I have had a +2S (big valve) for nearly 6 years now. Ever since day one it has made what I can only describe as a rapid “ticking” sound when you accelerate. The sound appears to come from the near side of the engine bay (that’s near side in the UK, so reverse that for everyone else!) It has never bothered me, as numerous Lotus specialists over the years have serviced (and driven) the car and none of them have commented.
But now someone is looking to buy the car from me, he’s asking what that noise is and I honestly have absolutely no idea! I guess it must be normal, or one of the umpteen Lotus mechanics who’s looked at it would’ve mentioned it - does anyone know what it is?
It’s certainly not pinking, because it’s coming from the wrong place and it doesn’t change in tempo or volume with the engine revs. And if it was, I’d have more than a right to be annoyed with the service engineers who didn’t mention it after 6 years! (Actually, 6 years of pinking and I probably wouldn’t be running any more, period…)
Anything tapping on the bulkhead is unlikely as well, because I’d expect this to make a duller sound. This is almost like a watch ticking - very high pitched.
To be honest I really don’t know and I can’t easily do a visual inspection now, because the car is in my rented garage, half a mile away, but Otto’s symptoms in this thread are exactly mine (except it never bothered me!) … lotuselan.net/forums/viewtop … 2584#12584
So since I can’t think of anything else it could be (and searching turns up nothing either) I’m guessing it’s a noisy electric fuel pump mounted in the engine bay. Unless someone has another idea?
One other thing is the noise comes from somewhere near some gubbins connected to the after-market Cobra immobiliser. Could that make a noise? Or could it have some sort of fuel regulator or pump as a part of it?
Hello
What about the headlamp vacuum; switch or non return valve depending on the position? Do your headlights stay down or do they come immediately up after a drive?
Robbie693: for 6 years? I would’ve thought that would’ve been picked up by someone and cause some damage?
terryp: could be - hadn’t thought of that - but headlamps operate fine and stay down for several hours after the car has been stopped. (They’ll creep up over night, but that’s hardly surprising…) But there’s a little vacuum pump on the headlamp mechanism isn’t there? Could it be noisier when the car is revving harder?
A slight leak from the manifolds wouldn’t cause any damage. It’s easy to check - have a look to see if there are any carbon stains on the head or hold a tissue next to the flanges with the engine running - if it blows around you have a leak
I have the same ticking noise. It turned up after a recent engine rebuild. Apparently the header doesn’t fit flush against the head. Slight gap by #4. In my case the header needs to be removed and replaned. Not a big deal. It’s on the “To Do” list, but a ways down. Dan
The description of your noise is exactly the same as I have been struggling with to locate on my '73 Plus2. The noise is not there when stationary and at tickover or when you increase the revs while stationary, but as soon as you are out on the road and you put your foot down, tick, tick until you back off the throttle. I was convinced it was an exhaust leak and where the 4 barnches meet into the Y piece and then into the main pipe, there were traces of black soot (my other problem is the engine runs very rich). So after removing the exhaust from the manifold back, I cleaned up all the joints and replaced system with copious quantities of exhaust paste it was all to no avail. The ticking noise remained. I have checked around the four branches of the manifold where they bolt onto the head but cannot find any traces of an exhaust leak. I think I might have another more scutinous look this evening. If you do find the source of your ticking, please post.
Most twincams make tappetty noises, some worse than others, without any problems. Just rest a long screwdriver on the cam cover and put your ear to the handle end and see if that`s where the noise is coming from.
Jim
One of the most obscure odd noises I’ve encountered was caused by the heater fan windmilling. Check by switching the fan on and/or changing the damper positions
Just to eliminate the electric petrol pump theory,
do you get a fast clicking when you turn on the ignition for the first time when cold that then slows down after a 5 seconds or so?
I once fitted a Morris Minor fuel pump to an Alfa Zagato without using rubber mounts - the sound through the metal bulkhead was very ‘distinctive’.
A broken valve spring can make a ticking noise. This would probably be present at all revs including idle but not necessarily. Check valve clearances and compare against previous readings.
No, silence when it starts. Only under power. I’m going to have a much closer look this weekend.
Bear in mind the noise has been there since I bought it, 6 years ago. I would hope that after 6 years of servicing, someone would’ve picked up on something like that… You never know, but I’d be both surprised and annoyed if it was a broken valve spring, as that sort of thing is supposed to be checked annually. That’s what I’ve been paying people for!