3408 in D9N

[RZucker]

I have an outfit with a 9N that wants me to replace their engine, It has a rod sticking out of the block... Knocked the starter right off. Now is where it gets interesting, 7 years ago they inframed this engine and it lived about 30 hours, It spun 2 rods and 1 main. After that fix,(crank ground .050 under) it broke the crank at about 100 hrs. They put a new crank and a couple new rods in it. now here we are, 600 hrs later. Is this thing jinxed or what? Ive rebuilt a ton of 3406s and around 3 3412s, all still running. What is it with the 3408? several people said "Dont touch it, get a Cat reman". Are they that persnickety?

 

[DPete]

That's a horror story if I ever heard one, enough to make a small contractor go down. Must be some kind of line bore or lube issue. I'm not familiar with the engine but have sympathy for the owner, probably don't have a core now with a hole in it.

 

[RZucker]

Yep, no core. Apparently the guy that did the first overhaul was a total pig as far as being clean, from what their guy told me. Pulled the heads without even cleaning the valley out.

 

[Mobiltech]

If it had been fixed right the first time it would be fine. Why would you cut a v8 crank .050 under. I wouldn't have put it in
It must have other lube problems or it didn't get stripped and cleaned properly

 

[DPete]

The air board here in Cali knocks a hole in the block on engines traded in for tier repower, don't know the regs or financial help up there but it might be time to update the engine, save them the trouble of ruining the block. I had a 623 done, the air board paid all but $10K on a new crate C-15, new everything from the trans forward, coolers, radiator,AC even put G nose tin work on an E, included dealer labor to complete. I think it had to be running though, worth checking to see what if any you states program will contribute

 

[RZucker]

If it had been fixed right the first time it would be fine. Why would you cut a v8 crank .050 under. I wouldn't have put it in
It must have other lube problems or it didn't get stripped and cleaned properly

Ive been doing a bunch of research on this one, and cat says .o50 under is good to go. But... I never saw the crank to see how badly overheated the journals were. Its one thing to regrind a worn crank to the next undersize, but to cover up damage?

 

[Andrew_D]

So if the block is pooched, do they have a line on a used block that they are wanting you to rebuild? (Combine 2 engines into 1??)

I'd be awfully tempted to go with the CAT re-man myself.

Andrew

 

[RZucker]

Something like that 2 into one thing. But Im not accepting my part til they realize where Im at. I am not about to let them set policy on a job like this and tie my hands to complain later.

 

[Dickjr.]

Guessing on my part that when you take both engines apart , clean have good components examined by machine shop or dealer , buy parts to reassemble , etc etc etc , a reman might be the way to go. I do know those things are not forgiving with even a minor issue.

 

[RZucker]

Yep. the autopsy on the original engine will tell the tale.

 

[Gavin84w]

3408 cranks are touchy especially if you don,t get the fillet radius right the cranks snap through there pretty easy, due to being 65 degree V and the pins offset they are not super strong there but obviously there are thousands of them out there giving no trouble but when you don,t do em right they will bite.

 

[Karl Robbers]

3408 cranks are touchy especially if you don,t get the fillet radius right the cranks snap through there pretty easy, due to being 65 degree V and the pins offset they are not super strong there but obviously there are thousands of them out there giving no trouble but when you don,t do em right they will bite.

So are they the same as Cummins cranks - dress a wheel to suit and grind the journal and fillets in one pass?

 

[Cam85]

Gavin 84 hit the nail on the head he is dead right.my advice go the cat reman it's easy it works and if something goes wrong the buck doesn't stop with u. Be careful this one could bit u in the bum dot ur I and cross ur t if u know wat I mean.

 

[RZucker]

Yeah, I surely dont want get into piecing the thing together with used parts. My suggestion was find a running take out and go from there. Sometimes that works out quite well. 10 years ago I found a good used D348 for a 992B thats gone 11000 hrs now and still ticking.

 

[JDOFMEMI]

If they first rebuilt it 7 years ago and it now has a whopping 600 hrs on it, I would guess the $$ for a Cat reman are out of the question.

I would be looking for a good running takeout, unless they just got a job that will put the kind of hours on that would justify a reman engine. I have not priced one lately, but I would guess you could buy a good running D-9N complete for less than a Cat reman 3408.

 

[RZucker]

Yep, Ive seen non Cat remans for around 35,000 exchange. And heard stories of a Cat reman at 60,000 installed.

 

[DPete]

I would consider the condition of the rest of the machine, here one wouldn't put big bucks into a tier 0 engine. Another option is find a reconditioned block, use what's good out of the old. Did it ruin the crank again? Sounds like they half assed it before, just cost themselves double or more.

 

[RZucker]

I dont know about the crank, Its a back burner project right now. The owner is going to count beans for awhile. She needs some undercarriage work too, And nobody knows the torque and trans history. Might just be time to upgrade.

 

[DPete]

Might just be time to upgrade.

Agree, if the rest of it is down not much point in putting big $$ into a dead horse