mike munro Posted April 16, 2016 Report Share Posted April 16, 2016 Hi can any one tell me if the 2.5 engine is a safe engine ad I've just rebuilt it done 350 miles and now the cam has stopped working,the dizzy is not rotating and all the valve gear is still. I was heading down towards newport at about 60 mph then all of a sudden the ignition and oil light came on and the engine just costed to a stop, there was no bangs or noises no nothing plus there seemed to be no compression when I tried to re start it. I also checked for spark none as the dizzy is not turning. I looked at it this morning and turned it over which it did with ease. I suspect the ti.ming chain has snapped or the bolts have sheared on the cam sprocket as the crank is spinning over with ease.... any surgestions please. Link to comment Share on other sites More sharing options...
dougbgt6 Posted April 16, 2016 Report Share Posted April 16, 2016 The 2.5 is generally reliable and I think you've put your finger on it, timing chain, securing bolts or you've lost all the teeth on the gears! What car do you have? Easier to get the timing chain cover off in situ on some cars than others. Link to comment Share on other sites More sharing options...
mike munro Posted April 16, 2016 Author Report Share Posted April 16, 2016 Hi I've got a GT6 MK2 (2.5 fast road build) with a fast road cam 285 duplex etc everything was new except the two bolts and the tag which I re used I'm worried that the valves have bent, the pushrods don't look bent there's no damageat all that I can see Link to comment Share on other sites More sharing options...
mike munro Posted April 16, 2016 Author Report Share Posted April 16, 2016 Hi I've got a GT6 MK2 (2.5 fast road build) with a fast road cam 285 duplex etc everything was new except the two bolts and the tag which I re used I'm worried that the valves have bent, the pushrods don't look bent there's no damageat all that I can see Link to comment Share on other sites More sharing options...
dougbgt6 Posted April 16, 2016 Report Share Posted April 16, 2016 I have a mk3, bog standard! Easy enough to take the timing chain cover off in situ and have a look. Although you can damage the valves/pistons when this happens, it's not certain. I had a cam belt go on a Vauxhall, no other damage. I also know someone who broke a timing chain on a GT6, again no other damage. If it IS the timing chain it might be worth buying a cheap Endoscope and having a look down the plug holes or, it's head off to check it out. Link to comment Share on other sites More sharing options...
mike munro Posted April 16, 2016 Author Report Share Posted April 16, 2016 Yes my mate got one I'm going to pick it up later on ,if the chain is broken I won't be happy with the supplier I'll let you know the outcome cheers Mike Link to comment Share on other sites More sharing options...
JohnD Posted April 17, 2016 Report Share Posted April 17, 2016 Unless you have an extreme head skim and domed pistons (which a 2.5 will NOT have) the Triumphs are not "interference" engines whose pistons and valves will ever clash, so you are safe. All good diagnoses above, but you will need to work out WHY this has happened. There is a keep plate under the two can sprocket bolts, that should be bent up to lock them. Its often lost or forgotten in a rebuild! But less often causes the bolts to be lost. John 1 Link to comment Share on other sites More sharing options...
david lewis Posted April 17, 2016 Report Share Posted April 17, 2016 good article in this months practical classics mag about gt6 cam timing--worth a look. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 17, 2016 Report Share Posted April 17, 2016 This could also be a fractured camshaft Link to comment Share on other sites More sharing options...
mike munro Posted April 18, 2016 Author Report Share Posted April 18, 2016 Hi as suspected the two bolt have sheared off even though the tab was on, one good thing the tab kept the bolts from wrecking the chain I only hope the engine hasn't been staved of oil as the bump stopped for S short time. Now I have the fun and games of getting the two bolts out of the cam I'd post pictures but not sure how to do it cheer Mike Link to comment Share on other sites More sharing options...
mike munro Posted April 18, 2016 Author Report Share Posted April 18, 2016 Hi as suspected the two bolt have sheared off even though the tab was on, one good thing the tab kept the bolts from wrecking the chain I only hope the engine hasn't been staved of oil as the bump stopped for S short time. Now I have the fun and games of getting the two bolts out of the cam I'd post pictures but not sure how to do it cheer Mike Link to comment Share on other sites More sharing options...
rogerguzzi Posted April 18, 2016 Report Share Posted April 18, 2016 Hello Mike Were the correct bolts fitted? as I find it hard to believe 2 x 5/16" bolts would shear off unless the the cam has seize in the block? Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 18, 2016 Report Share Posted April 18, 2016 Have been trueling the web for old money bolt specs these need to have a short shank to locate the gear and be t or v on the head as theses are tougher than the std bolt r or s markings more modern bolts have the dimpled head and raised radial lines and need to be 8.8 or10.9 they take a lot of unsimpathetic loads as the cam rattles round pete 1 Link to comment Share on other sites More sharing options...
JohnD Posted April 18, 2016 Report Share Posted April 18, 2016 How deep in the cam shaft boss are the broken-off stubs? They shouldn't be tight in there as they would have been tightened (or Not! were they not torqued down? and loose so the sprocket rattled araound and broke the heads off?) onto the sprocket. Without the heads, they should come outeasily. If reachable, then a fine, pointed drift to tap them around with a light hammer might turn them until you can grip with pliers. OR, is this one case in a million where an "Easyout" will actually work? When they do come out, some close inspection of the threads in the boss, as they will have taken a beating from a loose sprocket? John Link to comment Share on other sites More sharing options...
dougbgt6 Posted April 19, 2016 Report Share Posted April 19, 2016 Was Mike's mistake re-using the old bolts? 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 19, 2016 Report Share Posted April 19, 2016 There was a general rule about not re using bolts on hard face fixings , like all bearing caps flywheels etc and cam sprocket fits into a hard face clamp, soft fixing like suspension and frabricated bits and bobs are less critical, I was involved with torque to yeild with early hi spec wrench this compared the climb in torque with the rate of rotation and blew whistles and bells when the parameters headed for the yield point of the bolt amazing on some applications you could almost double the torque , but on hard surfaces there was little to gain, Once a bolt was torqued to yield you could not achive a second re use so I guess re use may have a impact , as would soft bolts , poor face conditions and lots more well the suns out for change Link to comment Share on other sites More sharing options...
68vitesse Posted April 19, 2016 Report Share Posted April 19, 2016 If you need to drill the bolts to get them out left hand drills are available, just need an electric drill which can be set to rotate anticlockwise. Heat and vibration from drilling will often losen the remains of the bolt. Regards Paul Link to comment Share on other sites More sharing options...
mikemunro Posted April 21, 2016 Report Share Posted April 21, 2016 Hi all thanks for the replys 1 I reused what I thought to be the correct bolts 2 the stubs came out by counter sink and drilling a small hole and using a bolt remover (which worked perfectly) 3 I took the bolts to a mechanic who instantly said that thay had cracked due to maby reuse or over tightening, I would say reuse as I torqued them according to the manual. I will check if the cam is free as it's been mentioned hopefully its ok. I've ordered new bolts and a new tab gaskets off Chris witor so that should the right ones for the job. I will let you all know how it goes thanks Mike Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 21, 2016 Report Share Posted April 21, 2016 Good is not looking a disaster keep, us all up to date how the refit goes pete Link to comment Share on other sites More sharing options...
mikemunro Posted April 22, 2016 Report Share Posted April 22, 2016 Have been trueling the web for old money bolt specs these need to have a short shank to locate the gear and be t or v on the head as theses are tougher than the std bolt r or s markings more modern bolts have the dimpled head and raised radial lines and need to be 8.8 or10.9 they take a lot of unsimpathetic loads as the cam rattles round pete hi Pete I've just received my parts from Chris Witor and he has supplied new bolts with the LETTERS A R B and then an S do you think these are good enough?? Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 22, 2016 Report Share Posted April 22, 2016 Chris gets it right , i will have a browse in the morning , as on a tablet its not the best way http://www.wanderingtrail.com/Mechanical/Bolt_Marking_Torque_Standard.htm pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 23, 2016 Report Share Posted April 23, 2016 http://www.thomassmithfasteners.com/technical.html#torque or http://britishfasteners.com/index.php/head-markings Link to comment Share on other sites More sharing options...
mikemunro Posted April 23, 2016 Report Share Posted April 23, 2016 Hi all received the new bolts and all the other things gaskets new chain tensioner tab , the bolts are marked with an S so thay are not high textile can any one tell me if these are the right ones I got every thing off Chris Witor so I presumed he would of sent through appropriate fixings. Thank Mike Link to comment Share on other sites More sharing options...
mikemunro Posted April 23, 2016 Report Share Posted April 23, 2016 Looks to me as the letter S is the same standard as 8.8? Thanks Pete for the links. Do you think these are the right one with the letter S cheers for the help and information. Mike Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 23, 2016 Report Share Posted April 23, 2016 oe was part number 100500 seems superceeded to 129361 its used in many high stress area's drive shafts props back plates etc. neither number is in my hardware catalogue....whos got a new version as the torque is 22-26 its higer than a std bolt 19-21 lbft so would expect a next spec up to T or V doesnt want to be too hard that can let go on shock attachments ...sorry grey is getting foggy ive just looked at old prop bolts ( same Pno ) an they are V abp abf is the maker Link to comment Share on other sites More sharing options...
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