Engine Noise 1978 E430 Avantgarde

[im2020]

On a long drive back from N Wales yesterday I noticed a quietish but consistent high pitched droning over and above the normal engine sound. As far as I was able to track it the noise was absent when decelerating and increased as I went up through the automatic gears and remained consistent when driving at 70-80 mph.

This morning on starting the car in P in my garage there was a deafening roar which immediately disappeared when I changed into D and edged forward but the coming and going of the sound described above remained as I went out onto the road.

Any ideas on possible causes would be much appreciated - engine itself, auto transmission, exhaust, etc.

Thanks

 

[im2020]

Sorry the title should read 1998 E430 Avantgarde

 

[grober]

Sounds transmission related. Check the transmission fluid level and have a good look at the propshaft U/J's and centre bearing. [ you might have to remove a bit of exhaust heat-shielding to get a good look]. My money would be on the autobox / torque convertor

 

[im2020]

Thanks Grober - will have a look on Monday with my technical mate.

 

[im2020]

Latest - I can't schedule the inspection until Wednesday - would I be OK to carry on driving the car until then?

 

[grober]

Have you got a transmission dipstick? If you have check the transmission fluid level [ there's a standard procedure for doing this hot or cold] If the fluid is low then a top up might sort things out -otherwise unless you know whats wrong continuing to drive the vehicle means there is a risk it might make things worse. " sudden mechanical noise" is usually the sign something important requires attention asap.

 

[im2020]

I haven't got a transmission dipstick so I'll have to wait until Wednesday to check that. Also I notice the red lock on the transmission filler cap is missing so I'll have to get one of them as well. I'm assuming the problem might be more than transmission fluid level. Wouldn't a low level show symptoms like slipping or getting stuck in gear? I haven't had that - just this additional noise (a bit like a quietly roaring wind) over and above the normal engine noise.

 

[grober]

I haven't got a transmission dipstick so I'll have to wait until Wednesday to check that. Also I notice the red lock on the transmission filler cap is missing so I'll have to get one of them as well. I'm assuming the problem might be more than transmission fluid level. Wouldn't a low level show symptoms like slipping or getting stuck in gear? I haven't had that - just this additional noise (a bit like a quietly roaring wind) over and above the normal engine noise.

Symptoms are more like a torque convertor problem than gearbox itself but again low fluid might be the problem. You can buy a dipstick tool online if you know the gearbox model/ number. An examination of the fluid can also give an indication of a problem if it indicates its contaminated with particulates.
Without the ability to perform these basic checks its difficult to give you the OK to drive the car if the noise persists

 

[im2020]

Thanks Graeme. I'll try to make sure that all these checks are run on Wednesday. I'm still curious about the almost deafening roar if I start the car from cold (which disappears when I put it in gear and edge forward). Anyway, more anon.

 

[im2020]

Investigations were delayed and are ongoing but I can report that the transmission fluid was not contaminated and was only very slightly low. We will do a full flush and look at the torque converter but would you think we are right to check the viscous fan clutch as well? The suspicion is that it might be locked or intermittently locking. That would seem to tie in with the "windy roar" but also with a loss of power that I hadn't noticed but has now been pointed out to me.

 

[im2020]

A closing report - not 100% conclusive but I'm back being very happy with my 1998 E430. While waiting for my indie to book the necessary ramps etc I sprayed the viscous fan clutch with silicone, brushed some gunge off and dripped some oil onto its shaft. The startup roar disappeared, most of the top gear windy sound went and the hesitation on accelerating was reduced. I did, though, need to do this again after 2 days to maintain the improvement. Then when the expert took it back he pronounced the fan clutch operational but replaced the mass air flow sensor and at my request fully flushed the automatic transmission fluid. Now there are no untoward noises and there's a good response when hitting the accelerator hard. I sense a curious little bit of auto uncertainty between first and second gears but as I said I'm now happy again. Conclusion - not 100% but MAF sensor seems to have been the main culprit.