Relative noobee here. I’ve been searching to see if I can swap an s70 2000 na automatic transmission engine into a 1997 850 na manual wagon with no luck. Is it possible and is it an easy swap. The 850 needs rear main seal and has 305,000km on it were as the s70 only has 122,000km on it. Any info greatly appreciated. Thanks.

 

which S70 engine? If possible when doing a swap, you'd want to keep the original ECU and wire harness and I'm not sure if the S70s ever came with an NA engine. If you try to drop in a turbo engine then you'd need the harness and ECU from the donor and that's where things can get interesting considering (read - not worth the effort). Also what engine oil have you been using? You can try switching to a "high mileage" traditional oil which has seal softeners which may help the rear main seal issue.

 

Thanks for the reply. I’ve tried the high mileage oil with no luck! I’m not sure yet which engine is in the s70, I’ll find out tomorrow. It’s a freebee, which is why I was interested. I’d be keeping the 850 a manual transmission.

 

the big change between 1999 and 2000 was that was right about when Volvo introduced their VVT engines which will make it hard to swap in without going to the donor's ECU. even if you pulled in that harness there will be issues like spoofing the PNP switch (google for solutions when doing a manual conversion) and then there may be compatibility issues to other computers. I don't think 300Km is all that high assuming the engine was properly serviced before the rear seal gave out. you may be better off just dropping the transmission and replacing the seal. (unless its got compression issues or consumes oil).

 

The 2000 - uses a drive by wire electronic throttle, with a ECU that controls spark and fuel injection with coil on plug ignition using an early CANBUS system. The 1997 has a throttle cable, traditional cap wires and rotor -

The 2000 will not be an easy swap. The block is going to be very similar so your transmission will bolt up. If all the mounting points are there you could transfer over your old fuel injection and ignition system. But a smarter mind than mine is needed to know if that is possible between a 97 and a 2000. Turbo was mentioned - there are non turbos in 2000. (I trust both your 97 and the 2000 are NA).

The 5244 engine used in the 2000 does have variable cam timing on the exhaust - Don't expect to get the to work.

If your choice is put a rear seal/clutch in your 97, or attempt to swap a 2000 engine into your 1997 -

I would choose - find a new car. A rear seal/clutch job will cost more (retail) than your 1997 is worth. Sorry.

If you can do the labor your self - and are really cash strapped - it might be your only choice to fix the 1997 - but I'm certain on a 27 year old car - there are many other things that need to be fixed.

 

Thank you all for the info and advice. The compression is 205,205,195,200,200 which is within spec. The vehicle has been well maintained. On the front end the only thing that hasn’t been changed are subframe bushings, rear shocks and springs are relatively new as well. I’m leaning toward doing the seal and clutch(original clutch still). Any thoughts on how that number 3 cylinder will hod up? Is it likely to deteriorate quickly?

 

Add a squirt of oil in each cylinder and do a wet compression test - if you are concerned about valves leaking

 

your compression readings are excellent so there's no reason for concern with that suddenly changing. I'd be concerned if you had something like a 10% difference or two adjacent pistons with lower compression. I think the plan to do the clutch and rear seal is the way to go. For the 850s the big maintenance items are the timing belt (which is when you can do a front main seal or a water pump and the serpentine idlers etc) and keeping up with the PCV system (replacing hoses and accessing the EGR stuff and cleaning out the block's ports requires lifting the intake manifold). Keep up with those and the regular oil changes using a high mileage formula (I always used OEM Mann filters which have a check valve in them ) and you should easily get another 50-75K miles (note we retired our 850T at 250K miles - due to rust and inheriting a 12 year newer car... which is what I'd expect for a properly maintained 850.

 

Mt6127, thanks. That is what I’ve been leaning to. I’m also thinking now would be the time to do the sub frame bushings. I’ve been looking at it as “buying miles”. With the cost of replacing the 850 with something a bit newer I feel it is worthwhile doing. Thanks for the confirmation on compression. I’ll be doing the seal and clutch.