Compression test and spark plug questions Topic is solved

[FireFox31]

I just did a compression test and changed the spark plugs in my new-to-me 2000 V70 NA with 200k mi. What I found seems bad so I could use some help to interpret my findings.

Spark plugs:
Around the installed plugs, cylinder 2 had 1/2" of fluid and cylinder 3 had traces of fluid. Both plugs were tightly installed. Is this engine in trouble?

The cylinder 2 and 3 coil rubber cone had separated from the plastic base. Unbolting them from the head caused them to push away from the plugs. Does this matter?

Installing the new plugs gave me about 20% more power. I had no misfires or DTC codes before doing the work.

Compression test:
I tested on a hot engine, unplugged each coil, removed the fuel pump relay, and had the gas pedal pressed to the floor.

Should I run the compression test with all five spark plugs removed?

During the test, should the engine crank as quickly as when it's being used?

I really hope this engine isn't worn out. Thanks for your help.

[abscate]

Calvin Coolidge version

No, normal

No, just stick them back on

Yes

Yes, with fully charged battery too, it will sound like a funny sewing machine

150-180 psi is fine

[FireFox31]

Thanks. I'll be checking the plugs probably every 1000 miles to see if that oil returns. I removed the cylinder 2 fluid before unscrewing the plug, yet still the plug electrode was dripping with fluid inside the cylinder. The top of the engine had lots of oil which pushed out of the fill cap, so maybe it dripped around the plugs from above? I replaced the oil cap and will clean the PCV soon.

[scot850]

Cylinder #2 and #3 get the oil from the leaking filler cap seal or a loose or split PCV pipe to the head.

Neil.

[FireFox31]

Cylinder #2 and #3 get the oil from the leaking filler cap seal or a loose or split PCV pipe to the head.

Thanks, this really puts my mind at ease. There was oil at the rubber seal around the cylinder 2 coil, so it seems likely that it came from the oil filler, not up from the piston. This is a huge relief. On with the restoration I go.

[amblerman]

Cylinder #2 and #3 get the oil from the leaking filler cap seal or a loose or split PCV pipe to the head.

Thanks, this really puts my mind at ease. There was oil at the rubber seal around the cylinder 2 coil, so it seems likely that it came from the oil filler, not up from the piston. This is a huge relief. On with the restoration I go.

Replacing the rubber seal in your oil filler cap is a way to cut down on that oil seepage.

it's surprising how tight the cap is when you replace that rubber seal/giant rubber washer in your oil cap.
I have a bunch of them and at this point I am replacing them every other oil change or once a year (whatever comes first these days)
They are cheap enough that I just bought a bunch last time I had an order to place.

https://www.fcpeuro.com/products/volvo- ... 80-940-850

[FireFox31]

Thanks. For some reason, I decided to replace the entire cap. The new one has an ad for Castrol on it which I don't love. I'll probably get a gasket and switch back to the old cap. But also, I will clean the PCV and replace that tube from the breather to the top of the engine.

[abscate]

What were the compression numbers like, Firefox?

[erikv11]

What were the compression numbers like, Firefox?

Agreed, always curious to see these numbers ...

[FireFox31]

The compression numbers were almost perfect at 200k miles and unknown (but seemingly good) service history. I tested on a 90+ degree day, on a hot engine, all plugs removed, throttle wide open, each cylinder tested two minutes apart, metal tester firmly screwed into each cylinder (by hand).

Cylinders are rows, crank # are columns, cylinder 1 is passenger's side, cylinder 5 is driver's side:
Cyl 1 2 3 4 max
1 110 150 170 180 180
2 120 165 190 200 205
3 70 150 190 210 227
4 130 175 200 215 222
5 130 170 195 210 220

The British Haynes says compression should be between 188 - 217 psi with 30 psi maximum difference between cylinders. So these numbers look good. They match my previous 2000 V70 NA with ~260k mi at 120, 160, 190, 200 psi.

Cylinder 3 chirped during each crank. Its first crank 70 psi is a concern. Haynes says the low 1st crank followed by increasing pressure indicates worn piston rings.

Cylinder 5 knocked during each crank which is a concern. Here's a video of the sound. Also notice the mist which comes up during the 3rd and 4th cranks. Oddly, this piston head looks very clean while the other four have black deposits on them.

What do you think about these results?