Volvo S60 t5 low compression but good performance

**Bigsi15** · Monday 28th December 2015, 14:13

Hi guys
Okay so the story, my 2002 Volvo S 60 T5 has been burning a lot of oil for a number of years now, gets through probably a litre in 4 to 500 miles. Smokes after running down a long hill but also smokes sometimes when you put your foot down hard and I've been at a loss as to why this oil is going. Pcv is clear, Had the turbo rebuild (but I question whether it was done properly) about a year and half ago thinking it might be that but now I think it might also be the valvestem seals as the engine seems to be full of gunk and probably wasn't well looked after and its previous life. Engine has only done 95,000 miles.

Anyway I came to compression test it today to see how things looked inside and the results were Not good.
My technique may not be the best but I remove the fuel pump relay and remove the coil packs from the wires and took out the plugs, then turn the engine over five times per cylinder. First time round I forgot to keep the throttle wide open however didn't seem to make much difference when I did

The results I got basically were cylinder one abd 5 were extremely low building up to a maximum of about 90, the other three werent are bad at about 150. Putting some oil in the low cylinders picked them up by about 20 but still not much better And doing it with throttle wide-open made no difference. Either way there is A big range in the cylinders

The only thing that makes me wonder is that the car will start hot or cold within 3 to 5 cranks which is better than my 850 starts with compression of 150 all round, it Also pulls like a train and 0-60 time seems somewhere within the target value of about seven seconds. Is there anything other than piston rings that can cause low compression but halfway decent performance? I thought bad compression would lead to struggling to start and lose a lot of power?

Thanks very much in advance
Si

**Orca2** · Monday 28th December 2015, 14:40

If the engine is only on 95 k and compression is really low I would suspect vaalves rather than rings. Especially if bunging oil in there doesn't significantly improve compression figures. Unless it has been seriously overheated or oil starved a 95 k engine shouldn't have significant bore wear.
I would take the head off before doing anything else , and of course it lets you assess the bores at the same time

**Bigsi15** · Monday 28th December 2015, 17:25

Thanks orca2 that is what I was hoping too. Guess it's a bit of a gamble on how far so I strip and try to repair, unless it's just a burnt valve it's not going to be cost effective to rebuild. Was thinking of doing the valve stem seals anyway so guess could go one further and remove the head. Tbh the biggest worry is the vvt setup on rebuild ATM...

**Orca2** · Monday 28th December 2015, 18:04

I wouldn't worry too much , you will get loads of info on here if you get stuck the technical expertise is second to none on this forum. Whatever you tackle someone has always been there before and will know what to do. ( usually not me I hasten to add )