MGB: Off with it's head - Could I be lucky lucky lucky!! Pics

My BGT was burning oil and running rough. I don't just mean a drop of oil but a gallon in the 190 mile drive home.

I've only just got round to investigating and after a compression test showing 90 on all cylinders I pulled the head.

I didn't expect to see what I saw.



Nothing serious at all. The bores have a very slight ridge at the top but I've seen worse. The pistons are a good fit and there's no sideways movement in the bores.

Puzzled, I turned the head over.



Apart from needing a good clean up, the only thing I noticed that was odd is the amount of oil between the pushrod holes and the combustion chambers. There was a similar amount on the block which I expected, but didn't expect to see it on the head..

I plan to run a straight edge over the head and block. Could I really be lucky enough to get away with a new head gasket???

If you burned a gallon in a 190 mile trip , you should have been leaving a huge smoke screen.At 90 on all 4 cylinders and that amount of oil use, I believe a head gasket is not going to fix your troubles. My guess would be rings are spent.

Hand turn the crank until all the pistons are at the same level, wipe the bores and take another pic, I see what may be an odd pattern on the walls. Your head looks like the exhaust valves are too pocketed. In a hipo application this can have a benefit but in an MGB it usually means a poorly redone cylinder head. I rather suspect valve guides may be contributing to the oil use issue but probably not the main cause. Possibly broken rings or perhaps misinstalled ones? Can you pull the studs, wipe, but do not scrape, the block deck and take a nice straight down pic. More pics and info are needed. How long have you had this car and what is the engine history?

Brad

Owen,

I once had an engine at my shop, that had removed the oil seperator out of the front tappert cover by a PO. The engin was supposed to be junk for burning lots of oil first. Fitting a new cover cured this problem. When you have the head on the bench, just check the cover for beeing ok.

Ralph

Thanks Keith. I was being a bit optimistic I suppose. It was laying smoke all the way home.

Brad.

I've had the car a couple of weeks and know nothing of its history. The valve seat recession is probably due to the used of the 'environmently friendly' unleaded fuel in the UK and this head obviously hasn't had the hardened valve seats fitted to reduce valve seat recession.

Once I get the valves out and see how bad they are I'll have to decide whether to spend £300 on a head with hardened seats or keep going with this one. I won't be doing great mileages so putting off spending that kind of money is attractive.

I agree that valve guides won't be all the issue as it smoked continuously whereas guides tend only to smoke after first starting or after decelleration.

I'll take some more pictures tomorrow in the light.

Thanks, Ralph. I'll check that.

After deceleration and You step on the foot feed,if it leaves a puff of smoke then it is pulling oil up past the rings due to the vacuum created from deceleration.
Or it could be from leaking across from the pushrod openings.

I'm glad the pistons look good but can you see how big the ring gap is? If you're burning that much oil, rings and valve guides seem to be a minimum fix. I'd also have the head pressure tested (not just magnafluxed) because a crack could be over-pressurizing the sump and causing oil not to drain back from the top end. That oil could go from the breather right into your intake manifold. Best of luck. Basil

[quote="Ralph 7h"]
Owen,

I once had an engine at my shop, that had removed the oil seperator out of the front tappert cover by a PO. The engin was supposed to be junk for burning lots of oil first. Fitting a new cover cured this problem. When you have the head on the bench, just check the cover for beeing ok.

Ralph[/quote]

I would agree ,you could have an engine sucking the oil out of the sump without it being dead. The low compression numbers , even across the board and high oil compsumption is what points me towards rings.

Thanks for all the input.

I've just had a visit from a mechanic friend who has looked at the engine, pronounced the bores & pistons good, checked all the breathers, all clear.

He checked the valve guides and found a little movement but not enough to account for the oil usage.

Looks like it has to be rings, either stuck or worn, so tomorrow is drop the sump and pull the pistons day.

Cover me, I'm going in.

[quote=oily-hands]
Thanks for all the input.

Cover me, I'm going in.[/quote]
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