Compression Check results, advice needed!

[dwaynos]

Hi, My 520i has reached 210,000 miles and every now and again she looses all power. I check the compression today and this is what i found.

Cylinders 6-1
100 230 210 170 180 220 PSI

Any advice as to checking the internals. With differences as much as that is there a big chance of piston rings/cylinder walls?

Thanks

[h2oyo]

Hi, My 520i has reached 210,000 miles and every now and again she looses all power. I check the compression today and this is what i found.

Cylinders 6-1
100 230 210 170 180 220 PSI

Any advice as to checking the internals. With differences as much as that is there a big chance of piston rings/cylinder walls?

Thanks

As long as you have been good with your oil changes and simple maintenance I would think its more the head than the something in the lower end. Put a little oil in each cylinder just before you check its compression and see if your numbers come up, if they do you could very well have ring or cylinder wall problems. I am still leaning towards some head work.
Just my 2 cents
Johan

[dwaynos]

HI, just checked the compression on cylinder 6 again. Put some oil in the cylinder and with the accelerator pedal on the floor it gave 250 psi as opposed to the earlier 100.
Any ideas

P.S. If anybody has a set of pitons i would happy to buy them

[whiskychaser]

Compressions should normally be within 10% of each other. No 6 is certainly a problem. If they all go up to 250 the valves are good but the bores/rings are not. This isnt good but it shouldnt cause you to lose all power suddenly.

[dwaynos]

they dont all go up to 250 i only checked number 6 and left all the other plugs in.

[Interceptor]

Before you do the engine overhaul, I suggest you try the following:
- warm the engine to operating temperature
- pour in LiquiMoly Motor Clean and let it idle for 10 minutes
- let it cool down a bit then throw out the old oil
- pour in fresh oil and LiquiMoly Ceratec
- warm the engine to operating temperature
- drive it like you stole it

...and then do the compression check the next day

[Tiger]

When doing compression check, all plugs must be out. You take the reading after the third jump. Not until all the way that it doesn't climb anymore.