I have a 1996 Volvo 850. It runs well, but the engine is 20 years old and I am concerned it may not last forever. The coolant is brownish, so I am afraid there might be a cross-contamination between the crankcase and the coolant channels. Also, some parts for this vehicle are being discontinued.

How viable would it be to replace the engine of a vehicle like this? It is currently a 4-speed and ideally I would like to upgrade it to a 5-speed turbo. Can I replace the engine with a non-Volvo engine, or do I need to replace it with a closely compatible engine? Does anyone even make compatible engines? What if I get a wreck? For example, what if I find an old, wrecked Turbo 850; can I just salvage the engine out of that, or would that be a bad idea?

  • @Hobbes Sorry, I should have said 4-speed. I have corrected the question. May 8, 2017 at 12:58

3 Answers 3


I had a volvo 240 estate and I fitted a Nissan TD23 engine with turbo into it.

Points to watch:

  1. Make sure you get the engine lined up correctly,
  2. Once the bell housing adaptor is sorted, go to AP Lockheed or equivalent and get the strongest clutch to fit both engine and box,
  3. Make sure the engine mounts are fabricated well : strength and weld quality,
  4. Use a fuel pump rated for the fuel: if you change from petrol to diesel then the petrol pump may not deliver sufficient fuel at higher engine speeds,

The brownish coolant : may just be old - when was it last changed? As for sourcing an old turbo 850 engine - the turbo will probably need replacing (a mate had an 850 T5 that he bought VERY cheap, used for a year then the turbo failed and that killed it).


Research the platform and find out what if anything else shares the same block, head, trans etc... you'll then know what intakes and maybe turbo setups are available, and the existing wiring harnesses and Ecu setups that can be salvaged instead of painstakingly patched together and programmed from scratch. Usually if you're aiming for a significant performance upgrade plus a transmission and or drivetrain conversion your going to be modifying and reassembling the components your swapping in. So if you're desired motor shares the same block, and you will have to tear it down anyway, why not just buy the new head, and use your existing block with some aftermarket internals that will have zero miles on them and be far superior to any components included from the factory today, let alone those from more than 20 years ago.

  • But don't forget to recalculate your cost estimates periodically, it's sometimes far more practical to say; keep your engine block or whatever systems and swap them into another related older car than it is to work around the list of obstacles required to stay committed to using the car you just already have. It's not convenient if it cost as much as a similar car that's half the work. May 9, 2017 at 17:30

The easiest approach is to buy a similar engine: anything from the same model range should fit without having to fabricate engine mounts etc, as listed by Solar Mike. These engines are generally very reliable.
If you keep your old transmission, it has to be strong enough to take the torque of the new one, I don't know if you can combine the automatic with a T-5 engine for example.

  • The 850 T5 was sold as auto as well as manual - the suto was what my mate had...
    – Solar Mike
    May 9, 2017 at 19:00

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