What would you do?

[Ethan Smith]

So i went and picked up an f350 the guy said had a hypermax on it. I had the intention of pulling it off and using it on my 6.9 f250 which is low in compression but bulletproof otherwise.
Well when i picked it up holy cow, all cylinders are running at 400+ psi except one thats dead from a burnt valve or shot rings or whatnot. Its a suuuuhweet potential work truck with airbags in the rear, theyre prolly shot from sitting though.
So my question is this i guess, my f250 is so low on comp that i reckon itd run a new turbo no prob so long as i monitor egts, but this newer engine somebody obviously took the time to build the whole truck up and it seems a waste to undo thier work.

 

[79jasper]

I would look into fixing the new engine.

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[Thewespaul]

Take your two engines and make one good one. What year is the truck?

 

[nostrokes]

I'd look at fixing the new one and down the road building up the 6.9 to have fun with

 

[hoodshauler]

Fix the new engine


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[icanfixall]

On the new engine find the bad cylinder and fix it. Might be a rocker bolt backed off or a bent pushrod.Valves usually do not burn in these engines.

 

[madpogue]

The one bad cylinder, is it low compression, or is it pretty-much zero?

 

[Joseph Davis]

Time to play Inspector Clouseau. It a good sign that a the cylinder are carrying 400psi most likely bad valve or bent push rod. I would get busy. Good luck

 

[Macrobb]

I'd pull the valve cover first off. Check for bent pushrods etc.

If everything looks OK, might just run it for a bit, get it warm, see if it clears up - might just be a bit of carbon or something, if it's been sitting for a while.

 

[Ethan Smith]

So i pulled the valve covers, no luck there, no bent rod and everythings rocking like it should no pun intended. Theres a knock tgat comes and goes thats definetly from that cylinder, i did a leakdown and got air out of the oil filler hole , so dang. Im gonna play the denial card and swap injectors on it and pretend everythings ok
id rip it open and fix the real issue but i aint got a covered shop to work in Wish me luck cause i love my otger 6.9 but its gutless and needs a full on rebuild but i gotta rebuild the c6 for it first Hey on the bright side i got my work lined up for me!

 

[Ethan Smith]

Well heck!! I swapped out the number eiggt injector, its still making a lotta blow by but the turbo works great! Was getting a little over 5psi rolling down the freeway. It knocks when i put it under load when im coming off a dead stop, and i gotta turn the running lights on when i stop so the policeman thinks ive got working brake lights Other than that shes an oilburner for surrr!
anybody got any idea why its knocking only under load? I reckon the rings are shot

 

[madpogue]

That would require a policeman with very poor eyesight, to be unable to distinguish between the brightness of taillights and brake lights.

 

[Ethan Smith]

Well im from springfield, and when they hire onto the force here they just pass applications out at the bars. Found the melted wire causing it today though! Now i just gotta figure out where the knock is coming from

 

[Knuckledragger]

Knock can come from low oil level, but usually goes away at speed. Also from worn wrist pin or rod bearings. A rattling or slapping sound would be worn piston and /or shot rings. Knock is a bad sound if it does not clear up with speed.

 

[catbird7]

Check timing.