bottom end and stuff.
How involved is getting the head serviced?  Is it worth just getting the head cleaned, new valve guides installed, along with exhaust valves/seats, then I reassemble everything else and use the money that I would save on purchasing the tools to complete the task?

[jtanguay]

almost sounds like a possibly blown HG to me. i've seen a toyota 2.4D with 300, 150, 130, 50 compression, and it was from burned valves from too high EGT's. the one with 300 psi was first on the manifold, the one with 50 psi was the one that got all 3 pistons exhaust gases before its own. but the VW manifold isn't setup the same way...

[Rabbit on Roids]

almost sounds like a possibly blown HG to me. i've seen a toyota 2.4D with 300, 150, 130, 50 compression, and it was from burned valves from too high EGT's. the one with 300 psi was first on the manifold, the one with 50 psi was the one that got all 3 pistons exhaust gases before its own. but the VW manifold isn't setup the same way...

if it were from a quantum or something like that, it could be possible, because they dump at #4 cylinder.

[wolf_walker]

It does smoke, only when initially accelerating, not on idle, not on deceleration, and not when maintaining speed.
You said it could be a valve issue, as in what? Valve seals, valve guides, etc...?
I would rather just take the head off and get it rebuilt rather than do the bottom end and stuff.
How involved is getting the head serviced?  Is it worth just getting the head cleaned, new valve guides installed, along with exhaust valves/seats, then I reassemble everything else and use the money that I would save on purchasing the tools to complete the task?

The bottom can wear but typically the heads go faster.  I'm un-convinced most people can rebuild one
of these heads correctly, I think I'd buy a rebuilt one from somebody reputable that does VW diesels a lot.
There are a couple outfits out there.

But, be sure that's it first. 
Smoke on acceleration is a diesel thing, it can be hard on a non-tweaked pump motor to tell
oil from fuel smoke.  They say a "light haze" is normal under accel, but that is pretty damn vague
in my opinion.  I don't pay a lot of attention to smoke personally, I watch MPG and oil consumption (OPG?).
Yours is way, way high, it ought to be screamingly obvious something is buggered it seems like.
A quart in a thousand miles don't scare me on these things when they are old, 3/4 to a quart in 30 MILES?
If that isn't a typo it's a crazy lot of oil.

[ffgb]

That isn't a typo.  I'll buy a gallon jug of oil, put in about oil everyday, and pretty much I need to buy another gallon jug by the end of the week.  At about $12-13 for a one gallon of oil, the price of driving this diesel is not cost effective.