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mg_tf
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Discussion Starter #1
I'm already collecting projects for my impending retirement and have been offered a dead 75 1.8 petrol. Don't know if its turbo or not.
The car has suffered a snapped timing belt, reportedly at 'low speed'.
As the K is an interference engine this means something is sure to be broken. Before taking this on I was thinking about removing the spark plugs and having a look with a snake-cam. If he pistons are holed this will be beyond me, but if it's 'only' bent valves I'd like to try fixing her, assuming no other problems. Car was a runner til this.
Here's the question. To time up a K you rotate the crank to line up the lower timing mark, and the upper marks on the cam gears should align at the same time. But, with the belt broken rotating the crank won't move the cams. Some valve will be open and the pistons will touch them.
Removing the head first stops that happening, but as I understand it you shouldn't rotate the crank with head off- the liners move.
Is it a case of removing the head, and somehow locking down the liners before rotating the crank to the correct timing position? Or some other trick?
I've been wondering about this for a couple of days, and someone on here must have done it.
Cheers All.
 

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From what you wrote, I think you’ve got it. Best to remove the head and lock the liners. However, with the spark plugs out, you may be able to gently rotate the crank mark into line, ie all pistons at the centre of their stroke. Just stop if you meet any significant resistance as it would be a piston / valve touching. Tbh you will probably need a new head, or at least some valves. Maybe holed pistons os scored bores as you noted. Good luck.
 

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mg_tf
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Discussion Starter #3
Good afternoon Gnu, Thanks.
Everything I've read makes it clear you need to get the head off to assess for damage properly. What I couldn't quite work out was how to get the crank properly timed for (hopefully) the reassembly before taking the head off. On reflection, I think you just need to get the head and decide if it's worth proceeding. I found a couple of pictures showing the liners clamped down to allow rotation of the crank- although I'm also reading that the crank can be difficult to rotate once the long head bolts are loosened.
Step 1, I'm going ot pull the plugs out and hopefully view the pistons. If they're holed I doubt I'll get involved. I'm running out of room on my driveway with the wife's Alfa, 3 TFs, a ZT and our lad's Astra, so you have to pick your battles. If it looks like a new head, or new valves, then I'll have a go. I'll have our lad keep an eye out at the scrappy for anything with a K sries coming in that might donate a new head.
Cheers!!
 

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mg_tf
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As I see it, lining the crank marks ensures the pistons are part way down the bore and out of the way of the valves. Of course, if the pistons are moving towards the top and you feel coming into contact with the valves ( locking up) then I would be rotating the cams slightly until you lose that locking up resistance.
Holes in pistons? Not generally the case, but yes if you can check then that’s great.
Economically worth doing? Unfortunately these are undervalued old cars now and no doubt you will have worked out the economics of embarking on this - with a view to a bit of residual profit?
As well as head gaskets, these seem to suffer from premature clutch slave cylinder issues which can often render the car to be beyond economical repair, and really you won’t have any guide as to whether this is likely to be a problem or not, unless there is invoice proof of it having been done.
Kind regards,
Austin.
 

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mg_tf
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Discussion Starter #6
Good evening Austin.
That sounds very reasonable. No financial sense in this at all, of course. I just like MGRs, so fixing one feels very satisfying. I already know about the dopey concentric clutch slave- hidden inside the bell housing? Genius.
Thank you for your helpful suggestions, and I'm going to try and get into this before the days get any shorter.
 

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If you've not started the job yet, and haven't decided to scrap the car, remove both camshafts, and carefully rotate the crankshaft into the safe position.

Then remove the head, you may be pleasantly surprised, and remember all of the 16v non VVC valves are interchangeable between engine capacities, and inexpensive.........a leisurely few hours could well see another car saved.

These are becoming a little thin on the ground now, and being an 1800 often overlooked, but nice nonetheless, and arguably the easiest of the lot to work on engine of those fitted to the 75 and ZT.

Best of luck

Brian :D
 

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rover_75
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I'm already collecting projects for my impending retirement and have been offered a dead 75 1.8 petrol. Don't know if its turbo or not.
The car has suffered a snapped timing belt, reportedly at 'low speed'.
As the K is an interference engine this means something is sure to be broken. Before taking this on I was thinking about removing the spark plugs and having a look with a snake-cam. If he pistons are holed this will be beyond me, but if it's 'only' bent valves I'd like to try fixing her, assuming no other problems. Car was a runner til this.
Here's the question. To time up a K you rotate the crank to line up the lower timing mark, and the upper marks on the cam gears should align at the same time. But, with the belt broken rotating the crank won't move the cams. Some valve will be open and the pistons will touch them.
Removing the head first stops that happening, but as I understand it you shouldn't rotate the crank with head off- the liners move.
Is it a case of removing the head, and somehow locking down the liners before rotating the crank to the correct timing position? Or some other trick?
I've been wondering about this for a couple of days, and someone on here must have done it.
Cheers All.
Hi
Fixed a few heads before if you look on the crankshaft pulley there is a mark line this up with the mark on the timing cover ( about 1 o clock and the pistons will be in this position . Hope this helpsI
135966
 
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