Combines 670T engine

[PETE]

I know the N6's with the 670HI need rod bolts at about 2500-3000hrs. Your motor is not wound as tight as the N6's but rod bolts would still be cheap insurance. I have a 7060 that ventilated the block at around 2500hrs and I suspect it was a rod bolt failure.

 

[tbran]

Things like that just happen sometime. Who knows the reason. I personally would not go into a 158hp 3500 until the 4500 hour range. Then go for the rod bolts and brgs. Any coolant in the oil or other abnormality would short this hourly recommendation. There is less weight thrown around inside and lower RPM's on this eng. than the 3750HI or 670I power plants. While we are on the subject, the N6 engines we are talking about have usually been "jucied" to overcome the HP requirements of a stock N6 P1 processor. Had HYPERIZING been around in the late 70's early 80's ...... geez what might have been... of course we would have pushed them that much harder... who knows.

 

[kernal]

We change rod bolts at 2500-3000 hours as part of preventive maintenance on these engines. We now have engines with over 6000 hours on sleeves and pistons with good coolant and oil change schedules.

 

[Marshall]

Can you replace the rod bolts without removing the rods or do the rods have to be removedIJ Do the rods need to be resized alsoIJ What is the best rod bolt for replacementIJ

 

[Dan]

I would never tell anyone not to put in rod bolts or bearings for there are just to many reasons that they could be bad over the years and hours. The 670T is as strong of an engine as any one out there. Has the engine ever been boiled causing anti-freeze to leak into oil during non use from a weeping head gasket. Has it had regular oil changesIJ Was engine ever reved with stiff oilIJ Has oil ever been thined with diesel from poor injector or running coldIJ I don't think there is any model Allis engine that has thrown a rod more often than any another model or make. If any Allis engine had more than its share it would be the high reving 670HI with Roosa Master pump that was used for the first three years in the N6. There are still plenty of them that have not been apart. Every one of them engines that did come apart had a blown engine oil filter that let unfiltered oil circulate threw the system. The oil filters were short then and would not let the cold oil threw when cold when reved up. The filter bypass could not handle all the oil either so the filter blew up internally. All the failed engines had broken rod bolts but it was the bearing that failed first. The bearing failed from junk getting by the filter. longer oil filters helped a bunch and higher capacity filter bypass valves were not far behind. I always suggest to idle engine until heat shows on gauge but not many do it. I'm suprised that there isn't more engines that come apart. I have taken out 3000 hour bearings to find them shot and I've taken out 8000 hour bearings to find them perfect. I do not normally replace rod bolts but sure do if custumer is worried about them. For your own peace of mind you may want to do bearings and then treat it well. Send in an oil sample from time to time to watch for trouble. It would be good to set valves, change anti-freeze, and tune up injectors if it hasn't been done lately. As a tip if you do pull your engine. Drill a 1_4" pilot hole threw engine back plate and frame mount toward the middle. That will prevent you from having to realign engine because you can use the 1_4" hole to get engine right back where it was. If you have failed any damper plates you should have engine aligned anyway. Have a good one.

 

[l3]

What about valvesIJ We've had trouble several times with this engine dropping valves.