Matt306 Posted October 9, 2017 Author Share Posted October 9, 2017 The head had new valves and stems and seats and skim before the car was recommissioned. No more than 4000 miles ago.I did do a wet test with oil as above the thinking was as the pressure rose slightly it was not the valve. It's simple enough to grind the valve again as the head off. Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 9, 2017 Share Posted October 9, 2017 The wet test is only really for rings, and should be done with engine oil not gear oil.You can still have a burnt valve especially if the tappets are a bit tight.They should be done done hot and i always back them off by having a just slight pull on the feeler gauge.Tony. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 9, 2017 Author Share Posted October 9, 2017 I thought tappets were a cold job... Especially with burning fingers. Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 9, 2017 Share Posted October 9, 2017 No, they should be done hot, as the metal parts will expand when hot and close the gaps.If you do them cold, leave another 3 thou clearance to allow expansion Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 9, 2017 Author Share Posted October 9, 2017 I got my friendly mechanic to have a look tonight, he suggested inverting the head and filling the combustion chambers with WD40, if they leak then we know its a valve leak. Inverted and filled them all only chamber 2 leaked WD40, finger down the manifold holes and they are all dry apart from Exhaust No2 Cylinder. He also spotted a slight browning (possible water leak) on the 3/4 gasket space, only weeping.Pics here again https://photos.app.goo.gl/jpyj9GUoabzVVI0t1https://photos.app.goo.gl/5S4SGKe6r1emdjtB2https://photos.app.goo.gl/fFxFZSWI0y1skfRM2https://photos.app.goo.gl/2w1kiBUSkqeG6JFm1 Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 9, 2017 Share Posted October 9, 2017 Thats good easy fix then. I did spot the 3 --4 bit on the gasket, but i thought stay with the compression problem, plus a new gasket will sort that out The valve might have been caused by tappets being to tight You will soon know when you get the valve out Quote Link to comment Share on other sites More sharing options...
RedRooster Posted October 9, 2017 Share Posted October 9, 2017 Guess your going to have to take that valve out & have a look. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 9, 2017 Author Share Posted October 9, 2017 Quoted from poppyman Thats good easy fix then. I did spot the 3 --4 bit on the gasket, but i thought stay with the compression problem, plus a new gasket will sort that out The valve might have been caused by tappets being to tight You will soon know when you get the valve out I think not as even on cold got low compression and there is a 10thou gap on the valve, and there is nothing keeping it open now and its leaking.Checked Haynes and the manual say " The valve adjustments should be made with the engine cold..." Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 9, 2017 Share Posted October 9, 2017 Hot or cold has been discussed on here before, but old habits die hard Having been in the motor trade for nigh on 5o years, i was always taught to set them hot.So really its up to what everyone wants to do.I have got to say though i have never had a burnt valve.You will notice in every hayne's manual a disclaimer at the front, so don't always believe what the manual say's They are not always right, and i dont profess to be perfect, but i have found many good tips on here, so we are alway's learning.Cheers, Tony. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 10, 2017 Author Share Posted October 10, 2017 Quoted from poppyman Hot or cold has been discussed on here before, but old habits die hard Having been in the motor trade for nigh on 5o years, i was always taught to set them hot.So really its up to what everyone wants to do.I have got to say though i have never had a burnt valve.You will notice in every hayne's manual a disclaimer at the front, so don't always believe what the manual say's They are not always right, and i dont profess to be perfect, but i have found many good tips on here, so we are alway's learning.Cheers, Tony. True, perhaps I should try them hot to cut out chatter and see the difference. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 11, 2017 Author Share Posted October 11, 2017 Still doing the repairs. On the exhaust on Number 2 piston the valve guide is worn. These were replace about 4000 miles ago. Any reason why it would wear so quickly? Any tips on replacing them? Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 11, 2017 Share Posted October 11, 2017 Have you compared it to the other valves? as they do have some play in them.Tony. Quote Link to comment Share on other sites More sharing options...
nang Posted October 12, 2017 Share Posted October 12, 2017 Engine Re conditioner told me several years ago when I queried getting my S's head done, don't be worried about a bit of play, it helps upper cylinder lubrication. I didn't and have had no drama's. 😎Tony. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 12, 2017 Author Share Posted October 12, 2017 Quoted from poppyman Have you compared it to the other valves? as they do have some play in them.Tony. It waggles about well, gas signs of combustion on the valve stem too. I temporarily tried it in another stem much less movement and another valve in the guide and there was movement. Quote Link to comment Share on other sites More sharing options...
poppyman Posted October 12, 2017 Share Posted October 12, 2017 As nang say's, i would not be to worried a bit of "ucl" will do no harm at all, just put a new valve in and make sure it is lapped in well Tony. Quote Link to comment Share on other sites More sharing options...
JohnD Posted October 12, 2017 Share Posted October 12, 2017 I don't care what an enguine reconditioner says, ANY waggle of a valve stem in a guide is too much.If the guides were replaced 4000 miles ago and now it waggles, then either that guide wasn't rplaced, or it wasn't reamed after installation.Miss that and either the valve seizes or wears quickly.JOhn Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 12, 2017 Author Share Posted October 12, 2017 Quoted from JohnD I don't care what an enguine reconditioner says, ANY waggle of a valve stem in a guide is too much.If the guides were replaced 4000 miles ago and now it waggles, then either that guide wasn't rplaced, or it wasn't reamed after installation.Miss that and either the valve seizes or wears quickly.JOhn Hmm I had all 8 replaced and U/L seats put in at an engineering shop. Valve is fine in another stem but not in this one, waggles about enough for me to know it needs fixing. Interestingly enough it is on chamber two where i had low compression issues Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 17, 2017 Author Share Posted October 17, 2017 Just an update, got the valve recut and new valve guide inserted. I cant work out why only one would wear so quickly. I then stripped the rockers, which had a new shaft about 4000 miles ago the shaft is now knackered. All the inlet rockers were showing signs of scoring. Now i do know the locating screw came out and I guess that led to oil starvation and caused the damage. I don't know how long the screw was out but not that long. How long does it take to cause damage. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted October 17, 2017 Share Posted October 17, 2017 I have heard that the new rocker shafts are made of cheese. Though It won't take long to do damage if the screw comes out, especially if the shaft turns so the oil feed doesn't line up. May be related to the guide problem. On that, does the rocker of the affected valve/guide have a wear mark/depression where it contacts the valve? If you have dink here it stops the wiping action happening and puts excessive side loads on the valve instead. Can be carefully ground back on an oilstone if not too deep.Nick Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 18, 2017 Author Share Posted October 18, 2017 they are all a bit ridged, i'll get an oil stone and have a go. Four of the rockers are knackered on the inside though and need replacing. I have the new shaft today the holes in the tube look much bigger and no flats by the holes. Ordered it from Canleys, came from COUNTY (Made in India) Quote Link to comment Share on other sites More sharing options...
JumpingFrog Posted October 18, 2017 Share Posted October 18, 2017 Quoted from Matt306 they are all a bit ridged, i'll get an oil stone and have a go. Four of the rockers are knackered on the inside though and need replacing. I have the new shaft today the holes in the tube look much bigger and no flats by the holes. Ordered it from Canleys, came from COUNTY (Made in India) FYI you can get hardened shafts (Moss), bought one but never fitted it (it's also made by County/XRN). I changed my mind and used a non-hardened one instead... I'd rather replace a softer shaft than have to replace the rocker arms, but this is only a theory I saw on another forum. YMMV, my engine hasn't yet made it into the car 🤔 .Whilst on the subject, make sure you clean out any swarf from inside the shaft (remove the end plug). Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 18, 2017 Author Share Posted October 18, 2017 Developments - can't fit Rocker shaft as the screw thread isn't there. The box indicates is for and MGA/B so if that is correct I might have wrong part. Quote Link to comment Share on other sites More sharing options...
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