42 replies to this topic

[Ipod]

Sounds like somthing in the bore, possably part of a piston ring,
Or a sticky valve
Pull the plugs and get pistons at TDC and go fishing with a magnetic wand to see if you can hook anything
Failing that pull the head off (gotta change gasket anyhoo)

[miniman3003]

The oil pressure looks healthy enough at just over 50 psi.

I would certainly go with The Matt and say that it doesn't sound like a big end. If it was, it would be a much more clunky sound and regular as well, a bit like a machine gun. This seems to be irregular in nature.

It does sound as you say as if "something" has broken off and this is what is being flicked around as the engine runs. I don't think I would run the engine any more.

I can't think of anything on the rocker gear that could break off and make that noise. If it were my engine, then I think the next stage would be to lift the head off and see what's going on inside the cylinders, scored bores, etc. Perhaps a chunk has broken off one of the pistons and is being bounced around in the bore. I have seen cases where a part of the piston has broken off above the top ring due to lack of oil.

If that doesn't show up what the problem is, then sadly it looks as if the only other option would be to lift the engine out and dismantle it. If it's a piston problem, then the engine is going to have to come out anyway.

If it is a loose bit inside the crankcase, I would be very careful when moving the car as if the bit settles down between the gears it could get caught up in them and then you might have some teeth broken off on what is presently a good gearbox and hence more expense.

Good luck with your investigations and keep us posted. This is an interesting one!

[tsumini]

No oil showing on dipstick does not mean "no oil".
Can't believe nobody recommended checking the oil filter for metal flakes/chips. Also drain oil from pan and look for metal. 1st thing i check with suspect oil system problems. If metal flakes/chips the engine is toast. If none then maybe no damage. If engine is oil starved it will seize within seconds.

[garrymacmini]

Start with dropping some oil to see if any metal as above, if there is then you may have serious issues, next up to the top, pop the rocker cover check rockers first, then crack head and check there see if there is any damage, if not then well you can figure the rest!

[tsumini]

Audio from a video recording is almost impossible to decipher. It sounds like a pffft of decompressing air.Having said that I would guess the noise is a muffled backfire such as a inlet vavle burned or stuck intermittenly. That is purely speculation on my part.

[Mini Cheddars]

Have you pulled the rocker cover off yet?

Did that last night on the hard shoulder with the RAC guy. He couldn't see anything untoward but he did comment on one of the springs (?) having very slightly less tension in them than the rest. That was on cylinder 1 I believe. Closest to the radiator.

Small ends tend to rattle under load though don't they?

I don't think its big end though, it could be a head gasket, did it get hot?

You can usually prolong the life of a knacked engine with some fresh 20/50 and some wynns oil treatment. I ran Poo like this for about 18 months before rebuilding his engine.

I didn't run it long enough this morning to allow it to gain temperature but I've never had any temperature problems since I've had it. Smiths temp gauge is almost always on halfway once it's warmed up and goes no further.

The above posts about not running oil low etc etc are all exactly right, BUT you did it, so no point rubbing your nose in it, what you need is a way out. If it is a standard 998 I wouldn't bother stripping it. Do an oil and filter change, keep a VERY close eye on the oil pressure gauge and watch for a decent 998 to come up in the ads on here or eBay. People are continually upgrading and running 998s don't cost a fortune ( yes I know you can buy trouble etc etc before anyone says, but I am thinking of minimum cost options).
you may even get lucky and find you have done no lasting damage. In the early 90s I was driving a Mk3 escort down to Harwich on my way to work in Holland for a year. The oil light came on, when I stopped the engine was nearly empty of oil due to a leak. I limped a mile to a garage, bought 4 lots of oil and limped the 300 miles to Breda in Holland. I got the seal changed and the mechanic said the engine would be completely scrap but it was still going 30000 miles later when I sold it. But I was lucky, I wouldn't recommend it for an engine. Good luck.

Good idea, actually. Have needed to do an oil filter change for a long time. I'll pop down Halfords soon and buy some bits.

Sounds like somthing in the bore, possably part of a piston ring,
Or a sticky valve
Pull the plugs and get pistons at TDC and go fishing with a magnetic wand to see if you can hook anything
Failing that pull the head off (gotta change gasket anyhoo)

Head should be coming off on Sunday with the help of a friend who also owns a Mini.

The oil pressure looks healthy enough at just over 50 psi.

I would certainly go with The Matt and say that it doesn't sound like a big end. If it was, it would be a much more clunky sound and regular as well, a bit like a machine gun. This seems to be irregular in nature.

It does sound as you say as if "something" has broken off and this is what is being flicked around as the engine runs. I don't think I would run the engine any more.

I can't think of anything on the rocker gear that could break off and make that noise. If it were my engine, then I think the next stage would be to lift the head off and see what's going on inside the cylinders, scored bores, etc. Perhaps a chunk has broken off one of the pistons and is being bounced around in the bore. I have seen cases where a part of the piston has broken off above the top ring due to lack of oil.

If that doesn't show up what the problem is, then sadly it looks as if the only other option would be to lift the engine out and dismantle it. If it's a piston problem, then the engine is going to have to come out anyway.

If it is a loose bit inside the crankcase, I would be very careful when moving the car as if the bit settles down between the gears it could get caught up in them and then you might have some teeth broken off on what is presently a good gearbox and hence more expense.

Good luck with your investigations and keep us posted. This is an interesting one!

Thanks for the information there, miniman. Good advice.

No oil showing on dipstick does not mean "no oil".
Can't believe nobody recommended checking the oil filter for metal flakes/chips. Also drain oil from pan and look for metal. 1st thing i check with suspect oil system problems. If metal flakes/chips the engine is toast. If none then maybe no damage. If engine is oil starved it will seize within seconds.

I'll get to doing an oil & filter change at the weekend.

So just off to pop down Halfords. Going to buy a compression tester, oil filter wrench, oil catcher, socket drive that works (mine's busted)... anything else I may need to take the head off? I have some bits already like 13mm sockets.

Oh and what size socket do I need for the sump plug?

Edited by Mini Cheddars, 01 January 2013 - 02:45 PM.

[Mini Cheddars]

Audio from a video recording is almost impossible to decipher. It sounds like a pffft of decompressing air.Having said that I would guess the noise is a muffled backfire such as a inlet vavle burned or stuck intermittenly. That is purely speculation on my part.

I know but it helps to some degree when you can't be here to hear for yourself.

I need Sherlock Holmes!

[mattdc2r]

Think i'd have had the head off by now. agree that the audio from the video doesn't sound like BIG end, but can never really tell with a camera phone.
Wouldn't advise you keep starting it up though, cause all you'll be doing is increasing the damage.
Hope you get it sorted soon.
Matt

[Mini Cheddars]

Think i'd have had the head off by now. agree that the audio from the video doesn't sound like BIG end, but can never really tell with a camera phone.
Wouldn't advise you keep starting it up though, cause all you'll be doing is increasing the damage.
Hope you get it sorted soon.
Matt

Just not had the time today. Just got back from Halfords though with a compression tester, large funnel with filter, oil drain can, oil filter pliers and a 24mm spanner for the sump plug. Had a look on here and that's what size someone said to use.

I just started the car to take that video. Only time I've started it today so was only for a brief period. I don't want to start it again if I can help it.

The instructions on the back of the Gunson Hi Gauge Compression Tester say to get the engine up to a warm temperature, but that of course would mean starting the engine which is something I don't want to do. But someone earlier in this thread said you don't need to start the engine.

What's correct?

Edited by Mini Cheddars, 01 January 2013 - 04:15 PM.

[mattdc2r]

it says to get up to working temp due to expansion of metal. Once everything is at normal operationg temp, then you can take the test. readings may be low if done cold.

[sledgehammer]

Don't worry about the warm up - just whip all the plugs out

and make sure out of gear

get someone to open throttle while turning engine , while you hold the compression gauge over the hole (unless you have a posh threaded one)

you are looking for a difference in pressure - if on 2 cylinders then may be head gasket

Edited by sledgehammer, 01 January 2013 - 05:37 PM.

[Mini Cheddars]

Cheers. I was hoping I wouldn't have to start the engine.

And FYI it is one of those posh threaded ones.

[sledgehammer]

Over the years I've had a few things causing a noise similar - random knocking -

A shell was spinning - cutting off the oil (knocking) , then would catch on the tang allowing oil to flow again - (quiet)

also a valve spring broke in such a way that the spring would ride up and close the valve , then go past the break and go slack & lose compression

fuel pump return spring broke causing a random slapping noise - but still worked

also had a ford 302 plastic sprocket chain lose a chain link - slapping the timing cover

would be nice if it was just a head gasket thou - although that is normally constant