XC90 V8 - mysterious engine oil (?) leak

leoxdeng · Jul 31, 2022

I hope someone could help me diagnose this oil/fluid leak on my XC90 V8, which has 72K miles. When I got the car a couple of months ago it was leaking engine oil from valve cover quite badly (entire engine oil pan was coated/dripping with oil) - and the alternator was damaged causing 'power system service urgent' warning light on.

3 weeks ago I took it to a reputable indy shop which had worked on this model before - they did a lot of stuff on the car - VCG reseal, timing cover reseal, new alternator, new belt and tensioner/pulleys, new FPS and PCV plus hoses. The only thing they didn't do/replace under the valve cover is the PS pump which is dry and good. They cleaned/dried everything including the splash guard.

I drove the car back from the shop for 50 miles - took off the splash guard and took a very good look - no leak whatsoever.

I then relaxed and drove the car for another 150~200 miles (only weekend trips) - during this timeframe I did all the drivetrain fluid changes myself including the infamous angle gear fluid.

A few days ago I noticed some drip leak collecting on two places - the light brown colour looks to me more like engine oil:

where the gear box is bolted to the angle gear (?? or perhaps it's where gear box is bolted to the engine?? - see pics)
where the engine oil pan is bolted to the engine block near the bottom of timing cover

Note that:

the alternator /belt area are all dry - so don't think this is from the the old valve cover leak
I've not noticed any change in engine oil level

Questions:

Could anyone take a good guess what may be causing the leak? The mysterious thing is - the leak appears on both sides of the engine block near the bottom
assume the lea is not from the valve cover - and the leak is really just a few drops after being driven for 100 miles or so - am I OK to continue to monitor it plus the engine oil level? I check engine oil level every time I set off /come back, but have not noticed any change in oil level.

Thanks in advance
Namo Amituofo

leoxdeng · Aug 1, 2022

Anyone has any ideas on this oil leak? I'm hoping it's not the real main seal... OR could it be front crank shaft seal??

Thanks in advance!

ggleavitt · Aug 1, 2022

First photo from Volvo stock, second from @DaPineappleDude.
Can also see these links for visual reference- 06 V8 XC90 Ocean Race Refresh_Nov20, 08 V8 XC90 PSP/WP/Hoses-0719

My guess is that you have another unresolved seep, possible at the timing cover. Maybe get photos of the motor front, top front/back, and bottom of the timing cover area. See the timing cover photo for areas of typical leaks (exhaust side more than intake), that's maybe what you want to focus on right now (my Ocean Race has the cover leak in the same spots as the photo, I have all parts to rework just need time to do it). It looks like engine oil to me in your photos but old PS fluid gets brown as well. I would visually "walk" the engine in its entirety and note anything and everything that's still seeping.

leoxdeng · Aug 1, 2022

Thank you v much. I’m taking the kids to another trip this weekend - after that I’ll find time to take a good look at the car. I usually drive it up on the ramps to work under it - but for this I’ll put it on jackstands and take off the front wheel to get a better view of the timing area.

cbv1 · Aug 4, 2022

get a paper sheet,a white one...put some oil from the dipstick in it,then put some from the leak and compare them..if they match then you know for sure is oil leaking...also compare them to the p/s fluid....you could have a rear main seal leaking or the p/s pump...good luck

qaz996 · Aug 4, 2022

The V8 has an upper and lower oil pan that are prone to leaking. I would suspect that.

Unfortunately, it's a pretty labor intensive job because you must hang the engine, remove the front subframe and LH (nearest the front of the car) exhaust manifold to drop the oil pans. It's been a while since I wrenched for a Volvo dealership, but I'm thinking about 6 hours labor.

But cbv1 is correct about verifying what fluid that is leaking first and his suggested method for that is valid.

vista88 · Aug 4, 2022

The power steering pump can leak from the fittings, fill the valley and leak out the back same as your pictures shows.

It should be green synthetic fluid but even that can turn brown from age.
Have you or someone else used red ATF in it as well?
Is the fluid level in the reservoir dropping?

leoxdeng · Aug 4, 2022

Thank you guys for chiming in. There is no noticeable drop in PS fluid level in the reservoir - I actually changed the fluid very recently (turkey baster method, sucked out all fluid in reservoir then filled with fresh Volvo PS fluid - did this 3 times with 1.5 ltre fresh fluid) and the colour is a pale green. I'm pretty sure it's engine oil - as last month the indy shop I took it to for VCG reseal job took everything apart and cleaned up and showed me pics - including the timing cover. I asked them to put in a new alternator at the same time (the car had 'power system service urgent' warning light when I just bought it) - I also asked them to check PS pump and if it had any leak just put in a new PS pump (not cheap I know) - the guys showed me pics showing the pump was bone dry.

It is possible the the PS pump has since developed a small leak though - you never know - I have the reseal kit so next time the valve cover needs to be opened up I'll take the opportunity to reseal the PS pump regardless of if it's leaking.

When I looked under the car the other day I could 'touch wet' a blob of what I make as black silicon sealant just sticking out of the timing cover - I believe that's the correct location but would like to jack up the car to remove a front wheel to be absolutely sure. Most likely culprit is the timing cover reseal job done poorly - having said that these guys at the indy shop are very good with their work - they cleaned up the whole thing so new leak is so obvious.

If it turns out to be something more cynical - I'll ask them if OK to continue to drive the car like this (it's really just a few drops into the splash guard every 50~100 miles or so) and top up engine oil as and when needed? Provided the leak is below the alternator as I paid £££ for the new alternator.

When the leak gets heavier - as when I can notice drop in engine oil level in any obvious way - I'll surely have it taken care of. This is probably one of the models I don't want to do any engine work myself - I don't have a garage or even a covered driveway and won't attempt anything concerning engine at the mercy of British weather. I may ask the shop next time if they can just drop the engine (don't mind paying a few extra hours labour) and replace the RMS and Front Crackshaft Seal at the same time.

leoxdeng · Aug 4, 2022

Well I jacked up the car and removed a front wheel to take a look earlier - frustratingly I still can't pin point the leak, but I'm now 100% sure it's engine oil. My PS fluid from reservoir appears transparent on white tissue, and the drip on the bottom of car matches the colour 100% with engine oil dipstick.

What I discovered is on the engine front side, the most leak accumulates under the AC compressor. So I assume the leak is somewhere above the compressor. The crank pulley and alternator and all other pulleys and aux belt are all dry.

And the leak also continues to come through the weep hole at back of the engine where it is bolted to gearbox.

Any clue /guess what may be the culprit?

stayfunny · Aug 4, 2022

unfortunately, the V8 is notorious and known for oil seeping so for a 2007, it is normal (kind of). I won't worry too much especially if you just got the VCG done assuming they did a good job. Just monitor how much oil you need to top off.
What I do regularly is to give it a good clean with brake cleaner and electronic cleaner for the Alternator. that way you keep the moose happy and clean.
What is the mileage ?
Cheers

cbv1 · Aug 5, 2022

looks like the upper oil pan may be your issue....the gasket material dries up and oil starts seeping all around...

leoxdeng · Aug 5, 2022

Thank you guys - it’s got just 72K miles on it - that’s why I was willing to fork out a chunk of money to do VCG and alternator jobs to look after it

.

I’ll look up on Vida where the upper oil pan is - heck it has two oil pans? Upper and lower ones?

It gets driven about 2-3000 miles per year only mostly weekend family trips. But if the upper oil pan leak can make way near alternator I’d still like to fix it. There’s nothing more that I dread to see than the ‘power system’ warning!

leoxdeng · Aug 5, 2022

Is the 'pan' in the middle that form the lower half of RMS the 'upper oil pan'? (Ignore the red circle it's an image I found on another post concerning the drainage hole which is not relevant to this problem I have).

It does not look something can be easily resealed without dropping the engine!

leoxdeng · Aug 5, 2022

I may be the only one driving my car with lots of ‘just in case’ in the boot

2 liters of ready to use coolant
1/2 litre of PS fluid
4 liters of engine oil
funnels
trickle charger

And all these in a full size spare tyre

ggleavitt · Aug 5, 2022

You likely are...

qaz996 · Aug 6, 2022

I've circled the upper and lower oil pans in your picture. The part I point at with the yellow arrow is the intermediate section which is NOT associated with the oil pans.

From my perspective as someone who has done several of these, it's not that difficult of a job. In fact, us Volvo techs used to consider it a "gravy" job. I described in my previous post what is involved to reseal the oil pans.

cbv1 · Aug 6, 2022

i believe there is an o ring in there also..ill have to check

leoxdeng · Aug 6, 2022

thank you - hmm gravy job!! I don’t have means to hang engine so will ask the shop to examine and get it done. Would it make sense to change RMS and front crank shaft seal at the same time?

qaz996 · Aug 7, 2022

leoxdeng said:
thank you - hmm gravy job!! I don’t have means to hang engine so will ask the shop to examine and get it done. Would it make sense to change RMS and front crank shaft seal at the same time?

The front crank seal and rear main seal are not really overlapping labor with the upper and lower oil pan reseals. That said, with the engine hanging and the front exhaust manifold removed, it isn't too much extra work to pull the transmission and replace the rear main seal.

Normal protocol when resealing the engine front cover is to replace the front crank seal as part of the job, so that should already be new from when the shop did the timing cover.

ggleavitt · Aug 8, 2022

Pan splits make perfect sense, just another material to get heat cycled and compromised over time. I've seen a few photos where the leak seems to be coming from around the oil cooler area. Pan split might be a contributor on the Ocean Race leaks but I won't know until I get to open things up to do the timing cover (with crank seal, it's pressed on the cover itself).

I just watch mine and make sure oil level is fine and there are no stains on my driveway (periodic pan cleaning). Bothers me but apparently not enough to make the time to fix it.

edit- clarify seal.

XC90 V8 - mysterious engine oil (?) leak

leoxdeng

leoxdeng

ggleavitt

leoxdeng

cbv1

qaz996

vista88

leoxdeng

leoxdeng

stayfunny

cbv1

leoxdeng

leoxdeng

leoxdeng

ggleavitt

qaz996

cbv1

leoxdeng

qaz996

ggleavitt

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