So I bought this 2006 XC90 with 106K on it from a guy on Craigslist a couple weeks ago. I paid less than half what it was worth on KBB.com, bought it from a guy in the richest suburb of KC who was the second owner and bought it Certified with 40K miles on it, it ran and drove fine even though the CEL was on, so I thought, how ****ed could it really be with only 106K miles, and figured he just didn't want it any more and was selling it cheap, so I got an incredible deal, right? Well turns out, of course, it was too good to be true. I took it to a shop to be looked over a couple days after I bought it and they ultimately found the CEL was a misfire code from low compression in Cyl 4, and it has around 85-90 PSI. There was only a +3 PSI difference when oil was added to the cylinder, so I am assuming the rings are fine and its a valve issue, but didn't do a leak down test to confirm (my next step).

Anyways, my question is, one of the many shops I called said they recommend replacing the whole engine on a motor over 100K miles, because with a new head, it will increase the PSI in the cylinder and will lead to pushing oil past the piston rings and make it burn oil. I talked to a friend of mine that is a Lexus mechanic for a living and has worked on domestics his whole life, and he had never heard that before, but when I googled it I found it to be a fairly common thing, but usually only in higher mileage engines, ie. 150K+. None of the other shops I have talked to even mentioned it.

I just wanted to ask here if anyone had any insight on the 2.5T specifically, and knows if rebuilding and reinstalling the cylinder head on this specific engine with 107K miles on it would give me more trouble than its worth, and I should just go with a replacement motor instead? I think the rebuilt head will be a bit cheaper, and I would like to keep my engine as it has relatively low miles and I already did around $800 worth of maintenance to the PCV, oil separator, etc. because the shop I went to f*cked me around on diagnosing the CEL the first time I brought it to them (long story, don't get me started lol). Any input is appreciated. Thanks in advance!

 

That makes no sense. I've done heads on plenty of high mileage engines.

 

Thanks for the quick reply ES6T. I kind of thought the same thing. While the seals will be new and marginally better than what is on it now, given that the head is already currently sealed and not leaking, I can't imagine the PSI would be *that* much greater than it is now. Plus I don't really see 106K as "high miles", but then again, the last car I sold was a Lincoln Town Car that turned over 271K the day I sold it . My mechanic friend I consulted with figured it was probably just a CYA move on the shop's part so I didn't bring it back to them complaining about it burning oil afterwards if it did happen, or they weren't confident that they could install the new head without issues afterwards or something. Really hoping I can get past these intial issues with this and drive it as long as I did my old Town Car because I really love the XC90.

 

So what is the compression on the rest of the cylinders? Wouldn't good compression there be a pretty strong indication of the ring condition and the likelihood of the proposed issue?

 

Not sure about the other cylinders but I assume they are fine. Honestly even with the low compression in 4 the car runs fine, which is why I bought it, but you can sometimes feel a little miss if you're sitting idling and wait for it. But there's no hesitation, bucking, jerking, etc. while driving so I assume the rest of the motor is fine. I will know more when I decide on a shop to do the work, I was just curious about the new head on an old motor thing and if it was a wives tale or not. I could see not spending the money to redo the head on a car with 180K on it but I think at 107K, mine will be fine.

 

I have V50 t5 awd with 165k and just lost compression in 3rd cylinder (165,165, 35, 156,175). Cylinder walls and look fine with scope. How much is a valve job runs about these days and do you know anybody in NY/NJ area?

 

I have seen many Volvo's with a loss of compression and it is almost always a burned valve, so replacing the valve and if your head is cleaned up, you should not need a complete valve job. As long as compression is good in all other cylinders, which it is, the one that is 156 may just need to be lapped for better seal. If you were not seeing any oil consumption or smoke when you first start, you don't need to change valve seals. Depends on if you are planning to keep vehicle for another 100K. As to cost, it is the labor that kills you, parts not so much. To prevent burned valves, always use higher octane, at least 89 and through in Lucas injector cleaner once every few months.

 

Started working on taking the head off in my garage. Junkers offered 250USD for my car so if it does not work out I have little to lose. I can get rebuilt head for 600USD. Is it worth it? Car is otherwise in great shape.