Knock knock

Rexximus · Post by **Rexximus** » Fri Jun 28, 2024 10:15 am

Heyo

Heading home from work the other day, sunroof open, windows down, jolly ol' time; when a couple miles from the house I heard a very unwelcome noise. Knocking under load and at idle, all relative to engine speed. Most of the way home at that point is downhill, thank God, so I just knocked it into neutral and rolled most of the way there.

Checked the stick, drained the oil through a filter - no horriby shiny surprises just yet. Took off the valve cover, checked up there, no metal, only very minor wear expected of the cams - cool. Spark plugs out, check the gaps, look at their condition. Cylinder 4's is a little gooey with black wet deposits, and the cylinder itself smells of petrol and oil. Shone a torch in there and the piston looks wet; the others don't look fantastic, but I think it's been running rich for a little while - but Cylinder 4 is where knock sounds strongest. So current theory is either a sticky injector or a dodgy spark plug has meant that C4 was being flooded somewhat, and it's possibly borewashed down and worn the bearings.

Haven't taken the engine out/head off yet so no idea if it could also be skipped timing (checked using marks and it seems to be in time, plus it wasn't in VTEC at the time so I don't think valves have smooched head) - but the short of it is I have no idea the extent of the damage or if it's worth saving this engine. Current plan is to take the head off, as that's fine, pull the block out and have it sent (or realistically rent a van and take it myself) to an engine specialist to have it inspected and/or repaired. Failing that, doa funky phresh facebook-engine special and just thoroughly inspect it, swap belt and sensors before putting it back in.

All of this to say - or ask - does anyone know of any decent engine rebuilders (preferably in/near Scotland) that would be down for this sort of work? I don't know what the budget of this little maneouvre is going to be but I have the figure "£2k" in my head. New engines seem to bounce between £500 and £2500 and that's not including any help I'd need putting it in/taking it out.

Any advice folks? I don't wanna scrap her (And realistically I'd rather sell to someone who'd engine swap her than that option), especially after the work Phil's done (and the new rear jacking points I've just had welded in) and I can just public transport to work in the meantime, but I need a lil advice on a plan.

Appreciate it

Post by **Merlin** » Fri Jun 28, 2024 10:20 am

Where is the noise coming from? Low down in the block or high up in the head?

I had an engine go on me as the main bearings gave out. But before it started knocking, we found metal in the VTEC solenoid filter.

Rexximus · Post by **Rexximus** » Fri Jun 28, 2024 10:44 am

Coming from low down in the block, held a socket extension to various bits of the block and head and it seems to be on the VTEC-side (C4) of the engine, low-to-middle of the block.
That being said I haven't checked the solenoid filter, I'll probably do that this weekend, grab a new one so it's at least out of the way

LIE · Post by **LIE** » Fri Jun 28, 2024 12:54 pm

It's worth checking the oil scoop as well.
Big bits can be sucked up there and oil may seem to be clear while draining.

stinkypaul · Post by **stinkypaul** » Tue Jul 23, 2024 10:08 am

How confident are you that the sound is a knock?
Have you tried running the engine and taking plug leads off in turn to see if the noise is due to a combustion problem in just one cylinder?
If the auto tensioner fails the timing belt can stay on but it causes the distributor to rattle (which is obviously by C4) but if it is that the belt won't stay on for long so take the cam cover off and take a look.

Rexximus · Post by **Rexximus** » Sat Dec 21, 2024 6:26 pm

Heyo,

Just a lil update for this particular case. Took it to U8 Performance in Perth where's it's being stripped and rebuilt at the moment, and the working theory is oil control ring failure when the head gasket blew. Weirdly there was very little glitter in the oil pan and both cams and main bearings are perfect, so it's purely just Cylinder 1's light dry scraping that caused all of this. Andy said given the state of things that it was likely this had been going on for a while.
Current plan is bore and hone the block, oversized pistons and rings etc. then rebuilt.

Either way it's in damn good hands at the mo. Plan is to get her rebuilt and back to me, broken in, a final road trip or two then selling her on - I got some saving for a house to do, annoyingly.

Pics of the damage

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sat Dec 21, 2024 8:45 pm

Thanks for coming back to update what this was. Very unusual for OEM rings to fail.
Props for sticking with it and getting it rebuilt - hope that all goes well and look forward to another update after? Shame you'll have to move it on, but we've all been there (any many have then come back after

)

Rexximus · Post by **Rexximus** » Mon Apr 21, 2025 2:19 pm

And after a few months (and several suppliers of wrong-sized bearings) she's back up and running!
Done 150 miles on the run-in oil, at 500 with the secondary oil, gonna swap the oil and filter again at 1000 just to be careful. But man, with a fresh engine this thing is an absolute dream.

Sadly I am gonna have to sell her, already stuck her up on autotrader and gumtree but I don't think I'll get much action. Don't want to, car is so damn special even the engine builder said he'd be interested if it's still up when he's looking but life's a bitch and stings when it wants to

Still! Gonna enjoy the ever loving hell outta this thing whilst I have it, living in Scotland has it's benefits - absolutely RIFE with beautiful B-Roads!

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Tue Apr 22, 2025 4:42 pm

Ah sorry to hear you're going to have to sell - definitely enjoy it while you can!!!