I have an 89 turbo w/ auto @156K miles. I have a problem with oil leaking from under the engine (seals?) and, to a lesser degree, from the oil filler cap. I estimate a leak rate of about a quart per three tankfuls. My car seems to blow out more oil the more I use the turbo. I thought it was a clogged crankcase vent system, so I cleaned it, and, with the oil filler cap removed, blew back through the oil trap, using the existing big hose. It had very little resistance, almost nil. I thought it could be the tyrbo going, so I pulled the turbo inlet hose and tried to wigggle the shaft, but it had no play. But the leak still exists.

Does anyone have an idea what could be causing the leaks, and, once the problem is found, will I need to replace the seals / gaskets?
thanks in advance

Rick

My leaks traced down to two simple things: a failing oil cap gasket and a slightly loose oil cooler hose fitting. Love those two dollar, one wrench repair jobs. Thanks to all that replied. Now to the crankshaft support bearing job......

I am amazed at the replies that tell you to clean the PCV valve. The PCV valve isn't dirty - it is non existent.
My 89 745TIC has had catastrophic oil losses (over a quart in 5 miles) twice. The first time @ 185k miles resulted in a complete rebuild including a new (unneeded) turbo cartridge. The second time happened with this "new" engine after 2k miles. Both times happened when the cruise control caused a downshift and full boost for a time at 4000rpm± on a mountain upgrade. Neither time did the plugs foul - this is a key. Before each loss oil consumption was about 1 qt/2000miles although the "new" engine was a tiny bit less. Most Turbo owners report similar oil consumption.
I puzzled over this last occurance because eventhough I caught it and topped up the oil with no harm, I was afraid of another rebuild and WANTED TO KNOW WHAT THE HELL WAS GOING ON. The key was the non fouling of plugs which told me that the oil lost did not pass thru the combustion chambers. It is impossible to burn that much oil without fouling the plugs!!! Hence it was not a case of a bad head gasket, valve seals, rings, turbo seals, or anything else that would have put oil thru the combustion chambers. The fact that my second occurance happened with a "new" engine and turbo backs this up. I deduced that the only way to lose that much oil was through the crankshaft seals. I suspected the rear seal because there was no trace of oil leakage at the front of the engine and because it happened on an upgrade when the oil would have been puddled (completely covering the seal) in the rear of the oil pan. Also the rebuild was required because the #1 piston had burnt, indicating a lack of oil at the front of the crankcase. My APC controlled boost was about 11psi, both times.
Looking at the breathing system for the crankcase you will notice a small hose going from the intake manifold to the plastic fitting in the large breather hose. Apparently it is there to vent the crankcase to the intake manifold when the latter is under vacuum. There is NO PCV valve in the system. My 245 TIC had no PCV valve either but it also had no hose from the intake manifold. Could it be possible that extended boost was transferred through this hose to the crankcase? Would oil puddled at the rear of the crankcase with 11 lbs of pressure behind leak out the rear seal at higher rpm? You betchm Little Beaver is my reply.
So how do you fix this? A check valve in the small manifold hose that lets fumes be sucked into the manifold but prevents pressure to be passed into the crankcase? Yes, such a valve is called a PCV valve. A check of the PCV display at your local AutoZone will will reveal a nice little black&white plastic jobbie with small barbed inlet/outlet tubes on it that will slip into the suspect hose with no clamps needed. If you pick the wrong one it is no big deal as long as it fits and is positioned the right way. Mine cost less than $5.00 and was installed in a few minutes by cutting the hose and inserting the PCV.
The result: I swear by my imagination that the boost response is quicker - I believe because the volume of the crankcase has been removed from the boosted volume. Not outstandingly quicker but a little bit snappier it seems to me. There is no doubt that in the 4000miles since I installed the PCV (and a new oil filler cap) THE OIL LEVER HAS NOT MOVED FROM THE TOP OF THE DIPSTICK!!!!! No oil consumption, none, nill, nada, ZERO. No imagination involved in this, it is the truth. I will not know the full validity of my theory until I get back up in the mountains and am not able to duplicate my catastrophic oil loss, but as of now I am convinced that I have found the answer. It all makes sense - the more you use the turbo the more the crankcase becomes pressurised and the more you blow oil out seals especially if the seal is completely submerged and cannot vent air. I can see no harm in the addition of this PCV - the manifold vacuum still vents the crankcase and the 245 TIC never needed it anyhow.
Give it a shot - its cheap, easy, and harmless. I have not needed to replace any crank seals but then again mine are almost new. If you aren't convinced after a few thousand miles then take it out and throw it away. You will have spent more for a quart or two of Mobil 1 than you did for the PCV. And a rebuild? Mine set me back about 4 grand. Its your choice, but I would like to know if your experience adds proof to my theory.

First, let's be clear. The V in PCV stands for ventilation not valve. I havn't heard anyone suggest he clean his nonexistent valve, rather check his Positive Crankcase Ventilation system, which he certainly does have.

The design of the 740 PCV sytem has a constant flow of air above and across the pipe that comes from the oil trap (think the top line in a T). During boost when the turbo is sucking in air the flow is from the manifold toward the air intake hose. During idle when there is a vacuum at the manifold and the turbo isn't boosting the flow is from the air intake hose toward the manifold. All the time fresh air is replacing the gases in the crankcase.

So you're suggesting during boost The flow from the manifold through the tiny calibrated nipple is greater than the flow that is being sucked through the much, much larger hose going to the air intake? I think volvo designed the size of the hoses to accomodate your concerns. Have you replaced the hose going to the air intake? If it is collapsing under boost it could possibly be causing what you are describing.

--
Paul NW Indiana '89 740 Turbo 108,000

not looking to pick a fight (honestly!) but im also strugling with a similar issue..and wanted to discuss what your proposing..

"The design of the 740 PCV sytem has a constant flow of air above and across the pipe that comes from the oil trap (think the top line in a T). During boost when the turbo is sucking in air the flow is from the manifold toward the air intake hose. During idle when there is a vacuum at the manifold and the turbo isn't boosting the flow is from the air intake hose toward the manifold. All the time fresh air is replacing the gases in the crankcase."

I struggle with this, under high vacume conditions in the manafold their will be almost no air movement into the front of the turbo (almost no air movement into the engine because the throtle is closed ) so the only movement on the crank case is any residual blow by from the pistons presurizing it, and the bleed thru the nipple into the high vacume in the manafold, so basically the nipple is providing a small air flow to scavange any blow by gassses that would otherwise flow into the air filter area....

Given that other than the breather box and blowby the crankcase is essentiually a sealed box (which is why the seals blow out if the breather gets blocked) where is this fresh air comming from??


"So you're suggesting during boost The flow from the manifold through the tiny calibrated nipple is greater than the flow that is being sucked through the much, much larger hose going to the air intake? I think volvo designed the size of the hoses to accomodate your concerns. Have you replaced the hose going to the air intake? If it is collapsing under boost it could possibly be causing what you are describing."

Hmm ok, in my case im assuming that the nipple may have opened out durring its life, and i have a fairly free flowing filter fitted so probably relatively little vacume from the turbo inlet to the filter so i doubt theire is actually that much vacume on the big hose...lets say its free flowing... now we have 8psi in my case hitting that nipple..now im with you that there aint NO way thats going to presurise the crank, but I'm wondering to myself if the turbulance it causes in the airstream entering the Y fitting has an effect....

my logic for all this, well not very scientific apart from...I plugged my little breather tube (no one way valve im talking plugged!) and I think my oil consumption also dropped markedly....like by a factor of 10!...

currently im playing with a catch tin inserted into the tube (note LARGE volume of air in this tin which should (a) cause any oil in the airstream to drop out (b) provide a buffer to any shock waves traveling down the pipe (c) let me see which direction down the pipe stuff is flowing...

this seems to have slowed the oil use markedly (not as much as plugging the pipe I think)..

Im also running the rinse cylce on auto-rx currently so that may be having an effect as well...

I know your all thinking im doing a lot at once..but you would be too with a b230ft that consumes (not leaks!) 1ltr oil per 150-200 miles! (note the above stuff has slowed this to 1/2ltr in 350 miles so far...and it seems to be leveling out to less that that!)

This looks like a good topic for us all to learn more about the turbo PCV system.

The flow of fresh air at idle occurs because there is a vacuum in the manifold. The fresh air comes from the turbo inlet hose - which is after the air filter, the source of all fresh air. You are correct that there is not much pressure at the intake but air flows from high pressure to low. The manifold is sucking so it pulls the air all the way from the turbo intake and hence the air filter.

My point was I don't think the crankcase could become pressurized by an unrestricted hose. The throttle plate is open so the pressure in the manifold should be about the same but opposite as the intake. It is sucking the air from the intake and shoving into the manifold. Due to the difference of the hose sizes that path should just feedback into the intake from the manifold AND the crankcase.

I think the source of the problem is the turbulence you mentioned. The design of the nipple points downward, I believe to mix the fresh air with the blow by gases. It may be the the turbulence is whipping the oil about. On new seals the may be OK but on marginal ones it may be a problem.

I, too, am in the process of an auto-RX treatment. I am on the first rinse phase and it seems to have quieted my engine already. I'm looking forward to completeing it all and getting some synthetic back in my brick.

--
Paul NW Indiana '89 740 Turbo 108,000

ok im cool about the flow of fresh air from the pre turbo intake via the breather hose to the manafold under vacume conditions (with a slight sceptasism that thats really a flow as i cant imagine that THAT much air can be sucked via the hole in the manafold fitting, and i suspect that blow by presure may well equal it out...) but to be pedantic that still means the fresh air isnt making the crank case..the only way anything gets in the crank case is blow by...

under boost aka open throtle plate AND an enginge under load a few things will happen..

1. blow by will increase markedly...
2. presure in the manafold will be about 8lbs/inch (stock)
3. maximum vacume will be created after the air filter (but looking at figure on turbo bricks by a guy who measured the air resistance by all componants of the air system we are talking SMALL vacume here..LIKE REALY small....

certainly your correct that the same air is being pulled through the filter as is being presurised in the manaofld, but the vacume presure is no where near 8psi (or about 160??? inches of water)..so we actually dont have balanced forces at work..

I agree the system should feed back (thats the way it was designed after all)..but Im just not sure it does effectively...

I have actually rigged a presure guage up to my crank case - i also have a calibrated boost gauge - and gone for a drive..(actually i sealled the pipe to the dip stick tube wihtout a dipstick in place) and was interested by the results...(note guage not terrably accurate at very low vacume/psi but you will see the point)

1. Idle, possible vacume on crank, small but there...ish
2. fast idle (reving car in drive), definate cvacume on crank
3. Normal driving..as per 1/2 dependant on engine revs etc..
4. Sustained boost aka up hill, foot down....8psi..crank appeared to be slightly presurised, im talking <1psi here but all the same...

now...
COULD that small orrifice with 8psi behind it produce < 1psi at the crank when combined with blow by and a turbulance being set up in the pipe acting a bit like a vapour lock...??

I think i buy that one....but then again im not sure

certianly my gut feeling is the oil usage i see seem to get worse with prolonged turbo use, or cruising with the turbo in balance (aka 0 vacume 0 boost) which might produce a 'stall' condition in the pipe...

Paul;
At last someone who understands the dynamics of what I theorize. The hose in question indeed attaches to the small nipple in your photograph. You may be correct in your assessment of the PCV system, you even caused me to go and check the large hose (its fine). So I guess I am not suggesting but indeed maintaining that the air flow through the small hose is larger than that being sucked through the much larger hose toward the turbo intake. Perhaps this is a finely balanced system by Volvo and the increased boost of my APC has unbalanced it. I don't know the answer. As I said I will not know the catastrophic oil loss answer until I am able or unable to repeat the phenomena under similar conditions. I DO know that the very same "new" engine that burnt the standard 1qt/2000mi around town has now burned 0qt/4000mi. The only changes being the addition of Deutsch #PCV 161 valve at the grand cost of $3.99 and a new oil cap. In the 4000 miles around town I have used the turbo to the tune of 18mpg and featherfooted it @ 21mpg. No oil consumption, period. That is a fact.

Your assessment means that the valve is detrimental by restricting the fresh air replacement of the crankcase gases upon turbo boost (i.e. a closed PCV valve). If this is so important why was it not a factor on my 1984 245 TIC which only had the large hose but not the small one. Had crankcase emission regulations changed that much between the B21FT and the B230FT?

Jim

I imagine this was to be an improvement to get the nasty gases out of the crankcase quicker. You're still sucking the gases out all the time but the exchange one way may not be as efficient. As you point out, the 240s didn't do it this way, so I'll bet you'll be OK.
--
Paul NW Indiana '89 740 Turbo 108,000

I've seen a few of your posts lately, and I'm sold on the valve, too... gonna pick one up.

- Brian '93 945T

i have similar thoughts...on my b230f i use awfull amounts of oil with no visible leaks (or smoke!) but recently I cut my little breather pipe and the oil use slowed to crawl...if any, i have re-established the pipe and put catch tin in it (to see if i have oil moving through that pipe...and yes i have a little (and i mean a little!) but the oil use seems to have increased markedly...

im with this that pipe needs a valve in it...on some engines at any rate, dont know why on some not others but my HUNCH is that over vigerous cleaning of the calibrated brass nipple in the manafold may open it out too much..

Great post. Makes a lot of sense. I will pick up one of these PCV valves on the way home.

the valve that your refering to; is this also called the "flame trap"? or is this diffrent?
Adam
1985 760TIC
219K
Bedford NH

I consulted with this board's FAQ on 700 repairs, as an attempt to diagnose the source of the leaks, which I assume to be excess crankcase pressure.

The turbo 740 does not have a flametrap, but a simple plastic "Y" that fits into a hose that connects with a oil seperator box, mounted on the block. after cleaning this with some carb cleaner, and checking the hoses for leaks, the breather system does not appear to be blocked. I can blow through it, and it has very little resistance, about what I would expect when blowing through a hose of comparable diameter.

So, could it be the turbo's oil seal passing turbo pressure into the crankcase via the breather hose? I didn't put much stock in this culprit, since the turbo was wiggle free.

Is there something else that could be the problem?

BTW, the plugs (bosch 4 tips) are light tan, and dry.

thanks again
R

"So, could it be the turbo's oil seal passing turbo pressure into the crankcase via the breather hose? I didn't put much stock in this culprit, since the turbo was wiggle free."

Rick

I don't understand your meaning here. The large breather line enters the air flow before the turbo. Indeed the more the turbo is being used (intaking air) the greater the vacuum at the entry point of the large hose. How could a leaking turbo oil seal pass pressure or oil via the large hose into either the crankcase or the combustion chamber? My point is that the turbo seals don't need to be bad or leaking for pressure to be passed through the small hose via this "Y" fitting into the crankcase. The natural function of the turbo passes the pressure through this small hose and causes some degree of leakage through the crankshaft seals, regardless of their condition. Hence the fact that a normal turbo seems to use a qt/2000mi where as a NA engine gets better oil consumption. Now why should a turbo engine burn oil where a NA engine does not? My theory provides an answer, ie. because the turbo is pressurizing the crankcase - a situation that is not possible with a NA engine. My catastrophic oil loss only occurs under certain conditions that are probably not an everyday event unless one is hillclimbing his 740 Turbo. I wonder if 740 Turbos have a DNF history (ie. blown engines) in hillclimb events?

Seriously, I can understand that my theory is unproven and perhaps unbelieveable but it is so easy to try and so inexpensive, why not give it a shot? I have seen no detriment on my 740 and cannot see how there can be one except for a little bit of wasted money and time. If anyone else has tried this had has found a detrimental consequence please speak up.
Jim

I know there is no PCV valve- the why I called it the Crankcase ventilation system, as referred to in "Crankcase Ventilation: A Treatise. [Don Foster]" This was my original source of information, when I thought the breather system was clogged.

Rick

I did notice that you refrained from using "PCV" in your post, I was referring to some of the suggestions that you need to clean the PCV. I have not read "Crankcase Ventilation: A Treatise" by Don Foster, were his conclusions similar to mine? I cannot help but think that others must have had similar catastrophic losses (hopefully without the damage) that I had and reached similar conclusions. It does seem weird that Volvo would have permitted such a condition to exist for the want of a inexpensive PCV valve. Are there no hills or lead footed drivers in Sweden? Why did they add this vacuum line in the 740 Turbo when they did not use it in the first turbo application - the 240? I have been a Volvo owner since 1963 and find this very odd behavior for them.

Jmars

whtas weirder is some docs refer to the line being capped in turbo's...but every one i have seen is there...

Assuming your PCV system is order, you may well just need some new seals. The the seal on the cap probably needs replacement and I would guess the seals for the oil cooler bracket and/or turbo oil return pipe. They are very likely leaking or soon will.

See http://www.brickboard.com/RWD/index.htm?id=752583 for a recent discussion on this topic.
--
Paul NW Indiana '89 740 Turbo 108,000

You would need to try to better isolate the leak, given the the extent of the leak, assuming that your pcv is not clogged anywhere (id you verify the brass nipple to the intake?) and functioning as expected, you likely have one major bad seal somewhere.

Wash the engine, with a degreaser (be carefull where) and try to isolate where the oil is from. It obviously always accumulates at the bottom, so you need to look upwards. Check areas like rear cam seal and cam cover gasket.

Good luck,
Greg
Montreal - Ottawa
Canada