Clarky Posted March 25, 2019 Report Share Posted March 25, 2019 (edited) Hello Just under 2 years ago I decided to start a full renovation on my TR6. Just prior to this I had some engine issues and although she did not smoke and hard plenty of power, I simply could not get here to run smoothly, particularly after she was hot. At the time I did some tests which I posted and received some really good feed back, including the rings are not bedded in etc. As mentioned at the time the engine had a full rebuild at some point in the past and had apparently only covered 500-600 mile since. Anyway amongst many other tests I got these results below: Dry test: 1 =218psi / 2 =207 psi / 3 =210 , but drops to 85. / 4 = 206psi / 5 = 210 psi, but drops to 135. / 6 = 212 psi Wet test: 1 = 238psi / 2 =220psi / 3 =250psi / 4 = 228psi / 5 =235psi / 6 =235psi Fast forward to this weekend I took the head off for investigation and snapped the following attached pictures. There are honing marks on the bores and despite looks they feel relatively smooth except on cylinder 6 where there is a score mark that I can actually feel with my nail, Interestingly though this cylinder did not loose compression. The gasket seems to have quite a bit of blackening between cylinders 5 and 4 and 3 and 2 as if they were leaking into each other. The cylinder head also looks good, although I have not inspected in detail yet. I would appreciate any feedback, Many thanks Edited March 25, 2019 by Clarky picture sequence required for cylinders Quote Link to post Share on other sites
John L Posted March 25, 2019 Report Share Posted March 25, 2019 I don't like the look of the scores in the bores, at what point in the bore are they orientated? Before you take the valves out, I would put some petrol into the manifold inlets and exhaust, put the head with the springs uppermost, wait a few minutes and tip over the head and see which valves are leaking. John Quote Link to post Share on other sites
Clarky Posted March 25, 2019 Author Report Share Posted March 25, 2019 Hello John Yes that was my next step on the head. I took the pictures from front to back, 2 for each cylinder but unfortunately could not up load all of them. Pretty much all the same except No 6 cylinder where I could feel the groove, but strangely during the test there was no compression loss, this is the 8th picture down. Andy Quote Link to post Share on other sites
Mike C Posted March 25, 2019 Report Share Posted March 25, 2019 Do the score marks line up with the gudgeon pins? Quote Link to post Share on other sites
RogerH Posted March 25, 2019 Report Share Posted March 25, 2019 Hi Andy, was the head re-torqued after the rebuild. The head gasket looks too dirty. Roger Quote Link to post Share on other sites
Clarky Posted March 25, 2019 Author Report Share Posted March 25, 2019 Hello No the scores are 12:00 and 6:00 O clock looking from the manifold side. The rebuild was done years ago before I bought the car, so no idea really, but it does look dirty. Its strange she always had plenty of power and no smoke, but started to get problems when she was hot and could not get her to run correctly. Do I need a rebore I'm thinking/ Andy Quote Link to post Share on other sites
Steves_TR6 Posted March 25, 2019 Report Share Posted March 25, 2019 Are the pistons the right size for the bores? Quote Link to post Share on other sites
John L Posted March 25, 2019 Report Share Posted March 25, 2019 It looks to me that it could have had the ring gaps fitted at the 12.00 and 6.00 positions, or the ends of the rings with sharp edges, normally I would always space the rings so the gaps were not in those positions. I think they will have to come out and inspect, the engine it could have also been put under heavy load early on in its life after the last repair, it may clean up using a glaze buster carefully, depending how deep the scratches are, and space rings accordingly when refitting. John Quote Link to post Share on other sites
Clarky Posted March 25, 2019 Author Report Share Posted March 25, 2019 Hello I am going to bite the bullet and as the body is off the chassis and I have good access, I have decided to get it re bored and honed etc. It needs closer inspection and as one particular groove can be felt I just need to sort it and be confident that she will go on for years. So I have contacted MEP Ltd are in Warrington not far from me and will do the job £150 + VAT then pistons and rings. It means an unexpected rebuild but that's life. Thanks for all the help Andy Quote Link to post Share on other sites
astontr6 Posted March 25, 2019 Report Share Posted March 25, 2019 1 hour ago, Clarky said: Hello I am going to bite the bullet and as the body is off the chassis and I have good access, I have decided to get it re bored and honed etc. It needs closer inspection and as one particular groove can be felt I just need to sort it and be confident that she will go on for years. So I have contacted MEP Ltd are in Warrington not far from me and will do the job £150 + VAT then pistons and rings. It means an unexpected rebuild but that's life. Thanks for all the help Andy Andy! I would also have your head and block face checked for flatness as I do not like those black burn marks on your head gasket, looks to me that the head is probably warped? You are doing the right thing getting the bores honed and make sure the new rings are fitted correctly. Bruce. Quote Link to post Share on other sites
Clarky Posted March 25, 2019 Author Report Share Posted March 25, 2019 Hello Yes that's a good idea. Many thanks Andy Quote Link to post Share on other sites
Motorsport Mickey Posted March 25, 2019 Report Share Posted March 25, 2019 (edited) It keeps coming up but in case there are owners who think that you have to put piston rings onto the pistons with the gaps staggered or they'll stay in their original positions on the piston within the cylinder bore...please read. http://www.diagnosticengineers.org/journal_ articles/Ring Gaps vs Knowledge Gaps.php Interesting eh... for what it's worth I always fit my Piston rings staggered it just makes me feel better, having confirmation that it doesn't matter a damn is just insurance...I can't possibly get it wrong ! Mick Richards Edited March 25, 2019 by Motorsport Mickey Quote Link to post Share on other sites
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