Help - knocking noise from tow bar/hitch/somewhere

[ValA.]

My OH is going mad trying to locate the source of a knock which appears to come from the Alko hitch, the towbar, or somewhere near that area. It is a definite knock when the car and caravan are going over bumps, it transmits and sounds to come from under the car, or at the very rear.It's nothing like the groaning or 'straining' that you sometimes get with an Alko hitch. He's checked the hitch head, and there's no movement, checked the overrun damper, no problems, regreased everything on the hitch, replaced the bolts securing the Alko head to the hitch again, as we had both bolts shear last year (which may be connected - service dept said that had never heard of it before).

The towbar is newly fitted, in about March this year, there's no play on the bolts anywhere. Our car is Mondeo Estate, and has spring assisters fitted to the rear springs. When we're not towing there's a very annoying, but much lighter 'rattling' sound which may come from the same source. The caravan is a Swift Speedbird, now ten years old, fitted with shock-absorbers, which he's also checked and which are fine. The caravan is newly fitted with a Ego motor mover, but nothing appears to be amiss with the fitting, which OH did himself and nothing 'knocks' when bounced around.

We've followed each other, towing, around our storage compound, listening to the knock - which is quite loud - but are not able to locate the source!

Any other suggestions. Box of chocolates for the person to suggest something which solves the problem! (Apart from selling the car/caravan -- we love them both!) He doesn't 'do' forums, hence my posting on his behalf!

 

[Reg]

My tow-bar is fitted to the rear chassis members with 4 bolts (2 either side) and it might be worth getting down and checking that they have been tightened to the correct torque.

If yours is fitted in a similar way that is!

The tow-bar manufacturer can give you the figures.

If there is any movement due to slack bolts then this could be the cause of the knock..... especially if it happens when going over a bump.

 

[Sproket]

Is there a possibility of borrowing another tow car & taking the van out for a tow ? that will help you eliminate the alko hitch / & the A frame

Or coupling up another van & take that for a tow to try & eliminate the cars tow bar ?

Its quite possible for the noise to be coming from something else on the car.....

How old is the car ?

Mechanical noise's tend to travel about in the car & sometimes are hard to find & eliminate

There is not a stone stuck in the coil spring of the car's suspension, i have seen that before

Are all the bushes on the shock absorbers ok ?

 

[sarahandher6dachshunds.]

if the sound occurs with the van on ,it could be car or van,if there is a noise just with the car when going over a speed hump.it will sound different,any noise as the car comes over the hump.if yes then look under the rear wheel arches,look behind at the rear suspension shocks,a big coil.look at the top and bottom the rubber gr omits,stop ends may be worn.you will need to replace.

the car may be bottoming out on humps and will be a loud bang,knock with the van on.

have you fitted an under slung carrier for the spare tyre?it could be bouncing up and down.

hope this helps.

 

[Dustydog]

Hi Val

"When we're not towing there's a very annoying, but much lighter 'rattling' sound which may come from the same source."

Carefully check the car's suspension springs back and front. It sounds like one of the springs has broken.

Hitching up is clearly accentuating the problem.

Cheers

Dustydog

 

[ValA.]

Thanks for that - we'll take the advice about trying a different tow car and a different van on our car. Brilliant idea and something we'd not thought of. Our friend has a Passat with a tow bar! We could also ask David who has the caravan next to us in the storage site, and is an old friend, to let us tow his van for a lap or two of the storage compound, which provides plenty of bumps! We'll also look at the springs.

The car is a 2006 Mondeo - and has been serviced and 'looked at' by our friendly mechanic, who is also a caravanner, and he can't find anything that explains the problem.

 

[xtrailman]

Has your mechanic checked the subframe bushes?

What reg has mentioned happed to me with my last xtrail, the noise got gradually worse, and was really hard to pin point.

But was a grinding type noise which only occur now and then.

I located the problem when it got slightly worse by standing on the tow ball 135 pounds, and the bar dropped.

I took it back to the fitters and although the bar was two years old they removed the bumper, and as reg said both bolts at each end of the cross beam were lose.

My present witter has nylock type nuts.

 

[hughdavies]

If the noise is there without the van then the problem will be on the car but made worse with the van on.

On the Mondeo there are two short linkages for the tortion bar with ball swivle ends, these are a common fault and difficult to spot, my money is on one of these. It was on my Mondeo.

 

[ValA.]

Thanks for all these suggestions. No chocolates awarded yet, but we're going back up to the van tonight for someone else to tow it around the storage compound (which has a long outer perimeter road which has the suitable bumps we're looking for), and then we're going to tow their caravan around the same road. That should certainly indicate where the problem lies.

We did remember that with our very first Mondeo we had a similar sort of knocking (just the car alone, not towing) so we're trawling back through memory to remember what it was and what the solution was. OH's currently looking on 'Honest John' for common Mondeo problems - and this rear knocking seems to be a common problem - with similar suggestions to on here.

It seems he's going to be busy now, eliminating all the problems it could be with the car. Let's hope when we have the trial drives with swapped vehicles that both the car AND the caravan don't end up having a 'knock'!!!!!!

 

[Grahamh]

Mondeo's (saloon) suffer from rear rubber bushes which are quite easy and cheap to replace. The symptom is knocking from the rear over bumps and around corners. Very common MoT failure item.

Graham

 

[Robtel]

From reading your post Val and not seeing any mention of detachable towbar I'm guessing you have the fixed type therefore the following info is probably not going to be of much help but I will post it anyway on the off chance.

My car, Freelander 2, was bought new in January tis year with detachable towbar fitted prior to collection by dealer. Towbar is labelled Land Rover but I believe it is a Brinks. Our recent trip to France was our first serious journey with it, previous outing had been relatively short with no problem. This time however we got persistent but irregular heavy clunking thuds coming from the area of the towbar. Everything would be fine for two even three hundred miles then there might be two or three of these clunks which could be felt as well as heard in the space of a couple of miles.

On return home I had a search online, found a Freelander forum and had a look on there. Seems this problem of heavy clunks and thuds is a known problem with this model of detachable towbar and modification kit was available for fitting under warranty. My car was in at dealers yesterday and new housing and new detachable towball fitted. Haven't had the opportunity to try it out yet but hopefully all will be well.

Hope this might be of help to someone.

 

[Oldsalt49]

Hi Val,

I had a rattling noise on my last car. This turned out to be corroded mounting on the exhaust shield at the rear of the car. I found it was worse when towing due maybe to higher resonance throught the exhaust. It maybe worth getting your OH to have a poke around in that area. Its just a hunch, but maybe a valid one?

David

 

[AnthonyNornIreland]

I had a knocking/clunking sound when towing, and eventually traced it to the support bracket for the solid rod running from the brake at the hitch to the wheels.

 

[ValA.]

The brake rod was what we actually thought might be the problem - but it was all checked over and cleaned and regreased, etc., before our last outing - so we think we've eliminated that. We didn't get to try out the alternative tow car/alternative caravan yesterday but should do it today, but OH has now asked our mechanic to have a look at the sub-frame bushes, springs, etc., after reading 'Honest John' about Mondeo problems and knocks!

Thanks everyone - I'll keep you informed.

 

[ValA.]

The saga continues. After emptying the car and the caravan of everything that could rattle or knock, we've isolated two sources of noise. The brake rod was hitting the cross activation bar of the motor mover, causing one metallic clunk. The plastic lid of the spare wheel compartment was the source of the rattle in the car. These have both been solved, but the knock continues.

We've not yet managed to tow our caravan with another car, but our son is coming with his Vauxhall Frontera tonight to tow us around the storage site, and we've arranged to tow our friend's van around on Saturday when he brings it back into storage. So, we haven't yet isolated the main knock, but thanks for the suggestion of the brake rod, Antony of N Ireland, which will get rid of one of the annoying clunks that we sometimes hear whilst towing.

 

[ValA.]

Definitely the car - OH has now towed another caravan with our car, and the knock is there, and our caravan towed by our son's car demonstrates there is no knock coming from the caravan!

Going into the garage today for our (caravanning - with a lovely new Hymer) mechanic to have another look at it. OH would (previously) have done it himself - at least sourced the problem anyway - but we've both too much on at the moment with various other things happening.

I'll report back on what turns out to be the solution.

 

[Dustydog]

You're getting there Val.

Keep us all posted.

Cheers

Dustydog

 

[ValA.]

Mechanic can't find any problem with the car! Nothing, absolutely zilch, nowhere, no-how!! However, he did say that none of the tow bar fixing point bolts were as tight as he would torque them - so he's tightened them all up for us (we think that our torque wrench may be faulty as OH had checked them himself - so are adding 'replace torque wrench' to the list of jobs).

Tomorrow we're back up to the caravan to tow it around the compound again, and I'll report back! Another friend, with a bigger caravan than the one we towed around, is back on Saturday, and we'll have another go with hers - and her OH has an estate car like ours, rather than a 4 x 4, so he's going to tow our van.

So, we're perhaps a little nearer, but perhaps not! Blooming annoying! Worrying thing is that it's not a little knock, but a blooming great one, and sounds like something nasty is about to happen!

 

[RonD]

Val,

My towcar was very noisy, making loud cracking, banging and creaking noises whilst travelling on anything but straight and level. Someone suggested I give the towball a good clean up with fine emery paper and clean the pads in the Alko hitch. Silence from then on...so it's a part of my routine now.

Ron

 

[david_374584300]

Have you checked the nose weight of the van?

 

[Sproket]

Have the CV joints on the car been checked ? as they can produce a loud crack & this happens....

CV joint 1

CV joint 2

Lucky the wife's disco was parked out side the garden gate when it went,she too had heard a loud cracking noise, but only very occasionally....

The cracking sound was the balls trying to escape from the cage that surrounds them & holds them in place.. the cage gave up..

They only tend to explode when the steering is on full lock, if the car is jacked up & the wheel rotated forwards... then backwards....then put it on full lock,& do the same again... you will feel any grating in the CV joint .....

They only take about an hour or two at the most to change...

 

[Sproket]

CV joint 2

 

[ValA.]

Thanks everyone who contributed - the problem is now solved! We've had about forty circuits of the bumpy road around the storage site tonight, and not a knock or a bump! It was obviously the towbar bolts - and we've since heard from a friend that he had a similar problem with a new towbar fitted at the same workshop. Obviously no-one has taught the new lad that the bolts need to be really, really, really tight - and then a bit more!

We've had all the car thoroughly checked, and there are no other problems, and the knock wasn't at all similar to the creaks, groans, and odd sounds which come occasionally from the tow-ball. Our son said that when he was sitting in the boot (better to locate the knock) it did sound to be coming directly through the floor, where he was pressing down with his hands to hold one whilst OH flung the van around in various figures of eight!

Anyway, we're reassured that we've sorted out the problem, and the brake rod clanking on the motor mover is also now sorted, the nose weight is measured before we set off, and adjusted accordingly, so hopefully our forthcoming trip will be a noise-free one!

Box of chocolates to the lovely mechanic who found the problem, I'm afraid, so no winners from here!

 

[hughdavies]

As I said erlier, the ball joint on the short arm linking the tortion bar to the wishbone go but due to the strain in the tortion bar this can not be seen by shaking it etc. put a jack on it to relive the pressure and then give it a shake or use a crowbar.

 

[Reg]

WHAT!!!!!!!

I CLAIM MY PRIZE - SEE THE FIRST REPLY TO YOUR FIRST POSTING!!!!

and I'll donate it to "Orphan Goldfish Society of Republic of Uzbekistan"