Thanks all for the tips and pointing me in the right direction.
I had exactly the same symptoms with the original 998 A+ engine my car came with. Changing the timing chain and tensioner did not remedy the problem. I even checked the cam to make sure no lobes were chipped.
I tried numerous things to no avail, the one thing I didn't try was an octane booster in the fuel to avoid pinking - if your engine is the city e they ran high compression to partially compensate for the over high gearing.
In the end I gave up and swapped in another motor. Hopefully you'll have more luck.
Engine came from a 1990 Mini City, I do actually also own an original low miles (20k miles) 1990 Mini City totally original, and the engine in that runs so sweetly, I know its possible for these late A+ engines to run sweetly and quietly! even on current 95RON unleaded.
It does sound a bit quieter now that you have adjusted the valve clearances. When you moved you camera to the area at the top of the timing cover it sounded to me like there was a scraping noise, this could come from a broken tensioner? When I did mine I drained the oil because I was doing a service anyway but I don't think you need to, especially as you need to jack that side of the engine up when you remove the engine mount. Replace the timing chain while you have it apart; it is a cheap part and you can time it easily using the dot to dot method, you don't need to use anything more on a standard engine. Just take your time. If you are going to all of this trouble, it might be worth you whipping the head off as well, cleaning up the valves and piston tops and replacing the rocker shaft. All cheap parts which could make a significant difference to the way your car sounds and drives. I did this on a 1275 over Christmas and found horrendous wear on my rockers (replaced for new) and a broken timing tensioner. Since replacing this the car runs very quietly and I have notice a massive improvement in fuel cunsumption. I always had problems with timing scatter and this has been almost eliminated.
It is a fair amount of labour to do both jobs and I also needed to whip the clutch cover off to replace a worn plunger when I did mine. If you have a few jobs to do it might be easier to lift the engine out and work on it although all of these things can be done in situ, just more fiddly.
I agree Im convinced at least part of the noise is timing chain/tensioner. I have purchased a new timing chain as advised. Im sure I will be able to change the chain, tensioner, gaskets + seals etc I just panic/over think things some times. Last year I changed the timing belt, tensioners and water pump on my 1998 Celica GT daily drive, looking at the Mini I have more room down the timing chain side of the engine with the radiator removed than I had on the Celica! and should be very much more simple than the DOC engine on the Celica. Soon after the clutch also failed on the same car, and no Garage would touch it as too old/specialist so ended up changing the clutch on the drive way!
Aiming to do the whole job with the engine in the car, luckily I did most jobs before fitting the engine, except the timing chain! The clutch is completely new including new plunger, release bearing, clutch plate and clutch arm etc covered only a few hundred miles.
Do you have any tips for knocking back the locktab on the crank pulley, my first though was fit the 1 5/16" socket and tap it with a rubber mallet. As the pulley is recesed it seems access is hard, which leads me on to how would you knock the new tab back over when refitting?
I have looked at posts regarding dot to dot on the sprockets, and can see I need the engine at top dead centre and the rota arm will be pointing to piston 4 HT lead. As both the crank and the camshaft seem to be keywayed and we are only dealing with one camshaft it looks like it will be difficult to go far wrong as long as the dots are in line before and after assembly, correct?
I have also purchased a new rocker shaft, and will inspect the rockers when out and post a picture here if unsure as to condition of rockers. I have read that removing the rocker assembly completely/ undoing the rocker shaft pillars/posts can disturb the head gasket. Don’t want to go as far a head gaskets at the moment if I can avoid it. However apparently it is possible to slide the rocker shaft out side ways after undoing the split pin on side, I read there is a locking screw somewhere, is this accessible in order to slide the rocker shaft sideways?
Interesting you mentioned timing scatter in your post, I felt when setting the timing with the timing light that the crankshaft mark was jumping around a bit, perhaps by 2 or 3 degrees, not massive but noticeable.
Change that coil! I bet your issues go away then. Don't buy anything with Lucas on it, its not up to scratch. Source one from Simonbbc.com Give them a call on monday.
We had the exact issue of lack of power (just changed the clutch!) then the issue started. We changed carbs, dizzy, new coil etc... countless bits then I went to go over it again a third time and thought I'd borrow the coil from my other mini.... Problem solved instantly! Fitted a new coil and it ran for 3 years with no issues.
Hope this helps and apologies for the story!
Cal
Thanks for the tip for quality coil. Only fitted the Lucas DLB105 coil and Accuspark electronic ignition module the day before starting this topic! All symptoms were the same with my original setups (59d points) and ballast coil - an old Bosch/Unipart item that must have been 30+ years old.
Had a look at Simonbbc eBay store, I image you mean the 'viper' coils they have listed. I agree the quality of parts these days can vary widly, however was impressed with the weight and overall quality of the Lucas item as far as modern parts go!
Im never sure I buy into coils being blamed a lot of the time for ignition problems. I do however come at this from a different angle from most car people. My old man worked for Marconi’s and moved on to become a DJ and Engineer on Radio Caroline in the 1970s (yes when it was on a ship at sea), some of the electronics/engineering skills have rubbed off! As far as I’m aware a coil is a basic transformer with a single primary and secondary winding, converting the 12v primary voltage into a very high voltage (tens of thousands of volts) on the secondary winding at very low current. I can only really see two fault conditions - open turn (ie no output at all), or shorted turn (lowering voltage on the secondary, possible internal arcing causing voltage fluctuations etc.). Its possible Lucas have cheaped out on the wire used in the windings and or insulation materials, making shorted turns more likely.
Im going to stick with the Lucas coil and run it for now. If it gives me any issues I will look at the coils offered by simonbbc. I also have a spare original standard Lucas coil from my Clubman Estate (dated 79), still works just looks a mess, that to was replaced with the DLB105 about 4 years ago.
Those crank dampers go bad with age. 2 parts held together with rubber. It’s not clear on the video for me, but if it’s gone bad replace it immediately.
Will take a look closely at this when its removed, if suspect I still have the old engine that came out of this car (a 1988 A+) so can inspect that and swap for that crank pulley.
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Thanks all will report back when I have got a bit further with the timing chain and rocker shaft replacement.
Edited by Norris73, 23 February 2021 - 12:34 PM.
