340 Tinkling sound up steep hills

My 1988 Volvo 340 DL (1.4 cc) is making a tinkling sound when under very heavy load travelling up steep hills. The noise is a loose metal to metal ‘ping’ sound and is surely pinking.

Under heavy acceleration, the pinking is not always apparent, however it sometimes tinkles for about 2 seconds max. Steep hills bring it on strong.

Driving up Fish Hill (long and steep) in the Cotswolds the other day set it off almost constantly as I held the accelerator over half way down in 4th gear at around 48mph to maintain speed.

Local mechanic told me pinking is either imminent head gasket failure or carbon build up, thus needing de-coke. Head gasket is fine, so is it just carbon build up? I thought modern petrol prevented the latter.

Could it be a possible carb problem such as incorrect adjustment of mixture settings, or air leaks?

Perhaps I should have carb looked at by volvo specialist to check all adjustments. Also, ignition timing checked.

The dis. Cap, rotor arm, plug leads and spark plugs haven’t been changed for 3 ½ years. Don't suppose this could be likely cure.

I am concerned as the engine is in good condition having covered 62,000 miles, and I have heard pinking can damage engine parts.

I would be most grateful for any advice on what I should do about this problem.

Thanks, Matt.

If there is nothing obviously wrong and the car drives normally it Sounds like it just needs maintenance and a good hard drive.

Replace all the service items and get the carb adjustments checked, normally an MOT will check the mixture is not too rich to cause carbon build up, but the short drive and choke use could cause extra build up. Usually I find its caused by too much fuel, or bad atomisation caused by airleaks, sticky throttle levers on the carb and subsequent wrong adjustment. It sounds like you know the causes so get the engine maintained then start looking for other faults.

I had a pinking 360 with a variable jet in the day when there were no emmission checks, needle/jets wear on these leading to loads of fuel use and black smoke under some conditions, even this did not cause excessive carbon build up, but it did cause pinking which was cured immediately I replaced the needle and jet and adjusted correctly.

Your carb won't have that problem but badly adjusted carb, breather problems, dirt air leaks are well known usually due to bad workmanship.

Provided you have the correct ignition computer, the timing should not be an issue, it not adjustable. A crank sensor senses the position of the crank and it electronically timed to a preprogrammed map. I've never heard of it but an ignition timing check would reveal if the advance vacuum sensor was faulty.

"Sounds like it just needs maintenance and a good hard drive."

That would be an "Italian Tune Up" Cures all manner of problems.

I like to give mine a good thrashing on a dual carriageway every now and then just to keep things clean.

Especially recommended just before an MOT

Will Plummer

Hi

Just another view point do you think the timing belt is on its way out at 68000 this has proably not been checked.A good test is to run the car on flat road put her into top gear at lowset speed possible.Then floor the throttle to see if pinkering occurs if the pinkering apears but disappears when the speed is bulit up up to say 55 to 60 the i suspect the timming belt is stretching under load, as described when climbing hills. the run on flat road will confirm this,and if the belt is on its way out then fix asap.

good luck with solving this one and lets us all know how you get on.
Mr wizzy

Mr Wizzy.
it's a 1.4 and they don't have timing belts....

Thanks very much for your suggestions, and sorry for not replying sooner.

I plan to book the car in for mainly servicing of the carb.

Agree that all it probably needs is simply general maintenance. I'll kindly ask my Dad for help with some of the other bits. (Shouldn't be a problem after offering to buy him a pint!)

Haven't started on it yet, but will keep you informed on progress.

Thanks again,

Matty