Failed compression test and misfire

[amorlv70]

And here is the valve cover underside, darkest at cyl5, and a badly taken photo of the gasket.

IMG_20230404_083848.jpg

IMG_20230404_000653.jpg

[amorlv70]

Originally Posted by dikidera

I've heard...and this is only something I've heard from mechanics. Is that the black deposits are not problematic. Whether this is because it's true or they don't know, that's a different story.

Point being, it may not be such an issue. Let them measure the clearances between the lobes and lifters, if they are within spec I would imagine there should be no issue.

Thanks.
I will report back when I have heard from the engine shop, most likely midweek..
I know that dark deposits can happen when oil gets a bit old, but this car has had oil changes every 6-8k miles since it was brand new and they are only present on the cylinders that had bad compression leading me to believe that this has been caused by an issue..

[abdiel]

Hi amorly70, the recommended NGK Plugs for your V70 are BKR6ETUC.
https://www.ebay.co.uk/itm/323961805277 is a reasonable price.

Alternative is BKR6EKUB.https://www.ebay.co.uk/itm/234908016646 and very reasonable as it is a 6 pack!

[dikidera]

Originally Posted by amorlv70

Thanks.
I will report back when I have heard from the engine shop, most likely midweek..
I know that dark deposits can happen when oil gets a bit old, but this car has had oil changes every 6-8k miles since it was brand new and they are only present on the cylinders that had bad compression leading me to believe that this has been caused by an issue..

You call that black? To me it looks very very ok. Tomorrow or the next day I will show you my valve cover.

[amorlv70]

Originally Posted by dikidera

You call that black? To me it looks very very ok. Tomorrow or the next day I will show you my valve cover.

For a car that has been serviced so regularly it seems a little dark, I wouldn't be concerned if it was uniform across all of the cylinders but it is not..

[dikidera]

Here it is.

[amorlv70]

Originally Posted by dikidera

Here it is.

That does look quite dark.
I wouldn't have been confused if it had been the same colour across the whole cover but it was not

[classicswede]

NGK BKR6ES are the plugs to use

[amorlv70]

Hoped I wouldn't need to post here again - but my car has started to sound slightly 'unsettled' at the tailpipe, so I did a dreaded compression test. This time, it was cylinder 1 the was bad, not 5. Though they're all slightly low.-

Cyl1 45psi
Cyl2 125psi
Cyl3 110psi
Cyl4 110psi
Cyl5 145psi

The car was underfueling on gas which I had adjusted at the end of last summer. I've done almost 30,000 miles since I last had this issue. But why just one cylinder? It was a burnt valve last time, so I'm assuming the same this time. Obviously a head off job again but I really want this to be the last time I have to do this
Does anyone have any suggestions.. I really want to keep the car on gas because it's so thirsty on petrol!

[dikidera]

These low compression numbers suggest either a worn out engine, or you have a bad gasket overall.

Btw, these engines cannot be rebored, the cylinder walls get too thin. If the gasket went bad, you need to resurface the HEAD and CYLINDER BLOCK. The cylinder block also warps as well as the head.

Those numbers are too low. The bifuel engine and possibly all of the NA engines need to have at least 180 psi. That is how much I got after I did work on mine due to a failed gasket. I then torqued it down not to 130 degrees at the last step but 150, with new bolts of course.