8N PISTONS

david gillet · Jan 25, 2009

Hi all,I have an 52 8n,I was getting a lot of white smoke from it.I did compression test,all cylinders were about 120 dry.It was running hot also.So I tore it down to find a bad head gaskit and valves needed new seals.I ground vavles and put in new seals had radiator redone.I pulled one of the pistons out to take a look and check rod bearings,The front and rear of the piston had scuffs from top of piston to bottom.it didn"t look severe,but you coould tell it was rocking around in there.Is this pretty normal for the 8n"s or should I replace all the pistons, rings and rod bearings.any info would be helpfull,As I just bought the tractor last year.It had been sitting for a few years so I don"t know the history on the motor.THank you David

JMS/.MN · Jan 25, 2009

Use mike to measure wear at the top, middle, bottom of the cylinder, and also check for out of round. Tech book will have details on allowable wear.

PaulW_NJ · Jan 26, 2009

I agree. I had the head redone on my International 240, and when I put it back together I suddenly had a severe oil burning problem in the bottom end that I didn't have before. The now "tighter" top end placed greater back pressure upon the bottom end. I later found out this is a very common situation. Definitely check out the cylinders with a bore gauge, but that only tells you the condition of the cylinders. You need to check if the rings are worn beyond specs by carefully removing a ring from the piston, and measuring end gap when inserted into the cylinder bore. And plastigage the bearings while you're at it. Better to do it all one time.

Hobo,NC · Jan 26, 2009

(quoted from post at 03:46:02 01/26/09) Hi all,I have an 52 8n,I was getting a lot of white smoke from it.I did compression test,all cylinders were about 120 dry.It was running hot also.So I tore it down to find a bad head gaskit and valves needed new seals.I ground vavles and put in new seals had radiator redone.I pulled one of the pistons out to take a look and check rod bearings,The front and rear of the piston had scuffs from top of piston to bottom.it didn"t look severe,but you coould tell it was rocking around in there.Is this pretty normal for the 8n"s or should I replace all the pistons, rings and rod bearings.any info would be helpfull,As I just bought the tractor last year.It had been sitting for a few years so I don"t know the history on the motor.THank you David

A N engine is not different than any other engine,,, scuff marks are not normal,,, are you sure you did find the problem 2 B in the head gasket,,, clean and check the head good cracks can B hard to C,,, it would Have been nice to locate the cylinder in question B-4 the tear down,,, if I were were you were I would go for the kill and replace the rings and pistons if the bore checks out are can B conditioned and still b in spec,,, its possible overheating caused the scuffs if it did then it also probably took the tension out of the rings tho your compression readings did not indicate that,,, a leak down test would have but its 2 late for that now,,, if you want it rite take care of what you C are it will always b their and will B a problem

http://www.theviperr.com/hobo_dnn/Default.aspx?tabid=68

Anonymous-0 · Jan 26, 2009

Not back pressure but higher vacuum when the valves are sealing tight Old chevy sixes were famous for doing this.

teddy52food · Jan 26, 2009

That was because most of the time , the valve seals didn't get installed right.

david gillet · Jan 26, 2009

Thanks all for the replies motor is in back of truck going to machine shop tomorrow.I am going to replace it all,I figure I might as well do it right if i'm going to do it at all.I am in the need of a hood and dog legs for it if you know of any let me know.I looked on ebay but they are mostly full of bondo,I have one of them already.I would like to keep it as close to original as possible. Thanks David

8N PISTONS

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JMS/.MN

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Hobo,NC

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Anonymous-0

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teddy52food

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david gillet

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