Exhaust rattle on 1600

[Paul Greenway]

A few weeks ago on the first time out this year the first job I did was top up the tank of my 1600 Sport. Unfortunately I filled it with V-Power diesel. What an idiot some might say and you would be right!

Within a mile the car started popping and banging and rattling so I pulled straight over. I knew exactly what I had done and checking the receipt confirmed my fears. I called the AA who sent out the 'Fuel Doctor' (eventually) to drain the tank, clean out the lines and the filters, check the carbs and top up with 10L of super unleaded. He got it going but it struggled (and rattled) to the fuel station where I brimmed the tank. It started running better and since then I changed the plugs and have done about 100 miles trying to get rid of the smell of diesel. Over this time the smoke has disappeared and the car is running great but under acceleration this annoying rattle remains which seems like a loose exhaust but am unsure. When I spoke to the Fuel Doctor at the time he said it has most likely been caused by back pressure when it was coughing and spluttering.

Does anyone on here have any other ideas? Any advice would be most welcome, cheers.

Paul.

[neil-yaj396]

Could a baffle inside the exhaust box have come loose?

[lancialulu]

Could it be pinking (preignition)? Residual diesel in fuel could effectively increase the compression and if ignition timing is not perfect it could pink.

[chriswgawne]

I cant see that your diesel mishap would have affected the exhaust system....much more likely to be as Tim says.
Chris

[Paul Greenway]

Thanks for the responses guys,

I'm not sure that it's pinking it appears more exhaust related. I thought the exhaust maybe loose but it feels solid enough and all the hangers are still in place. I cannot hear an rattling when idling & adjusting the throttle, it just seems to appear when accelerating in 3rd or 4th or caught in the wrong gear going up an incline for example.

[lancialulu]

Thanks for the responses guys,

I'm not sure that it's pinking it appears more exhaust related. I thought the exhaust maybe loose but it feels solid enough and all the hangers are still in place. I cannot hear an rattling when idling & adjusting the throttle, it just seems to appear when accelerating in 3rd or 4th or caught in the wrong gear going up an incline for example.

definately pinking scenario

[jus]

It sounds like pinking to me. The only other thing that I can think of from what you describe, is the engine moving under load causing a part of the exhaust to touch either the bodywork or the gearbox. Retard the timing (after marking the current position) and see if it stops it to rule out pinking.

[Chris Hopkins]

Having owned two 1300s and one 1600, I have found that it does not take much to cause the 1600 to pink where as the 1300s are far more flexible/forgiving and takes a lot to make them pink.

[Paul Greenway]

Gents,

How does a mechanical layman tell at idle if it is pinking? Is there a way?

I took it out again yesterday and the pinking/rattle is considerably less pronounced than it has been over the last few weeks since the diesel episode. It's starting better, idling better and smoking a lot less too.

All advice welcome. Cheers.

Paul.

[jus]

Not at idle. The engine needs to be under load. Going up a hill in 4th or 5th, that you would normally be in 3rd for and then giving it some accelerator pedal should cause the noise - if it's pinking. But - you might also induce the noise if it happens as a result something touching the exhaust as the engine moves - which it will under load. The best way to rule pinking out, would be to retard the ignition by a few degrees to see if it changes or eliminates the effect.

[Charles Frodsham]

It does sound like possible pinking as suggested by other members.

Pinking on a 1600 is a very particular sound once experienced, and I find surprisingly loud. Typically occurs, for example, on a slight incline with relatively low revs, say 2500-3500, and is provoked by gradually depressing the throttle. To my mind, it sounds like it is comes from the exhaust manifold at the front of the car, rather than the rest of the system to the rear.

Diesel mixed in petrol has the effect of lowering the Octane rating, so pinking is more likely. I would assume that the diesel, which is more dense, may end up at the bottom of the tank if the car is left for a while??? I assume you brimed the tank with Super unleaded?

[Paul Greenway]

Thanks all again for your comments & advice.

The more people respond the more it does appear to me to be pinking.

Charles- your description is spot on, my car does exactly as you say although the last time out it seemed quieter, ran better, smoked less than immediately after my diesel escapade. The diesel was sucked fully out of the tank and removed from the lines and filters to the best of the mechanics ability. I filled up with V- Power immediately after the event & once half full, brimmed it again. Next weekend I will run it again and brim it again then change the plugs once more & check out.

If it pinks again, how do I overcome/resolve this matter? Will it be a simple fix at a trusted garage or is it a big job on a Fulvia? Reading up on pinking/pinging/detonation/preignition reveals a mine field of responses- some ok other not so and has just left me confused.

[Jai Sharma]

It sounds like pinking to me too. I would drive it about trying to avoid pinking much) to ensure you get all the diesel out (cleaning and pumping seems unlikely to me to remove it all).
If it remains then as said above the ignition needs retarding slightly. Put some paint on the distributor to mark the position and then undo the one nut at the dizzy base and rotate it slightly so the spark comes a tiny bit earlier. I think it needs rotating anti clockwise but can’t remember. You can see the direction it goes with the dizzy cap off, when you crank the engine. It really is a very small movement, do that and see if it is better.
You might find once you have run a few tanks through you can return the dizzy to the original position if small amounts of diesel are gone. Leaving it backed off will lose a little performance otherwise, assuming of course it was set perfectly in the first place, which is always a doubt.

[Charles Frodsham]

Typo I think……Spark needs to come later i.e retarded, clockwise I think.

Any decent garage should be able to help with minimum cost and effort if you don’t feel you understand the process. Where are you based…..is there a fellow member nearby?

[lancialulu]

Virtually always you know if you are retarding the ignition when twisting the distributor ever so gently (clockwise from  memory) with the engine running as the engine slows. If the engine runs faster youhave advanced it....