sammy340

OK

My friend just messed up his truck because when i did a compression test i had 400 PSI on all the cylinders except on #5 which was 180 PSI.

So..........i pulled the head off and sure enough i can see some scoring on one side of #5 cylinder. My question is........what the heck happend? Appears that rings are bad. As for overheating....could this be the cause? The pistons show absolutely NO sign of overheating.....so i don't think this was a EGT issue.....maybe engine temp issue? Do you think that metal got down into the crankcase and hurt the crank? What do you guys think the proper repair procedure would be?

I asked him about the temps and he said he can't remember.

Any help appriciated

Jeff

wannadiesel

Sounds like it got too hot and seized. A plugged/missing piston squirter will do that. Odd that it's #5, usually it's #6 if it's EGT and #1 if it's cooling system.

I think it's gotta come out and get bored oversize on that hole at a minimum. If the miles are low the bearings are fine, the oil filter caught all the big crap. If the miles are high (over 200k) roll in new bearings on the rods at least. Keep the pistons and rings in order (very important!) and put all the rest right back where they came from. Check that oil squirter good, there are metal ones available to replace the original plastic ones.

sammy340

wanna

Can you explain to me where exactly the oil squirter is located so i can see if it's missing........

thanks

wannadiesel

They are up in the main webs, you have to pull the crank and bearings to get them out and inspect them. Plugged is bad, broken is pretty much as bad because they just kinda bleed oil off the main instead of squirting it on the piston.

sammy340

Wanna

So do i think i could get away with just pulling the crank and piston #5 and get it bored out with all the others in there? I wouldn't mind getting all new metal oil squiters as well. I still am a little vague on were to look for the oil squiters but i'm sure i'll see them when i get the crank out.

Monty

Be careful pulling the connecting rod out of the bore. If you arent real careful, you can break off the piston coolers since they are plastic and simply press into the top of the main web. However, you said the piston looked good so IMO the piston cooler should be good. Any sign of a piston cooler failure would definately show damage to the piston. Was the scoring on the cyl walls at the ring gaps? Sounds to me more like you have a failed ring, however, I dont know how deep of scoring it has.

IMO, if your going to have the crank out, get new rod brgs, main brgs, new rings on all cylinders, inspect all pistons, wrist pins and wrist pin bushings, bore downed cylinder, and inspect head and valves.

Underpsi

sounds kinda expensive , sorry for your loss

bigragu

Is it obvious? If so, I was just curious...I wouldn't know.

sammy340

The motor does not run smooth at any rpm..........

sammy340

Don't worry guys........no loss at all........wasn't my motor and my friend has a spare anyway.....

The question is.....do you guys think it would be worth it to fix? Like if i get one cylinder bored out do i need to get them to do all the cylinders?

I would like to do this as cheap as possible....i wouldn't mind putting all new rod and main bearings.....but pulling each cylinder and doing the rings sounds kinda like quite the job (especially since it ain't mine ). The main question is..........do i have to bore all the cylinders if i bore one out?

wannadiesel

No. It's pretty common to just fix what's broke and send 'er on down the road. If it's like most Cummins 5.9's, you can still see the cross-hatch in the other 5 holes.

Put more stock in what Monty has to say than whatever I come up with. He actually works on these things every day.

sammy340

Wouldn't having one bored out cylinder change the pressure of that cylinder causing uneven force on the crank compared to the rest of the cylinders?

Monty

Well, you can get away with it if your on a budget. However, it will be unbalanced and IMO I wouldnt risk it especially if you are going to be bombing it. You just sounded like you were on a tight budget.

I am a little biased and somewhat of a perfectionist so my thoughts may differ from others. But, if this were my engine I would go ahead and bore all 6 get oversize pistons and rings or bore and sleeve for stock pistons dimension. While you have it at the machine shop, you might as well have them inspect the main bearing bores, rod bearing clearance, crankshaft rod journal for out of roundness, cam and bushings, head fluxed, straightened, new valve seals and valve springs wrist pin and bushings etc.

I mean, how far are do you want to go? Sure you can patch it, but IMO your living on borrowed time. I dont see why you are worried about pulling the other pistons out. You already will have the head off and #5 out, pulling the rest and re-ringing is no big deal. Plus, how are you going to know that the rest of the cylinders are not out of round?

sammy340

Monty

I know exactly what i should do. But here is the arguement.

I can go to the local wreckers and pick up a cummins 5.9 with about 150,000 Miles for $2000.....


How much do you think i'm looking at by the time i end up maching all 6, new pistons, rings, main brgs, rod brgs?

But if i did do this, then she'd be really good to go for some serious bombing

I'll have to run this all by my friend and see what he thinks.......


Jeff