Grinding Noise at low idle

oh dont you just love these undefinable noises - the best ones are those you only hear under load, when the car is driving

if you suspect peripherals like a PAS pump or a water pump try listening to them using a (long) metal rod by way of a stethoscope. its easier than taking off all the belts and you dont risk any overheating.

I wouldnt dismiss the auto box as a cause right away - it could be the torque converter.

the fact that you only hear it when the engine is warm points to a bearing - once oil or some other lubricant warms up it becomes less viscous and looses its 'padding' effect so worn parts can rub against each other.

good luck

Tom

Have you checked the alternator? ther bearing on them go and you get an awful noise.

Hi Mark,

with the bonnet up, is it possible to roughly locate where the noise is coming from? if it is indeed the alternator it should be pretty easy to spot as it it is high up at the front. Gearboxy noises are best located from underneath.

with the previous engine and box in my car I heard a rumbling noise at idle that disappeared at higher revs. it came from somewhere around the torque converter - whether it was the engine or the box I never found out...but its gone now.

I always hear noises in my car that no one else seems to hear...

Try using a bit of rubber or garden hose against your ear and then pointing it around the engine............that will hopefully narrow down the area where the noise is coming from.

Be careful though not to get wrapped around the fan and pulleys.

That's almost narrowing it down to the Water Pump.
It won't be the servo as there isn't anything to make grinding noises, that's assuming you are referring to the brake servo. If you aren't then it could point to the Steering Pump which is at the front of the engine

Have you still got the mechanical pump? This may be the cause.

The cam shaft does wear but causes misfires and bad running - shedding of case hardenng etc from the lobes also does the rest of the engine no good at all.

Not a good idea using synthtic on a worn engine unless its thick - you should be on 20/50 mineral - see earlier threads

Mark as much as you like synthetic oils, these engines and their associated mechanical components were not designed for use with synthetics. General component fit and the age of a lot of the mechanical parts do not yield the tight clearances of the CNC manufactured engines in modern cars. The Rover oil pump for instance is more about pushing oil through the engine in volume rather than creating high pressure. The 10W-50 oil your using though high in ZDDP is too thin for the rover pump. Synthetics also drain back much quicker than old style mineral based oils leaving thrust and wear surfaces critically exposed and unprotected. Clearances are much greater in these (used?) engines requiring a greater volume/film of oil between components and/or working surfaces. Engine bearings may be fine, but the clearances between the oil pump gears and their respective housings may be too great to pump sufficient oil (in volume) to stop metal to metal contact. These oil pumps were probably designed in the 1930's and are quite ubiquitous on a lot of American engine designs, not all V8s. You state that the noise disappears above 1000 rpm ...when the pump would be working more efficiently. Dump the oil your currently using and try a mineral based 20W-50 or 25W-70 (Penrite has the right additive package) and see what happens.

* Whatever you do...don't put a flushing oil through the motor.

Mark, one problem at time! Let's sort this one first and then we'll attempt to sort the next issue.

My 20W50 has not yet arrived. I managed to get 2 canisters at a very reasonable price just for checking effect on that noise.

BTW:
By what means does the cam get its oil?
Is it oil throw-off from the crank ?

Mark

Mark, the clock has an old-fashioned clockwork movement and the louder noise every few minutes is the spring being electrical wound.

I have owned loads of cars,including all marks of rover/humber/hillmans/fords and jags all of them doing well over a 100,000miles,and i run them all on deisel oil including a 5 series bmw with 475,000 on the clock whitch is still going strong today.so that is what is in my p5b,hope this helps

I must say that I do not find any of them very good at keeping time,I keep looking for a quartz clock that will fit my p5b and will not look out of place,I keep looking on ebay but can not believe the price they go for.