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MG Midget and Sprite Technical - Engine advice required

Yet again im after some advice !

I have a midget 1500 . On start up im getting lower engine rattle for a few secs which then goes off . Also when the engine has warmed up im getting the same lower engine rattle when accelerating .
Could it be the crank bearings ? or conrod bearings ?

would appreciate your valuble advise
D Stratton

Either or both, in my opinion. And if those are worn, then the crankshaft thrust washers probably are as well - and failure of those can bring the whole plot to a shuddering, expensive halt.

You can inspect and replace the thrust washers and bearing shells with the engine in situ, by the way.

-:G:-
Gryf Ketcherside

Wow...perhaps its time for that K-series

I think your looking up the right scottish mans kilt, id add trust washers to the mix

you will need to get some magnaflux tape and spend a saterday afternoon dropping the pan and having a looksy to really know whats happening

Is there any chance it could be a loose exhaust, they will make an awful clatter
Prop

Oh its quick type gryf got me by a word...he is fast today...hahaha

Wow almost the same thinking verbatem.... How rare is that

Prop
Prop

almost certainly conrod bearings and a typical 1500 sound! What's your hot oil pressure like (running and idle)?

Now the good and bad news... It's made worst by the oil filter draining whilst the car is standing and needing to be filled on start up. Hence no oil to the bearings for the important first few seconds. It may well run like that for quite a while but as the boys say, if the thrust's drop out you're sunk.

There's no point just changing the rod bearings and not the mains and thrust washers. The crankshaft will almost certainly need a regrind as well.

If I were you I'd just drive it for the summer (if it ever arrives!) and do a rebuild over the winter.. When you do, fit an oil cooler as this will prevent the filter draining down.

Or buy a recon unit from PB as he's close, pays your money, take your choice....

MGmike
M McAndrew

On my 1500 I used to change the mains and big end shells, and thrust washers, as a routine service item every 24,000 miles. Never had a crank regrind though. If you catch them early enough, it is the shells that wear and not the crank.
Guy

I would echo Mikes comments and the oil pressure question.

It's always so hard to get the idea of noises, so it would be worth getting it to Peter Burgess as he is so close and discuss your options with him.

Sometimes wish that there was a way to put up sounds rather than pictures, as one persons rattle is another persons banging!

rachmacb

Thanks for the kind comment Rach.

Guy, having recently rebuilt a 1500 I'm in agreement that prevention is better than cure and a change at 24 to 30K is a good idea. Unfortunately for D Stratton I think he's gone a bit past that point! My guess is somewhere around the 70k mark!

MGmike
M McAndrew

Most likely to be big ends. I echo the comments about the thrusts.

Personally I would get it looked at lest you end up with a rod (usually number 3) making a high speed bid for freedom through the crankcase.

I recommend the use of tri-metal bearings for the big ends on a 1500 and I check the thrusts every 40,000 miles.
Deborah Evans

Im in the camp of dont drive it till its fixed, right now you looking at a couple $$$$ to replace the main, rod, and thrust bearings and a saterday to do it, but to contine driving as is and just completely trash out the engine, and your looking at several $ thousand dollars


I guess it comes down to how much money you willing to risk or trade for a few hours of extra pleasure

Id think even if you did a full rebuild now compared to driving an extraa 3000 miles you would still be way ahead of the curve ...could well be the differance of a crank polish vs removing 20 thousands simple cause the shells where shot and you drove it an extra 3000 miles scaring up the journals

Just my 2 cents

Prop
Prop


Don't keep driving it until you know what the problem is.

Props 2 cents is worth every cent, in this instance perhaps that advice is even worth a dollar. If it is a bearing that rattle early on may not be too expenisve to sort out but if you keep driving it, then it certainly will be.

Another 2 cents worth.
Greg H

Thanks for all your comments and suggestions .
I already have an oil cooler fitted so dont need that . As far as the rattling goes , drove it to and from work without any rattling at all . Funnily enough i only notice it making the noise when im on the same stretch of road near where i live !
The road runs past a school and has speed bumps so im slowing down and speeding up when it makes the rattling .

Ive had the midget 3 months now and done about 2.5k miles . Gave it an oil and filter change when i got it .
As ive got to drop the sump again to cure a slight oil leak i think i might as well do the crank and conrod bearings and thrust washers while im at it .
Out of interest how do i find out what size bearings i'll need ? it would be handy to have them when i start work on it rather than removing the bearings then ordering new ones !
D Stratton

"Out of interest how do i find out what size bearings i'll need ? it would be handy to have them when i start work on it rather than removing the bearings then ordering new ones !"

Unfortunately there is no way to know what size bearings you have fitted without popping the old ones out - it will be stamped on the reverse side of the shell.
Deborah Evans

D - you said you only notice it on one particular stretch of road?

Are you sure that it is just on that particular stretch?

The reason I ask is that my 1275 - although not the 1500 - HATES one particular stretch of road, which just so happens to run through the village! It makes all sorts of strange noises and behaviour going along it. I'm not sure what your particular area of Derbyshire is like, but, this is due to a historical reason with the ground underneath the tarmac, so, could be that there's nothing wrong with your engine!!!!
rachmacb


I wouldn't go changing the bearings until you've correctly identified the problem because it may not be a bearing. It depends on your definition of a rattle.

If you are going over the speed bumps then accelerating with out changing down you are loading the engine up more than normal. If the bearings are worn out this can cause a bearing knock because with the extra load the oil doesn't stay in where it should. What's the oil pressure like? If the bearings are worn the pressure drops off.

Alternatively if you've got the engine timing advanced too far the rattle could be nothing more than preignition (pinging). It will be exacerbated if the engine is hot or by warm weather. Retard timing problem fixed.

If you get a mechincally minded person to listen to it they should be able to very quickly tell you the problem.
Greg H

>>Ive had the midget 3 months now and done about 2.5k miles . Gave it an oil and filter change when i got it.<<

the mileage is great for the car but just doing an oil and filter change when you got it was good but not enough

your problem could be anything from the tyres onwards (or could still be engine)

a great way to solve this and help prevent future issues is to do a full and proper 36,000 mile service

just doing this service might find or eliminate this and other issues

do a full and proper 36,000 miles service only miss out items that you have 100% proof have already been done very recently, including;
g/box and back axle oils
brake and clutch fluids
coolant
dissy cap, rotor arm and leads (buy good quality ones) - http://www.distributordoctor.com/rotor_arms.html
fan belt

For a coolant change drain the whole system - engine block, rad and heater matrix if you can get any of these out to give them a good shake at the same time as flushing and back flushing then all the better - the sequence is use cleaner as per its instructions then flush, back flush and flush and continue this until water runs clear, refill with the correct coolant mixture but bear in mind in tap water isn’t always the best water to use

If you clean the whole of the coolant system and also renew the seals and foam around the heater matrix you will find the heaters can get very hot

As new rubber cooling hoses tend to be poor quality now this is also a good chance to change them to silicone and rounded-edge clips - http://www.classicsiliconehoses.com/

Be aware that brand new parts can sometimes be faulty, especially electrical bits (see just above) so don’t discount them when problem solving just because they are new, buy good quality parts

always have the battery in good condition and all battery connections and leads clean, secure and protected, same for all electrical wiring and connections

Check the age of your tyres if they are 6 years old or more replace ASAP regardless of tread depth, this will improve the braking, steering, ride, handling and possibly noise and safety of the car greatly

Follow regular checks, servicing and maintenance as per owners Handbook

Drive in all weathers, the Midget hood should be very watertight if fitted correctly and the heater is more than adequate, if working correctly, for the small cabin

Do not do any cosmetic or improvement work for at least 12 months of regular use, unless you need to replace parts or components, as you may need to use the money elsewhere on the car

Also very useful, you can get suppliers catalogues for free to get you started to see where things go but in my personal opinion they’re not as good as a paper copy like - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Parts_Lists_3.html

You can also get an excellent DVD that includes original Parts Catalogues, Parts Fiches, Workshop Manuals and owners Handbooks to have in electronic format - http://www.motoringclassics.co.uk/heritage-range/c380/pg1/sr1

Oh, and buy an owners Handbook and read it thoroughly as it tells you so much you need to know to own, drive, service and maintain your car and it’s very useful to have as a paper copy even if you get electronic copies later, one example, other suppliers around, ask owners clubs – http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html

Cheers, carry on enjoying your car
N Atkins

In light of this new info... Id go back to my orginal posting, and look for a small exhaust leak or loose exhaust connection...alot of tiimes (and my old work truck is absolutly notorious for this) a small leak will sound like a bearing just banging away, and will only be heard on accelerarion or under load...so my next nickles worth of advise would be to look there after the bearing issue is but to bed

But .... Yes all the above suggestions are known leagitimate areas as well.

Exhauste noise has become the bain of my daily drives

Prop
Prop

Thanks for all your replies
D Stratton

This thread was discussed between 22/07/2011 and 23/07/2011

MG Midget and Sprite Technical index

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