Burning Oil

I have a newly acquired 85 QV which needed a lot of TLC and hadn't moved for years. It has about 92,000 miles on it. First items for replacement were the starter motor and fuel pump and a cleanout of the fuel system in order to get it running last year. It ran ok but one of the cylinders wasn't firing -- no fuel due to a plugged injector. It received 8 new injectors, spark plugs and new ignition wires and ran well on all 8 cylinders. So I decided to put more money into it. Lots of cosmetic items. Then it was on to new timing belts and bearings, a new fuel filter and new coolant. Another test drive and still ran well. Engine temp came up promptly but didn't overheat. Electric cooling fans turned on when they needed to (they got a new thermo switch). New brakes all around, new wheels. Another test drive, no problems. Altogether I put about 100 miles on it for test drives. The last thing I did to it was to change the engine oil (Shell Rotella 15w40 conventional) and filter (not a fram) and change the gearbox lube to redline last week.

Now the @#$%^&* decides it's time to start burning oil. Lots. It doesn't start burning it right away on start up but rather takes a few minutes to show up. If it were the valve stem seals, I would expect a more immediate puff of blue smoke on start up but there is no smoke until a few minutes of running. Could be the rings which doesn't make me happy but it's odd to me that the smoke started happening so suddenly. It's not leaking oil onto a hot manifold, the smoke is certainly coming out of the engine exhaust. I don't think the oil is overfull although I did put in 10 quarts initially, I took 2 out when it looked like it was too high on the dipstick. Still has good oil pressure.

The only paths I know of for oil to get into the cylinder would past the valve stem seals, past the rings or through the crankcase ventilation system. The inside of the hose for the crankcase ventilation system which connects to the air filter box doesn't appear to have oil residue on it. Does anyone know of another way for oil to get into the cylinder?

The other clue is that now the engine doesn't warm up quickly and might not even get to the running temp of 195 unless run for 15-20 minutes. That might be an unrelated thermostat issue but it, too, has just started suddenly after the oil change.

Maybe should have left the old oil and fram filter alone.

Any great ideas why the sudden oil burning?

 

Those motors did not have a reputation for burning oil. Are you sure it is not overfilled? How much did you put in it? How long has this been observed? Have you run it enough to burn out something that may have gotten in? Short version is I have seen them take an hour or more at a high idle to burn out oil that got in the cylinders and exhaust system. The last item I would suspect is pistons/rings. Valve guides/seals is a possibility but again not a problem they are known for.


What specifically was done between when you did not observe oil smoke and when you did?

 

I think I have put about 50 miles on it since it started burning oil. The only change between not observing oil burning and oil burning was changing the oil. I'll admit I'm not too sure where the "full" mark is on the dipstick but I only have 8 quarts in it and the level appears to be at the notch near the top of the copper part of the dipstick which I think is the full mark.

 

Are you sure it is oil smoke?
Is a plug/plugs fouled with oil?

Other possibilities could be too heavily choked or even cracked head leaking antifreeze into a cylinder.
Of course, in both these situations the smoke would smell distinctly differently.... very sweet for antifreeze and heavily gasoline if a choke (fuel/air) problem.

 

Pretty sure its oil smoke. Blue and a definite smell of oil.

 

OK.
Well, you sound adept and mechanically inclined, so it's on to pulling the plugs to check which cylinders are involved, AND a compression check to narrow it down.
Keep us informed!
Thanks.

 

If it was not burning oil and now it is, limit your search to what happened in between. The valve guides did not suddenly go bad. Or the rings.
I would be shocked on a car that old if it did not have a bad shift shaft seal. Id change it to be sure the motor oil stays where it belongs and the gear oil stays where it belongs. Then when car is level drain both. Then put 9 pints in the gear box and 8 quarts in the motor and run it for 2 hours and see if smoke gets better.

 

That's my plan. I have the results from a prior compression test so it will be interesting to see if there is any difference. I was just hoping that there was some stupid Italian engineering item on the car which could accidentally introduce oil into the cylinder.

 

I have heard of the shaft failure issue. If that happens, does the gearbox flow into the engine oil or is it vice versa? In other words, which level is supposed to be higer?

 

To check level of motor oil = start engine until warm, stop engine and wait 5 to 10 min. Now its time to check your level ! Oil also can come via the air inlet. A clogged blow by system. Did you check the air filter housing ?
https://www.eurospares.co.uk/Ferrari/Mondial/Mondial_3.0_QV_(1984)/PartDiagrams/015/Blow_-_By_System?_gl=1*4eaq07*_up*MQ..*_ga*MTUwMjkwOTA0LjE3MTg5OTUzNjE.*_ga_HH3QNDJH8C*MTcxODk5NTM1OC4xLjEuMTcxODk5NTM4MS4wLjAuMA..

 

Here's where I am so far:
Compression check -- results similar to test done a few months ago with pressures ranging from 125 to 140. Seems a little low to me but the numbers are fairly even between the cylinders. No pressure decreases in any of the cylinders when comparing first test result to most recent test. So, no new broken rings or leaky valves.
Blow-by system is clean and not putting oil in the air intake. That's not where the oil is coming from.
Gearbox oil level is consistent so I'm not getting gear lube into the engine or vice versa. I don't smell any gear lube in the engine oil. Engine oil level increase not coming from gearbox.
Spark plugs are black but not wet except for one cylinder that hasn't been firing. That cylinder has spark and compression and I think way too much fuel. Overall, the engine seems to be running rich. Adjustment of the mixture screw on the fuel distributor is ineffective to lean out the mixture.
Fuel pressure test. 60 psi consistently whether at idle or on the road. Will hold pressure for at least 1/2 hour when not running. Doesn't seem like the system is leaking fuel thru the injectors when not running but I am suspicious that its dumping fuel, especially into one particular cylinder which isn't firing, while its running.
Engine oil is gasoline contaminated and level increases rather rapidly. It's over-filled by more than a quart after a 1/2 hour of running. I'm on my second oil change in 60 miles.
The only way I see that fuel gets into the engine is through the cold-start injector or the 8 other main injectors. I disconnected the cold start injector and it's still too rich.
After sitting unused for more than 10 years and being almost 40 years old, I think the little o-rings, gaskets and seals on the fuel distributor have failed and fuel is just going anywhere it wants to inside the distributor. I'm going to give rebuilding the fuel distributor a try. There are some instructions on cis-jetronic website and I have a Bosch book on the cis system.
Does anyone have any hints or tips on fuel distributor rebuilds?
Does anyone know what the fuel pressure setting should be?

 

What version 1985 QV? Euro (K-Jet without Lambda) or US (K-Jet with Lambda)?

Way too low -- should be more like 75 psi (regardless of version), but there are other pressures to confirm/deny. Here are some F references that you might find useful:

This is the Mondial8/QV WSM that covers K-Jet without Lambda (Chapter D):
https://www.dropbox.com/scl/fi/twng41f9fpi3ipww7q95v/Mondial8qv_workshop_281-83.pdf?rlkey=5sgpj4yz33jepzrec4x8lcwel&st=4iwi4qdr&dl=0

This is Service Bulletin 10-13 that describes K-Jet with Lambda:
https://www.dropbox.com/scl/fi/dvnqxo0lc057vo4pmg4bo/Service-Bulletin-10-13-Bosch-K-Jet-with-Lambda.pdf?rlkey=1ki6jghpubkys1czr1jio08gh&st=bupf3qm5&dl=0

Good luck with your resurrection!

 

Thank you for the documents. Looks like the primary pressure should be between 4.7 and 5.4 bar so I'm low at 4.1 bar. It doesn't look like one can adjust the fuel pressure externally but rather its controlled by the primary circuit pressure regulator and perhaps adjustable by adding or removing shims. I plan on doing a rebuild of the mixture control unit so hopefully new o-rings on the pressure regulator will cure my low-pressure situation.

 

Did you follow the WSM method for checking the oil level...dry sump you know...

 

Hello, your story reminds me of my former Mercedes 560 SEC when I bought it... It was almost inused for 10 years. I drove it 100 kms to get it back home, and drove it around a little before doing an oil change. And after it, very big oil smoke, it killed definitely the valve seals. It was really an off/on thing due to the oil change. They were totaly rigid when I put them off.

The smoke was very thick at idle, with a heavy smell of oil burnt. ( there was no smoke when I bought the car) Changing the seals solved the problem.

 

So the smoke has been resolved. The culprit was the fuel distributor. After a rebuild of the distributor and a third oil change in 63 miles, it runs well and no smoke. I didn't find anything grossly wrong with the distributor but the various o-rings weren't as soft as they were 39 years ago. After I rebuilt the distributor, I went to do my first startup and it wouldn't fire. After a little diagnosis, it wasn't getting fuel. I found out that the tank was empty. My fuel gauge doesn't work but I didn't expect that. It used a full tank of gas in 63 miles and appears to have dumped most of that into the crankcase. Now all 8 cylinders are firing and it comes up to temp quickly.

The cause of the smoke was a high oil level which was mostly gas, Now the oil level is constant and no longer gassy.

Previously, I had only driven a 7 cylinder Ferrari. They're better with 8.

 

How did it dump the gas into the oil? Past the rings? That seems a bid odd if it was that large a quantity. Keep us posted!