TURBOTRONICS

hi all my dad has a 79 mg bgt and has asked me to look at it as it was running a little off and it was chuffing a lot from the oil filler cap.
now when i disconect the crank breather pipe from the carbs it runs better but there is a lot of carnk case presure and a lot of smoke with it. i take the rocker cover of and run it and the smoke is coming from the push rod tubes for cilinder 1 and 2. has any one any ideas as to what it might be?

NotoriousREV

It's probably just old and worn, I'm afraid. Almost certainly worn bores with loads of blow-by. Time for a K-series upgrade?

TURBOTRONICS

it was fine till he checked the oil and noticed it was a bit low so he toped it up and now its smoking from the breathers and the oil filler cap it is a little over full but only by a small amount

J4CKO

iTrader: (1)

I would get a compression tester, suspect that the bores are letting pressure past thats pressurising the system, could be that too much oil has gone in ?

Sometimes a thicker oil can help, these old lumps should be on 20/50, modern thin oils are not suitable.

Has it been stood for a while ?

The Zohan

Agreed, modern oils are not ideal, too thin.

It it has been stood it could be the rings gummed up, valves sticking a bit, all sorts. Did you check the oil on level ground?

TURBOTRONICS

iv done a compression test and 2/3 are right down i think it might be head gasket im going to take the head off at weekend to have a look. seems strange that 2 and 3 should be so low

J4CKO

iTrader: (1)

Yeah, looks like the gasket has gone between those two cylinders (and elsewhere by the sounds of it) allowing gas to pass between them, should be a reasonable job to do though.

TURBOTRONICS

do you think it would be worth putting new valves in and a bit of work on the ports while its off

fivetide

iTrader: (1)

Saves you taking it apart again at some point doesn't it? if you can get the bits i'd go for it, at least you'd know it was done then.

5t.

Old Battered MGB

Hello and how do you do.

My first post and what better way to ‘start’ than to try and help somebody with their car problem.

From what you (and others) have written I would try the following before you go ripping of its head:

Firstly have you taken it out for an actual run? …if so does it loose power and start to ‘chuff’ on a hill/incline?

Secondly replace following items
Oil filter (’79 model will be screw on type) – they can become blocked on an old engine (£4 approx.).
Oil filler cap (part no. GFE6003 – as per all B.M.C/Leyland 50’s to 70’s vehicles) as it also serves as a breather (£3approx.).
Spark plugs – Champion N9YCC I find best for an old B.M.C engine (the double copper core type) or failing that N9YC but not RN9YC which are resisted (£9.approx for set of 4). I take it HT leads are fine?

Thirdly check following
Carburettors – are the dashpots filled with oil to the correct level (‘3in1’ oil best for this), no oil in ‘em can cause stuttering and pathetic acceleration. Take it Air filters are clean-ish?
Breather tube/tubes from crankcase panel (below exhaust manifold area) to carburettors – are they blocked? If so just discard them for now and let it ‘breath’; but do replace eventually or else it can make car ‘stink of old oil’.
Distributor – Is advance and retard tube/pipe ok running from vacuum advance part of distributor across to Carb inlet manifold; sometimes they just vibrate off! I presume points and condensor are fine/replaced? Also check inside of distributor cap for hairline cracks (or replace anyway, cost £5 approx.)

I realise you said compression is down but with a bit of fettling (my suggestions above) it’s surprising how long you can keep an old B.M.C/ Leyland engine going.

As for taking head off (if it does have to come to that) due to a suspected head gasket failure (and after all what I have suggested it will probably still come to this), you will (as another person posted) probably find it has gone between 2 and 3 Cyl’s. Reason I say this is because you mention nothing about loss of water (I presume that has been checked? Did it blow white smoke out when on the road test?).
A WORD OF CAUTION- It may NOT be a head gasket gone but a CRACKED HEAD! Unfortunately this problem with ‘B’ Series engines as used in Morris Marina 1.8’s, 70’S Sherpa Vans, Morris Oxfords, Austin 1800’s etc (and many others) due to it’s ability to have lasted so long in many of the classics that have lasted are now suffering this problem quite simply to age engine has reached (the most recent one was made in around 1981).
So before ‘pulling the head’ make a few enquires/check you can get another /locate a decent second hand one (New there about £400 !!!) if need be.



Finally my most humble apologies if you have done most of what I have already mentioned. Only trying to help in what little way I can.

Good luck

TURBOTRONICS

Thanks mate unfortunately I have actually tried every thing you have said. There doesn’t seem to be any water loss not of and considerable amount any way, and as the engine gets wormer the chuffing gets worse to the point of chocking the engine if I leave the breathers on the carbs. When I had the rocker cover off there seemed to be plenty of oil coming from the rocker bar as I had the engine running on tick over but lots of smoke or oil vapour coming from the pushrod tubes for cylinders 1&2. But I have noticed that on the spark plug side there is a lot of discolouring of the paint work on the head between 2&3 as if to much heat. I think my self it might be time to remove the head and hope its not the head but just a gasket unless you can think of any thing else I might try

J4CKO

iTrader: (1)

My Fiat Coupe Turbo did the 'chuffing' from the oil filler, needed a rebuild and a new turbo (separate issue), I would say that its probably bore wear based on what you have said, i.e. down on compression, the crankcase is being pressurized by combustion gases.

At least they are a reasonably cheap and simple unit to do, you could rebuild it, rebuild and uprate or find out about swapping for a more modern unit if funds allow. Simplest answer if it is knackered is to get a reconned or second hand unit, an days work with a hoist to swap over.

I understand your headache on this but think about a mate of mine who has a Healy that won't go and a V12 E type that overheats all the time, overheating Jag V12's are not good, especially as its always been topped up with tap water and no anti freeze.

Old Battered MGB

I have had that in the past in EXACTLY same place on a '77 BGT and it WAS a cracked head! ...the crack went from one valve port across to spark plug hole and then along to next valve port area. On my car it had gone for some time (about 8months we think) and was not discovered until discolouration of the area you mention (by which time it was finally running 'rougher' and 'crack had got worse).
How the engine had run this well in this condition at all to me is testiment to the superb strenght that the old 'B' series engine must have (strength in it's build, most certainly not in it's performance ).

Sorry to condsider it to be worse case situation.

I did for a while think ‘chipped’ valve or stuck valve (but you’ve checked valve rocker operation and a chipped valve is unlikely to cause ‘chuffing’ and breather problems).

Keep informed as I am interested.

TURBOTRONICS

Right now iv had the head off de cocked it skimmed it re ground the valves and ported and polished it and last night I refitted just the head and rockers no manifolds or any thing else. Then I did a compression test and found the following
1= 150
2= 45
3=145
4=150
So it wasn’t the head gasket or at least it wasn’t coursing cylinder 2 to be so down it might have caused 3 to be down as there was slight blow threw. I then used a compressor to pressurise the cylinders
1 was fine it forced the engine round
2 hardly moved and you could hear and feel air coming from pushrod tubes
3&4 was the same as 1
And iv noticed that the oil smells really bad of burn to so im now thinking of broken rings on cylinder 2 and im not looking forward to taking the sump off and taking the piston out as iv never done this not with the engine still in the car any how
And ideas or suggestions would be a help

matchmaker

Sounds like rings. Depending on how access is to the sump, may not be a major job if you can get the car over a pit or ramps and get the sump off. I don't know how access is on an MGB, though. I had a Triumph Vitesse where the front chassis crossmember ran under the sump, therefore sump off was an engine out job

The compressions look good on the other cylinders. Another thing to check is if the bore is scored on no 2. If so, might mean a rebore

HTH.

TURBOTRONICS

The bores look good hardly and marks what so ever I think we caught it in time but there is a lip at the top of every one so I think it’s a little tired now and I think the cross member is just in front of the sump so I should be able to get it off ok im just worried about getting the piston past the lip at the top of the bore

TURBOTRONICS

Hi all just an update
I took the head back off last night and decided to put a little paraffin in each bore just to make sure my thought was correct and after a very short time number 2 was empty 1/3/4 still have paraffin in them this morning. I drained the sump last night to and got the car up on ramps ready for the sump off tonight and hopefully piston 2 out

TURBOTRONICS

Hi all
Right IV got the piston out and both compressor rings have shattered literally
So I need new rings dose any one know of any where I will be able to get some tomorrow in the northwest area preferably in the Wigan Leigh Warrington area

Old Battered MGB

Only place for MG parts I can think of is 'MOSS' in Manchester

Moss Manchester
111-117 Stockport Road
Cheadle Heath
Stockport
Cheshire SK3 0JE

Tel:- 0161-480-6402
Fax:- 0161-429-0349
E-Mail: manchester@moss-europe.co.uk

Also these guys might help:

BRADFORD PISTON & PISTON RING CO.LTD.
Unit 22 Missouri Avenue, Salford
Gt. Manchester, M50 2NP, UK

Established in 1935

Tel: 0161 736 5211 Fax: 0161 736 4785
Email address: bppr@btconnect.com


So it was the rings ...hmm...has engine been stood for a while? Reason I ask is the actual 'block'/piston/crank part of a 'B' series isn't that prone to any form of problem except worn bores etc due to age or crankshaft problems on early models if thrashed (despite even there age).

TURBOTRONICS

The bores are worn a bit but I think we should be able to get away with just rings and scrapers. The shells seem ok to. I carnt believe there is no damage to the bore when you see how many pieces the rings are in

SwissTony

iTrader: (19)

matchmaker

Glad to hear it's OK so far

I still have the scars from the last time I dropped the sump on a car

(Triumph Dolomite Sprint, big end bearings, 1981 , sliced open finger with Stanley knife when I was scraping off old sump washer )

TURBOTRONICS

Iv done that before but luckily it was just my thumb, to think of all the think iv done to my self while working on cars makes me cringe.

Right just waiting for the rings to turn up then I can fit them.
I have never fitted ring before so not to sure what im doing, do the rings have to fit in a certain way?
Do the rings have a top to them?
I know the scraper fits on the bottom but not to sure about the other 2
Any advice would be grate
Ta

J4CKO

iTrader: (1)

I think its a case of just using a compressor to compress it, lower it in and torque it back up, though I am fairly certain a glazebuster is required beforehand to deglaze the bores so the new ones bed in.

TURBOTRONICS

so i have to deglaze the bores before i fit the new rings can i use very fine wet and dry to do this?

J4CKO

iTrader: (1)

Not sure, you need someone with some more experience than me.

TURBOTRONICS

Thanks J4CKO
Can any one else help me on this as I need to put the engine back together tonight or at least put the pistons back in tonight

TURBOTRONICS

I fitted new rings to the pistons lastnight and fitted the rings torked the head back on and did a compression test compression is back up just have to build the rest back up today

The Zohan

Cool, good luck.

Enjoyed reading this thread, bought back some fond memories of classic car ownership

TURBOTRONICS

Thanks I will post the results this afternoon when its all back together