Celica GT4 Compression Test

Ben Tyrie

I touched on it in my previous post but my new Celica GT4 was in need of a service when I picked her up. Even though I have tonnes of receipts and documents in the car's history folder, for my own piece of mind I wanted to ensure I did all I could to prolong my driving enjoyment.

First up is performing a compression test to check the health of the pistons and rings to ease my mind that there's some life left in the engine!

Compression Test

With the TMIC removed, access to the top of the engine is possible. Each cylinder was tested in turn by removing a single spark plug and screwing in the tester in it's place. I then removed the EFI relay from the main fuse box (located next to the battery) to allow me to turn over the car without it firing up.
The ignition was cranked for 3-5 seconds and then the results of the tester gauge checked.
The gauge is then reset, the tester removed and spark plug replaced. The whole process is then repeated again for the remaining 3 cylinders.

What we're looking for ideally is all 4 results to be within ~10% of each other.
As you can see from these images, the results are hovering around 170-180 PSI.
In this case, I'm happy given the age of the car and mileage of the engine (Odo is reading 127000 miles but I am yet to discover if that is a mix of KM's and Mile's - the history may tell me if its been played with).

What is also evident from the pictures is the oil marks on the top of the cam cover. That's the next job, source and fix the oil blow/leak!

Next up: