Author Topic: Told 'might need new engine' over low cylinder compression  (Read 361 times)

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Offline Whelp

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Told 'might need new engine' over low cylinder compression
« on: November 26, 2018, 05:38:44 pm »
Got car second hand (Mazda 6) back in March with 120k miles on clock and FSH. Once I had it, I brought it to local main dealer for service and all checked out.
Then two weeks ago, the engine inspection light came on. I was away from home and brought it to the nearest Mazda dealer and they hooked it up and said it was only an emissions monitor and I could fix it up at home.

So I brought it in to the same local dealership on Weds expecting a quick job. I first got a call telling me it was the ERG, then another one saying they needed to do a full compression test.
Then they said compression was low in cylinder 1 and I could be looking at an engine replacement! They said they'd get on to Mazda under the goodwill programme and see what the outcome was.

Not mechanically-minded so I sought advice and was told to ask them for the compression test results, which came back as 230 psi in all but one, which was 210 psi.

I've since been told these are nowhere near that bad. Certainly I hadn't noticed any impact on the driving. Thoughts?

Much obliged.

« Last Edit: November 26, 2018, 05:40:45 pm by Whelp »

Offline apav

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Re: Told 'might need new engine' over low cylinder compression
« Reply #1 on: November 27, 2018, 03:08:56 pm »
Is this one of the early third generation cars? Most of them had their engines rebuild. They can check with the VIN.

Service history does not mean a lot. Yes they change the oil and if they remember the filter, but as the engines are not designed properly, they require extra maintainance which is not in the booklet, e.g. injector seals, oil pick up, cleaning EGR, manifold, turbo, etc.

If on the other hand, this is an approved used car, you use the 12 months warranty to rebuild the engine.

I am not sure about the compression threshold but the third generation engines are low compression. So that could mean that they have very little tolerance on how much they can lose out.

If you have still have any warranty, ask them to clean the EGR, and find out whether the warning light will go off. If nothing happens, it could be for an engine rebuild as they guess.