MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Water Pump and Tacho

I have just got back from a great day out in the midget. 150 mile round trip with no real problems, well OK just the one or two.

The oil pressure seemed quite constant when cruising at about 50 - 60. Water temprature was good at 170 (f)ish appart from when is slow traffic when it raised to 190 and maybe a tad above, but soon returned to normal when we started to move again.

No 1
I started to notice a "squeeling" noise from the front of the engine, it was definately on the outside and thankfully not in the block. When I was parked I got the bonnet up and had a better listen. It seemed to be the water pump, although it appears to working OK, but I imagine this a sign of the bearings starting to wear. Am I right in my thinking or should I be looking elsewhere?

No2

I have had concerns about the accuracy of the tacho since I have had the car (2 years but not many miles!) Whilst out today when cruising at about 50 the tacho was showing 5500 rpm, but the engine did not seem to be working to hard. Can anyone give me an idea of what revs I should be seeong as it seems a bit high.

Thanks again.

Tony
Tony Brough

The squealing noise could be the fan belt slipping, or it could be the water pump bearing failing. Is the fan belt very tight or very loose? Ideally you should be able to deflect it about half an inch with your thumb on its longest run (NOT while the engine is running of course!!!!). If you have any doubts about the belt, replace it - they are cheap.

Is it an A-series engine or a Triumph 1500cc?

The tacho is miles out if your speed was really about 50 mph. On a 1275 car you should be seeing a little over 3000 rpm at 50 mph. At 5500 rpm you would be doing 91 mph! On a rubber bumper 1500 cc car you should see about 2900 rpm at 50 mph.
Mike Howlett

Thanks Mike
The fan belt is tight but not too tight so it is likely the bearings are beginning to fail. I will try to loosen the fan belt a little and see if it makes a difference before I start ripping it out.

Its a MKII 1098 A Series so I would imagine similar to the 1275.

Thought it was a bit high, definately not 91 mph.... Judging by the speed of the other cars when approaching speed camera's I would say the speedo is accurate.

Tony Brough

I assume it has the 1098 engine and if it has the correct back axle ratio it should be 15 MPH per 1000 revs, so 52 MPH gives 3500 revs.

The noise apart from the fanbelt or water pump could also be the dynamo.

Trev
T Mason

Tony,
as Mike and Trev have put about belt, water pump and dynamo

If it’s not the fan belt then for the water pump and dynamo you could try carefully spaying the shafts of each with a little thin lubricate as this might wash out tiny grit that might be the cause or just give enough lube to the shaft and stop the noise

If the noise continues investigate further don’t ignore a water pump or you could have overheating problems or ignore dynamo problems or you’ll be getting slow/low electric items and starting problems – a good quality battery will help no end if the dynamo goes faulty, or at any other time really
Nigel At

Re. query No 2:
Your high tacho reading is similar to what I experienced when I fitted electronic ignition. If your tacho is a a RVI model (current fed)with electronic ignition you'll need to change to the later RVC model(points and electronic) which picks its voltage input from the negative side of the coil. You can have the existing RVI type modified.
Derek Stewart

Thanks for the replies.

I had a good listen and it is definately the dynamo, it sounds as if the front bearing is failing.

So I will start to look around for a replacement.

If anyone in the midlands has a spare please email me tonybrough AT who2click dot com

Cheers

Tony
Tony Brough

You could try dribbling a little thin oil around the front bearing. Some should get in and may quieten it for a while.
Mike Howlett

Thanks Mike

I will give it a try. I am planning on touring around Wales the week begining 15th August for a week so I need it sorted before then. It seems a shame but I cant find any details on the bearing or I would have a go at changing it as it is still charging OK.
Tony Brough

You can get new bearings for your dynamo from AH Spares. Front bearing £5-50, rear bush £1-50 plus VAT and P&P.
Graham
Graham P 1330 Frogeye

Tony

You have mail
Dave O'Neill 2

This thread was discussed between 31/07/2011 and 03/08/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.