Strange noise from engine/gearbox??

[GordonM]

First of all apologies, I am not technically car minded and this is the first Mercedes I have owned.

Its a 10 year old C180 auto with 82,000 miles.

Bought it from a friend at work and although I do enjoy driving it, it is certainly very sluggish compared to other cars I have owned.

It also (and this is the real question) making a strange noise occasionally but fairly regularly when the car is 'toiling' up hills... say in 4th gear at 40mph on a steady fairly steep incline.

The noise I cannot trace but my laddie reckons it was coming from the gearstick area. My wife reckons the engine itself but it does seem to be 'low down'...

Best way to describe it is a 'flapping/rattling' noise. It goes if I lighten up on accelerator or drop to 3rd gear.

Guy who sold me it said its 'pinking' - I have no idea if the noise I am hearing is pinking or not. I have no idea what pinking is lol!

The thought of a bust gearbox fills me with dread so do any of you knowledgable chaps have any ideas???

I did troll the forums and found that I could put a fuel cleaner additive in and try 'resetting the gearbox' which might help...

Once again sorry for lack of tech details - if I can I will record the noise and link it here.

 

[fnkhan68]

Good news is the pinking noise has nothing to do with the gearbox, usually oocurs when correct fuel mixture is not being burned or timing is out. My old car once had the same problem, changed the HT leads, dist. cap and rotor arm and problem was solved. I believe your car has coils instead of Distributor but I would start from the basics and check the leads and plugs first. Your car must have a cat so the mixture does not have to be manually adjusted, lots of knowledgeable W202 owners on this forum aswell so you should get a greater degree of advice. If im not mistaken, could also be the MAF but someone more knowledgeable will correct me here.

 

[Brian WH]

When was it last serviced??

If not recently then it is due one every 10,000 miles. It may need new spark plugs at that mileage and adjusting the timing will stop pinking. I would suggest you get a reputable garage to look at it to put your mind at rest and stop all this speculation as to what it could be.

 

[GordonM]

It was last serviced 3000 miles ago by the guy who sold me it...

Having done a bit more reading, I'm gonna try a couple of what appear to be simple steps before I part with £40 per hour for a garage to look.

I've bought some STP Fuel System Cleaner...

I've also sourced a new MAF for about £50 on ebay (is this a good price) and that does seem like an easy part to change over... (is it?)

After these 2 steps I will see if the car improves. It seems from others with similar symptoms to mine, that the MAF sensor has been to blame.

 

[Brian WH]

It was last serviced 3000 miles ago by the guy who sold me it...

Having done a bit more reading, I'm gonna try a couple of what appear to be simple steps before I part with £40 per hour for a garage to look.

I've bought some STP Fuel System Cleaner...

I've also sourced a new MAF for about £50 on ebay (is this a good price) and that does seem like an easy part to change over... (is it?)

After these 2 steps I will see if the car improves. It seems from others with similar symptoms to mine, that the MAF sensor has been to blame.

Your choice mate, but anyone who services their own car and leaves it pinking doesn't know what he is doing!!

 

[Parrot of Doom]

On my last car I had some pinking, caused by low fuel pressure. It sounded like nails in a tin box, matched to the engine rpm.

You should get it sorted, if its a timing problem it shouldn't be a big deal to fix.

At that age you should also have the gearbox ATF replaced.

 

[Ian_C]

On my last car I had some pinking, caused by low fuel pressure. It sounded like nails in a tin box, matched to the engine rpm.

You should get it sorted, if its a timing problem it shouldn't be a big deal to fix.

At that age you should also have the gearbox ATF replaced.

I 2nd the gearbox ATF change, it's insurance for your gearbox and the cost is much less than a new gearbox.

There are a few very good independants on this site which would do you a good price. One in Portsmouth, one in Preston and a few more I may have missed.

Ian

 

[diy_dan]

It was last serviced 3000 miles ago by the guy who sold me it...

Having done a bit more reading, I'm gonna try a couple of what appear to be simple steps before I part with £40 per hour for a garage to look.

I've bought some STP Fuel System Cleaner...

I've also sourced a new MAF for about £50 on ebay (is this a good price) and that does seem like an easy part to change over... (is it?)

After these 2 steps I will see if the car improves. It seems from others with similar symptoms to mine, that the MAF sensor has been to blame.

why are you changing the maf when you dont even know if the problem is fuel,ignition or gearbox, you might as well give me the £50 instead and if your so call mate had service the car the stp will be a waste of time so you might as well give me that money as well. those cars have an ignition processor and might have a knock sensor as well so in theory they should never pink, If its a timing problem then thats worrying.you sure the noise isnt bigends?

 

[TonyVianoAmbiente]

It was last serviced 3000 miles ago by the guy who sold me it...

They all say that, don't they?

That usually means that, at best, he changed the oil and filters, and maybe not even that.

You should take the car to a reputable independent Mercedes specialist and have it serviced now. It need not cost a lot of money. If you try replacing parts yourself when you have no idea what you are doing, you will waste your money for sure, probably without solving anything.

If the engine is pinking, it will be easily and cheaply solved by having the car serviced. If you waste time messing about changing things that don't cure it, you could do the engine a lot of very expensive harm.

 

[fredfloggle]

If you have ever heard pinking or for that matter diesel "knock" you will know exactly what it is - the pinking you hear isn't the problem , it is the pinking you don't that puts holes in pistons and melts valves .
You can without a doubt "control" pinking with a slight modulation of throttle position - many things will cause pre-ignition, timing too far advanced - mechanical advance weights stuck(where fitted) - crappy petrol - plugs too "hot" - coked up head/ valves , but like I said you won't miss what the noise is .

Old way of ignition timing old high compression engines was to advance the ignition to the point where a little "shower" of pinking could be heard under full load , full throttle low rev conditions , then back the timing off just a tad ( you got a feel for it on the micrometer adjustment of the old lucas distributors) .

 

[GordonM]

thanks for all replies -

The fuel system cleaner went in today (cant do any harm) and although my garage are on holiday at the moment I am going to make arrangements to pop up and hook it into their diagnostics to try and isolate the cause of the noise before I do anything more.

 

[GordonM]

Solution:bannana:

would you believe it was nothing more than the heatshield from the exhaust manifold.

It had corroded and slid down the pipe and was just hanging there. At certain revs etc, when the engine was vibrating at just the right frequency, the knackered heatshield was just resonating and rattling around!

£40 to fix - could have done it myself for free.

 

[Dieselman]

Yes we would believe it, it's not uncommon, I suspect you are now enjoying your car quite a bit more now.

Anyway nice fix and thanks for letting us know.