Guess My Problem

[minor65]

Tonight on my way home from a evening car run, approx 10 miles from home when doing 40/45mph on a road with quite a lot of uphill and downhill straights. A loud knock came quite suddenly into the big 1098. Prior to this inwardly I had thought to myself (although it did all the hills in 4th gear) I was having to go into the hills flat out to do it in top. Usually the car would laugh at hills and always have plenty more throttle, though not tonight.

Anyway, suddenly a loud knocking noise appeared (me and dad looked at each other with worried expressions). At first it only happened with heavy throttle, no noise with light throttle. 2 miles later noise got much worse and now no power. After having to pull in off the main road, the checks begun. Removed each plug lead from plug one at a time with engine running, cylinders 3 +4 showing no difference when removing leads. Removed plugs on those cylinders and both sparking, oil and water all good and no mixing, oil pressure light acting Normal/staying off. Nothing more we could do there, so decided to limp her home ( roads where quite quiet and mostly downhill at this stage).

When home we tried a quick compression check (using the thumb trick). Doesn't seem to be any compression in cylinders 3+4, won't know for sure until I borrow compression tester from work but I'm fairly confident. Initially we thought head gasket but would it make knocking noise.

First thing is to do a compression check, then pull the head off if required. Headgasket fitted/valves reground approx 5,000 miles/6 years ago.

Feel free to have a guess and will keep you informed.

[callyspoy]

My dad removed his engine as he developed a very sudden knocking/rumble and thought he'd somehow knackered the bottom end; turned out to be just a head gasket. This was only a few months ago.
So yes, a head gasket can cause a fair amount of noise. Easy enough to take the head off and inspect as you say, i guess it could be a damaged/burnt valve, but then it's unlikely to have done that on 2 cylinders at the same time.

I'm going with head gasket.

[MarkyB]

If you can't detect compression with your thumb there isn't any!
Just get on with replacing the gasket.

[minor65]

I'm away on holiday now for one week, so nothing will be done until I get back. If it is just the head gasket I will be very suprised as the noise is quite bad.

[Biggles1957]

Exactly the same symptoms when my head gasket went - blowing between 3 and 4. Makes a horrid scary noise but a quick easy fix!

[bmcecosse]

It is exactly the head gasket. You SHOULD NOT have continued driving it - the hot gases may well have burned the head and/or block. Blown gasket requires immediate engine shut down......and either fix it there and then - or get towed home.

[minor65]

Well our Branch Regional Rally was on today, but unfortunately because I was minorless so close to the rally I had to attend in my modern. When we got home I decided to remove the head, so we had an idea of what the problem was (so it doesn't ruin the holiday which starts tomorrow)

Once the head was removed it was all clear to see the issue. Whoopee Blown Headgasket between cylinders 3 + 4. I thought that's probably what it was but because it made such a knocking noise I was more worried. Then checked the block / head / valves and top of pistons all excellent, no wear or damage.

On the top of the pistons I looked to see if the engine had been rebored at some point, the writing on them all say M2007 then the usual MOWOG, then N34. I thought it should say something like 0.20 /0 .30 etc. It must have been rebored at some point as the engine in the car is the original (engine number on block matches heritage cert) and has 122000 miles (mot's to prove).

I forgot that I actually have the gasket set already (for a spare engine that I haven't got round to rebuilt) so will wait until I get back before getting stuck back in to it.[frame][/frame]

[DAVIDMCCULLOUGH]

Thats blown out quite a big chunk Andrew, bet your glad thats all it was.

[minor65]

Absolutely David.

[callyspoy]

Whilst i agree with BMC, i have to admit that it isn't always practical to just stop and get recovered. I had to limp home in mine a couple of months back due to a suspected head gasket, i was just just as happy and relieved as you are!

How many cars are there that you would be happy only the gasket went?! If i tell any of my friends about head gaskets all they know is that they are fiendishly expensive to replace; the joys of driving a classic as a daily!

[stevey]

well, glad its straight forward anyway.

[bmcecosse]

It is extremely foolish - and could be extremely expensive - to keep driving with a blown gasket. Seriously - always carry a spare, (and you will have water anyway), and just change it - only takes 30 minutes!!

[madmoggy]

GOT one at work the same.
OH and sometimes we just have to get home under our own power,cant always carry a workshop and spares dept in the boot.
Im sure you will be fine with a gasket change.

[bmcecosse]

A head gasket is easy enough to carry - surely...... Just keep it flat - maybe under the rear seat... You seriously risk severely damaging the engine - but I suppose if you don't mind that - carry on!!

[les]

30 minutes to change the head gasket, there must be pit crews queueing up to sign you!!

[aupickup]

[madmoggy]

And thats on the side of the road aswell

[JOWETTJAVELIN]

A call to the AA would be in order (hopefully as a member), then change it at home with the correct tools and plenty of time and nothing to worry about.

[bmcecosse]

Working at side of road gives every encouragement to get it done quickly.....

[katy]

Especially if its raining or snowing.