Loud knocking from engine when accelerating

[Sips]

Hi guys,

An awful post I fear to be my first but I think 'Mog' ( not the only one in existence but we are not very imaginative with names! ) has a terminal issue with her engine.

When accelerating there is a loud knocking coming from the engine, way louder than pinking. With the bonnet up and revving it slightly it sounds like it is coming from the head and it sounds like a beetle when idling. The oil pressure light works when started but isn't coming on whilst running and there is oil in her.

Annoyingly mechanically she is spot on but the body is shot! I think she is shot completely now!

She covered about 500 miles a year before we bought her in April, we have done 3000 miles in her since then and she hasn't missed a beat and suddenly when cruising at 50 mph today after about 40 mikes she started doing the above.

I live very close to the Charles Ware centre and when I bought her they cast an eye over her. I bought her to restore and use as our wedding car but they suggested if I were to restore one not to bother with her. So the question is if the engine is shot where do you draw the line?

I hope someone will be able to give us some good news that it may be something simple but I fear not! Help!

FYI she is a 1966 2 door saloon de lux model with a 1098 engine

[simmitc]

Soounds like a head gasket. Do not run the engine until you have checked the compression. If it is the HG, then you can do bad damage to the block by running the engine. If you have not already done any harm, then the gasket is cheap and easy to replace. If damage done, then the head will need skimming, and possibly the block also. As to what the rest of the car is like, can;t really say from current information. Any car can be saved, but it's a question of cost.

[bmcecosse]

Second vote for head gasket - off with it's head.......

[Sips]

Thanks for the replies.

I will get stuck into the head and see what things look like.

What sort of damage am I looking for when I take it off? I guess water in the oil and vice versa but is there likely to be mechanical damage?

Having cut my teeth on 90's cars with alloy heads a skim was always in order but is that the same with an A Series engine?

[MarkyB]

The oil pressure light works when started but isn't coming on whilst running and there is oil in her.

The dipstick is for checking the oil level, the oil light is more of an engine knackered warning light
Cast iron heads rarely need skimming, it's worth putting a straight edge over it to be sure though.

[bmcecosse]

Almost certainly blown between two cylinders - so no water/oil mix to worry about. As long as it hasn't been run any distance like that - just clean up and fit a new gasket unless you see any obvious errosion. Retorque the head (44 ftlbf) after the first heat cycle.

[Sips]

Right, decapitation it is then!

I am in Bristol so near Charles Ware's (Hence a Morris Minor as my first classic) are the head gasket sets fine from here? I have been reading a few threads about differing qualities of them from various suppliers.

Spanners out on lunchbreak I think!

[simmitc]

With the head off, you will probably see the failed gasket very clearly. If the engine has been run for any length of time with the gasket blown, then you may see a groove or "V" in both the head and the block at the same place where the gasket failed. If you're lucky, then you won't see any damage. Any marks will be obvious. Still worth checking with a sheet of flat glass to identify any low points that require attention.

[bmcecosse]

Check the cost before buying.....we are not allowed to say anything about Charles Ware. Best source of a gasket (I find) is your local Autoparts place - gasket for a 998 Mini is what you want (no need to buy a 'gasket set') . Go in wearing overalls/dirty hands - and ask for a discount. May as well get a spare while in there. I carry one in my car all the time........

[Sips]

Great, good information. Lines between read!

You all hit the nail on the head, head gasket gone! So now the question is to skim or not to skim. I have posted some pics below but I have not cleaned the faces yet, just got the gunk off the piston heads. What is general consensus on this?

[Sips]

here is the block[frame][/frame]

[Sips]

here is the head[frame][/frame]

[simmitc]

Unfortunately photos are only 2D, so it's difficult to tell whether those are grooves or just marks. I'd be tempted to skim the head (it's easy to strip and carry) and then just polish the block, fit a new gasket, and see what happens. If it works, then you've saved a lot of time and money. If the gasket blows again, then stop the engine straight away before the head needs doing again, and get the block done. However, skimming the block will require a complete strip and rebuild, so assess the general condition and consider whether to do anything else at the same time. Fingers crossed for you.

[MarkyB]

Agreed, hard to tell from the picture.
Wipe off any carbon, put a straight edge across the dodgy bit and a light behind it.
If any photons escape underneath get 10 or 20 thou skimmed off the head.

[Sips]

Very true, I think I will clean it all up tomorrow and try to get a better gauge of how it is then. From looking at it in the flesh it seems to just be marks. If there is any imperfection I take it I will be back to square one?

Out of interest how much does a skim cost roughly? If I have it skimmed do I need to change anything in the head i.e. valves? It has hardened valve seats already.

The great news in all of this is I remembered today how much I love playing around with all of this stuff, just need to back myself more to do it. I am even going to crack out the welder at the weekend and get practising ready to tackle the body!

[les]

Enthusiasm is half the battle won.

[bmcecosse]

It will be fine -I'm sure. Don't be tempted to rub at it with emery paper or anything like that. Run a straight edge over the faces by all means - but I would clean carefully and try a gasket. DO NOT use any 'gasket goo' - DO wipe the gasket with a thin film of grease, and torque to 44 ft lbf. Re-torque after the first heat cycle - and then reset the valve gaps of course.

[Sips]

Been shopping for a head gasket, but am unsure which type to get (took your advice on the Mini 998 one BMC) Should I stick to Copper which was what was there or is fibre OK?

The heat cycle you mention, does that mean just run up the car to full operating temp without driving it then cool it and retighten?

Last question, I take it the car must have overheated to have blown the gasket (not sure when this happened, not in my ownership anyway!) so should I change the thermostat as well? What is the reason for 2 different heat options with the thermostat?

Thanks in advance!

[bmcecosse]

Copper gasket is better in my mind -but actually there is probably nothing wrong with the 'fibre' one. Yes - start and run up to temp at fast idle, then allow to cool (but doesn't need to be cold), and retorque and set the gaps. Thermostat is likely ok - the 88/92 stats are for winter use - to get good heater action. Probably wise to use a 74 stat in summer though.

[Sips]

All sorted now, bombing along again!

Thanks for your help.