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 - Engine judder, blue smoke and lack of power

Hi, being relatively new to this forum and a novice when dealing with MG engines (although i did strip down an air cooled vw engine a few years ago) could I ask the experts...

We recently bought a 1970 midget(1275) and up to a few days ago put up with the blue smoke on start up (not evident once warm and not noticed when we bought the car!!) There's now lack of power - the car feels like it's 'holding back?'. Could it be worn piston rings at best? or something more serious?

Anyway i'm now getting engine 'judder' which is almost shaking the car to bits!

Any ideas...HELP!!!!!!!!!1

Darren

Stu Dickens

Hi, being relatively new to this forum and a novice when dealing with MG engines (although i did strip down an air cooled vw engine a few years ago) could I ask the experts...

We recently bought a 1970 midget(1275) and up to a few days ago put up with the blue smoke on start up (not evident once warm and not noticed when we bought the car!!) There's now lack of power - the car feels like it's 'holding back?'. Could it be worn piston rings at best? or something more serious?

Anyway i'm now getting engine 'judder' which is almost shaking the car to bits!

Any ideas...HELP!!!!!!!!!1

Darren
D Jones

Try a compression & leak down test before you take anything apart, could be a head gasket.
cheers
Brad
B Richards

Thanks Brad,

I'm ok with a compression test - i think my dad still has the kit to check this but what does a 'leak down' test involve?

cheers
Darren
D Jones

Darren,
you connect a compressed air supply via an adapter into a spark plug hole, then listen to see where the air escapes i.e. exhaust, carbs, dip stick tube..it will give you an idea of where the problem could be.
Your local garage will have the necessary tools for the job.
cheers
Brad
B Richards

Thanks again Brad,

In your experience could some of these symptoms be down to poor compression etc? It's strange cause the guy we bought it off said he'd recently fitted a new 'unleaded' head. I'm beginining to wonder whether he did the job well?

Cheers

Darren
D Jones

I had the same last year, occured very suddenly. Took the cylinder head off and found the gasket had ripped between cylinder 1 & 2.

Replaced head gasket and all fine with the engine now!
M Andrews

Darren,
Before a compression rest, are you sure it is firing on all 4?
With it running, and using a pair of insulated pliers, remove each plug lead in turn. If one DOESN'T make it run worse when removed, this would indicate that that cylinder isn't firing. You can then check for spark, check plug etc.

Don't assume that the smoke and lack of power are both indicating the same problem.

Blue smoke could be a red herring!

Guy
Guy Weller

Could be a poor gasket, i use original metro turbo head gaskets nowadays, the only ones i've found to be reliable. About £20 from Avonbar.
The nuts needs to be checked for tightness a short time after changing the head gasket, as things settle down, have you checked them?
Brad
B Richards

I agree with guy completely on this one...Im guessing the blue smoke is a red hering also most likely just worn valve stem seals.

being that you just got the car and trully dont know the real history of the car, Id start with a total tune up

plugs, wires, points, condensor, rotor bug, cap belts, hoses, oil, coil, thermostate, filters antifresse, rad caps... a good complete carb cleaning and adjustment .....everything

But do it in chunks....in other words igintion, then fuel system then belts and colling system, Id also check and adjust the valve timing...

this may seem a bit over kill....but these cars are maitance hogs....I say get all this stuff out of the way now, at the vary least your going to get a good working undrstanding of how the car goes togather,

Id probable do the comperssion and leak down test 1st just to get you in the right direction


Harbor frieght has a decent leak down kit fairly cheap

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94190


prop
Prop

this seems like deja vu.......

Have you got an image of what the plugs look like. I think mine was down to two/three factors.

Head did not feel tight when I went to remove it ciopuled with bore wear.

Strangely I ahd the same smptoms as you and have been through that process.

I would recommend the pressure test first mine came out at 45psi....pretty low.

So I would say prepare for the worst....

Shaun
Shaun

If, for the moment, you set aside the issue of blue smoke then a car that judders and lacks power sounds to me like a misfire. This may be connected with the blue smoke,could be a gasket problem or burnt valve or broken rings, but may not. Check the simple things first, that is all I am saying.
It could be something as simple as a faulty plug or bad lead. You haven't, by chance swapped the leads around have you? Compression test is very informative - assuming you have, or can borrow a tester. But always check the simple things first.
Guy Weller

This thread was discussed between 20/08/2008 and 21/08/2008

MG Midget and Sprite Technical index

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