Cylinder head swap

[Wally2]

Hi all,
Going to do the cylinder head swap in the next couple of weeks, got all the bits including a shinny copper head gasket. The manual says not to put any jointing compound or grease on the joint, which is what I did last time and ended up with a water leak on refilling the radiator. The leak sealed after running the engine up to temperature but after a couple of hundred miles has returned.
So have any of you used any jointing compound or grease when replacing the cylinder head gasket? If so can you recommend any particular type? Or should I do as the manual says and leave it dry?
Cheers
Chris

When I said 'in the next couple of weeks, I did mean it but still not got it done! too busy driving it!
Had the 'new' head skimmed and valves checked - it appears that it has not been converted to unleaded as it doesnt have hardened valve seats (asper the ad on fleabay!)! Never mind I'II just keep putting the additive in. Good job I had the valves checked as one was not operating properly and the guys had to take it out and refit it properly.
So just got to get my finger out and get it put on - Maybe come winter time!!
Chris

[grantourer]

Chris, surely it would be better to do the valve seats, than carry on with additives. Then it is fit and forget, no more hassle.

[Wally2]

Hi Graham,
Had I known that the head had not been converted as per the ad I proberbly would have had the valve seats done, however, now that I've had it skimmed etc. and the fact that I'm doing less than 2000 miles a year and I dont push it, I'II stick with the additive.
Cheers
Chris

[janz]

Well, my 848 is happily running, unconverted (fingers crossed and knock on wood n all that). Doing the mileage I do in it - about 1500 a year max - uses about one bottle of Redex a year (based on the fill up, guess - squirt the Redex - that'll do..... bit more smokey sometimes, bit less others ) Even when I had the head skimmed and valve stem seals replaced, it never dawned on me to have it converted - just wasn't really a problem..... and it still isn't. The garage wanted an extra £120 to do it at the time.... that's about 24 years worth of Redex Hope you're still on dynamo.... and pos earth of course..... although I must admit, I'm thinking of changing that.... if only for corrosion reasons

[Wally2]

Hi Jan,
Yes still on dynamo and points etc. but am neg earth! Head skim and valve check cost me £30, full conversion to unleaded quoted as £250!
Chris

[janz]

That would be 50 years running on Redex..... leaded and smoky rools

[Wally2]

Well I've started!!!
Heads off, rads out, just got to clean everything down and then start putting it back together again!
Now I have both the heads side by side, the valves on the 'new' head are approx. 2mm shallower than the 'original' head, I guess that could be a combination of the skimming and that its from a 998cc not an 848cc. Wonder what effect it will have on performance?
Chris

[Tim]

I'm not sure what you mean by 'shallower', are the combustion chambers lower in volume? What are the casting numbers on the two heads?

Tim

[Wally2]

Hi Tim,
Yes the chambers are different in depth but the same shape, my original one is approx. 25ml and the new skimmed one 21ml (measured by filling chamber with water), I think the new head has perhaps been skimmed more than once as overall depth (top face to joint face) is some 2mm less on the new one.
Old head number is 2A629 MOWOG 13 10 5 'new' one is CAM 4810 12H5.
Chris

[Wally2]

Just about all back together again.
Last year when I had to change the head gasket, upon completion I filled the rad and got a leak from one of rear corners of the head, once started and warmed up the leak reduced but never stopped entirely. I read a post on one of the mini forums where a chap said that after replacing a head gasket he started up with no water in to prevent leaks at the gasket, just to get the head & block warm then switched off left it to cool overnight, retightened the head bolts next day and then filled with coolant.
So I'm trying it this way, have done the warm up with no water and will retighten tomorrow and fill up and then see what happens!!
Chris

[Daniel]

Chris,
I´ve never heard of warming up the engine without water in and then tightening again. Doing this is quite dangerous as the engine can get too hot very fast!
Normally there shouldn´t be any leak after tightening the nuts. I´ve learned to carefully drive the first 500-1000kms and after that re-tightening the nuts and that´s it.
The problem you´ve had with the old head sounds for me like a deformation of the head.

Daniel

[Wally2]

Hi Daniel,
I only ran it for a few minutes jut to get some heat into the joint, I will be retightening after a few hundred miles as well, and I always take it easy, not much choice with an 848cc engine!
Hopefully the problem last time was the head, the replacement has been skimmed so should be ok and this time I've used a copper topped gasket.
Chris

[Wally2]

Left it overnight then retightened the head nuts and filled with coolant. Had a slight leak on the bypass hose, thought for a moment it was the stud into the head (nightmare!!!) but it just need the clip tightening up.
Ran it till warm but didnt seem to be getting any hot water into the heater, so stoped the engine, disconnected the heater feed pipe and carefully tipped some coolant down the pipe, reconnected restarted and we now have a working heater!!!! Just in time for winter, it seems to chuck out a fair amount of heat as well.
Interestingly now that the temp gauge sensor is below the thermostat instead of the heater take off point, the readings seem more reliable. Before I was getting readings of 70 to 80 degrees C which I thought was too low. Now I'm getting between 80 and 90 which seems more realistic (I can tell when the stat opens as well), then I put the heater fan on and it drops a good 5 degrees.
Still seem to be loosing coolant from the rad cap though?
During

After

The bores of cylinders 2 & 3 which when I replaced the head gasket last year seemed in a pretty poor state, on inspection this time (after approx. 1600 miles) seem to be not as bad, they are still marked but no where near as bad as they looked last time.

Only had a drive round the block today but it does seem a little livelier, better compression?
Chris

[Daniel]

Oh! I have already seen much better cylinder walls!!

But good to hear that the gasket is no longer leaking and that you feel the engine is a bit livelier by the better compression.

Daniel

[Wally2]

Hi daniel,
So have I, Nos 1 and 4 were much better! I think at some time in its past the engine has not been run and had stood with 2 and 3 pistons down and perhaps the plugs out, hence the marks. I should have taken pictures last year when I had the head off, they looked even worse. I was fully expecting to have to have a rebore or relining of the cylinders but the thing goes pretty well and for less than 2000 miles a year hopefully it could last me out.
Chris