This is more of an opinion thing.

I have a car that I enjoy driving, don't really want to take it apart and not have it available (also use it for hauling "stuff" when I buy "stuff") for an indeterminate length of time. It is (mostly) stock but runs well.

However, with 200k on the car, and original head etc., I have the bug to install several upgrade parts that I have for the car (head, turbo, IP, timing chain and tensioner parts, oil pump and chain, windage tray, injectors, cam, mounts, etc., etc.) and gain a freshened engiine and likely about 50hp.

Tearing into the existing engine means that I might or might not finish it, ... ever?

So, I also have a nice OM603.960 on a stand, 247,000miles and perfect cylinder walls, that I could build. The car would of course no longer have the original block, and having the engine out gives me more time to never complete the process, which means that I'll likely also be buying seals, bearings, possibly rings and/or pistons, ... who knows what else escalating the cost for little or no reason and pushing completion further into oblivion. Then of course I need to do the swap, ... which could also delay completion.

So presuming that I will actually complete this project, which would you prefer: Pull the existing engine and upgrade it so that you have an original block still in the car (knowing that the '87 300TD is a fairly limited-production car, especially rust-free ones), ... or rebuild/upgrade the spare engine and stuff it in when ready?

Also for consideration is I could sell the spare engine and transmission to finance some/all of the parts in the upgrade, faster than selling the pulled engine when the project is finished (no longer an unlimited budget guy).

Oh, forgot to mention that the spare is also still mated to the spare transmission, ... might as well freshen that too in case there's any money left.

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Gone to the dark side

- Jeff