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MG TD TF 1500 - Odd Noise

I have a hollow ringing type noise at low RPM. When the engine is warm, it seems to almost or completely disappear. However, even when warm, I can hear it quite clearly (briefly) only when the engine shuts down. My hearing is not the best these days :-)

This all started a while after I replaced the water pump. I'm not saying it's definitely related. There was no rubbing of the pump then, but I have my fan belt really loose now, as recommended. Could it be the fan belt is too loose, or should I investigate elsewhere? Any and all suggestions appreciated.

TIA

Larry
L Karpman

Larry, Take the belt off completely and see if the noise goes away. If that is not where the noise is coming from, then leave the belt loose. Cheers - Dave
David DuBois

I had a similar sounding noise in my TD some years ago and it turned out to be the gear on the starter motor's Bendix drive was occasionally touching the rotating flywheel's ring gear
G.E. Love

Larry

I had a strange "tinkle" coming from the front of my motor at idle but once I took the car on the road it seemed to disappear. I tried disconnecting the belt and the noise continued. As these engines can be expensive to repair, I pulled the engine, hoping that maybe it was as simple as the timing chain tensioner.

The engine is in pieces on my bench and everything appeared just fine but I did find the cause simply by accident. I moved the generator and heard the same sound......there was a loose washer on a bolt holding the generator to the engine. Simple fix but the engine is totally apart and just waiting for the cam to be rebuilt now.

Brian
Brian Smith

OK, I removed the belt and the noise is was gone completely. I experimented with the belt tighter and looser when I put it back on, but the noise resumed no matter how tight or loose.

So, I suspect the water pump & pulley or the generator, as these were not driven while the belt was off and the noise stopped. I will await my mechanics stethoscope to arrive and check them both. They make no noise when turned by hand.

Any other comments or suggestions appreciated.

Larry
L Karpman

Larry; Stethoscope should help tell the tale - most of the time the last thing you touched is the likely culprit. But-always a but,eh?-the crank pulley can make a noise when they crack at the keyway. Will change when the belt load is removed - might be worth look if you don't locate the noise in the pump or generator. Dan
Dan Craig

I got the stethoscope today. Here are my results. In order from quietest to noisiest are:

1. Water pump (almost no noise at all)
2. Generator (some noise, but sounds normal)
3. Tach reduction gearbox (louder and scratchier than the others, even with fresh oil)

I'm not sure how to judge my results. The noise on shutdown is almost gone though. Can anyone shed light on what I should be hearing from these units?

TIA

Larry

L Karpman

Larry,

Is it anything like I experienced a while back and described on this thread?

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=200309191952355688

If so, I'm guessing the starter bendix.
Stan Griffis

I'm betting on the belt. I do not hear this noise while driving, only on shut down now. But then again, as John Twist found out, my hearing is not the best.

I just checked the starter and all I hear is a faint "whirring" noise. Very slight.

Larry
L Karpman

larry, if it is tied to the fan belt...this may be a stretch, but how do your fan blades look? anything from a crack to loose blades to some sort of debris on the leading edge can cause a noise. regards, tp
tom peterson

Tom: I have the MGB 7 blade plastic fan, and it's tight and fine. I don't think I have a major issue with the noise, as the noise is not longer audible while listening under the bonnet with the engine running, it is greatly diminished on shutdown now after readjusting the belt and using some belt dressing. I'm guessing the belt is slipping slightly when the engine stops.

Larry
L Karpman

Folks. We are forgetting the basics. Always first go back to what you did first. Larry, what did you change? Ok, you replaced the water pump. Noise was not there prior to this? If not, you need to look there.

What else did you remove? I used to have a similar noise from a set of aftermarket metal air filters. They were hitting on the carb. and gave a ringing metalic sound.
Bruce-C

Bruce: The water pump is very quiet when checked with the stethoscope. I can't say with a certainty that the noise was not there before the old pump failed. Right now, there is no noise when the engine is running, and it was only evident just before the fan stops when the engine is turned off. Right now, it won't make the noise on shutdown, so perhaps the problem is solved. Thanks all for your input.

Larry
L Karpman

This thread was discussed between 19/03/2009 and 22/03/2009

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.