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My model of MX-5 is: __NC Kuro Edition
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I’m based near: __Blackpool
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I’m looking for technical help or recommendations on: __Engine noise
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I’ve made a bit of a pig’s ear of this post already so here’s what I really want to know.
I had the BBR 200 upgrade 18 months ago and never noticed anything unusual until the Elvington world record event last summer. Driving around the circuit at slow speed highlighted an irritating engine ticking noise under revs. I’ve had it back at BBR and they assured me this noise was normal for their cams and to go and enjoy the car. Now I’m not doubting their word, but I’d feel a lot better if others with similar upgrades were experiencing the same issue. What say you……?
I suppose you have been driving the car since summer? Oil level checked and is correct? Never overheated?
Where the noise coming from?
If its from the cams - and i suppose they are high lift cams - it may be the valves. A bit tricky this one tbh
They recommended a thicker oil, the exact spec escapes me now, but it hasn’t made any difference. I’ve had no issues whatsoever with over heating or anything else and the car drives great. I drove 90 miles yesterday to the lakes where it became noticeable and irritating again hence the post. Note, it only does it when the car is well warmed up.
……yes they are high lift cams.
well if I were you I’d try figure out where the noise is coming from.
My guess:
If its from the top, as I said before its the valves. not sure if the noise is “normal” but I’d be asking to understand the why. I dont know their process but generally if you make changes to the head and you haven’t taken the valves out you don’t need to reseat the valves. if you have taken the valves out I’d want to reseat them. do they change the valve springs as well? I dont know. The valves due to their mass have inertia and if they are pushed further out as the cam lobe moves from the max lift to lower, it may loose contact with the rocker - so the roller is now unloaded and when the spring pushes it back it makes contact and this is perhaps what you may hear. If this is the issue the remedy for that is aftermarket lighter valves not oil change.
If its from the middle of the engine it maybe the piston connecting rod (commonly called bottom end) - that’s a rebuilt
not sure what they mean about thicker oil. the oils have two numbers lets take for example 5w-30 and compare that with a 10w-40. the first number is the behaviour of the oil when cold, and the second when its warm. I forget the exact test they do but the numbers relate to oil viscosity - or how “thick” the oil is at that temperature. so 5w-40 in colder climates is probably better as the oil will be more fluid in cold temperatures and will help lubricate the engine during start up but in hotter climates the 10w-40 is probably better as the 40 means the oil flows better - therefore better lubrication when the engine is running. its s compromise.
If BBR regrind OE cams to produce more lift (and alter the timing) the base circle will be smaller, which could result in the HLA’s running out of travel to take up the slack, however I would have thought that given the numbers of engines they’ve modified and the reputation they have this is unlikely. If the cams are produced on virgin blanks this won’t be an issue, as the base circle would be standard size.
Low oil pressure could be a problem, as could worn HLA’s,(which could tie up with it being worse when hot) but without hearing it it’s impossible to even attempt to diagnose, it’s all just supposition.
A video with sounds would help.
Also check out the bearings on the items driven by the serpentine belt, eg tensioner, idler, alternator, the A/C PS and water pumps, and the belt itself!
It is possible to run the engine briefly without the belt (fiddly removing and replacing it). If the noise is absent, then don’t worry about the engine and instead check the ancillaries.
While the engine is OFF and the belt is still off try turning each ancillary pulley by hand, they should be silky smooth with no snagging or noises.
A mechanics stethoscope is a handy tool for pinpointing where a noise is loudest, but also remember metal transmits noises well over distance.
In the past I’ve also found a bit of old 3/8" plastic ‘fish-tank tube’ can be useful for the more inaccessible spots
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Im just talking generally here regarding the skyactive engine…
Do you know whether they disabled the skyactive (HCCI) function? The engine mode is inherently noisy and was introduced by Mazda to lower emissions at part throttle - and although i understand why they did it i don’t really think it should be implemented in a sports car. The ticking (or knocking) noise could be that - primarily because combustion happens quite violent as the fuel combust due to autoignition and not due to sparking.
This however would not be present in an NC
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Im going on a tangent here so please excuse me. I wouldn’t expect mazda to only use this mode on start up, the reason I’m familiar with it is because i worked on this engine mode back in 2005-2008 while i was an RA at Birmingham uni. Mazda was so far ahead and everyone was playing catch-up and in the end mazda were the only company to successfully implement it. As i said the mode is to reduce emissions at part throttle, is really hard to control and i don’t really think it suits a sportcar as engine knock is an inherent consequence.
If i were a tuner and ecutec are able to write a custom firmware for the car ecu I’d completely disable skyactive if possible.
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If its the valves, I’d be asking BBR to clarify what springs were used, have they taken the valves out? have they cleaned the head and reseat the valves (is this needed?) - Basically I’d like to know what changes were actually made other than the high lift cams. If they know what the noise is and where it comes from, can they clarify what it is other than stating “its normal”
I only have the BBR full exhaust and tune so my engine is pretty much stock - so I cant check on my car.
The springs are used in order to keep the valves in contact with the rocker and the roller on the other side to be in contact with the cam. so opening and closing of the valves is controlled. IF that’s the issue and believe me valve lift is a big powertrain issue for all engine manufacturers there is two ways I can see it being solved. Stiffer springs however this will introduce more wear, lighter (and generally more expensive valves) this will help remedy the issue hopefully keeping the same springs.
Yes BBR do fit stronger springs and retainers when they change camshafts on the Super 220 package to prevent valve bounce at the higher rev limit. I am almost certain that they do not remove the cylinder head to do this. There are tools available that allow you to change valve springs without removing the cylinder head.
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Thanks for all your input folks. Just to add a bit of background, I’ve owned it from new, it’s been garaged all its life, only ever fed Shell V Power, it has a full main dealer service history and it’s biggest threat is being mollycoddled to death! I’ve taken on board all comments but have come to the conclusion that I either constantly worry about it and let it spoil my enjoyment of the car, or trust what BBR emphatically assured me and just get on with driving it. If at some point I end up with my feet on the tarmac and a smouldering engine on the pavement next to me, I’ll take it up fervently with BBR.
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A pragmatic decision which fwiw I wholeheartedly agree with, although it may be worth starting a paper trail (email detailing your concerns, subsequent visit and outcome) just in case……
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Does the ticking sound as though it’s at full engine speed or quarter?
If its at quarter speed, it could be a leaking exhaust manifold,/gasket which does sound like a ticking noise.
As suggested, use a tube ro pinpoint. If it’s a leaking exhaust manifold it will be very obvious as the leaking gas will be very audible through the tube.
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Latest update…… I had the car serviced last week - so the oil level was and still is fine - prior to a camping trip in Somerset from which we returned yesterday. During the trip, in fact whilst driving through the Cheddar Gorge, the ticking noise suddenly became alarmingly louder. Thinking at first it could possibly be the acoustics of the area coming into play, it soon became apparent it wasn’t. Long story short, the AA came to it and diagnosed what he thought to be a hydraulic lifter issue and ‘advised’ not to drive it (as is standard AA garb for any engine noise), though under duress he admitted that if it was him, he would probably risk it. As I only have roadside cover through a bank account, the price to low load it home was £1200!!. I then rang a local to me outfit that said they’d come and get it for £750. A word from a couple of knowledgeable MX5 owners agreed risking it, so I drove home the 240 miles under 3k revs. Unusually, the noise had quietened down to pre-trip levels on arrival home, but I have it booked in with a local independent performance specialist on Tuesday. I’ll not be driving it again until the noise is sorted. I’ll add that prior to this trip, the car had only done 1100 miles in the last 12 months.
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really want a BBR 220 but stuff like this is coming up far too often with modified engines
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