bullhusk Posted June 3, 2012 Share Posted June 3, 2012 I was checkin out my Brockway today, I've got about 3or 4 loads of Q/P to run from PA to my site. Well I see some oil around the front cyl. head and the block, so I clean it with some brake clean and start her up and sure enough I could see some bubbles and a little oil seeping between the head and the block. I just had the motor done about 9 months ago and I don't think it has 1,000 mi on the in frame! Oh well I guess It's back to the F-Liner dealer! They said they checked the block deck..but who knows??? Well anyway thats why I don't like to do my own motor work, cause if it don't work out....ya just bring it back!!BULLHUSK Quote Link to comment Share on other sites More sharing options...
BOB DINGSDALE Posted June 3, 2012 Share Posted June 3, 2012 Have them check to see if you have a broken head bolt.If not retorqe heads.Should be done after refit anyway.Bob D Quote Link to comment Share on other sites More sharing options...
jaysm35a2 Posted June 3, 2012 Share Posted June 3, 2012 Withs the diff between the 250 Cummins and the Super 250? Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted June 3, 2012 Share Posted June 3, 2012 On any of the older cummins it is no common to see a head gasket leak oil. It is seen some times but in order for the head gasket to leak oil the oil ring seal around the pushrod channel would have to be damaged. This is seen when guys use a sealer or get some oil on the rubber seal when insatlled and the pressure when torqe is quashing it out.I would use brake clean and blow the oil out from under the head and run and watch for oil coming from a rocker box shaft seal.A oil ring or plug is in the ends of the rocker box holding the shaft in. It is common to see then leak and drain down and run into the gasket. If you get oil between the head and block on a new engine when hot and running it will bubble out. Dont waist your time retorqueing the head bolts on a cummins.A good way to find oil leaks is get it hot clean with brake clean and a blow gun. Then at 1500 rpm put a finger over the blow/by tube for maybe 5 seconds and relase the pressure and repete this untill you see the oil. This will induce more pressure to crankcase and make the oil leak faster.Dont over pressure or some else could happen. glenn 1 Quote glenn akers Link to comment Share on other sites More sharing options...
bullhusk Posted June 3, 2012 Author Share Posted June 3, 2012 On any of the older cummins it is no common to see a head gasket leak oil. It is seen some times but in order for the head gasket to leak oil the oil ring seal around the pushrod channel would have to be damaged. This is seen when guys use a sealer or get some oil on the rubber seal when insatlled and the pressure when torqe is quashing it out.I would use brake clean and blow the oil out from under the head and run and watch for oil coming from a rocker box shaft seal.A oil ring or plug is in the ends of the rocker box holding the shaft in. It is common to see then leak and drain down and run into the gasket. If you get oil between the head and block on a new engine when hot and running it will bubble out. Dont waist your time retorqueing the head bolts on a cummins.A good way to find oil leaks is get it hot clean with brake clean and a blow gun. Then at 1500 rpm put a finger over the blow/by tube for maybe 5 seconds and relase the pressure and repete this untill you see the oil. This will induce more pressure to crankcase and make the oil leak faster.Dont over pressure or some else could happen. glennGlenn, The first thing that i looked for was oil at the rocker assm. but the area is bone dry, I will try the vent tube, and if that don't work I think the dealer puts a dye in the oil to find the area of the leak, Thank you for your input !! and I learned something new!!Ernie DS Quote Link to comment Share on other sites More sharing options...
bullhusk Posted June 3, 2012 Author Share Posted June 3, 2012 Withs the diff between the 250 Cummins and the Super 250?A Cummins 250 is a 855 ci motor, a Super 250 is a 927 ci. The Super has the same piston bore but a longer sleeve, the crank has a longer stroke and the block is higher. The rod's have 4 bolt caps. and I was told when they were doing the rebuild that the heads are diff. as well. At the time of the rebuild about 9 month's ago the price of a reman Cummins head was 3,600.00 bucks! and you would have to wait for your head cause they do not stock the head, I'm sure I could have gotten one a lot cheaper from an outside vendor. Now as far as power goes, the motor is lazy but is a torque monster, you have to shift the truck diff. when loaded an empty, when loaded I just use low an direct on the aux. (5X4) untill I get into 5th and then I kick it into OD, now when I'm M/T I use direct an OD. I had an A-Car at Colonial with a 6-71 Detroit, and and the same Spicer Air- Matic 5X4, and it was a lot better truck to shift! and I think maybe It was because the Detroit was a lot faster on the rev's then the Cummins??.... I would like to put some more fuel to the pump, or turbo the motor and make it a Monster 290!BULLHUSK Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted June 4, 2012 Share Posted June 4, 2012 A Cummins 250 is a 855 ci motor, a Super 250 is a 927 ci. The Super has the same piston bore but a longer sleeve, the crank has a longer stroke and the block is higher. The rod's have 4 bolt caps. and I was told when they were doing the rebuild that the heads are diff. as well. At the time of the rebuild about 9 month's ago the price of a reman Cummins head was 3,600.00 bucks! and you would have to wait for your head cause they do not stock the head, I'm sure I could have gotten one a lot cheaper from an outside vendor. Now as far as power goes, the motor is lazy but is a torque monster, you have to shift the truck diff. when loaded an empty, when loaded I just use low an direct on the aux. (5X4) untill I get into 5th and then I kick it into OD, now when I'm M/T I use direct an OD. I had an A-Car at Colonial with a 6-71 Detroit, and and the same Spicer Air- Matic 5X4, and it was a lot better truck to shift! and I think maybe It was because the Detroit was a lot faster on the rev's then the Cummins??.... I would like to put some more fuel to the pump, or turbo the motor and make it a Monster 290!BULLHUSK Sorry to differ but the block is same high.We use to convert them because a fleet had some here that had maybe all of them crack or break the crank we would install a.855 crank and rods with NH 250 pistons an a turbo kit and build a NHt 270.They would last longer then.And the heads was same as the NHT 290 or 250 except the 250 did not have hard valves on the intake like the 290.Its been long time since i have worked on them but we was in the changing of them over big time for awhile. I think me and another mechanic converted 25 of the one Kroblen (KRX) had.The engine model was N927 and there was also a turbo model in bigger HP built but never seen one.The story of the block being higher is not uncommon because it sounds that if the strock is longer it would push the piston out of the block but realy the rod is shorter than a 855.We had two of them in the shop in the same week for a over haul and we found a crack in both of their cranks.Crank running from the oil hole over.It was not longer after they was outr of production till the cranks could not be found.So if any on has one and it needs acrank just change to a 855.The oil cooler was differnt than the 250 but if was larger so no problem. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
theakerstwo Posted June 4, 2012 Share Posted June 4, 2012 Fogot to say many of the N927 was rated at 270 HP 1 Quote glenn akers Link to comment Share on other sites More sharing options...
bullhusk Posted June 4, 2012 Author Share Posted June 4, 2012 Sorry to differ but the block is same high.We use to convert them because a fleet had some here that had maybe all of them crack or break the crank we would install a.855 crank and rods with NH 250 pistons an a turbo kit and build a NHt 270.They would last longer then.And the heads was same as the NHT 290 or 250 except the 250 did not have hard valves on the intake like the 290.Its been long time since i have worked on them but we was in the changing of them over big time for awhile. I think me and another mechanic converted 25 of the one Kroblen (KRX) had.The engine model was N927 and there was also a turbo model in bigger HP built but never seen one.The story of the block being higher is not uncommon because it sounds that if the strock is longer it would push the piston out of the block but realy the rod is shorter than a 855.We had two of them in the shop in the same week for a over haul and we found a crack in both of their cranks.Crank running from the oil hole over.It was not longer after they was outr of production till the cranks could not be found.So if any on has one and it needs acrank just change to a 855.The oil cooler was differnt than the 250 but if was larger so no problem.Yes I agree with you on the block, it was the service manager at the rebuild shop that said 'you can't tell the diff by just lookin at it' but you are not the only one who has told me about the crank prob. and converting them to a 855!! I hope that I don't have any crank trouble, but if I do, I have a nice 270 big cam III with a intercooler that I will rebuild and transplant it into her! I know about the 270 hp version so I just might have the pump recalibrated so as to give me a little boost Thanks againBULLHUSK Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted June 4, 2012 Share Posted June 4, 2012 The difference in the blocks is the 927 had 6 bolts holding the oil cooler to the block and the 250 855 had 5 bolts hanging the oil cooler. Quote glenn akers Link to comment Share on other sites More sharing options...
bullhusk Posted June 4, 2012 Author Share Posted June 4, 2012 The difference in the blocks is the 927 had 6 bolts holding the oil cooler to the block and the 250 855 had 5 bolts hanging the oil cooler.Why didn't they just take a 855 and turbo it instead of doing all of the strokin and changing,?? it must of cost Cummins a fortuneBULLHUSK Quote Link to comment Share on other sites More sharing options...
GreenGiant2 Posted June 4, 2012 Share Posted June 4, 2012 didnt know that they made a bc 3 in a 270, thought the smallest was a 290bc Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment Share on other sites More sharing options...
bullhusk Posted June 4, 2012 Author Share Posted June 4, 2012 didnt know that they made a bc 3 in a 270, thought the smallest was a 290bc290 it is, with an intercoolerErnie DS Quote Link to comment Share on other sites More sharing options...
Dietrich Posted July 4, 2019 Share Posted July 4, 2019 Worked on a fleet of T/A Ford L 9000S in the early to mid 70's, all were equipped with Super 250's. NH 250's were still pretty common. We had a Cummins engineer who traveled the country as a trainer. I asked him why Cummins went to all the trouble of making a new engine that had the same power as the old 250? His explanation was that Cummins wanted to develop a higher horse power naturally aspirated engine but said that as development continued, it couldn't meet evolving emission standards. Quote Link to comment Share on other sites More sharing options...
JerryB Posted July 13, 2019 Share Posted July 13, 2019 Let’s not forget a NH 250 did not have piston coolers. The Super 250 has piston coolers and could be built to a 420 easy enough Quote Link to comment Share on other sites More sharing options...
deere_8820 Posted January 12, 2023 Share Posted January 12, 2023 I agree with you bull dog. I have a super 250 that I built. With a HT 3B blower built for a lot of "wind" my own timing concoction, hard pistons and clevite H bearings. The "staying together factor" is limiting RPM to about 1800. It will stand in the wind with any 500HP power plant. Get 6+ mpg with a 13 speed, 3.55's and 22.5 tall rubber. Quote Link to comment Share on other sites More sharing options...
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