Triumph 6 cylinder engine death rattle - please explain

[Forkie]

Ok so as title - i have looked extensively on this in last few months and have NOT got anywhere, not definately anyway....so in other words, i am asking the experts what the 'death rattle' actually is, what it sounds like, what causes it, and what is actually making the rattle - top end or bottom end.

I await replies....

[Charles H]

The rattle is the big end bearings knocking. This is commonly heard on start up especially on cars that have nor had a spin on oil filter conversion. The original design allows oil to flow back to the sump and therefore on start up the big end bearings do not have any oil until the oil pump fills up the filter and the pressure rises.

[Roscoe]

My understanding of it is that the big end bearings are designed to hold the oil in the bearings until oil arrives from the pump under pressure the fact that the bearings knock on start up usually means they are worn which causes the oil to drain out the bearings and back into the sump.

The PI I had in the early eighties had a badly worn crank and main and big end bearings I rebuilt the engine with help from a first rate mechanic with re built crank and bearings and new piston rings.
The engine never knocked or rattled on start up after that and still had the original oil filter on it, if the spin on oil filter was available then I might have put one on.

I am certainly going to put one on the PI I have got now as recommended by Chris rabbets, but I am going to get him to do it as now I can afford to get someone else to do the work where as when I was younger I couldn’t afford the professionals.

[Dave B]

To be fair, it is a simple job to fit a spin on filter adaptor.....just one bolt...remove old filter & bowl....fit new 'o'ring in block.... fit new filter & housing....one bolt....Done!

[Forkie]

Im going to have to send this info in stages, i keep getting timed out, try to send a longish post and its gone Purchased in 2006 at 46k,more or less one owner,everything standard factory including bowl type filter element. That went as soon as , replaced with an adaptor from Moss and GF166 filter. Being an 'S' on Auto, the filter lies at 45 degree-ish due to the pipework beside the sump. Only covered around 1500 miles before decision was made to pull from road to refurbish, which took way longer than expected. I do not recall any unusual noises from that period.

[Forkie]

During the long lay up period, any time the engine was going to have a run, the leads and or plugs were ALWAYS removed, to allow on spinning the starter the oil pressure to build/ light to go out before then going for all out proper start up. Always started well with no issues, and i let it get to normal temperature before shutting down. I also changed the oil during this period.
Fast forward to the end of last year when she was off to get sorted , i or that should say we , as my youngest at 12 is well keen on her - had quite a lot to do to get mobile again, to be able to drive out of it's nest and on to the back of a truck. So over several weeks there were several starts and moves, all the same way as before as it was so cold, and a week or so between moving. Early January we get her back, with some issues still to sort,mainly the 'box - which is still waiting - why did i say those words ' there is no rush, i know you are busy'....

[Forkie]

Being the time of year it was, the first few months were sporadic with getting her out - and as we still seem to be limited to 40mph, only around our local area - but at least it keeps everything moving and i still get to enjoy driving her again, albeit not very far. I kept on with the leads off /prime oil around way of starting. Until we had the chance to use her 2 days running ,and so it was the second day when we went for an actual jump in - pull choke - start engine as normal that i heard this rattle . Obviously the lad could tell by my reaction that something was amiss - he said he had heard it before, on one of our trial start ups a few months back - he caught it on film, i didnt realise, so we must of had it running two consecutive nights then - that period for me was a bit of a blur - getting so much done on the car right before Christmas, and still fitting work in....

[johnnydog]

Later engines fitted with HS6 carburettors didn't have as much room for the air filter box, hence the 'elephants truck' collector box and remote filter container. The slant of the later engines with the additional spacers also meant that if using the oil filter conversion, the longer filters fouled the lip on the chassis leg, and required the lip filing down to accommodate them in the near vertical position.
Another point to bear in mind is to check that the filters supplied actually do have a non return valve - those recommended from CW do have the non return valve, but some other makes and some shorter filters don't, which defeats the object of the conversion.
This has been discussed previously, but I don't have the conversion on any of my Triumphs. If they have been standing for any period of time, or starting from cold, I churn the engine for a good few seconds so that the oil light goes out before pulling the choke out. Even if the oil doesn't go out with this procedure, when the engine does fire, the oil light goes out virtually immediately. None of them have the so called 'death rattle' when the engine fires. If your engine does have this symptom, then an oil filter conversion will help to a degree, but won't alleviate the problem - a bottom end rebuild is the only real way to cure it.

[Forkie]

Back to now - so the rattle went very quickly - no more than two seconds - all sounded well so we took her out and about. Sounds ok, starts well ,in fact it starts better hot than cold, but the carbs need setting up properly. The other thing that occured on this run out was the lad wanted to take some short videos so picked a local quiet spot. Whilst in to D or R, holding on the brake before moving, the oil light was just flickering,until i moved off - then it goes out. Nothing when on the move, or just at idle in P or N.
I have since done a test of starting up, from cold, with everything connected but no choke - filmed this so i could look back and see how long it took for the oil light to go out. So from first crank over, it took 12 seconds ( with one switch off and back on again) for that light to go out I then pulled the choke and started ok. Current oil is Halfords Classic 20/50 with a CW non return valve filter, which are the only two things that have changed engine wise.
The noise to me sounds up top, which is why i mentioned in the initial post but noises do travel i suppose. I am not expecting any positive comments back on this, and to say i am a little cheesed is an understatement, as i thought i was doing all the right things. So i now could be looking at gearbox AND engine rebuild - obviously she is not keen on leaving its nest

[johnnydog]

The oil light flickering on tick over in drive or reverse does indicate that the oil pressure is too low. The oil pressure increases as you pull away which is why the oil light goes out at this point.
Had it not been for the death rattle, I would have suggested changing the oil pressure switch, but I suggest the problem is elsewhere.
Would it not be relative simple to just plumb in a temporary oil pressure gauge under the bonnet? You can take if off a two way adapter from the same gallery as the switch - one side for the switch and the other for the pressure gauge, or just temporarily do away with the switch until you have checked it with a gauge? That would give you some idea on the oil pressure before you start more remedial work.
Some oil pressure switches extinguish at only 3psi, so if yours is flickering in drive whilst stationery, it suggests your oil pressure is way too low assuming your switch isn't faulty.