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        General >> Problems >> Low rumble/noise from middle/back
        
(Message started by: Mike_Floutier on Jan 3^rd, 2007, 6:11pm)

Title: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 3^rd, 2007, 6:11pm

Hi Guys,

Firstly thanks again for the instructions for replacing the prop-shaft centre bearing; it took a while but all went back well and the residual whistling noise disappeared after a day or two.

Trouble is that the "Low rumble/noise" coming from the centre/back of the car (which has so far got me changing the bearings (wheel as well as prop-shaft), brake discs and tyres (well it needed them anyway)) has not changed a bit. Man is that frustrating!!

My latest theory is that it might be the drive-shaft CV joints. It's done nearly 250k miles and there is a lot of black grease all over the relevant area. I did check the diff. fluid level btw and it was fine and the fluid looked and smelt fine.

I see in the "manual" that they should each be packed with 90 grams of grease.

1. Do you think this could be "my noise"? and

2. Should I remove them to dismantle and clean before re-greasing or could I re-grease them in-situ?

Thanks!

Mike

Title: Re: Low rumble/noise from middle/back
Post by solarpanel on Jan 3^rd, 2007, 7:28pm

model/year???

Title: Re: Low rumble/noise from middle/back
Post by hellblue on Jan 3^rd, 2007, 9:10pm

Is the answer in the title? in the middle at the back! diff? diff noise tends to come & go as you get on & off the gas,cv joints dont tend to make that rummble noise.

Title: Re: Low rumble/noise from middle/back
Post by Matt on Jan 3^rd, 2007, 10:26pm

the prob is balanced using the 4 bolts that hold it to the diff, if the bolts dont go back in exactly the same places, the prob can run out (think of it like balancing your wheels) the bolts are slightly diffrent lenghts

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 3^rd, 2007, 10:33pm

Thanks guys,

Sorry for not mentioning it, it's a '97, 2.3 auto saloon running on lpg.

I thought of the diff. but the fluid looks fine and in any case the noise is not related to the power input.

As to cv joints rumbling, I too haven't heard this before (only a sharp cracking sound occaisionally); I guess I'm hypothesising desperately.

Anyway, I thought it couldn't do any harm to grease them. It's not a loud noise, only one of my passengers has noticed. I thought if they were dry they would make some extra noise. By the way it becomes noticable around 50/55mph and is drowned by wind and tyre noise by 65/70.

Will let you know how I get on but any other ideas would be welcome.

Mike

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 3^rd, 2007, 10:38pm

Hi Matt,

Thanks for your suggestion. Your post must have gone on while I was typing.

I was very careful with the prop, numbering the bolts and marking their positions on the diff. input flange. In any case the noise is the same before and after prop. bearing replacement.

I've been aware of the noise for around 60/70k miles but it's got steadily worse so I've started to trace it before it becomes an impediment to my work as a private hire driver.

All ideas welcome

Mike

Title: Re: Low rumble/noise from middle/back
Post by mr._floppy on Jan 4^th, 2007, 12:54am

CV joint trouble would manifest itself more ( or maybe less ) when going round corners or if you had a trio of russian lady shot putters in the back seat ( as you do :o ).

My money's on the diff. :-[

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 4^th, 2007, 8:10am

Thanks Mr F,

Will keep you posted.

Mike

Title: Re: Low rumble/noise from middle/back
Post by Highlander on Jan 4^th, 2007, 1:31pm

Mike, have a look at the diff bushes
Yours will have two at the rear of the diff and two at the front.
If it is one of them you might be able to see where its been rubbing, do you get a knock from the rear when you put your foot down or slacken off the throttle?

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 4^th, 2007, 3:44pm

Thanks Highlander,

No, there's no knocking and no difference in the noise during acceleration or engine braking.

These bushes you mention, I take it I'd have to dismantle the diff. to look at them - the very idea terrifies me; it's only a fairly quiet noise. I'd be worried I couldn't get it back together again - like trying to fix a watch or something.

Mike

Title: Re: Low rumble/noise from middle/back
Post by Highlander on Jan 4^th, 2007, 3:59pm

no they are on the outside of the diff, where it mounts onto the body

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 4^th, 2007, 5:35pm

Haha, that's a relief, thanks!

I'll have a look when I grease the cv joints.

Mike

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 4^th, 2007, 5:41pm

Even more haha, I just looked at the manual for overhauling the diff. and was flabbergasted to see that Ford mention 24 special tools needed.

Don't think I'll be touching anything like that

Title: Re: Low rumble/noise from middle/back
Post by 12reps on Jan 8^th, 2007, 8:25pm

Hi Mike,
I have a similar problem to you. Between the speeds of 50-60mph I get a humming noise from the back end. Over 60mph the noise seems to dissappear. I went down a large bank with the box in neutral and got exactly the same noise. Jacked up all 4 wheels but no play on any of them what so ever. Not sure where to start; diff, CV joints or wheel bearings. I will be watching your posts with interest.
Cheers Allan

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 8^th, 2007, 10:49pm

Hi Alan,

Yes it's a strange one. Some days I think I'll put up with it and other days I think; "I must do something about it!"

I've been reading around a bit today and some people talk about worn shock absorbers causing strange tyre wear both of which could be behind it; ie the worn tyre making a funny noise and the worn shock making it louder 'cos it's worn.

Also, I checked my records and was surprised to see that I renewed the other back wheel bearing over 140k miles ago so that could also be a contributor.

Basically my plan now is to:

1. Replace the nearly worn out rear off-side tyre (uneven wear!)

2. Grease the cv joints (they take nearly 1lb of grease!) and check the diff bushes.

3. Replace the rear shock absorbers.

4. Replace the rear off-side wheel bearing.

5. Remove the front under-body heat shield - to see if it's being rubbed by the prop-shaft donut.

Stopping at any stage if the noise disappears of course.

Will let you know how I get on

Mike

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 16^th, 2007, 8:53am

Hi Guys,

Thought I'd let you know how I'm getting on with this and ask for a bit of advice.

Well, I replaced the worn tyre, it was badly worn on the inside shoulder only but it made no difference.

Next I removed the front underbody heat shield to see if it was being rubbed by the prop-shaft vibration damper but it didn't appear to be.

Also I replaced both the rear shock absorbers. The old ones were fairly useless compared to the new ones but alas the only change here was that the ride seemed even harder than usual - certainly no change in the noises that are bothering me.

Finally, so far, I removed the left hand drive shaft (more fiddly than I imagined). I expected that it may have lost it's grease but what I found was that there was still a fair amount of grease but it seemed to have set hard like clay. I could just about move the joint but only with considerable force.

Could this be causing some noise? I tried forcing as little more grease in but there wasn't much room for more. I had run out of time at this stage so I had to reassemble it quickly for work.

I guess I ought to take the thing apart completely and clean out all the old grease and fill it with new stuff.

Will let you know how I get on

Mike

Title: Re: Low rumble/noise from middle/back
Post by jonnycab on Jan 16^th, 2007, 9:12am

Hi Mike...sorry I can't offer any advice, but out of interest....
....When you replaced the rear shocks, did the ride height change at all ? :)

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 16^th, 2007, 9:55am

Hi Jonny,

No, no change in the ride height in spite of being much harder to compress.

Looking forward to hearing peoples thoughts on the effects of hard, clay-like grease in cv joints.

Mike

Title: Re: Low rumble/noise from middle/back
Post by Dave on Jan 16^th, 2007, 10:07am

Hi Mike,

can't say I have any experience of CV joints personally but did a quick Google search and found this:

http://www.bbc.co.uk/dna/h2g2/A693948

Sounds like your CV joint grease should be rather more runny than it is.

Just how pliable is it? Is it quite hard?

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 16^th, 2007, 12:01pm

Hey Dave,

Nice link to the article about cv joints, thanks!

Two obvious points relating to my situation arise from this article.

1. It says: "CV joint grease is very slippery stuff and, when it gets hot, it runs all over the place" whereas my grease is almost solid; like one of those cylinders of liquorice in "liquorice allsorts", if you know what I mean. It's like, if I bent it, it would snap.

2. "they will usually last at least 100,000 miles" well mine has just got to 240,000 miles so I guess it's time to refurbish them.

Thanks again!

Mike

Title: Re: Low rumble/noise from middle/back
Post by Mike_Floutier on Jan 17^th, 2007, 3:06pm

Ah, interesting follow-up here.

As I'm a "professional" driver I was a little concerned about the time it would take to remove the drive shaft and refurbish the joints - ie would it interfere with work; especially if I broke them somehow.

So I started looking at replacing them instead - specially as they're so old.

Fordpartsuk who are usually pretty good said they would be around £450 per shaft.

So I tried http://www.247spares.co.uk/ford/index.php?vehicletype=car . I was very impressed. I put in my car reg. and it came back with a description of my car. I then entered the drive shaft detail and my phone number and clicked "submit"

Hey presto, 2 minutes later (literally) the phone rang and this guy offered to post me the drive shafts, completed with cv joints, for £30 (yes thirty quid) each plus £15 post and packing. They were from a "T" reg Scorp and you can guess what I replied. What can I lose?

I asked him if he'd made some mistake and he jokingly offered to increase the price. After a chat, it transpired that some parts just don't have much demand - which is understandable - hence they are just happy to get rid of them for a song.

Will let you know if it does the trick.

Oh, and another advantage is that I can refurbish them at my leisure, before fitting them. How good is that?

Mike

Title: Re: Low rumble/noise from middle/back
Post by Highlander on Jan 17^th, 2007, 9:18pm

£450?? ?? ?? ?? ??

I'm assuming (from past experience with Ford prices) that isn't a typo