I have been trying to diagnose a mystery oil leak that has been accounting for about a quart of oil in my 1998 V70 XC AWD 2.4 turbo, having been told my a mechanic that oil was finding its way into my turbo, thereby reducing the amount in the sump. NO oil is evident under the car or in the exhaust. I don't think the problem is to do with the turbo itself, but is due to the PCV system being blocked. The oil trap was changed only 16 months ago, so it's unlikely that is already fouled again, although it is possible that the shop that changed it didn't change all the other hoses in the pcv system. There is some oil vapor blowby evident when I withdraw the dipstick half way, and there is evidence that some oil has been finding its way past the filler cap seal and down under the plastic cover on top of the spark plug leads. I have now been able to check the compression on my car; cylinders 1,2,4 and 5 are all pretty consistent around 170, which is within the normal range. However, cylinder 3 was only showing +/- 55psi, so I put a small amount of 10-30 oil in the cylinder and took another reading, which was only +/- 10psi higher, and which suggests, I think, that there is a sticking valve or a poor valve seat in that cylinder. I believe that had the pressure gone to normal when I added the oil to the cylinder, it would have implied a defective piston ring rather than a valve issue. When accessing the spark plugs, I loosened the metal pipe between the turbo and air cleaner, and noticed oil at the end that connects to the turbo, possibly being blown there by the turbo. I'm thinking that I have a partially blocked PCV system, which is mostly responsible for the oil use. Does that seem correct? Can anyone confirm that it seems that my piston rings are OK but that I have a valve issue in cylinder #3? What is most likely to be the problem with the valve(s) on cylinder #3? Is accessing the valves as a bad as it looks from the valve cover on a V70? Lastly, if I don't appear to be burning oil, doesn't it follow that my valve issue isn't part of my oil loss?

This is a lot of questions I know, but any help is appreciated.

 

It's likely to have a burned valve, and a car that age is in need of valve seals and can consume more oil than normal through the turbo. A balloon or latex glove over the dip stick tube will tell you the extent of blow-by.
All this is said not knowing the mileage on the car or how quickly the oil is disappearing.
Adding compressed air to that cylinder at TDC compression or BDC power will tell you which side is leaking, but you have to pull the head to find out for sure.
When you have the head off you'll have time to check the crank case vent system.
Add spacing, the post is hard to read.
Ed

 

SEAFOAM the engine and try again

 

This is off the subject.
I just joined today.
I can't figure out how to start a new thread.
Can you advise.
Thanks

 

if the flame trap was not done correctly, ie cleaning everything or replacing it with new parts, it will burn a ton of oil, also clog the box back up really quickly.

 

I'm new to this.
Can you advise on how I can start my 1st thread?
Thanks

 

VFLXC90 - Go back to top of the page leave this thread by clicking on the Volvo V70 forum, then choose the forum you wish to be in - looks like XC90, and look for the 'New Thread' button near top right of the page - click there and post your message.

 

Thanks for these replies. JRL, can you give me some tips on Seafoaming the engine? Lifesgoodhere, is there a drain plug on the oil trap, and, if so, how is it accessed? Is draining the oil trap and replacing the upper hoses etc of the PCV system ever an option, to save the lengthy job of replacing the trap? Thanks.

 

no, when the PCV system clogs, you MUST replace the box (no drain) clean block passages, clean all hoses. MAKE SURE FLAME TRAP VALVE NEAR TURBO (NEAR THROTTLE BODY) IS CLEAN. I always replace every hose and remove intake tube (turbo) remove valve on non turbo and clean that. There is no getting around replacing the flame trap, go to long and pressure can push seals out, ruin turbos, damage head, ruin cat-converters. The all somes from simply not maintaining your car correctly, and or using cheap oil.

not cleaning that valve which is often over looked, is what causes them to clog back up again. Seafoam WILL NOT HELP YOU!!!

 

Hello Lifesgoodhere - thank-you for the good information. How do you rate the FCP Groton PCV service kit for my V70 turbo, which costs $125? Also, which oil do you recommend for my car? If you prefer synthetic oil, which non-synthetic oils do you recommend? Thanks.

 

Very cheap. I have always used VOLVO OEM parts when doing the flame traps. This prevents comebacks for flame trap issues.

I look at it like this, 2003 newer, Synthetic cheap stuff, with can of BG Products MOA, which that can makes the oil even better than Mobil1

2003 older, 10w40 conventional if it has less than 175k miles, 20w-50 if over 175k. Run same weight year round, you aren't going to hurt anything doing so.

 

I have on '04 XC90 5 cyl turbo 110K miles...leaking, shop thought cam seals, head gasket, and turbo leak....no way all happening at once...not a Volvo shop, be reputable. They have yet to suggest PCV/flame trap. Others I have spoke with doubt the head gasket or turbo is bad-is a flame trap replace the fix? What else in addition should be cleaned or replaced? I have read the PTC nipple, and maybe additonal valave(s) need cleaned (one involing the turbo?)..can you list out all that should be either cleaned or replaced?

Approx costs at Volvo dealer? I am in midwest (Central Indiana)

Also, I should be using full synthetic on oil changes? AND that additive you spoke of?