Can't seem to get major fault diagnosed - what would you do?

chubsta

I have never been in this position before so am looking for advice.

2106 model car, which I absolutely love to bits, until a few weeks ago it was by far the best car I have ever owned and I am quite attached to it. Probably valued around the £8000 mark if working fine.

Unfortunately it has developed a knocking noise on acceleration which is proving tricky to get diagnosed/fixed.

Initially I took it into a trusted local garage - they had a it for a couple of days and did lots of diagnosis work (no point listing everything here but they spent a whole day on it). Couldn't diagnose the problem as they felt it was not part of the drivetrain etc and they don't 'do' gearboxes - paid for 2.5 hours diagnosis work (even though they didn't get to the root of the problem I have no issue as they put more work in than they charged me for).

Decided to bite the bullet and take it to the main dealer - I had to have the vehicle serviced anyway so got that done, then they started diagnosis. Despite getting the gearbox out and replacing what they said was a very worn part the problem persists and they are starting to struggle with what to do next.

Obviously I really want this fixed and my biggest fear is that the main dealer will decide they just can't get to the root of the problem, give the car back to me and just charge me for the diagnosis time, which is currently around £700, although to be fair that is probably a fraction of the time they have put in. I will then be left about a grand down overall and am still at square one. And where would I go next - if the main dealer can't find the fault then what hope elsewhere? 

So, now to the point of the post - if the dealer can't diagnose/fix so they just wash their hands of it - what would be the best course of action next?

I continue to try to get it diagnosed - hopefully the next place will find the problem and get it fixed - but if two places have struggled this could go on forever and its not cheap!

Take the car to somewhere like webuyanycar and get rid of it - haven't really looked into this, have sold a car to them in the past and was very happy but although they seem to just require a car be a 'runner' I am very doubtful about giving them a car that has a known problem. I would obviously take a hit on its 'normal' value but then it's not working so would have to suck it up.

Try and sell it privately with the known fault explained to the buyer - really don't want to do this as wouldn't want the risk of any comeback.

Im guessing no dealership would want it as a trade in?

The money involved in this isn't the big issue - I want my car fixed if at all possible but until the actual fault can be identified I have no idea and don't just want to keep throwing money away with no result - even if someone looked at it and said the car could never be fixed and just needs scrapping then at least I would know and would just be forced into getting a replacement car.

So, sorry for the long, droning post, but what would you do - carry on trying to get it diagnosed with the understanding the problem may never be found (although I originally thought such a symptom should be easy to find), or just cut my losses, try to get rid of the car and have the expense of getting another (probably the same model but newer as I love it). If get rid of the car, what is the best, no comeback place, to do so?

RogerPensionGuy

Can you advise exact model car it is please? 

chubsta

Kia Sportage 2016 1.7 diesel

Bigphil1474

When I traded my car in at a dealer they just asked me if it had any MOT on it and gave me their book price off my purchase. They didn't ask about any known faults or issues, and I didn't volunteer any. To be fair it was only a £1,500 old Fiesta so maybe not so much an issue as they'd likely just take it to the auctions to get rid. A newer car that they'd want to sell on their pitches might require more rigorous assessment. 

Sorry, can't help on the knocking problem, but would suggest you try a KIA owners club/forum and see if it is a common issue. I have driven loads of cars over the years, and when I've had one with something wrong that can't be diagnosed/fixed I've just carried on driving it until scrapping if I can, or offloaded (as with the Fiesta).

chubsta

Thanks for the reply, as its a main dealer I am guessing it would go straight to auction if they did take it in as there are no 2016 cars on their forecourt.

Despite it being a lot of money I am currently looking towards getting rid of the car as there are other factors around inconvenience which mean I just want an end to this and to get back on the road - ideally it can be fixed for a reasonable price but at the same time I can't wait weeks only to find it can't.

Mildly_Miffed

What sort of "knocking"?

Where from?
Any acceleration at all, or just harder/lighter, high speed/low speed?
Is it 2wd, awd? Petrol, diesel, what capacity? Manual, auto?
2016 was a model changeover year - last of the old or first of the new?

chubsta

2016-2021 model, diesel 1.7 manual 2wd - to me it felt like one cylinder was not firing but there are no fault codes at all. When you put it under load in acceleration you get a thudding feeling through the steering wheel that increases in speed as the car speeds up, change gear and it starts to happen again, the tempo is more about the speed of the engine than the speed on the road, very hard to describe. When you get up to a certain speed/revs in a higher gear the thudding kind of stops but it almost feels like the engine is moving a bit, as I said very hard to describe!

without knowing anything about car mechanics I would describe it as the top end of the engine is fine (no fault codes, starts and runs fine), everything after the gearbox has been checked by two garages and all seems ok, so the problem must lie in between.

Mildly_Miffed

If it increases with engine revs, not road speed, that would tend to rule out the gearbox/driveshafts/etc.

If there's no fault codes, that would tend to point to something external to the engine - perhaps the auxiliary drive belt or one of the ancillaries driven by it.

If you turn aircon off, does it make a difference?

I wonder... DMF?

Arunmor

Does it make the noise when revved hard in neutral?  Isolating where the noise is coming from is the first step and potentially very tricky.

RogerPensionGuy

Sounds like nothing inside the engine at 1st glance. 

Sounds like the condition varies a bit under load acceleration speed.

Being FWD, guessing a lumpy drive system could be felt on steering. 

I would be temped to to drive car at maybe 40 MPH in 3rd, 4th and 5th, put gas peddle down hard getting to maybe 55 MPH. 

Note how it feels in the above test. 

Then see a good local mech and fully explain what you notice completely. 

From limited information, I would guess drive shafts system could be involved. 

Suggest plenty of searching on Internet for that model car and symptoms. 

Link below maybe of interest. 
***

https://www.driveshaftuk.com/the-common-signs-of-driveshaft-problems/

chubsta

Cheers for the detailed replies - the car is actually still at the main dealers, did hope for an update today but it never happened. 

To clarify, the knocking noise happens mainly under load (so accelerating or going up hill etc), the best way to describe its rate is that it would seem to me that it would be where power goes into the gearbox rather than where it comes out, so it increases until you change gear then the rate drops down again but then increases again as you continue accelerating.

internet research is not throwing anything up for me at the moment apart from pretty genetic stuff that has hopefully already been ruled out.

in neutral there doesn’t seem to be a problem which points me towards the gearbox. When I discussed the potential of it being a gearbox problem last week I was told Kia prefer to repair rather than replace so hopefully they will be able to actually find the problem soon.