Cylinder Compression is Up 15psi

[hodgepodge79]

I recently did a compression test on my 22re, and the results left me a bit puzzled.

My 4cyl has 277K miles on it, and it burns about 1 quart of 10W-40 every month. In August 2004 I did a compression test and the readings were as follows: 140, 143, 150, 147.

Two days ago, I did another test and the readings were HIGHER: 153, 160, 165, 160.

What would cause this? I have two theories that I would like everyone's opinion on:
1. Carbon build-up on the piston and head/valves have caused an increase in compression due to reducing the effective volume (but not likely).
2. The oil rings on each piston are gummed-up in their grooves and allowing oil to pass onto the compression rings creating a better seal and hense, higher compression.

In either case, should I run some type of cleaner in either the gas or directly to the cylinder in order to clean it up? Or should I leave it be?

 

[hossmaster]

Or you could rebuild it and reduce that 1 quart a month usage. Not much you can do, or should do but keep the level up and save your pennies.

 

[rook]

carbon build up can cause an increase in compression, more likely to happen in carburated nascar engines than a 22-RE

not sure if piston rings would cause the higher compression, due to the type of rings on a piston and funciton of each one for this engine are not familiar to me.

have you checked to see what the compresion range is for the engine and if so is it within spec.. you have roughly 10.8 to 11 percent increase, I'm wondering if atmospheric conditons can contribute to the different readings..

with the increase in compression, have you experienced any detonation? what octane do you typically run?

 

[hodgepodge79]

have you checked to see what the compresion range is for the engine and if so is it within spec.. you have roughly 10.8 to 11 percent increase, I'm wondering if atmospheric conditons can contribute to the different readings..

with the increase in compression, have you experienced any detonation? what octane do you typically run?

120psi to 171psi are the spec for this engine (per Haynes manual), so I am within spec, but this engine has 278,000 miles, it shouldn't be reading so high.

As far as detonation,...I wouldn't know what to listen/watch for. What are the signs or symptoms of detonation? When engine-braking (down-shifting into second or first and letting the engine slow me down before stopping) I do get the occasional slight "POP" from the tail-pipe.

I always, without question, run the cheapest octane gas I can get, ie 85 or 86.

A few gearhead friends suggested running SeaFoam in through the vacuum intake and gas tank. That would clear-up any ring or valve concerns.
Would anyone recommend AGAINST this?

 

[Uneek]

As far as detonation,...I wouldn't know what to listen/watch for. What are the signs or symptoms of detonation?

It'll be a knocking or pinging sound.

 

[ovrrdrive]

I'd suspect either a bad test last time, carbon buildup on the pistons, or fresh oil on the rings.

Btw, for tech questions on these older 22re, I've found yotatech to be a better resource.