Mark from OZ Posted September 23, 2009 Share Posted September 23, 2009 Hi all. Can somone please tell me why i am cracking pistons ? Engine E 6 320 standard fuel not over heated oil squirters ok timing 24 degrees by plate on pump and by book Re built jan 07 242858ks No 2 and No 4 cracked 6 / 08 340480 ks Now. pistons are genuine Mack from Mack but made in INDIA all after production pistons made there now. Never had any trouble ever beforeGot me beat.....Mark Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 looks like a casting faultdefinitly wern't there whe i put it in Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 original piston in there for 11 years perfectoff set combustion chamber as standard Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 New piston central combustion chamberlike the 4 valve may be one size fits all nowNote spray patters are gooddefinitley the right pistons sold for 2 valve Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 Quote Link to comment Share on other sites More sharing options...
fjh Posted September 23, 2009 Share Posted September 23, 2009 Are you possitive the piston coolers are aimed correctly!the coolers got to hit the piston correctly or they can over heat!We have cooler targets to check em after liner install.the spray for the cooler needs to head basicly straight up from the nossle hitting 5 or 7 oclock on the piston, stick a welding rod in it and see where its heading!as you said the injector spray looks fine Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 Hi fjh I have the target for the piston cooling jets. They were in the spec and careful when fitting the rods down the bore. The brown stain inside the piston is uniform on all........ Mark Quote Link to comment Share on other sites More sharing options...
Bollweevil Posted September 23, 2009 Share Posted September 23, 2009 Hi fjh I have the target for the piston cooling jets. They were in the spec and careful when fitting the rods down the bore. The brown stain inside the piston is uniform on all........ Mark Heat checking on a high millage engine is not uncommon. What condition were the rings in? Damage from detonation is more common to a gasoline engine, but from what I can see the top ring land has had too much heat. Check the ring ends to see if they have butted. If that is the case slip one into the bore and check the end gap. I can't think of another reason to fracture the second ring land. If the ring gap is correct, and the rings have butted together, You are putting too much heat into it. Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 23, 2009 Author Share Posted September 23, 2009 bolweevill thanks Now the engine was fully Rebuilt pistons rings liners whe whole deal Jan 07 ring gaps spot on done 41833 ks cracked 2 /4 nov 08. put it down to bad luck Now No 5 cracked in the steel insert, done 139455 ks sept 09 piccy later. the thing is pistons 1 3 6 are still good standard fuel pyro never goes over 4/12 to max 5 degrees C. owner driven by me. Sitll 99% cross hatch marks in the bores. Me thinks crap parts. Remember the original pistons were in there for11 years and were still serviceable.......Mark Quote Link to comment Share on other sites More sharing options...
fjh Posted September 24, 2009 Share Posted September 24, 2009 bolweevill thanksMe thinks crap parts. Remember the original pistons were in there for11 years and were still serviceable.......MarkHave to agree! An old Bob Serger song comes to mind!Take them old pistons off the shelfput em back in there by yourself todays pistons anit got the same soul! So put em back in there respective holes.You get the drift! Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 24, 2009 Author Share Posted September 24, 2009 Have been thinking of PAI rebuild kit this timehave used PAI in the past with no worries at all if Mack can only supply the after market stuff they have lost me. Is PAI still made in the US? may bee they have better quality controll. going at this rate i will have to put zippers on the heads........Mark Quote Link to comment Share on other sites More sharing options...
Bollweevil Posted September 24, 2009 Share Posted September 24, 2009 Have been thinking of PAI rebuild kit this timehave used PAI in the past with no worries at all if Mack can only supply the after market stuff they have lost me. Is PAI still made in the US? may bee they have better quality controll. going at this rate i will have to put zippers on the heads........Mark They still have pistons listed on their on-line catalog, didn't say who made them. 770 822 1000 is their number. Quote Link to comment Share on other sites More sharing options...
skip Posted September 24, 2009 Share Posted September 24, 2009 Have been thinking of PAI rebuild kit this timehave used PAI in the past with no worries at all if Mack can only supply the after market stuff they have lost me. Is PAI still made in the US? may bee they have better quality controll. going at this rate i will have to put zippers on the heads........MarkGday mate. I got a PAI kit from gleemans and it was a good price. Its a 285 EM6 and its used oil from day one. I took the heads off and all of the bores are shiney. Its had RX super in it the whole time. Its done about 150000Kms. Hard to work out, and it may be a once off, but if I had to do it again I would be thinking of using genuine parts. Skip Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 24, 2009 Author Share Posted September 24, 2009 Thanks Bollweevil Gleemans have a kit in stock Skip don't know why your's pollished the liners I use rx super and never had an oil related problem My engine has 98% hone marks still in the liner Its just crap parts. Saying that it most probablywas a faulty batch pistons 1 3 & 6 are still good piston 5 was still good til this week 2 & 4 cracked at 41833 2 & 4 replaced at that K's still good Mark Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 24, 2009 Author Share Posted September 24, 2009 All the pistons that failed were at the steel ring land Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 24, 2009 Author Share Posted September 24, 2009 picture sez it all it think Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 24, 2009 Author Share Posted September 24, 2009 Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 25, 2009 Author Share Posted September 25, 2009 Picked up the Re build kit. It seems that all the 2 valve pistons are of the later design. I am sure that it was just a faulty batch. They seem to be a little better finish. After a lot of reserch i now know the company's that manufactured them. Never had a piston failuer in 30 years ofMacks. The PAI Kit was $2772.25 AUD so not too bad. Time will tell.........Mark Quote Link to comment Share on other sites More sharing options...
HK Trucking Posted September 26, 2009 Share Posted September 26, 2009 Regarding the difference in piston top configuration, I recall seeing a Mack service bulletin back around the mid 90's discussing that change, and the fact that more combustion "rattle" would be noticeable in engines fitted with the new design pistons.I put a set of those updated Mack pistons into a 237, and also put a set in a 285 back around that time and never had any problems with them. But that's when Mack parts were still being made by Mack and not subcontracted to some low bid company in India.Perhaps V*lv* has subbed out all the Mack replacement parts manufacturing to 3rd world sweatshops.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 26, 2009 Author Share Posted September 26, 2009 Thanks HK. I have been pulling my hair out or what's left over this. They jus talk round in circles down a Mack now as they are non current item now I have learned how to decipher the markings and serial No's on the piston tops and the different suppliers. All made over seas now. I put it down to a bad batch / quality controll on the day. The set i have now is fron a different builder and looks a better finish itm I'll put them in and see what happens. Thanks Mark Quote Link to comment Share on other sites More sharing options...
Mike Posted September 28, 2009 Share Posted September 28, 2009 Mr. OZ Let us know how it goes with this kit. Looks like i'll be following you with a re-build kit for the 673P for my B. Thxmike Quote Link to comment Share on other sites More sharing options...
Mark from OZ Posted September 29, 2009 Author Share Posted September 29, 2009 Mike i will let you know how it goes. Should be good That particular brand uses MAHLE brand, Google them up very good brand. Certanly better than the other brand........Mark Quote Link to comment Share on other sites More sharing options...
mackmech Posted October 1, 2009 Share Posted October 1, 2009 are you sure pistons aren't hitting the heads? If not i agree with bollwevil improper ring gap or over boost. Quote Link to comment Share on other sites More sharing options...
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