28 replies to this topic

[flamenco]

Hi everyone,

I have been using my 1970 mini 850 for quite some time now after a head gasket change (it's been about 4 months now), and it all went plain sailing. Today I started it and took it out of the garage so that I can give it a wash, and it started and sounded beautiful, as always. However, when I finished washing it up, I started it again and it sounded very awful!! Some first checks I did was, unplugged the HT leads one by one to see if there was any misfiring, and it turned out that when I removed plugs 3 & 4 (i.e the two fartest from the radiator), the engine behaviour remained unchanged, whilst when I removed plugs 1 & 2, the engine stalled. Therefore the problems seems to be coming from cylinders 3 and 4. I checked for spark and there is spark in all plugs and, since I don't have a compression tester, I cannot say whether there is the required compression, however when I removed the plugs in cylinders 3 & 4, it seemed that there was a bit of compression, or at least I could feel compression when I placed my finger in the plug hole. Also, checked the distributor, and enerything seems fine in there.

I also changed the rocker shaft because it had some play, and struck the valves with a soft hammer just to make sure that they aren't sticking..but the problems still persists.

Here's a video of the engine working at idle (it almost stalls at idle now, and there is loads of vibration!), so that you can get the idea of the strange noise it is making..any help would be greatly appriciated..



regards
Jeremy

[Broomer]

How hot did the engine get when the head gasket went previousaly?

sounds like head gasket.... unlucky. my 998 blows a head gasket between 3&4 every 2-3 months.

Edited by Broomer, 14 June 2008 - 02:33 PM.

[flamenco]

when I changed it, it didn't get hot, and it didn't sound like this either

[Broomer]

last time, i parked up, let the engine cool, came back started it, went to drive off and it made a tractor like noise. limped it home ran a compression test and 3&4 were reading something pathetic.

only a compression test will reveal, but if youve got a spark and you remove leads 3 and 4 and it makes no difference, its likely to be head gasket.

[flamenco]

Why would the gasket blow again after 4 months then??? I torqued everything up and did everything as it should be!

I think I will be replacing the engine very soon then!!!

Can somebody else please confirm it's the head gasket???

[Broomer]

Why would the gasket blow again after 4 months then??? I torqued everything up and did everything as it should be!

I think I will be replacing the engine very soon then!!!

Can somebody else please confirm it's the head gasket???

im not confirming it. did you have the head skimmed perviousaly? was the head retorqued after the initial fitting?

[flamenco]

I never had the head skimmed, I've owned the car for only 7 months now..and yes, I left about 50-60 miles and re-torqued the head as well..

[Broomer]

head could be warped. block could be warped , head bolts could of stretched. or maybe your just unlucky.

[mr_apples]

are your plug leads on right, 1-3-4-2 try swapping 3 and 4 over (remember the dizzy runs anti-clockwise no1 near top, 3 on the left so on)

if you have just washed with a pressure washer a bit of wd40 to dry the electrics out may help

if its head gasket they usaully run rough at idle but smooth out a bit when you rev it (unless its really f@#?ed)

its unlikely for the head gasket to go just driving it out of your garage, unless you really thrashed it

[flamenco]

I didn't use powerwash, just the usual bucket of water! Also gave plenty of WD40 to the electrics and made sure the distributor cap was dry on the inside..

I'm sure the leads are right, it worked perfectly this morning (and yesterday)!!

[mr_apples]

always best to be sure

double check everything just to make sure its nothing serious.

i would do a compression test if everything else looks ok

any water in the oil or the cooling system pressurising up when its running, symptoms of head gasket faliure

[The Matt]

Sounds like too much of a coincidence not to be damp gotten somewhere. Pop that dizzy cap off and go from there!

[flamenco]

As I already said, I took out the distributor cap and it was dry, no signs of water or any form of dampness..

Also, no water in the oil, however if the gasket has gone between cylinders 3 & 4, as far as I know it wouldn't effect the water and oil mixing up?

[mr_apples]

no it wouldn't, but still worth checking

if it is the gasket between cylinders it should smooth out when you rev it up (unless its really fubar, unlikely to be that bad)

if it pops from the carb or stalls its probably ignition related

[flamenco]

yes it does get a little bit better if I rev it up, therefore it has to be the gasket has gone between bores..

Well, it seems there's nothing else to do, I just have to replace it I know it's just a day's work, but it's still tedious!!