compression test? worth doing?

londonTiger

Thinking of buying a £30 compression tester and do a compression test on my car during the spark plug service. I was just wondering whether this will tell me a lot about the egine or will it just be scratching the surface with regards to the condition of the engine.

WellKnownSid

Age / mileage / any problems?

What would you do if you had a duff reading?

Marktheshark

When engines lose compression they tend to do it in style, broken ring, bent valve.

forgotmyname

It will tell you nothing unless you know how to use it.

You would be really unlucky to scratch the engine with one.

londonTiger

WellKnownSid wrote: »

Age / mileage / any problems?

What would you do if you had a duff reading?

13 years old 1.6 golf 121,000miles on the clock, i got it 4 years ago with 95000 on the clock.

if it's got bad compression it will determine the attitude to the car. it's valued at £1000 now. drives superb, wouldn't think twice about using it to drive from london to leeds, and back again same day, which I did last october.

but if it has bad compression i would probably ditch it before a clutch or cambelt is due in 2 years time.

straighttalker

You only test the compression if there is something wrong with the engine. Yours sounds fine so why buy a £30 kit too test it? Use the £30 for an oil and filter change.

Ps do you want to buy some anti bear spray? £30 a tin and I guarantee you'll never be attacked by a wild bear in the UK.

arcon5

Oil pressure test would be more indicative of engine wear


It's a waste of time with no benefits in this situation. You might find it consistently lower than spec, doesn't scream impending doom though unless the engine has running issues

arcon5

Marktheshark wrote: »

When engines lose compression they tend to do it in style, broken ring, bent valve.

No they don't

reeac

If the engine idles smoothly then the valves are OK. If it doesn't burn oil then the rings and bores are OK. Bearing condition ...listen for rattles especially when revved up and then allowed to slow down to idle again. A compression tester can be used to confirm a burnt valve but not much else.

WellKnownSid

londonTiger wrote: »

if it's got bad compression it will determine the attitude to the car. it's valued at £1000 now. drives superb, wouldn't think twice about using it to drive from london to leeds, and back again same day, which I did last october.

I predict a compression test will show you have a slightly worn engine, so that's £30 saved. Unless you're having a particular problem, all you'll discover will be exciting new reasons to worry unnecessarily.

londonTiger

the american car youtubers seem to be all about their compression ratios and compression testing