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MG Midget and Sprite Technical - Help me diagnose a rattle?

Picked up my midget yesterday and I've already developed a problem. I'm used to fiddling with mainly aircooled engines and also had a sidevalve for a while, so I'm not completely at home with the MG yet. I'd appreciate some help with diagnosing the problem.

1965 Mk II Midget. Original 1098 engine with unleaded conversion. I won it on ebay. It drove ok when I tried it out although I only really took it around the block. Trailered it home due to the distance involved. I took her out today in the sun but soon developed an annoying rattle which turned into quite a loud rattle. It is mainly present when under load, accelerating up to a cruising speed, or going uphill.

It disappears instantly if I take my foot off the throttle.

It is still there when cruising at a constant speed but not so easy to hear. Sounds like something is loose and rattling although I accept it may be all sorts of things. Very difficult to identify where exactly the noise is arising but it appears to be the front end of the car.

At rest in the drive it is difficult to reproduce just be revving the engine but as soon as I try to pull forward in gear, it appears.

The fan belt appears to be tensioned ok. The engine mountings look ok, I don't think the rubbers need replacing but I can change those as part of the diagnostic process if necessary.

Does this problem sound characteristic of a known problem? If not, where do I start? Internal to engine or external? Could it be something to do with prop shaft or universal joint?

I have a garage full of tools but little knowledge of the MG engine and drive train. I think I'm going to be learning quickly! Any and all suggestions welcomed. Thanks,

Stuart
Stuart K

It is possible that it could be pre ignition or detonation, although I very much doubt it from your full desription and if you have knowledge of other engines then I assume you know what that sounds like.

Other than that I am struggling to decide

Does it do the same in all gears?
Does it do the same at all speeds?
Robert (Bob) Midget Turbo

if it (only) does it under load I'm thinking pinking too.
David Smith

Under load it is very noisy once settled into a steady speed it is still present but quieter. Present in all gears and seems to be there at all speeds. Not present when revving in neutral.

I've never witnessed pinking before so don't know what it sounds like but this is a clanking rattle like metal on metal.

I'll check the plugs and timing tomorrow and make sure the distributor isn't loose and get her up on some axle stands and have a good look around.
Stuart K

Go and see John Collins, Stoo. Someone else needs to hear it. Bill (small dark green pleasure machine) is probably near you too - and lots of others.
Nick

How loud is pinking? My wife tells me that her boyfriend of 25yrs ago had a Spitfire that pinked and that it sounds more like tinkling.

This is a loud, people turning their heads in the street, rattling noise.
Stuart K

Stuart, drop me an email on green_mx5@hotmail.com and I can send you a manual, where are you in warks? I'm in tamworth,
John Collins

Could it be as simple as a loose exhaust? Under load it would vibrate, uphill gravity may pull it rearwards...

just a thought?!
Rob McGeown

Im thinking its in the exhaust.

a Loose nut someware, maybe a small hole, or the donut ring is missing or worn out at the header and the pipe connection

I got the same problem on my work truck, But im to cheap to get the exhausy fixed correctly...I got a leak at the joint where the header connects to the pipe because I never replaced the donuts...aka No donuts, and 2 small holes in the system someware....it seems to go way (noise)on the decent of a high hill with no acceleration being used. but vary noticable when you apply the gas pedal

That Being said, I hope thats what My Truck is suffering from ....Dooonks!!!!

Prop
Prop

Is it in all gears?
Nick

Yes it is in all gears. It does sound like it could be a loose exhaust. I gave it a good tug underneath and seem solid. I'm hoping for some time and fine weather tomorrow to get her up on ramps and have a good look around. It really does sound like something is loose and rattling away.

John, thanks for the offer. I have a copy of Haynes and the reprinted owners workshop manual to work from. I'm in Rugby.
Stuart K

I had similar problem on a 1500 midget, see my blog at http : // 1964 mgmidget (dot) blog spot (dot)com /

remove the spaces and replace dot with full stop as i don't seem to be able to post link properly. Look for posting from 21st feb 2008 and it will tell you the proble that I had, otherwise heres the entry which I added,

"this was a sqeaking, rattling, vibrating sound that came from the front passenger side & footwell area. I originally thought exhaust catching body, but it wasn't, then I thought maybe the engine and/or gearbox mounts had gone soft or failed as the noise was mainly there on overrun or decelleration, this also made me wonder about the condition of the diff. I also thought that maybe the clutch release bearing had gone. All pretty big jobs.

However on looking at the propshaft, especially the front u/j, I thought I'd have a closer look at that first. I removed the propshaft and I've never, ever seen a u/j in such bad shape, there was so much play and wear in it, I couldn't believe that it hadn't failed totally before this."

Its a pain to check uj on a-series engined cars, but if you are stuck, I've got a few early propshafts here,

Regards,
John
John Collins

Well I have plenty of ideas to follow up on, thanks all.
Stuart K

gearbox ratle?
not uncomon for a A-series box
Onno Könemann

If it's a loud rattle that corresponds with engine revs - I'd say straight away you could have a big or little end gone. If you want advice the chap to talk to is Rod at the Southam Mini and Metro Center 01926815681. He's only 10 miles away and one of the best 'A' Series guy in the Midlands - he does full builds and rolling road too should you need it. The last time I was there they had a stroked Mini on the rollers giving 123 BHP at the wheels.
f pollock

Onno thats so true, Im so spolied with the 5 speed, I completely forgot how much the ribby rattled around, and always in the rev up to shift position...great point.

Prop
Prop

Is it a rhythmic rattle or slightly erratic. Rhythmic would be a turning part (big end/little end, gear box), erratic would be something like the exhaust or a cracked carb heat shield. But the U-joint sounds like a likely candidate since it could be either rhythmic or erratic.
Martin Washington

Update.

Didn't get a chance to look at things until late this afternoon. I found the exhaust had movement where it is attached to the manifold. I couldn't get at it easily so just tightened up the nuts until it was all firm. Cross my fingers and went for a quick spin - problem had not resolved in fact it was worse, now present when revving in neutral. However inspection of the engine bay now revealed soot splashes around the area suggesting that it is blowing exhaust around. I presume tightening the bolts just made things worse as it didn't bring the two ends together as they should. So in order to get at the joint I removed the carbs (the nuts holding them on were not on that tight I discovered) and heat shield. Took the joint apart, applied some exhaust gum, reapplied the manifold clamp and refitted the carbs. I also checked the torque on the manifold nuts and found them to be loose too. Thought I'd better check the cylinder head nuts but they were torqued correctly. By this time it was 10pm so I called it a night and will see if the problem has improved in the morning. If not then I'll be checking the prop shaft and U-joint next.
Stuart K

wow,

Stuart. you must have had the guy I had several years ago...everything finger tightened....seriously with that much wrench work, Id say your in the right ball park.

fingers crossed for you

Prop
Prop

How's your oil pressure?
Nick

No one has mentioned worn universal joints yet. These rattle under load and become a lighter rattle on the over-run. Is the noise present when engine is running but car stationary? Chris
Chris H (1970 Midget 1275)

Chris, thought I'd mentioned them in my previous post? my 1500 midget that I had at the time was nearly undriveable due to the noise and when I removed the propshaft, the UJ was nearly destroyed!

John
John Collins

Update for those that are interested.

I took the car to Rod at Southam Mini and Metro and final diagnosis is that it was pinking (never thought pinking could make that much noise) due to a blown cylinder head - not good :(

He is going to take the head off this weekend and examine the block and then give me the bad news. Worse case scenario is I'll have to put a new engine in, but at the very least looks like a rebuild. There goes my summer.

Can't believe the car wasn't doing it when I test drove it.
Stuart K

Blown cylinder head or just gasket?

Either way, new head/grasket should do the trick... less than a day's work (+less than a morning's work for someone with experience).

Summer's not even started and you shouldn't miss one day.

A
Anthony Cutler

He was worried about damage to the casing and valves. I'll have to see what he finds. But the evidence wasn't good as by the time I got to his place oil pressure had fallen to 30 and was only 10 at idle and the temp had risen up to 200.

I can do a head gasket with my eyes closed but it may worse than just that.
Stuart K

Stuart

MAY be

isnt the same as

WILL be

these engines and heads can take a lot more hammering than you'd think.

The low oil pressure and high temperature just decribe a fairly normal overheat situation. I have a nice collection of "overheat situation" tee-shirts...

Car still blatting along nicely.

Fingers crossed for you, gonna be a longer summer than last year anyway, the weather gnomes owe us big time for the last couple...
Bill sdgpm

Indeed.

Bill is looking on one bright side, which I share. Iron engines are as tough as old boots, esp if allowed to cool naturally.

The other option, if the 'worst' happens, would be based on the initial letter of your surname (frankly I'm becoming a touch sensitive to banging on about transplants...) which seems appropriate.

[Mind you, a K wouldn't appreciate that amount of hear treatment!]

A
Anthony Cutler

Well if I do end up considering a new lump, where do I go to read about the K series? I was just going to drop another 1098 in if need be. Will a 1275 just drop in or would it require changing all the ancilliaries?

Stuart K

Found your K-series website. Nice! Probably outside my budget at the moment but something to aspire to.
Stuart K

stuart

Your wasteing your time dreaming about K series engines, Bill and Anthony are right, these little engines can handle ALOT of abuse, thats what makes these cars so appealing to most of use they can be modified so easily the engenering on these engines are basic at best, super simple towork on , rebuilding the head is not a big deal, plus there are tons of spare parts lying around...if you need some good valves im sure we got no less the 100 sets between all of us here in our spare boxes

even if the tops of the pistons are toasted, its not that big a deal...get some 21253s pistons from mini spares, throw in some new bearing shells while your there, hone the clyinders, your down maybe 3 days to a week if you got a pro on the job...its not the same as rebuilding a 2007 BMW 6 series engine

Prop...My glass is half empty, Who drank my water ...Prop
Prop

Naturally I am pleased I was right from the word go, however on the other hand it is a nasty problem for you just entering Spridget ownership and I feel really sorry for you.

I am not as hopeful as others, they must have had far different experiences to me with A Series engines over the past 40 years.

When Detonation/pinking/preignition occurs the following things can happen. Enormous amounts of heat are generated in the engine. This heat causes excessive expansion of the pistons and rings which leads to partial or total siezure of the engine (this can cause more heat build up. Thus the pistons are generally knackered and the bores in the cylinder block become badly scored and can often be past reboring. On top of this the headgasket can blow especially between number 2 and 3 cylinders, in really bad cases the block between the cylinders can be severely damaged beyond repair (looks like someone has attacked it with a burning torch) and the block becomes useless. This all can depend upon how long the detonation has been allowed to exist.

So Stuart from your point of view at least now you know what Detonation/pinking sounds like (many people do not!)and in future you will be smarter. Secondly lets hope that you will be lucky and the engine is salvagable with either a headgasket or a rebuild.

Yes a 1275 will simply drop in so perhaps you would want to go down that avenue.

What ever! I have my fingers crossed for you
Robert (Bob) Midget Turbo

Well I have just been to look at the engine with the head off. It had blown the gasket between 1 & 2 cylinders and there was a clear crack between 1 & 2 on the head itself. It was also a 1275 head on a 1098 block. The valves didn't have enough clearance and were slowly making their own space in the block as was evident by the semicircular groove they were making. If this was the only problem I might get away with just putting a new head on but Rod reckoned that with the sound of the engine, the significant loss of oil pressure and overheating that the bottom end would almost certainly need rebuilding, if not the whole engine. Factoring in the cost of rebuilding it would actually be cheaper for me to get a new rebuild on exchange from somewhere like Bumper to Bumper who currently advertise at £675 plus VAT. It would be even cheaper if I did the engine exchange myself rather than pay Rod £45/hr for it. So I'm having the car trailered back to my house and then I'll be looking to replace the engine.

There is no such thing as a bargain!

Still at least this way I'll get to tidy up the engine bay properly and I'll get a crash course in MG maintenance.

So any recommendations for the supplier of a new engine?

Easiest for me would be exchange like for like and drop another 1098cc in. I could get a 1275 but I think that would require a different dizzy and the carbs would need rejetting?

Should I start a new thread specifically about that?

Stuart K

Stuart

Get in touch with me at carl(dot)bintcliffe(@)ntlworld(dot)com

I may have something that may be of interest to you!

Cheers Carl
C Bintcliffe

hi stuart
you could try these people i know they do 1098s from my morris minor years
i would start a naw thread if i waz you

good luck

steve.p.

stephen parker(73 oew rwa midget)

sorry 4got the link
http://www.britishclassiccarspares.com/
stephen parker(73 oew rwa midget)

better still
http://www.britishclassiccarspares.com/acatalog/Online_Parts_List_ENGINES_LEAD_FREE____EXCHANGE__2.html
£675 exchange

steve.p.
stephen parker(73 oew rwa midget)

Thanks Stephen, they are Bumper to Bumper under another name.
Stuart K

sorry just notice you have seen it
stephen parker(73 oew rwa midget)

Stuart,

Surprising the problem didn't show up on the test drive and a shame about the engine, sounds nasty for it to be chewing itself up. I did a 1275 head on a 1098 and it went really well, but I knew the block had to be pocketed first for it to work. Have you asked the PO whether the intention was to fit a 1275 head, maybe it was supplied in error?.
David Billington

Not yet, although I will be contacting him to tell him what I found out. In with the receipts for the previous work on the car is the bill paid for reconditioning the head for lead free. No mention of it being a 1275.
Stuart K

Stuart now you have been stung you need to try and come out on top. Go for a 1275 and you will not regret it. It will seem a little more expensive to start with but will be worth all the effort in the long run
Robert (Bob) Midget Turbo

Pics as promised. First the block showing the areas where the valves have been hitting. Maybe these areas were machined but the valves show a corresponding area of wear.




Stuart K

The corresponding area on the head:




Stuart K

A crack starting?




Stuart K

And the blown gasket:



Stuart K

well I wouldnt use that gasket again Stuart

The block doesnt look as if it has been pocketed, neither do the valves show any sign of it having been done

Probably someone who had been told that ALL A series heads fit all A series engines, or who just couldnt be a***d to find out

Bob's advice is good too, get a 1275 if you can.
Bill sdgpm

That confirms what I thought. It wasn't the PO's fault either. I have the receipt from an Engine Reconditioners for converting the head to lead free and surface grinding. Pity they didn't know how to fit a 1275 head. They also robbed the PO. The receipt from 2004 was for £305.
Stuart K

Stuart, Im sorry, BUT GET a Lawyer....I know the laws are differant from our 2 countries

But I cant belive if you got on video, the mechanic dumping suger and fine sand into the gas tank, then you buying the car 2 days later, that the mechanic is exempt....its no differant your case, the machanic is responsiale....And I cant belive this damage ONLY started when you purchased the car and not before

It dosnt matter that you had the engine disassmbled, they would have had to also 2 days later


agian this is not a "worn out" item like a headlamp or a fan belt, you Unknowingly and under false pretense purchased a botched repair, I cant imagine that the mechanic didnt know he was installing the wrong head...

I want to know, did the seller tell you it was an expermential head, yes or no? If not why didnt they? you cant tell me they didnt know....after all there are NO mechanics that will go thur all that truble and never tell the owner what they are doing, and even if that is the case...you got the meachanic "dead to rights"

PULL the DAM* trigger man, dont volenter to get the shaft. Jesus!!! you have a case, have it looked into at the least


Prop
Prop

Stuart

I have heard that sometimes a 1275 head can be fitted to an small bore block without pocketing, as long as the exhaust valves are recessed further into the head, and there hasn't been much head or block skimming. Looks like the valves were only just touching, so maybe someone tried a dummy build, found it wasn't binding, then went ahead.

In case you are interested, I have a Marina short engine in my garage, with the correct midget flywheel. It hasn't got a backplate but you can use your old bits and bobs to make it complete. I might also have a head that could be used, with a titilate first, if you don't want to use your old one.

Let me know if you are interested.
Matt
07736 425739
Tarquin

If the engine reconditioning firm were just converting/ working on / a head supplied to them, but not assembled by them to the engine, then it wasn't their fault. If the PO decided to get hold of a 1275 head, get it converted for unleaded, and then fitted it without carrying out any checks or research, then the fault is entirely down to him.

And, although "buyer beware" applies, if you buy privately and ask specific questions of the seller, they are legally obliged to tell you truthfully what they know. e.g "has there been any crash damage?" and "have you had any engine problems?" they are obliged to say what they know to be true. The difficulty of course is proving what was and wasn't said at the time. My guess is that you are on your own now.
Guy Weller

Stuart - you haven't said what you want out of your Midget. If you want the chance to tune it up with tasty go-faster gear in the coming years, you'd better go for a 1275. If that's not your first concern, and you'd like to be the custodian of a rarer model that goes pretty well, look for a 1098 head.

Don't know which I'd do.
Nick

This thread was discussed between 01/05/2009 and 14/05/2009

MG Midget and Sprite Technical index

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