XC90 V8 2008 Noises at speed & Transmission issues

If the prop shaft spins in park, then the prop shaft isn't doing anything useful anyway. It's 6 x allen key bolts at each end at the CVs, plus two tiny bolts holding the centre bearing carrier. If you undo the centre exhaust bracket and the 3 other rubber exhaust donuts (assuming single exhaust) then the exhaust dangles down on the ground and you have enough access to the prop shaft. There should be just enough wiggle room to pry the shaft out - it'll be tight but it'll come out.

I have two "known good" valve bodies - my car has had two transmission builds because of other issues, and we replaced the valve bodies "whilst we were in there". You're welcome to have one to try if you pay freight from Sydney. I only kept them because sometimes I come across complete cars cheap with transmission shift issues…but I don't need any more cars now.

If the car is more than 10 years old and hasn't been resealed yet, the timing cover will be leaking. Nothing dripping on the garage floor seems to be my pressure point - my sister's V8 has the same kms as yours, and the previous owner (personal friend) paid for the engine to be removed 50,000km ago for the timing cover to be replaced…and it's also leaking now. grrrr…. I resealed mine 6 years ago and it's just starting to seep again. Nothing dripping yet, just weeping.

Power steering pump leaks at about your kms - the oil leaks into the V and drips out between the transmission and the engine (centre left of car). Most folks mistake it for the rear oil seal leaking but that doesn't ever seem to happen.

FCP Euro do a timing cover kit including valve cover gaskets and everything you need to do the job properly

https://www.fcpeuro.com/products/volvo-timing-cover-seal-kit

https://www.fcpeuro.com/blog/volvo-v8-timing-cover-seal-kit-really-quick-product-review

There's also a cheap as chips O-ring kit for the power steering pump which I'd do whilst you had the top of the engine apart.

https://www.fcpeuro.com/products/volvo-power-steering-pump-o-ring-kit-36000748s

You may find the wrong fluid in the system - they really don't like general ATF. Just draining and refilling with the recommended fluid might be what you need. There's also a filter in the reservoir which might be clogged - you need a new reservoir if this is the case.

No worries. I've been looking after 3 of the V8s in our family and friends. Mine has just over 450,000km and still going strong. I've now had the torque converters replaced in all 3 to cure the transmission shudder - mine had been done just before I bought it but unfortunately some numbnuts left the torque converter bolts finger tight which resulted in the recent transmission rebuild. I have 2 used but still perfectly working valve bodies - in all likelihood I'll never use either so I'd rather they get used by somebody. Just PM me your address and I'll get one off to you.

I use FCP euro for parts as preference. Never had a problem with them. There's supposedly a postage discount for Ozvolvo members but I've never used it. I just keep a shopping list going (with 3 x V8s, a C30, S40 and V50 amongst the friends and family we combine postage for group buys)

When you go to do the timing cover seal - nothing complicated, just tight and methodical. Takes a lot of patience.

Of particular note: the ignition coils are earthed on several of the cam cover bolts. The eyelets will probably twist off when you undo the nuts. These days if they're turning with the nuts I just cut the black wires close to the eyelets and install new terminals when it goes back together. I bought my XC90 dirt cheap because the mechanics had broken the rear earth wires when they resealed the cam covers (with silicone only…grrrr…) and the car was only running on 5 cylinders.

When you get to the lower inlet manifold, be very careful with the brittle black plastic fuel pressure sensor housing leading in to the fuel rail. The housing and sensor live just under the throttle plate housing. It's incredibly easy to break off the plastic hose into the housing - and it's part of the fuel rail, NLA and incredibly expensive to replace. I had to fabricate one from scratch because once again the previous "mechanics" had only left 3-4 mm to clamp the rubber hose to (as well as butchering the fuel inlet quick connects). I made one in stainless steel but I don't have any fabrication facilities any more.

Volvo steering fluid is "Pentosin" - locally available Penrite LDAS has been fine and has corrected all power steering fluid issues.

Common knock points will be sway bar links and upper strut mounts. Strut mounts get a very hard time and one friend with a lead foot killed his really quickly over speedhumps. I'd look there first. Have a look at how much the strut centre nuts move when you bounce the front of the car. Should be only a few mm.

You may even find that the strut to bearing hub bolts are not tight enough (1:12 in the video above)

Lamar I guess my last question, is there anything else I should be proactive on with this car ? I have Vida ( owned a couple S60 T5 in the past ) so I don't mind properly getting this car back to stage 0 as best as possible . I am feeling a bump in the steering , and am unsure if it's coming from the rack or something like the sway bar or links are bad.

It's worth checking over the engine and subframe mounts, squishy or cracked mounts can introduce all sorts of vibrations and steering vagueness.

Tie rods/rod ends and the rack are worth checking not least because by the time you're under there looking at engine and subframe, it'll take no time at all to wiggle everything around.

If the source of a leak is uncertain best thing to do is hit everything with parts cleaner or degreaser, get it all spotless, then drive around until the leak shows again, if still not obvious usually you can differentiate atf from engine oil by it's feel on your fingertips, the smell, or dab it onto a tissue and check if it's red.

Volvo recommend 5W30 with 15000km service intervals. With 200km on it, we run W40 oil as well. Mine has 450,000km so I'm buying 5W40 or 5W50 in mine, (Penrite HPR5 or HPR10, whatever is on special) but always 10,000 intervals. The 5W30 special spec oil is an attempt to meet the ULEV pollution goals, I'm more interested in long life. Absolutely no difference in fuel consumption. Always use 98 fuel though.They seem to run "hot" under bonnet, just slightly under half on the gauge. I've towed an S40 up from Wollongong in 45 degrees with 5 people and A/C on full…never got hot. Only seen one get warm when the fan wasn't plugged in properly. Relax, and trust the product.

Is the crossmember still installed for the centre bearing ? It supports the thin heat shields and they will bang around without the centre bearing support installed. Is the output from the angle gear still OK ? Sometimes the output shaft will destroy the output bearing and the shaft rattles around without the prop shaft there to contain it. Lastly, without the resistance provided by the prop shaft perhaps the stripped splines on the angle gear collar are still making contact occasionally. Mine made a clicking noise for 10,000km or so after they stripped last time.

Lamar,

I'll be driving through Brisbane in just over a week. Can I drop the transmission valve body to your place on the way through ?

If I ever get around to repairing my angle drive, I think I'll weld the coupler sleeve to the angle drive. You need to make up a locating plug to make sure it's centred, but apart from a new angle drive I think it's probably the best option.

Polestar were the in-house tuning company for Volvo at the time. Our C30 manual has the polestar tune, which raises power of the 2.5 from 230hp to 250 hp. On the S40/C30 cars it's just a software flash - I'm pretty sure it just raises the turbo boost and remaps the accelerator pedal. Polestar tunes were (are still) available for most of the Volvo models. I don't know what the tune would do for the V8, but the torque output already stresses the rest of the driveline. I wouldn't want any more power.

Polestar did the engine modifications to the V8 to run in the Australian Supercars.

Polestar are still linked to Volvo technically - the Polestar 2 shares the platform with the XC40 I believe (which is why it still has a transmission tunnel in the cabin…)

Hi Lamar,

That looks pretty typical. If you bought a new angle gear collar, you'd find that it's quite a sloppy fit on the angle gear splines. Hardly any interlocking means the new sleeve will strip out "prematurely" - within 10m when I did mine last time. I had an angle collar with perfect splines, but the gear had several missing teeth and it made a hell of a clicking driving along.

I've bought 2 replacement angle gears now, from reputable wreckers and "low mileage" cars…all the same junk.

I think you've got only 2 choices.

Spend a fortune and a lot of machine time, and weld the collar to the angle drive permanently. Means the angle gear can't easily be rebuilt again, but I figure it's basically junk now anyway. Then you've got to overhaul your prop shaft as well, which isn't technically rebuildable but can be…but expensive as well

Or, just leave the prop shaft out, put it together again as it was (grind out the angle gear stripped splines if you want to have no clicking or rattle in the future) and just use it as FWD.

I've tried the expensive way, but couldn't find a good enough angle gear. My sister's and my friend's V8s have functional AWD (and it works great when it works) but theirs have way less kms. Mine just isn't worth throwing that kind of money at, unless I can find a salvage wrecked XC90 with no kms for cheap. I looked into whether the diesel angle gear may have had a gentler life (because I understand the D5 only kicks in the AWD when it slips, the V8 has 80kW going to the rear every standing start…but I could be wrong there)

nh2868 - Interested in your opinion: What causes these things to go bad?

I've had an angle gear strip a tooth, but have usually only come across stripped splines in the angle gear side of the coupling sleeve. I think a coupling made of swiss cheese together with excessive clearance on the angle drive splines leaves very little bearing surface under load. The other 2 x V8s I play with have noticeable wear on their splines as well, but don't chew out the new sleeves I've installed like mine does. I had thought that the pressure sensor in my Haldex could be providing too much grip on take-off but I've changed the pressure sensor and serviced the Haldex again. The pressure sensor was uprated from 4 something or others to 8 (all you can buy now).

If you partially lock up the Haldex (ie "Instant Traction") and take off on full lock often in the city then I think the torque applied to a weakened /worn / sloppy spline is what kills them. The transmission splines are a much closer fit and never seem to wear at all.

If I have the angle drive out at some time I'll look at welding it as an experiment (since I have a good Haldex and prop shaft at quite some expense) but I clocked over 456789km last week and I'm not pulling it apart just for the fun of it.