Compression test + oil consumption (1 Viewer)

NaterGator

On Gilligan's Island
Joined
Oct 20, 2006
Messages
1,634
Location
Gainesville, FL
 
Due to some unexpected cruiser troubles I had to drop it off at a dealership before heading out for a trip (second time this has happened, I should learn my cruiser problems always crop up right before a trip) so while it was in I had them run a compression test I'd been meaning to do. Anyways, I can smell the oil burning and if the exhaust wafts past through some setting sunlight I can see the blue tint to my exhaust (though it is not otherwise visible)... I'm running Rotella 10W-40.

So my compression test came back:
Cyl 1 - 170
Cyl 2 - 130
Cyl 3 - 170
Cyl 4 - 170
Cyl 5 - 170
Cyl 6 - 170


Cylinders 1,3,4,5 and 6 seem great. Cylinder 2 is definitely the outlier. When I finish this semester I gotta get it home and re-do the compression test myself and try adding a little oil directly to cylinder 2 to see if compression increases significantly, thus I would know it's the piston rings. That said, my service advisor is a very knowledgeable sounding guy but he left a voicemail saying my compression was within spec and the techs suspect it was valve seals.

I'm not sold *but* I want to know if there is any possible valve seal explanation for oil burning after only two or so hours of 'off' time and if anyone has encountered consumption from valve seals under operation. I've got a laundry list of things to do when school finishes (such as puck-spec checking) that may or may not help, but I'm going to put forth every effort to not drive it in case I've got a cylinder ring/bore problem in the chance there is anything I can do to salvage the motor I've got and not have to source a block whenever the hypothetical problem in #2 gets too severe.

Could use some advice from the shadetree experts. :beer:
 
Joined
Apr 23, 2008
Messages
270
Location
Sunnyslope, Phoenix, Arizona
Try this.

Compression Pressure:

Minimum [1] 883 kPa (128 psi)
Standard [1] 1,176 kPa (171 psi) or more) Pressure Difference:

Between Each Cylinder 98 kPa (14 psi) or less) [1] @ 250 rpm


Posted wrong engine specs earlier. Looks like cyl #2 is a lil low but still in spec. I'd say do the rings in that cyl when you get time. :meh:
 

powderpig

SILVER Star
Joined
Jul 12, 2005
Messages
1,026
Location
Boulder Foothills, CO
 
 
 
#2 is not with in specs compared to the rest. It is When looking at the 128 psi, you need to take in to consideration all 6 cylinders. They all should be close to each other. #2 is more than twice the between cylinder readings.
You may need to do a cylinder leak down test to see where the compression is going. You either have some problems with rings and cylinder or a valve problem.
The dealer ship is wrong on this, saying everything is with in specs.
 
Joined
Aug 11, 2005
Messages
3,312
Location
Alabama
 
 
 
When a valve seal(s) first starts leaking, it will only smoke upon startup. When they start leaking more and more, there is noticeable smoke while driving. Much more smoke is apparent when going from high rpm to low rpm very quickly, i.e. changing gears. This happens because at a high rpm, lots of oil is being pumped up to the valve train and when you drop rpm suddenly, a greater volume of oil leaks into the cylinder.

That is the experience I have with bad valve seals.
 

NaterGator

On Gilligan's Island
Joined
Oct 20, 2006
Messages
1,634
Location
Gainesville, FL
 
Ok, well I'll hope #2 is responding to a leaky/out of spec valve and that it's the seals that are the problem (my other compression #s look so good it'd be surprised if the rings in one cylinder were acting up).

Guess I'll still plan on the May overhaul. Trying to get further info from the tech at the dealership to see if they dropped oil in and retested, but I guess I won't know until I see the cylinder. I'm also working on seeing if my dad can snag a decommissioned endoscope from the hospital that I can inspect the cylinder walls with. If so, that would shed alot of light on the situation (bad pun intended)

Thanks powderpig, austin, and fatfish :flipoff2:
 

NaterGator

On Gilligan's Island
Joined
Oct 20, 2006
Messages
1,634
Location
Gainesville, FL
 
Rats, got in touch with the tech at the dealership. He said adding oil brought the compression back up = rings are failing :mad:

I know LX_TREME managed to R&R his pistons without pulling the engine... I'm hoping to not have to go that route for a while though :doh: I told the dealer I was planning on doing HG etc work in May and his reply was "if you're already spending all that money and doing all that work, why not just replace the block too?"... :confused: how do you jump from a ~$1k HG overhaul to a new block is beyond me. I think last I saw CDan said the going price for a new 1FZ block was over $4-5k... :eek:

Oh well, starter is acting up again and I have to get back to school tonight so back to the dealer it goes :frown:
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom