Veitchy Posted March 28, 2006 Share Posted March 28, 2006 G'Day Blokes,I am just pulling down a Superliner 500 HP V8 for a friend. It's run 2 big end bearings on the crank, and generaly made a mess of the engine. I have heard that the V8 has a lot of trouble with cranks and was wondering if anyone can tell me if there is anything in the design to make them weak there. The truck is 1988 manufacture and they are using it to pull a 2 trailer roadtrain (2 tri axle semi trailers with a 2 axle dolly to support the second trailer) with a payload of about 50 ton. It's been going well for several years but has now blown up bigtime. Some of the "experts" they have been talking to are advising to put in a Catterpillar but I know they arn't keen to change unless the Mack is going to give repeated trouble. The block and heads will be apart tomorrow and we are sending them to be crack tested so we have a bit of time to find out more about the service history of this type of engine.Anyone got any ideas ?Graham, from Quairading, Western Australia. Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/ Share on other sites More sharing options...
twostickmutt Posted March 28, 2006 Share Posted March 28, 2006 put a kitty cat motor in it and you'll only pull 1 of those trailers. when i ran my 500 i was always told to keep the "butress screws" tight and i never had any problems. this probably wasn't your problem but just a thought. j.j. Quote and remember "PREFORMANCE COUNTS" Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5131 Share on other sites More sharing options...
Mack Doctor Jr. Posted March 30, 2006 Share Posted March 30, 2006 I know i was told never to lug the motor down when i drove. My old man said macks have weak lower ends which are suseptible to spinning a bearing or throwing a rod. he always told me he'd rather see me run the shit out of it than lug it. Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5156 Share on other sites More sharing options...
Veitchy Posted March 30, 2006 Author Share Posted March 30, 2006 The bloke who drives it is an experianced driver with a lot of years on an "Atkinson" Cummins 350 HP, and before that on "Inters". I think he would keep it spinning nicely but not over reving.We got the engine out and pulled right down, it was surposed to have been overhauled not long before they bought it, but looking at it it may have only been an in chassis rebuild. It has run the number 4 main bearing and that may (?) be what caused the number 4 & 8 big ends to give out. The rest of the engine is in real good order and no visible cracks in either block or heads but we will get them checked anyway. The mains look like they havn't been disturbed and are a lot more worn than the big ends. The pots and pistons have definatly been replaced, but you could do that without removing the crank.The main reason I asked about their reliability is out here the V8 doesn't have the same reputation as the Mack six cylinder, and we were wondering if they are well thought of stateside ?Anyway I will let you all know how it turns out.Graham Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5158 Share on other sites More sharing options...
mackcl96 Posted March 30, 2006 Share Posted March 30, 2006 The v8 4-valve cranks are fine but rods and mains need to be done more often then a inline 6.Pushing a piston on an angle is more work then up and down. the way i did it was at 300 thousand miles on a 4-valve. 150,000 on a 2-valve they were the ones for weak lower ends. my way of being sure Also doing rods and not mains was a bad idea on the other owner.The crank dose not need to come out for mains. Quote Thanks for hearing me out.You can have the soap box now---------JIM Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5163 Share on other sites More sharing options...
Timothy Maikshilo Posted March 30, 2006 Share Posted March 30, 2006 Graham, there are a lot of V-8's still on the road in northern new england and the guys who have them don't want anything else. I've seen a number of them in Canada too. They're still pretty popular and I too wouldn't want to part with mine,Tim Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5171 Share on other sites More sharing options...
Veitchy Posted March 31, 2006 Author Share Posted March 31, 2006 Thanks fellers,I think the owners will keep it original. I was talking to Roger (one of the brothers that own it) and he was telling me the late model Scania they hired to finnish their carting didn't have the power of the "old Mack"even though it is surposed to be bigger. They quite like the truck and have been happy with the performance of the engine, right up until the bang.When something like this happens you always end up with all the "experts" giving "usefull" advice and there is a bit of a cloud over V8 performance out here, but no one can tell me what is wrong with them. It sounds like not much as long as you do your maintainance right (and these blokes do) and drive them right.I will let you all know how it turns out,Graham Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5173 Share on other sites More sharing options...
Veitchy Posted April 18, 2006 Author Share Posted April 18, 2006 NOT WHAT I WANTED TO HEAR ! Just got back from the easter break to the news that the block has been condemned by the expert.Cracks radiating out from the cylinder recess to the head studs, the fellow who checked it said its not uncommon and not advisable to use it. Sounds like $$$$$$$He recons one of the heads has a small crack too !They have found another engine, but it needs doing up as well, so I don't know which way they will jump.Have you blokes heard of them doing this in the U.S. or Canada ?OH well, back to the old drawing board.I will keep you postedGraham Quote Link to comment https://www.bigmacktrucks.com/topic/1011-v8-crankshafts/#findComment-5416 Share on other sites More sharing options...
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