"Ticking" noise when accelerating

[greg.harvey]

Hi all,

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?

Look forward to enlightenment!

Rgds,

[rocket]

Pinking?

[Jason1]

Servo pipe tapping on the bulkhead?

[greg.harvey]

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.

[greg.harvey]

Having done a bit of research, I wonder if it's a fuel pump? References:

http://www.lotuselan.net/forums/viewtop ... 3440#43440
http://www.lotuselan.net/forums/viewtopic.php?t=491

[paddy]

I guess the obvious question is do you have an electric fuel pump and, if so, where is it?

Mine is in the boot and, as with some of the commenters on thread you referenced, you can hear it at idle but certainly not under acceleration.

Paddy

[greg.harvey]

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!) ...
http://www.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?

[Robbie693]

Exhaust manifold to head leaking?

[terryp]

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?

Terry

[greg.harvey]

Thanks for all the suggestions!

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?

[Robbie693]

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

[greg.harvey]

Ok, thanks - I'll check that.

[collins_dan]

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

[gwiz22]

Greg,

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.

Regards
Graham
'73 Plus2 S130/5

[greg.harvey]

I'm not alone!!!

Well, likewise if anyone works it out before I do... I'll certainly keep you posted.