Wife's car is a 2004 Volvo XC 70 with ~170K miles. Started running rough on Sunday and check engine light came on. DTC reader gave code P0302 (misfire cylinder 2). Had it towed to the shop that works on it thinking it was likely the plugs or coil issue. He called this morning and said he believes it likely needs a motor replacement due to compression readings.
Compression readings (cold) are #1 - 155 #2 - 105 #3 - 157 #4 - 120 #5 - 155
Based on the readings on Cylinder 2 and 4 and the fact that the car sat without being driven for about 2 months that we have likely damaged cylinders 2 and 4 because the oil coating was lost by just sitting there.
He said he could attempt a "band-aid" fix by pouring Marvel Mystery oil in the affected cylinders to see if we could restore the compression pressure but doubts this would be a long term fix.
He has sourced a replacement motor with 68K miles on it that he would install for a total of $4500 (including the labor).
He is an honest man who has never tried to screw us over on this car and I don't believe he is doing so now, just wondering if others have seen this issue and have tried the band-aid option with any luck?
Your thoughts and experiences are appreciated.

 

You need about 100 psi for a cylinder to fire.
Do not waste your time and $$ on Mystery oil. During the compression test it would have been a good idea to squirt a little engine oil in #2 and see what a wet compression resulted in.

If the compression stays the same with a wet test - you probably have a burnt valve. A valve job should cost a lot less than $4500.

 

what we talked about this afternoon was that a valve job might fix it, it would also mean I have an engine with a “new” top end and 180k on the bottom end when for about 1000 more I could have much newer engine all the way around and a car that should last another 10 years since my wife doesn’t drive much. Trying to decide between fixing it and keeping the car, or just getting rid of the car……

 

I would not count on your Volvo lasting 10 more years - Look around, how many 30 year old Volvos do you see on the road? Many times when a car this old needs an expensive repair my customers would move onto something else - for it's not economically reasonable to spend more than the car is worth for repairs. (see kbb report below) I would never sell a $5000 job on a $3000 car, and if the customer really wanted it done I would ask for most of the payment up front - for if anything happened during the repair process - I would end up with a car that was not worth what I had put in it. (made that mistake a couple of times) For a DIYer - it's a different story - but it's never wise to spend more on a car than it is worth. For instance - you spend $5000 putting an engine in your car ("sorry it took a little more than he thought") and drive away happy. On the way home some idiot runs a red light and hits your car. Your (or his if insured) insurance company will give you LESS than $5000 when they total it because of what the 20 year old xc is valued at.

Your old engine - when the head is off it would be a good idea to address the PCV system. They clog (especially if the car is only used for short trips) and cause mayor problems. The easiest time to do that is with the intake manifold/head out of the way. Has yours been replaced? It's a pretty expensive job by itself - As far as "180k on the bottom end" - Volvo does not have a problem with "the bottom end" (unless the oil pickup clogs due to lack of oil changes and not using synthetic oil). To verify the condition of your "bottom end" - when the oil pan is off cleaning the PCV oil passage in the block - remove and inspect the rod bearings - you will normally find them perfect.

So with your "new" engine - you would want to make sure the PCV system is perfect also - I have had many customers come in with less than 100,000 miles with serious PCV problems - several turbo cars where due to lack of oil changes (or simply "sort of" following the 7500 mile chart) have clogged oil pickups, causing turbos to die due to lack of lubrication. You have no history on the "used" engine - and in my career I've been presented with used engines to install - that were worse than what I was taking out!

Many other items to consider over the next 10 years. Radiators and other cooling system components have a finite life expectancy and will need replacement. Many xc transmissions, angle gears, driveshafts have expensive problems. Front suspension control arms, ball joints, struts, engine mounts, Heater fan motors, compressors, ABS control units, DIMs, ---- many things break on these cars with enough time. Sorry for your loss.