I’m looking for technical help or recommendations on: An Engine Rattle
Posted here a month ago about this issue, my car rattles on startups when the oil has had time to drain from the pan, as it’s warmed up (and the oil is thinner) it seems to be doing it more. The dealer i bought it from thought it was a timing chain tensioner and replaced that, the problem still persists. The car has been doing it for about 4 months now, in that time i haven’t been driving it gently so i really doubt it’s rod bearings or a main bearing as i would have thought that would have gone pop by now.
I’ve had a few people say it could be oil just taking time to fill the top end of the engine and rattling whilst it’s doing that which would be fine as the engine is almost on 100k and that’s still something i can live with. The idler pulleys and tensioner for the aux belt are all very rattly however even with the belt off the engine still rattled slightly (only started it 3 times so can’t be sure if the fact it rattled less was a fluke) and i don’t have the money to replace them before the 6 months of consumer protection i have from the garage expires.
I’m just looking for some advice on what to do and where to start looking for anything to conclusively find out what is causing this rattle.
I could tell you, but I doubt you’ll be driving 4hrs to get here. I could have told you/them it was a complete waste of money doing the chain tensioner (if they actually did it) as that won’t have been cheap.
You’d be better off taking it to an engine specialist.
Does it use oil at all and over what kind of mileage? I’m guessing it does.
When was the last time the oil filter was changed?
It doesn’t burn any oil at 90k miles, it’s in otherwise perfect condition, no hesitation anywhere in the rev range. Oil filter was changed at 86k and 88k to diagnose this issue, seemingly made not much of a difference. I am inclined to believe they replaced the tensioner as they gave me the old tensioner, chain and guided and all the reciepts as well as an invoice.
Just found this video which has the same rattle at about the 31 - 37 second mark, which was eventually solved by replacing the alternator pulley, the noise is the only time i’ve heard my exact noise outside of my car, just weird that it doesn’t go away completely with the belt off, it’s a massive headache
Now we get the video we wanted in the first place.
If it’s under warranty I don’t know why you’re paying the bill and it’s odd how it uses no oil.
It sound like bottom end knock to me, but I can’t commit as it’s not in front of me. Decent engine builders have an ear for it, which is why I suggested you go see one.
If it is it’ll knock very lightly (and undetected to the average Joe) on the over run. Shame you changed so many filters because the evidence will have been in there and still might be.
Engine failure is not always binary.
The only other way is to get someone to drop the sump, but before that cut the oil filter open for an inspection.
It’s a shame in a way it’s a cheap car with dealer mark up, because legally proving it will cost a good chunk of the car itself now.
The message to anyone else reading this is don’t ■■■■ around, go see someone who knows what they’re talking about immediately. Poirot never solved a case after some other A hole had trampled all over the scene and lost all the evidence.
If you’ve ever watched a crime/murder drama on TV or witnessed it for real then you’ll have seen how well they protect the scene of the crime. That’s because after every other amateur has had a go the easy evidence is long gone and the job gets much harder.
As engine builders all we want to deal with is the facts, but sadly human nature gets in the way which makes things difficult.
I can’t hear any of the signature rod knock rattle in the RPMs it usually shows up at which is what is driving me mad, there’s slight rattling from the idlers and tensioners but can’t hear anything from the engine, also surely with rod knock wouldn’t it be very time limited I’ve driven this car almost 4000 miles and up to redline almost every day and it’s not got appreciably worse, surely lends credence to something else being at fault
My advice would be to return it and get your money back. Then post up some details of it on the internet incase anyone else tries to buy it.
It’s odd how you’ve hung onto it for so long and not done that straight away.
At this point you won’t get all your money back. The difference will be based on time, not how much you used it.
But you think now the alternator pulley assembly might be at fault and you cannot afford the repair. This is a part that could fail at anytime, including many other parts. Its an old car, and its inevitable repairs will be needed during your ownership. Probably need to review what budget you have to maintain any car for the next couple of years at uni. My first car at uni was a 7 year old 1981 Mini van, completely rotted to the core (showing how far cars have come in the anti-corrosion stakes). It kept breaking down, and I couldn 't afford to fix it. Complete mistake, but I learned from it. During my second stint at Uni (PhD), it was a 1983 VW Polo; ran like a Swiss watch, only owed me oil changes, tyres. Boring perhaps (though they seem to have come back into fashion lately) but it served a purpose. But I forgot all those lessons and ended up with a 5.0 Cougar with two burnt exhaust valves in my first real job…
Back in the day, when there was a student running anything remotely interesting, unless they were wealthy, they would be seen fixing the car themselves in the carpark. This is why NBs make more sense as a car to run on a shoestring. Parts are generally cheap, lots of perfectly good pattern parts when they are not, and the cars are not complicated, without need for special tools.
The message should be don’t buy a car you can’t afford to run. It will end in tears. Not redlining the engine everyday might help contribute towards building up a repair fund.
Just took it to a specialist and he suspects its a bad oil pump causing the timing chain to rattle on startup, he doesn’t suspect rod knock, so I’ll get some more opinions, can’t get another mx5 in as good condition if I return it.
It’s not the oil pump so i’m lead to believe that was no specialist in these cars or engines.
To change that is another big job, but as the sump will come off anyone doing it can check for rod bearing damage so at least they’ll know then for sure.
I don’t know why you’ve come here for advice because you’ve ignored most of it.
I just don’t see how it can be a engine bearing with the ammount of miles I’ve put on it and how hard it’s been driven, bearings do not last long when they go and do not progress slowly, I’ve spoken to performance link (who builds mx5 race cars and just works on mx5s) and they think it’s timing chain rattle caused by something, when everyones telling you different things it’s hard to know who’s right, no point getting upity about itm
I also usually have about a £1000 buffer for affording to run things but thats was eaten up after I spent about £2.3k fixing my previous VW Up! And about £500 on getting this mx5 back up and running (aka servicing, rust treatment,etc) , it’s just come at a bad time.
