Base S 70 non turbo has 259,000 miles. Over half highway miles. Always kept the car up. The S70 pleases me a lot. Using about 1 quart oil every 350 miles. Has always used oil since I bought her with 75,000 miles 8 years ago. Currently driving 300 highway miles a week plus 50 miles in city. 23 combined MPG. No smoke, but some light blowby on the tail and tailpipe. Transmission shifts fine as it did at 75K. Question: Can I put money back into the car and have a dependable ride for another 150K?? I may choose to be buried in her!

Hi-Yo Silver Away!

It's not a fun job, but at those miles I would suspect the valve seals need to be replaced - a take the head off procedure, with 20 valves! I assume there is no oil leakage at the rear cam seals.

Eventually, with the oil burner, your CAT will become clogged and your CEL will light up.

Since it used oil at an early age, get a warm engine compression test to verify that one of the piston rings hasn't frozen.
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My back feels better when I sit in a Volvo seat

What about the Transmission? Local St Louis Indie and Indie from Kentucky say don't flush tranny it could dislodge something and cause failure. Kentucky Indie does not want to pull the engine to rebuild because its a backbreaking affair. Does a head and valve job on my Base S70 require pulling the engine? Thanks for your input Klaus. Darn, maybe the Lone Ranger needs a Corolla.

Head removal leaves the engine in the car. The intake and exhaust manifolds need to be unbolted, exhaust is a bear with rusty bolts. Then the cam cover and head are removed.

Before doing that, which can cost up to $800 depending on the shop, get a compression test. If the rings are suspect, try adding 2 table spoons of Marvel Mystery oil to the suspected piston, or even all of them, and let the engine sit overnight with the spark plugs removed. It will be a little smokey at start up, but it might free up any ring problems.

As for flushing the tranny, the Indies are correct if a machine is used to do the flush - never let anyone use a machine! You could wait for a Saturday/Sunday morning and dump the ATF from the sump and then refill to the same mark on the dipstick (it will appear to be overfull by at least a quart), probably 3-4 quarts of new ATF.
Or you could buy 10-12 quarts of ATF and flush the system yourself by disconnecting the cooler line from the radiator and letting the engine pump the ATF into some plastic gallon containers.
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My back feels better when I sit in a Volvo seat

Thanks so much Klaus. Your the Best!

Mr. Blake Perrott,

Sir, may I please urge you to first inspect and verify the positive crank case ventilation (PCV) on the engine of your normally-aspired 1998 Volvo S 70 is in fine fettle and is without blockage and vacuum leaks.

A clog forms from condensating hydrocarbon products from engine combustion leaking past the oil control and engine compression piston rings, the value guides as to valve guide seal and valve guide journal wear. Clogs first form at the PCV sieve or flame trap or valve. With such clogs at the PCV sieve, flame trap, or valve, the engine-block mounted oil separator breather box itself can become clogged.

A clogged PCV will increase oil consumption and force oil out the lower engine oil seals and, in worse case, gaskets. Lower seals can become dislodged over time due to clogged PCV and high engine sump pressures in hard, or spirited, driving.

Also, a clogged PCV prevents the engine intake vacuum-driven combustion (consumption) of combustion products and other hydrocarbons that boil off with hot engine oil and combustion blow by. This is a necessary emission control.

If you do not have an OBD-II code scanner, may I also suggest you contact your local Kragen, AutoZone, and like auto parts stores, so you can check for OBD fault codes across all control systems before cracking the engine open on your 1990 Volvo S 70.

I'm unsure of when value guide seals, and in turn, the valve guides themselves (and the space between the valve stem and inside diameter of the valve guide itself, become a wear item needing replacement on your 1998 Volvo S 70.

Also, if you are able to find and clear the PCV clog, and oil consumption remains an issue for you and your 1998 Volvo S 70, may I suggest an engine compression or leakdown test?

An easy way to verify a clear EGR, with a cold engine that is OFF, is to remove the one or two EGR system vac vapor hoses at the air intake port (manifold - these are ports on fuel injected cars) or throttle body. Clean the end of the vacuum hoses. Remove engine oil fill cap, and then blow through the end of the one or two ends of the EGR vacuum line. Can you easily blow through it? Hear the air displace through the engine and out the oil fill cap? Your EGR may not be clogged or entirely clogged at all. On this board, some may use a method to verify EGR vacuum through the EGR vac vapor line piping through the engine block by loosening the oil fill cap so it rests, yet is not locked on the engine oil fill cap stem. Start the engine and observe the oil fill cap, Should stay on teh engine without rattling or moving off the engine oil cap stem mount.

Another symptom of clogged EGR is the engine oil dipstick popping up out of the tube. Though, at the mileage and age of the 1998 Volvo S 70 you own, you may want to consider replacing the engine oil dipstick O-ring, at the top of the engine oil level check dipstick. This symptom is more apparent on white block turbo charged engines, as the turbo charged engines routinely generate much higher pressure in the engine oil sump chambers.

As I'll be in back in St. Louis MO, the town of my manufacture, in some weeks or so, I'll be glad to stop by and help in person.

My offer stands for all used Volvo owners in the St. Louis region. (Just diagnosis. Not repair. I hate to see folks get ripped off by the auto repair facilities.)

Questions?

Hope that helps you,

Museum of Transport on Barrett Station Road in St. Louis County, MO.
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Thank you KittysGreyVolvo..... 25,000 miles ago I had the Indie replace all hoses, oil trap and intake manifold gasket in the hopes it would help the light oil blow by and reduce oil consumption. Please note I call it blowby but it could be too rich of a fuel burn, but this wouldn't effect oil consumption. Would it? I had also noticed when the engine cover was removed there was oil laying around the spark plug wells. Tonight I did lift the dip stick while the engine was running. No oil came up. Slight steam or smoke was emitted. I also opened the Oil cap and a small amount ie a few drops landed on the engine cover. I then put a small plastic bag over oil crankcase opening and it did not have a vacuum. I spoke to an Indie whom I had asked Volvo questions previously and he is going to do a compression test some time next week as Klaus suggested. Kitty stay in touch since your in St Lewis. I have joined the local Volvo club but have not been to any meetings.

#1: oil on the cam cover, under the black plastic cover, is from an old dried up oil cap gasket. Get a new one after you figure out what is causing the lack of vacuum in the crankcase.

#2: positive pressure in the crankcase, check two items. The vacuum line from the intake manifold starting just to the left of the #1 cylinder and going under the manifold to the flametrap by the throttle, may be clogged or the elbow is cracked at the bend by #1 cyl. This is a small diameter hose and is easily clogged.
The flame trap may have a plastic screen in it. Throw it away!

The diagram you saw in Kitty's post is wrong. The lines coming out of the oil separator box should be reversed. And it is for a turbo. So the large line that goes to the throttle area is what your flame trap connects to.

#3 Check the air pipe from the air filter to the throttle body for cracks. Also loog for disconnected or cracked small vacuum lines/elbows. These items can change the vacuum pressure in the intake manifold and reduce mpg.

OIL consumption: none of the above should have any bearing on the engine drinking oil. Excess vacuum (which you do not have) would draw crankcase vents through worn valve guides and suck up oil. This still sounds like the rings are letting oil get by them and getting into the combustion chambers. A compression test will show if this is so, and the repair cost 3 times as much as the car is worth.
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My back feels better when I sit in a Volvo seat

Thanks Klaus I will check the elbows and trap and run a compression test.

Ran a compression on Base S 1998, Cyl 5=120 dry. Did not check wet.
4=110 dry. Did not check wet.
3=100 dry. Wet=98?
2=90 dry. Wet=130
1=135 dry. Did not check wet.

Checked all elbows which were OK. Car had a new PCV replacement kit installed 23,000 miles ago. Will check the Flame trap and hoses early this week. Above Compression numbers are low assuming normal is in the 150 PSI range. This is the reason I didn't run a wet test on all cylinders. Last Thursday drove from St Louis to Evansville IN and returned. Car performed well since I only drove 55 MPH. Little trace of uncombusted gas or oil blowby.
Can I treat the car gently and get some more miles out of her?
Can I just cleanout the flame trap and reuse all the hoses on cleaning the PCV? Thanks guys.

Those are poor readings. There is no way that cyl #3 should have less compression with oil added. Was the engine warm when you did the test? A cold engine will always test very low. I consider anything below 120 low, and #2 is probably where your oil consumption is going.

Try a tablespoon of Marvel Mystery Oil in #2 (preferrably all of them), let it sit over night, then run the engine. MMO can remove some harmful deposits around the rings and loosen them up.

Should you run 'slow'? Try keeping the revs over 2000, that is the point where the valves will start to turn and clean themselves off, in normal driving. Avoid revving above 3500.

When you clean the flame trap, throw away the plastic screen if it is present. Check the small diameter vacuum line that goes to cyl #1 at the intake manifold. That is the vacuum line that keeps the crankcase from over pressurizing. The line is very small and tends to clog up.
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My back feels better when I sit in a Volvo seat

New compression test cylinder 1= 160 dry
2= 154 dry
3= 138 dry 150 wet
4= 130 dry 170 wet
5= 120 dry 165 wet
Added 2 tablespoons of Marvel Mystery Oil to each cylinder. Let sit overnight and when I burnt off the Mystery oil the scene was reminiscent of all of us running behind the mosquito truck fogger in those precious days of youth!

Will clean out the PCV tomorrow. Klaus I use the term flame trap interchangeably
with the term PCV oil trap. It is my understanding the 1998 Volvo Base S70 has no Flame trap thus no screen to remove. I do however intend to clean the existing oil trap and hose that runs from near cylinder 1 to the trap with water and soap. Please comment on the cylinder pressures and reusing the existing parts and intake manifold gasket. Blake

Mr. Perrott,

You write. "... too rich of a fuel burn ..."

If the fuel to air ratio is too rich, you may have an engine control issue. Why I suggest you check the OBD-II for fault codes on all control systems. Also, if the engine is burning a rich fuel to air ratio, you'd see black smoke out the tail pipe. Most any cause of even a mild fuel to air ratio imbalance would set one or more engine control system fault codes, and very likely the check engine light (CEL) illuminates and remains on.

Such a fuel to air ratio imbalance at engine combustion, either too rich or too lean, shall ruin the catalytic converter. You may also not be able to pass MO-state emissions.

Yes, please review all of KlausC' suggestions. A compression or, more thoroughly, an engine leak down test can reveal the cause of engine performance issues.

If the engine is burning a rich fuel to air ratio, it would not effect engine oil consumption unless really excessive, like a leaking fuel injector (doubtful). If the if the engine is burning a rich fuel to air ratio, you'd smell the excess fuel in the oil at the oil fill cap or oil on the end of the dipstick tube. (Do this on a cold engine. Engine oil should not smell of gasoline. Unless a faulty control system or component or through motoring use as in how you use the vehicle.)

Yet such concern may call into question how you drive your 1990 Volvo S 70. If you regularly commute, so the engine and engine oil fully heats, combustion by products, like water, unburnt fuel, and other hydrocarbons products, boil out of the engine oil, and get consumed through the PCV system. On engine intake vacuum, as it rises, when you maintain a light and even pressure on the accelerator pedal, or (if fitted) employ cruise control, at a sustained freeway speed, the throttle is about closed, raising engine air intake vacuum, so combustion vapors from the engine oil sump are consumed by the engine through the PCV. Though somewhat unrelated, the EVAP cannister check valve opens from both the raised engine vacuum and / or the positive pressure in the fuel tank, while driving, fuel sloshes around in the fuel tank, and fuel tank temps rise.

If you perform short trip motoring only, on the streets of St. Louis, that does not allow engine oil to get fully heated, and you drive this way exclusively, your 1990 Volvo S 70 can suffer, the PCV will clog, and sooner, and you'll form other emissions issues. Using dino (not synthetic) oil exacerbates the issue.

You can also form clogs in the throttle body, too, at the vacuum inlet pipes for PCV.

The engine cover? The engine cowl with the Volvo logo and engine model name on it, or it says something like 20-Valve in white lettering? So you can see the five spark plugs wires, and ignition power stage on each wire at the spark plug.

Road grime can naturally collect in the depression accommodating the spark plug.

If the spark plugs were not properly torqued (not too tight, that's aluminum thread in that cylinder head!), the interface between the sealing washer at the spark plug body, at the top end of the thread on the spark plug (opposite the bottom end with the spark plug electrode), may not be wholly sealed. Too low a torque value, or the spark plugs have been removed and replaced too many times, flattening or distorting the sealing metal washer on the spark plug, or, someone installed spark plugs too tightly, stripping the aluminum thread in the cylinder head to cause blow by, but not ejection of the spark plug from the spark plug hole with stripped thread.

You don't mention these problems, tough. If you've removed the spark plugs, how did they appear and smell? Normal? Dry black carbon is too rich a fuel to air ratio. Shiny, oily black stuff on the spark plug electrode end could indicate, as KlausC states here, a frozen oil control and / or one or both compression rings. So, please try KlausC' suggestions before cracking that engine open!

And try the OBD scan check.

You may be able to remove the PCV pipe from the engine air intake side. At the PCV sieve, flame trap, or check valve, just down stream, are one or two pipes .... well, i found a diagram using the not so useless Bing image search ...



This diagram may be for Turbo-equipped S 70. I'm not sure.

Looks like a Volvo diagram. On a cold engine .... Verify the dip stick tube is properly installed into the oil dip stick tube. You may want to remove the hoses where they connect to the engine air intake and, after cleaning, blow through these to check for clogs that are partial or complete. Maybe stop one end of one hose and blow through the other hose you removed from the air intake. Remove the oil fill cap. You should be able to blow easily through the large vapor PCV line that connects to the air intake at or just before the throttle body. (Use something to stop of the other line that come out the top of the PVC breather box / oil trap. Conversely, replace the oil fill cap and blow again. You should encounter great resistance as you exhale forcefully through the PCV vapor line pipe at the throttle body end. With the engine oil level dipstick properly sealed in the dipstick tube any air you hear moving should be inside the engine, usually through the piston rings. Remove the oil dipstick tube and exhale again, it should be easier, though oil can come out if your 1998 Volvo S 70 is not resting on a flat surface.

I then put a small plastic bag over oil crankcase opening and it did not have a vacuum. And the oil dipstick was in the dip stick tube when you did this?

You may want to inspect the air intake system, from the air filter, down stream, for vacuum leaks. Again, a fault code may be set of an air intake leak is more than the Bosch Motronic control system can compensate. It only costs a little time to check for OBD-II fault codes.

Do you have engine oil leaks at the lowest seals around the front and rear of the engine? Another symptom of a clogged PCV system is the engine oil level dip stick will lift up after spirited, or hard driving. Though your engine may have a catch to secure the engine oil level dipstick in place. I forget right now.

I hope you have a trust-worthy independent mechanic service. Some bad actors in St. Louis that repair Volvo autos. Check with the BBB, and with one giant salt grain, the opinion web sites.
- https://www.brickboard.com/SHOPS/
- http://www.volvomechanics.com/
- http://www.mechanicsfiles.com
- http://www.cartalk.com/mechanics-files

If you feel you are able, you could perform an engine compression test yourself, unless the quote you receive from your chosen independent Volvo auto repair service is acceptable to your wallet. An hour and no more than two hours of labor. They can check spark plug condition and reset spark plug gap, if you use such spark plug types.

I think that does it. I hope not to confuse you. Please see KlausC' suggestions.

Questions?

Thank you,

John D. McGurk's Irish Pub, 1200 Russell, Soulard, St. Louis MO.
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The Volvo 164: The Mightiest of All Volvo Automobiles in Perpetuity