Knocking at idle after fully warmed up

[jonspurs]

Happy Friday All,

Firstly, thank you everyone for your tips, advice, and help here over the years
Secondly, my 2006 231hp 76k miles RX-8 that I've had for 15 years has started making a knocking noise

It happens when the car is fully warmed up and at idle, after around 10 minutes.
I also notice the oil pressure gauge randomly drop to zero. This goes back up after a quick blip of the throttle.
The oil is topped up, as well as the coolant.
I think the knocking disappears when revs increase, or it just may be the sound of the engine drowning out the knocking.
When I open the bonnet, the whole engine bay feels very warm, hotter than I used to remember.

https://youtu.be/Q8QGjMQ-zh4
https://youtu.be/RTf9iJtJLfk
https://youtu.be/cpjEhfh02U8

Before it's warmed up, or before 10 minutes, there is no knocking, and oil pressure does not drop.

https://youtu.be/3bkGrdKLVQI

I've researched here, the RX8Club forum and YouTube...most of which had an SSV issue, but this sounds different.
One comment in a video said it was a bearing that had gone for his car.

Can anyone have a good guess at the issue? Am I looking at a rebuild/new engine? Or could it simply be the oil pump and/or oil pressure regulator?

Thank you, for your time, and help!

Jon

[warpc0il]

First thing, have you checked the engine mounts?

Is the exhaust standard?
Specifically has the cat and/or catback been changed?
Is the joint between the cat and catback a proper swivel-fit; that is a donut seal held between flared ends of the pipes by spring pressure, that allows the joint to move while remaining gas-tight?

[thatturborx8]

Sounds like ssv rod to me

[rx8hunter]

Definitely the SSV

[jonspurs]

First thing, have you checked the engine mounts?

Is the exhaust standard?
Specifically has the cat and/or catback been changed?
Is the joint between the cat and catback a proper swivel-fit; that is a donut seal held between flared ends of the pipes by spring pressure, that allows the joint to move while remaining gas-tight?

Engine mounts - not checked - will try to look under soon
Exhaust - standard
CAT - original/factory installed/nothing has been changed
Swivel-fit - I'm not sure - but the car is fully stock

Thanks,
Jon

[jonspurs]

Sounds like ssv rod to me

Definitely the SSV

I thought the SSV rod sounded differently in the other YouTube clips...I'll see if I can try and put my finger on it.

Any ideas on the low oil pressure at idle?

Thanks,
Jon

[jonspurs]

Watching yous second video i do realise that the engine might not be in its best mood unfortunately

[jonspurs]

Oil pressure that falls bellow the sensors' range is common when hot, which is one reason why many of us use and recommend 10W40 oil rather than 5W30.

Check the idler pulley on the A/C drive belt, as these can get noisy and sound a bit like your video.

[jonspurs]

Hi all,

I forgot to mention that the car won't hot start, unless I wait 10 minutes for it to cool.

I also spoke to some rotary specialists and they think it's the stationary gear bearing and low compression.

I've been going in circles in my head, whether to get it rebuilt (£5k), or have a new engine (£10k), or sell it/webuyanycar/trade in and get a new car. I've decided it's been a fun 15 years, and it's time to move on. It's a shame because I love my car, and it has never let me down. Will be a sad day when/if it actually goes...

And thank you all for your help with this thread and other tips and information over the years.

Jon

[350matt]

I'd say you should be able to get a rebuilt lump for less than 5K but I'm guessing you need someone to remove the old and fit the new , hence 1500quid on top of what an RRP lump would set you back


sorry to say the we buy any car mob won't give you much for it

[hachiroku]

RRP offer a "Fully fitted service £2,575 Incl VAT"
https://www.ryanrotaryperformance.com/r ... ndard-plus

[Timmy2]

I've had a very similar noise on my PZ and even changed the oil to a thicker grade to try and cure it .
Have you tried holding the ssv rod on the actuators still with a screw driver as that's what mine was .
Mine certainly sounded terminal but its still soldering on on its original Engine at 90,000 miles.
Good luck
Tim

[jonspurs]

Thanks Matt, Dave and Tim for your replies.

Yep I spoke to RRP and though the base is £2.5k, I'd need fitting.
I 'll try holding the SSV rod again though the noise doesn't seem to be coming from there.

I've since test driven a few cars, and the only ones I liked were the Tesla Model 3 (effortlessly quick, though doesn't look amazing) and a Mazda 3 e-Skyactiv X (looks really nice inside and out, though obviously not as quick).

Although I was looking to move on, I'm being indecisive now whether to move on or rebuild...will update you all..

Cheers,
Jon

[jonspurs]

Hey all,
It's been a while and just to say I've decided that I'll reluctantly sell my RX-8.
Thanks again Dave and Tim and everyone for your help and responses.
Is it OK if I post it in the For Sale section?
It's a January 2006 build, so it's before the crazy tax band price hike.
Completely stock - new Mishimoto radiator and new coolant tank installed by Essex Rotary a year ago. Wearing Michelin Pilot Sport 4.
I also have the XCarLink adaptor to sell - https://www.xcarlink.co.uk/mazda-usb-sd ... del-v.html

Thank you,
Jon

[jonspurs]

viewtopic.php?f=145&t=54767

[jonspurs]

Hey All,

I thought I'd update this thread to close this story.

It was a hard decision...but I eventually sold my car.

After test driving loads of cars, I wasn't a fan of petrol autos, as they do feel laggy and slushy...now I get why they are called slushboxes. At the same time, I'm not sure if I wanted another manual.

But I do love the instant torque of EVs. There is no 'slush/lag' like a petrol auto. So, I wanted an EV with RWD, similar acceleration to the RX-8 though not a big car, space for at least 4 people, decent boot, good forward view, and something different to a Tesla.

And I now have an electric Cupra Born V2. Driving it is effortless. The torque is addictively fun, but also dangerous, because it builds up speed quietly and quickly. It's also relaxing...I press a button in start/stop traffic and the car will accelerate and brake by itself.

I love my new car, though I also do miss my RX-8, the feel, the sound, the looks. If I could have kept it alongside (money no object), I would have.
Maybe I'll return to rotary in the future, when Mazda release the RX-9.

I'll be around, and thank you everyone for sharing stories, advice and help over the years in this forum :-)

Jon