Head gasket?

[M_and_B]

Our 1966 traveller has performed well since we got it in March until yesterday when the engine began rattling and there was a loss of pulling power.

There's a spark at the plugs, no excessive exhaust smoke, good oil pressure (tickover 35/40, revs 60 plus), no bubbles in radiator. I don't have a compression tester.

By trial and error I've established that removing the plug leads from cylinders 3 and 4 makes no difference to the engine ticking over, whereas removing leads from either 1or 2 causes it to stop. So I believe the issue lies with a head gasket blow probably between 3 and 4 but just wanted to check that I've not missed anything else before taking the head off.

[mike.perry]

If you turn the engine over with the starting handle you should be able to feel the difference in compressions. Most likely head gasket but possibly a valve, either way its a head off job.
You did not have anything planned for the weekend did you?

[bmcecosse]

Off with it's head!

[M_and_B]

Thought it would have to come off! The weekend is already booked up with a local car show, so it will have to wait while we go in the pick-up but I might find a little time tomorrow night. I'll let you know what I find.

[M_and_B]

Found a little time last night, head off and there's a nice gap between 3 and 4.

In taking out the last push rod - back of engine - I must have raised the cam follower with it as the rod now sits too high compared to its mates. Is it just a case of firkling carefully until it re-seats or chest cover off and moving it around?

[bmcecosse]

At least one rod will always sit high.....

[moggalot]

Oil suction has almost certainly lifted one of the followers out of its hole. Sounds like the chest cover will have to come off, just to be sure. (Is 'firkling' a real word?)

[bmcecosse]

In which case the rod will sit low (not high) as it sits on the cam - or may even fall down into the sump......

[M_and_B]

I'm assuming the reason one should be higher is due to that valve being fully open.

I'd also thought that a disturbed cam follower could be the issue - either that it had "turned " in the hole (i.e. its base was offset in someway in relation to the cam shaft) or come up and was sitting on the top of its hole..anyway I'll crack on and check as I go.

Firkle - to mess around with until the item in question does what you want... I'm sure it will eventually find its way into some dictionary of common useage.

[bmcecosse]

10/10 M & B - I expect it will be fine - but just turn the engine and check they all go up and down before fitting the head.. Of course - you have to wonder WHY the head gasket blew in the first place - did it overheat or run short of water?

[philthehill]

Firkle must be a localism variation of fettle.

[M_and_B]

Of course - you have to wonder WHY the head gasket blew in the first place - did it overheat or run short of water?

Hmmm, water level was OK as was oil, fan belt not slipping, no apparent blockages. I'll check the 'stat later and flush the system after reassembly. From the info file we have it was fitted 8 years ago with a recon engines and unleaded head. Not too old but there's these comments about parts not lasting as long as they used to, so may be it's just it's time.

[bmcecosse]

As long as there is no scouring of the surfaces - it should be fine with a new COPPER gasket - smear of grease, and torque down to 44 ft lbf in stages. And then retorque after the first heat cycle - very important.

[M_and_B]

Firkle must be a localism variation of fettle.

Possibly very localized as we also use it in the sense of investigating by feeling around. So a surgeon might firkle around inside of you or you can firkle under a car seat for that elusive coin that fell out of your pocket.

Gasket ordered but now off for a break so it will all have to wait a week. Hopefully there'll be some sun.

[M_and_B]

Having cleaned the remains of the old copper gasket off the head I found a very small track between cylinders 3 and 4 - see photo. I'm assuming this is what caused the blow and replacing the gasket won't solve the problem and what I need is either a skim(?) or replacement head. Is this a fair conclusion or am I being too pessimistic?[frame][/frame]

[bmcecosse]

Oh dear - you need to determine how deep the crack is and assess if skimming would remove all traces of it... Otherwise - time for another head.

[M_and_B]

He ho... thought it would be the case! It's difficult to see the depth but I've found a local engineering company and taking it round later for an assessment. Is there a skimming tolerance for the heads before you get issues with valves hitting pistons etc?

[M_and_B]

I can forget the skimming option! Crack goes down the side by about a fifth of an inch so need a replacement head. Any offers?

[morris van]

My head gasket blew on my moggy van last week and water and oil levels were alright . I have removed the head and has blown between 3 and 4 . I have cleaned the head and valves and all alright got a new gasket set today and hopefully fit head in day or two.

[M_and_B]

That's where I thought I'd got to yesterday but once I'd cleaned the remains of the copper gasket off the gap between the cylinders there was the crack, as in the photo. I was then hoping it was surface level but when it was cleaned up you can track it down the sides of both cylinders - still hairline but obviously enough to cause a problem.

It sounds like you are more fortunate and can now look forward to refitting.