[tphaeng]

I'm about to purchase a n54 135i. I asked the owner if he could do a compression test since the car is heavily modded. The tester that was used for a harbor freight one.
All cylinders ranged from 95-105.

Is this a low reading?

Maybe it's the tester?

The seller says he's used the tester on 3 cars before and it always reads low. highest he ever got it was 110.
Looking for some insight.

thanks!

[Sgop335]

Originally Posted by tphaeng

I'm about to purchase a n54 135i. I asked the owner if he could do a compression test since the car is heavily modded. The tester that was used for a harbor freight one.
All cylinders ranged from 95-105.

Is this a low reading?

Maybe it's the tester?

The seller says he's used the tester on 3 cars before and it always reads low. highest he ever got it was 110.
Looking for some insight.

thanks!

I had my 2007 n54 done recently at a bmw indy, ranged from 168 - 182 psi.

[upshift_downshift]

100 psi is low for an engine with 10.2:1 CR.

If the "tester always reads low", it's leaking or the gauge is bad and you can't really trust it. It's just a gauge attached to a tube after all.

I'd recommend you get a PPI and have them check compression independently. A seller making excuses for low compression is a bad sign. Why doesn't he get a new tester if he knows the one he has is bad?