Who's that knocking?!?

More accurately, what’s that knocking? Just recently my BBR Turbo has developed a really worrying (and loud) knocking noise when warm. It’s got worse, too. Sounds like a tractor! The level of vibration feels as if the engine/transmission/car is about to shake itself apart! Temp & Oil Press. gauges seem to be reading ok, it’s not smoking, it will just occur at random (usually during a longer run) & sometimes goes away, & when it does so it’s throughout the rev range (though not at idle). Today was the worst it’s been & also smelled hot (though gauge still read ok & coolant level ok). Incidentally, today also featured a squeal from the front end (but i think that’s merely a belt tension issue). Any ideas? could it be as drastic as a big end issue? Going to try & get it in somewhere, but just wanted some opinions, thanks…

Hi Richd, sorry to hear of your problem, if you rev up the engine and let you foot off the throttle do you hear the knocking noise if so you could have a bit of pistion slap,this usually happens when hot, have you done a compression test even if it just to rule out a loss of compression (rings or valves) or you could have a problem with the hydraulic tappets the oil gauge is more for show on these cars, the squeal could be a belt slipping or the alternator at fault.


 Couple of things to check rule out: presuming your engine has a short-nose crankshaft (1990 vintage) check for possible backlash in the bottom pulley as the woodruff key slot may be worn and allowing the pulley to rattle back and forth (relatively easy fix available involving Emetal). The other thing I would have a good look at your engine mounts, as the BBR produces a lot more torque and is therfore likely to tear the rubber in the mounts, if a rubber mounts has split or come apart you may be getting excessive vibration into the subframe and body.

Hope you get to the problem soon and it isnt an expensive repairThumbs up

Dr. EunosGeek

Turbo bearings? If your oil pressure is ok then it’s not big ends, do a compression test to rule out a broken ring, have a look at the crank pulley as Taff suggests, although in my experience when the pulley fails you lose all the power at the bottom end and it suddenly all happens at about 4.5 k RPM

Thanks Gentlemen, I’ll look at all those options when I get chance. I’m hoping it’s something (relatively) simple like the pulley, or the engine mountings. Turbo bearings? the turbo seems to be working ok, though I’m led to believe the boost was increased to produce 180bhp, that said there’s an extra cooler fitted to help…   I’ll also do a compression check, flush out the cooling system & change the plugs while i’m at it. If I replace the mountings are uprated ones available from anywhere?

Thanks again Smile

Well, in the end I’ve put it down to a siezed (on) front brake caliper… With that replaced (plus the wheel bearings on both sides) I enjoyed a fault free (well 99%) 140 mile trip to the Hope Valley Motorshow.

Thanks again for all you’re help & advice, guys.Smile