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Who has blown a mini eng up https://www.ausmini.com/forums/viewtopic.php?f=2&t=50253	Page 1 of 2

Author:	david rosenthal [ Fri Feb 13, 2009 11:18 pm ]
Post subject:	Who has blown a mini eng up
I am interested in the events and what the engine was doing when it blew up. ie accelerating, de-accelerating , just engaging or just releasing the clutch. What broke,ie main brg cap,crankshaft, conrod or piston I was having a discussion with some-one today about his troubles with his engines failing at various times. These engs are used for racing and he has done everything to build a performance eng, balancing, wedging,polishing etc etc. Then something lets go with a bang. I asked him the same questions and I wonder if others have the same answer

Author:	TheMiniMan [ Fri Feb 13, 2009 11:38 pm ]
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wow,,, now i sooooooo hope i don`t hex myself when i say this,,, but i havn`t lunched an engine in my life (yet) I know heaps of people who have tho,,, some were fangin along the hyway & others were just plodding around town,,, sorry but i`ve not much more info than that,,,, all sorts of fatigues cause all sorts of carnage in these ancient old things,,, seems mostly rod bolts (or inadequate / lack of attention when tightening or just soft stretched re-used old carp bolts/nuts) & cranks having an argument within itself & then another argument wih the side of the block imediately after a bit like this forum sometimes I know a few fellas & i won`t mention any names) that live here in Brisbane & work as mini specialists who have actually had the con rod/piston assy come "Through" the fire wall & bang up against the seat crossmember ... yep,,, that means it`s come through the cam shaft breaking it half,,, then through the block, obviously taking a dam big chunk out of that & then through the fire wall & into the passengers side, banging into the seat crossmember & landing in the foot well,,, pretty scarey hey????? rod bolts/nuts & their fittment,,,, & cranks i`d say are the most prone David,,, holes in pistons & piston melt down the sides are pretty dam common tho too i spose,,, too lean,,, too hot,,, poorly set up rings,,, too high compression,,, over advanced ign,,, any/all combinations of all of the above & then add a big bloody over rev & you have a dam good receipe for dissaster a head gasket thats been weeping,,, then starts to blow & it`s left for way to long & the hot spot that`s been created than makes the piston edge dam hot & starts to melt down a gudgeon pin circlip fitted the wrong way round or not clipped in properly & slidey slidey goes the gudgeon pin into the bare wall,,, that`s a good one too,,, i`ve seen many engines that have just been re-ringed & bearingd & shoved back together with rail way track trenches in the bores from an obvious previous gudgeon pin gash crickey,,, this is a good thread too,,, you start some dam good threads David Cheers

Author:	david rosenthal [ Sat Feb 14, 2009 12:01 am ]
Post subject:
That link to youtube you put up about the poor little valve spring getting a flogging just shows the sort of sress and strain a eng has. Then you look at a V8 or V12 formula 1eng that is doing 20,000 rpm

Author:	jbeenz [ Sat Feb 14, 2009 6:21 am ]
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Ive poped a couple of 998's : First one, 110k on the "highway" (Whangarei - Auckland), 2 people plus a weeks gear, Had a 3.44 diff so was sitting at 4k, it had done the same journey many times, and had been "Rebuilt" by previous owned 10,000k before, sitting at constant rev's, started up a small hill and a rod bolt let go, and exited stage rear through the block and gearbox. - The block is still usable...just ventilated Second one was an old engine, smoky rattly old thing with no oil pressure, it spun a bearing under deceleration at 50k, So poor mantanance or just plain wear was to blame there. Then again, i pulled down an 850 that was running sweet as a nut to find the mains through to copper... This will be an interesting thread

Author:	drmini in aust [ Sat Feb 14, 2009 6:31 am ]
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Hmmm where to start- My 1st blowup was an 850, it broke the crank through the front web. Too many revs by me and the PO (a BMC mechanic). 2nd blowup- a 1098 bored to 1220cc with Imp pistons, 544 cam, 1275 head- after 20,000 miles it started using oil and blowing smoke. Too many revs (8500 at times) a circlip had broken and a gudgeon pin gouged the cylinder wall badly. The new 1098 crank by then had 8 cracks in it when magnafluxed, 2 on each bigend journal. 3rd `minor blowup'- my 1310 with 45,000 miles up running Mahle flat top pistons decided to overheat a piston at Wakefield Pk track day, and it went a bit out of shape and rattled. I limped it back home to Sydney though and the bore was fine. 4th `minor blowup'- my freshly built 1360 overheated the centre main bearing at Wakefield Pk, almost spun the shells, but not quite. Reason- not enough crank endfloat- (it had .003") the thrust washers had the bronze peeled off like fish scales. S crank needed the mains reground to fix. I have been told by those in the know that centre main cap breakages are the result of using the engine for braking. This is what brakes are for...

Author:	Oscar [ Sat Feb 14, 2009 7:26 am ]
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Only had one... Was in the process of building a new engine for my rally car back in the 70's. Didn't have it ready in time so took on an event with the ol smokey engine still in place. Armed with a boot full of spare oil off we went. Topped up at the end of the first transport and hit the forest. After only a few minutes the poor ol thing had consumed all the oil and the pressure was gone!! The road was one car wide with a vertical rise to the left and a vertical drop to the right. Had no choice but to press on for another 2 kays to a spot where we could pull over. Pushed the clutch in and the donk seized solid. I'll never forget the noise or the smell........ Found all these lovely curved blue shims that used to act as bearings lying in the sump!!!!!!

Author:	chopchop [ Sat Feb 14, 2009 8:01 am ]
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I put a massive hole in the block of my 1100 on the freeway from murray Bridge to Adelaide at about 2am in the morning after a fight with with my then girlfriend. I was revving the hell out of it and then bang, it let loose and just like in The Blues Brothers Movie oil and smoke went everywhere filling the cabin. Was a nice sleep in the back seat for the night and then had to hitch back to Adelaide, pick up a trailer and ute and go pick it up. Spewin!

Author:	justfanginaround [ Sat Feb 14, 2009 8:23 am ]
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we have had many ..... a 1275 stocky that broke the crown wheel on a gentle take off a 1100s that broke the crank in 3 spots at 12,000 rpm at sandown raceway we forgot to change into 4th gear while passing a MGB and only relised at the other end when we went for 3rd and found it was allready there a 998 that had been used for a very long time. It put the piston pin from no2 into no3 bore stoping to rotation instantly a 1380 hottie on the dyno while running it in had massive rod failure distroying the block, crank, rods and box and the list goes on ...........

Author:	Rookiepilot [ Sat Feb 14, 2009 8:49 am ]
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I had an 1100 run a bearing at Winton. I decided to give my brother a drive for helping me build the car. It was fitted with an oil temp gauge (the sender was the one that replaces the dip stick), which went off the scale prior to no oil pressure. "Informed opinion at the time was I was running the wrong oil, Castrol GTX. I was told at the time the detergents in the oil and the combination of a mini gearbox acted like a mixmaster and was turning the oil to foam. Not sure on that one. My race engine, a 1380, never gave me any mechanical trouble. I am not the original builder but the crank is only running the two top thrust washers on a two bolt mains, I suppose to stop pinching of the crank at high revs. I've since been told this is old school and not required, but it seems to be working for me. Other things that were hammered into me when I started racing was don't use too much ignition advance (mine is 32 degrees), and as Doc has said, don't use the engine for braking, as sudden deceleration will snap a mini crank in half.

Author:	Beanie [ Sat Feb 14, 2009 9:46 am ]
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I have broke a STD LRG jurnal crank... 1380 not balanced to many revs off the start line felt funny but didnt pay any attention to it as it hit fourth it just went bang ( mind you kept running ... Could actually restart it after) made some real bad noises And i have had a valve grab the guide cos i didn't allow enough clearance

Author:	sports850 [ Sat Feb 14, 2009 9:49 am ]
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I've never blown one that spectacularly , spun bearings before , dropped the center main thrust washers twice but all were stopped before too much damage . Had a piston flattened out because of a spring washer bouncing around in the cylinder , mushroomed the head of the piston till it locked in the bore and all the rings were shattered into 1/8" to 1/4" lengths and looked like a mountain range in profile ...

Author:	speedy [ Sat Feb 14, 2009 10:14 am ]
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This gets my vote for the biggest blow up posted on here. http://www.ausmini.com/forums/viewtopic ... light=hole

Author:	graham in aus [ Sat Feb 14, 2009 12:05 pm ]
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^^^^ good effort!! I've done a few, this pic has been on before, but.... Down the hill from Regate at Donington in third, slip 'er back to second to take the old hairpin, wait. wait, wait for the apex, back on the power scream up the hill, 8500 in second just as I lift for third BANG! clatter clatter hmmnn no go! The marshall at the next bend gave me half the cap back later!

Author:	Tombo [ Sat Feb 14, 2009 3:30 pm ]
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My most smashing time was when the heavily worn cross pin in the diff broke. It felt like the diff was locked, hard steering, so i got in a turning lane to go right and sat there a moment. When i went to take off it felt like the brakes were locked, eventually with 5000 rpm and a heavy release of the clutch i got going. The cross pin and spacer got under the front of the crownwheel and i had forced it throught the gearbox case. 5l of hot oil spilt across a main road makes a fine mess

Author:	aaron [ Sat Feb 14, 2009 3:52 pm ]
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Ive had three 1st was a fresh rebuild that i had paid good money for. Crack tested crank hadn't been crack tested..... easing out onto the road with 2.5kish on the pedal. 2nd - Just bought the car and was driving home. melted a piston.... There was no Oil or water in it... surprise surprise 3rd - Diff sipder gears exploded. Diff pin was richard. Whole motor was srtipped and rebuilt again. Cheers Aaron

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