Since rebuilding and getting some break in miles, I'm doing some harder than normal acceleration and letting the engine spin higher than you would in daily driving in aid of seating the rings all the way in the cylinder bores. It's been so long since I've had a healthy motor that I can't recall...
Is it normal for the oil in the 6.9's sump to be all bubbly coming right up to the fill cap after hard running?
I have never seen this on mine, so I can only speak from my own experience, but this sounds a bit unusual. Are you sure you did not perhaps overfill the system? I'm sure you know this but on the 6.9 you check the oil with the motor fully warmed up and running, and only then should it read between the high and low mark on the stick.
Yes, I check and without the hard driving, no foaming and level is correct.
I'm talking about full throttle to redline driving. Been years since I've done that. Pre rebuild, that kind of driving would belch out a huge cloud of smoke that gets you a stiff fine around here.
I've never run across this myself, but quick search it is not a good thing. Air bubbles. : Poor lubrication. Since it is a dry sump even more odd. Overfilling a regular engine the crank would whip the oil. Is this a new rebuild? Mixed lubricants can cause this. What oil did you use? Maybe assembly lube mixed with the oil could cause this.
You're sucking in some air somewhere. Check the hose connections from reservoir to sump. Also that o-ring along flange fitting which extends into sump.
I will check. Can you help me with terminology? The sump is the tank welded to the fender. What is a reservoir?
I'm pretty sure in this case dry sump tank = reservoir. You will see 3x hoses running between the - let's call it "oil pan" to avoid further confusion - and the dry sump tank. You will also see the flanges mentioned at the "oil pan" side. Good to check all these hoses and connections for tightness.
Mr Erbe is on the money.
I recall having this sort of frothing when the sump hoses were leaking. It took two or 3 refits and some hylomar on the paper gaskets to get it leak free, and I'm thinking that flat ring could be your issue. As an aside, I wouldn't be too heavy handed (footed?) with the engine if you haven't done many miles. That's my opinion anyway, until any teething issues like this are sorted .
Tim
Regarding the o-ring, that was the problem I had. Symptoms were that (1) the oil pressure gage did not peg at start-up and (2) when the car made I believe a left hand turn the pressure would drop.
Also, to save time, just check first the suction hose from the reservoir. The other is the return but unfortunately I dont recall which is which.
diagrams
Thanks all for the tips. Did any of you experiencing frothing have oil leaks?
I had that happen to me a while back, it turned out that I was low on oil. I would also notice the oil pressure drop on fast left turns. The problem went away when I added a couple of quarts of oil.
I had oil leaks externally at all three fittings.
I would change the oil again and confirm it is at the correct level as Alabbasi said above (operating temp, engine running).
It there are leaks present or if this doesn't sort it out, I would double check all the O rings if you can.
Tim
Yes from memory there are orings as well as a gasket (s) where the flanges connect to the oil pan on the motor. I recall changing these out during an oil change and at that time all those parts were still available ex Classic Centre for not too much coin.
All set to buy and install new seals. But before I do that, need to ask a stupid question. It's been so many years since I had normal oil level readings -- car was burning 1 1/2 quarts per 100 miles before rebuild.
When you stop the car to take an oil reading, do you leave it running after driving? Or do you as the manual suggests, stop the engine for a couple minutes, then restart, and take the reading?
The reason I ask, is if I shut down, wait 2 minutes, restart, let it idle, and check the oil, there's no foaming. All the bubbles burst.
Personally I just let it idle, then take the reading with the motor running. Never been an issue for me. Most important is for the motor to be fully warmed up.
level ground...hot idle..no bubbles.
We have all new seals and fittings and no oil leaks---and a foamy oil tank. Oil in reservoir is bubbly only on top, solid fluid in the bottom 1 1/2 feet of the tank leading us to believe that it's on the return side.
Two theories. We have seen hoses that "gas" but don't weep fluid. But the hoses look pretty dry for the that to be happening.
The pick up for the return side of oil pump has a leak. One other thing, is my shop says they've seen this a couple times before. Foamy tank, no leaks.
Interesting. Are they original hoses? If so it might be worth having them remanufactured. I had mine redone with an externally braided truck brake hose that was available in the correct size for all three and is suitable for the purpose (still no leaks after almost a decade).
Tim
They are original. Almost all of the rubber on this car is OEM. Nice heated garage and no smog here.