4.0t replace/update

[PaS6]

After some long searching I have finally become the owner of an 2018 S6. The car has a blown motor (stage 3 build) that I knew when I purchased it. My plan is to replace the engine with a used one and I would like recommendations as to what items or systems need attention on this motor when replacing? Timing Chains, fuel injectors, valve seals, ?? I’m new to this engine platform but not new to engine rebuilding.

[SteveKen]

After some long searching I have finally become the owner of an 2018 S6. The car has a blown motor (stage 3 build) that I knew when I purchased it. My plan is to replace the engine with a used one and I would like recommendations as to what items or systems need attention on this motor when replacing? Timing Chains, fuel injectors, valve seals, ?? I’m new to this engine platform but not new to engine rebuilding.

I did something similar last year by swapping a long block.

I kept my chains but replaced the tensioners and guides.

Also remove the intakes and inspect the valves for carbon and have them cleaned if needed.

Also have the injectors serviced since it's really hard to do when the engine is installed.

Water Pump, turbo oil screens and PCV are easy to do and not too expensive as preventive maintenance while the engine is out.

[Burkeomatic]

All good advice. I'd definitely make sure to get the valves cleaned and the injectors serviced before reassembly.

Oh, do you know why the engine blew up? I'd figure out the cause of that too so you don't have a repeat.

[PaS6]

Thanks for the insight and recommendations. Most of your suggestions are things that had considered. Was there a particular reason you changed guides? Are they noted for failure? As to the valve carbon, is walnut blasting sufficient or is head removal and disassembling recommended?

[PaS6]

Valve cleaning and injector cleaning/testing in the plan. As to the blow up, I haven’t disassembled anything yet but the bore scope inspection was ugly. Looks to be a 1/4” by 1” hole at the top of the bore into the water jacket . I suspect lean, piston, ring failure and then continued operation under boost until the cylinder wall gave way?? One indication why the injection cleaning and testing is in the plan also. Do you guys have any injection shops that you have used and would recommend?

[Burkeomatic]

Yep, just walnut blast it, no need to disassemble.

Maybe run WMI or Port injection to keep em clean.

[Botbasher]

After some long searching I have finally become the owner of an 2018 S6. The car has a blown motor (stage 3 build) that I knew when I purchased it. My plan is to replace the engine with a used one and I would like recommendations as to what items or systems need attention on this motor when replacing? Timing Chains, fuel injectors, valve seals, ?? I’m new to this engine platform but not new to engine rebuilding.

Why wouldn't you refresh ALL the chains and guides while you have the motor out? Is their proof that it's been done on the donor recently?

I make it a policy to replace RMS's and any unaccessible parts (chains, seals, etc...) that are buried while I have them out. I can't imagine swapping a motor, not refreshing the chains and 6mo later having a death rattle or leaky seal/o-ring requiring the motor to come out again.

With the motor out, it's not really all that much work and after seeing the condition of several low and high mileage V6 motors guides, I'd never pass on the chance on anything with rear chains. I just pulled my 4.0t pan, and even with fully documented dealer maintenance @ 130k there were guide chips in it, so I'm already planning a 150k refresh!

To each their own, but I buy once, cry once and hate doing a job twice!

Cheers,

KS

[markc34]

Yep, just walnut blast it, no need to disassemble.

Maybe run WMI or Port injection to keep em clean.

(Sorry Quick hijack here) - Just bought a C7.5 'stage 4+' with port injection, but not 'activated/tuned', 60k miles. Would you think I'd need to have it walnut blasted before finishing that portion of the build? I'm in SA as well.

[Botbasher]

(Sorry Quick hijack here) - Just bought a C7.5 'stage 4+' with port injection, but not 'activated/tuned', 60k miles. Would you think I'd need to have it walnut blasted before finishing that portion of the build? I'm in SA as well.

WMI can reduce the build up depending on it's composition. It might simply stop the new build-up, meaning a blasting would be needed.

There's no way to tell. I have had 2.0s on WMI self clean and not. No telling!

Cheers,

KS

[Audibellybutton]

with port, if it was running it then no you dont need to walnut blast

[markc34]

with port, if it was running it then no you dont need to walnut blast

60k miles no PI, now has PI. Maybe I’ll start a thread. As I know there are some guys here that may have added PI without cleaning first. But I know it’s a case by case basis, probably should wait until I need some other major service and blast it then and start the PI…

[Audibellybutton]

Nobody is walnut blasting these. That doesnt mean they dont get carbon build up, but it is not as big of an issue as previous engines. I am running water/methanol for the last 30k miles, I did not do any cleaning prior and my valves are nearly spotless the last time I had the car apart. Port is not the same as WMI, but assuming you are running ethanol, your valves should be pretty clean after term use

[markc34]

Thanks for the input!