Early 1.9 to 2.1 conversion - stop me if I'm being stupid!

[kevtherev]

there has been the wrong antifreeze in that for some time and looks like never changed.
but they're ok.
the head mating surface can be salvaged ok too, no need to skim.
Perseverance with the stuck liner..but heat might help.

[CJH]

there has been the wrong antifreeze in that for some time and looks like never changed.
but they're ok.
the head mating surface can be salvaged ok too, no need to skim.
Perseverance with the stuck liner..but heat might help.

Yeah, there was a good lump of dried rust flakes inside the water pump (should have taken a photo), so it was clear that the maintenance had been lacking. But given that, I was surprised how good the studs look - the coating of orange looks, in most places, to be what's deposited out of the coolant, rather than being the studs themselves rusting. That new stud composition must be working.

I'll be picking up an engine stand in the next day or so, so it'll be easier to tackle the stuck head from below.

Did the date stamp style look familiar by the way? And assuming it hasn't been ground off, should there be a serial number somewhere for me to trace it's origins?

[CJH]

OK, I'm stuck now. I can't get the second head off. I've got the engine on a stand now, and it's upside down. I've removed the rocker shaft and the eight stud nuts. I've also removed the pushrod tubes for access. Have I forgotten something? Is the left head different from the right head in some crucial way?

I just can't budge the bottom half of the head seal. In fact I'm fairly sure it's not that holding it, as I've used a knife to remove the excess seal from the outside of the join and then pushed the remainder of the seal inside. So I reckon it's probably the liners corroded onto the head and the case. I've tried whacking it via a wooden block on the underside of the head, but it doesn't move in the slightest.

I'm not going to put anything between the head and the case as I'll damage the mating faces. It feels like I need some sort of puller, maybe with the legs behind the lip of the head where the pushrod tubes go, and the point maybe on top of one of the head studs.

Anybody got a better idea?

[CJH]

Looks like we lost a few posts to a database crash - I found them in my local cache.

Some good advice from weimarbus

If the engine has been badly stored then the pistons could be corroded to the bores/liners, try turning the engine on the stand so that the spark plug holes are at the top and squirt plus gas down the holes, leave for a couple of hours and then repeat, then try turning the crankshaft by the flywheel to try and unseize the pistons. Also the MV engine that I rebuilt had been stored with one head down hill in a shed and water had collected in the cylinderhead cooling chamber and frozen causing a crack in the water jacket, this took ages to find as it only leaked when the engine warmed up and I got a slight coolant drip overnight. The head had to come of again to have it TIG welded, so it may be worth having the heads crack tested while they are off it may be cheaper than another gasket set

I wrote:
Thanks for that. Yes, I was planning to get both heads crack tested - looking for a local machine shop that can do that for me while maybe fitting new valve guides.

I did wonder whether it might be a stuck piston, so I tried turning the crank and it's all moving freely. I wondered if it was perhaps a vacuum, since all the valves are shut, but since the crank turns very easily I guess the gaps in the ends of the piston rings are enough to prevent that.

The head's still stuck. I've removed the rubber seal by cutting it away. If I lever the head I'm pretty sure I can feel all 8 studs moving fractionally in the holes in the head, so I don't think it's a stuck stud. I'm fairly confident it's just the liners sticking. I've tried making hardwood wedges to drive along the gap, but they just get chewed up.

I'm worried that if I keep whacking the head from the outside I'll do some damage, so I'm wondering if I should separate the case halves, pull the pistons out, and then try to drift the head off from inside the case. With a small section hardwood drift I could probably tap on the 'meat' of the head rather than the valves. I guess I'll also have access to the bottom of the liners, and could try to drift them out too. Any thoughts?

Your last paragraph sounds like a good plan, you would then be able to apply appropriate heat, also worth TAPPING the head studs on the ends with a smallish hammer they should 'ring' if not then maybe the liners have corroded to the studs around the base of the liner

I wrote:
Thanks - I'll give that a try this evening then.

Updated account:

Code: Select all

Engine                                                    £200
Fuel to collect it                                         £60
Engine stand                                               £41

Total so far                                              £301

[CJH]

Hmm - so much for that plan. I've got the two case halves apart - note that this wouldn't be possible without getting at least one head off, since there are stud nuts at the bottom of the water jacket. Thankfully all the studs and nuts have undone relatively easily. But I can't separate the case halves completely since the pistons won't pull through the bottom of the case - there's parts of the case that get in the way. I hadn't envisaged that.

So I need to remove the pistons on the side where the head is already off (rawlbolt gudgeon pin tool required) to get that half of the case off. But even when I've done that it means my plan to take the pistons out from the other side, so that I can 'push' the other head off, won't work. If I remove the big end bearings to get the crank out, I'll still be left with the pistons and con rods blocking my access to the underside of the head. I could obviously push on the con rods, but that would put the top of the pistons in contact with the underside of the head. Would a good square push be ok or would I damage the pistons?

[T25Convert]

Hi,

When rebuilding mine I came across the 'reach a round' technique ( ) on an american site.

You'll need a thin walled (14mm?) socket, a bendy joint and extension bar. With this you can get down the sides of the piston and undo the con rod nuts - I did it with one cylinder where the gudgeon pin would not come out. Works well if you take your time!



There are people in the States who have changed their big end bearings this way without splitting the case - now that's a bit mental!

In terms of the head, you may also find that there is a build up of grime/corrosion/sealant around the studs where they run through the head holding it on, plus gas down around studs may help.

Good luck!

Cheers,

Alex

[CJH]

Thanks Alex

That's a good tip if I get stuck with a gudgeon pin. In fact I've got one out using a drift (the one nearest the hole in the side of the case), but if I can't pull the other one out with a rawlbolt I'll give that reach around technique a shot. I've sprayed Plusgas around the studs where they go through the head, and I've tried a bit of heat. I'm pretty sure they're all free, although there's one that may well be stuck still. It's either that or (at least one of the) liners being stuck top AND bottom.

My plan now is to disassemble the crank as far as possible, and then attempt to push the head off with the pistons. I'll put the big end caps back on. Since they're still in the liners I can't get anything but a good square push, and the pistons are obviously designed to take load in that direction, as is the underside of the head. They're not designed to actually touch the underside of the head though, so I thought I'd stuff some rolled up paper towel through the spark plug holes. Also, I want to double check what part of the big end caps I'd be pushing on - again they're designed for load, but only really on the con rod bearing face, not the outside of the end cap.

I'm a bit stuck for a means to provide a good 'push', so I'm bound to contemplate whacking the con rod end cap with a wooden mallet! Is that safe?

You know, as I write this, it's seeming like less and less of a good idea. I think I might just disassemble as far as I can and then find a machine shop that can pull the head off. There's plenty of gap where the rubber seal fitted but not much to push on other than the tops of the studs. A machine that could 'pull' the case rather than 'pushing' the studs would be better.

[CJH]

Well the crank is out, leaving just the two pistons in the stuck barrels. But now I can see that the barrels appear to be moving at their bases if I lever the head from side to side, so I don't think they're stuck after all.

I've checked the studs again, and 7 of them are definitely moving in the holes when I wiggle the head, but the 8th one (one of the two in the middle between the valves) seems to move with the head - I reckon it's seized to the head.

I've tried alternating heat and Plusgas, I've tried putting a stud nut on and tapping it with a hammer. There's a 4-5mm gap under the head now that the rubber seal is out (although the liners will stop it going down), so I've tried putting a stud nut on and winding it down as hard as I dare, but it's not budging. I don't want to snap the top of the stud - I almost wouldn't mind it snapping between the head and the base of the water jacket, but if I just snap the exposed threads off I'll be in a worse position.

I think my next effort might be to try one of those stud removers - maybe twisting it out of the head will be more effective than trying to push the head down over it.

[T25Convert]

Sounds less fun!

How about supporting the head but leaving the case unsupported (so the case is in effect hanging off the head by the stubborm stud).

You could then run a nut onto the top of the stud to protect it (and stop the case dropping to the floor if successful) and give a few good clouts with the big hammer?? That way you are driving the case down aided by gravity, rather than trying to leaver against the fragile bits.

Might require a bit of head scratching about how to support the head but might give yo a better chance of getting some real force onto the stud....

Good luck....

Alex

[CJH]

Good idea - that'll definitely be more effective than clouting the stud with the case supported - it'll give me a bit of downward force rather than just shock/vibration. Supporting the head could be the issue though - I'll sit and stare at it again, for inspiration.

Strangely the top of this stud seems to sit a couple of threads higher than the one next to it. I wonder if it maybe wasn't wound fully into the threaded case hole when it was installed. I don't think that's the cause of my problem though, since the stud shank has a smaller outside diameter than the threaded section. Unless of course the wrong stud was fitted?

[T25Convert]

Indeed - some thought and staring required!

I'm a gambling type so my logic would go - if head won't come off its worthless anyway, so why don't I stick a longish M8 bolt / stud into each exhaust port (where the pipes would bolt on) and use these to support. I'd run the risk of knackering the exhaust ports (although the holes might be pretty tired already!) I'd give it a gentle tap and see if anything made a creaking noise or bent, then I'd give it some welly!!

If you are less risk adverse than me you may need to make an elaborate set of wooden chocks.

Hope something works, its so frustrating when you get so close but one small thing stops play!

Alex

[CJH]

The exhaust ports are the obvious points I agree - I could even pop the exhaust pipe stubs back on I guess. I'm also thinking that since I don't trust that slightly longer stud anyway, and I'm going to replace it, maybe I could get a dremel into the gap between head and case and just slice it off. Some risk of damage to the mating faces, obviously, but presumably I'd still be able to get the case part of the stud out, and the head part might then twist out more easily.

[CJH]

Hope something works, its so frustrating when you get so close but one small thing stops play!

Yes, but MUCH less frustrating when it's only (supposedly) a 'winter' project! It'd be very frustrating to face this with the engine still in the vehicle, and the van off the road as a result.

[CJH]

I bought one of these stud removal sets from Machine Mart - A bit more expensive than the ebay version, but I was passing.



The 8mm socket worked brilliantly on one of the seized exhaust studs, but unfortunately there isn't quite enough of the head stud showing for me to get the 10mm socket to lock onto it. A couple of other studs (exhaust, thermostat) were just a fraction too short too - it seems like these things only work as long as there's over a cm or so to work on. Tsk. So it looks as though I'm going to have to get one of those Irwin sets and accept that the top of the stud will get chewed in the process.

Somebody I spoke to suggested letting some rust converter fluid (Vactan perhaps) soak into the threads, the theory being that the converted rust is softer than the rust itself. Does that seem feasible?

[kevtherev]

converted rust is softer than the rust itself. Does that seem feasible?

it's still rust..only with the phosphoric acid on it's inert for a few atoms in on the surface

Iron (III) oxide + phosphoric acid yields black ferric phosphate + water