mikehayes

Here's the story: 16V 87' engine that's been swapped into an '84 chassis. I rebuilt the engine myself, but it was my first ever rebuild, so it's very possible I did something wrong. I'm confident that I gapped the piston rings correctly, but I did not remove the valves from the head (meaning I didn't replace the valve guides/seals). I had a shop examine the head, they cleaned up a few valve seats, I did a compression test, and it read very good. I did an oil change at 100 and 800 miles respectively, and the oil checked out fine both times, didn't look or smell burnt. I baby'd it for about 500 miles before running it hard. This weekend, with about 1200 miles on the engine, I left to do a 2000 mile round trip road trip to the tail of the dragon. Drove 9 hours on the highway Friday with no problems. Saturday we did 100 miles of very hard, high revs driving on the tail of the dragon and other roads. Temp gauge was firmly planted where it should be all day, oil pressure was always pegged at 5 bar at high revs, right about 3 when hot at idle. Running 20W50 Valvoline racing oil. Sunday morning I get in the car, it doesn't want to start. Sounds mechanical. I give it gas and it starts, but sounds like loud injector tick/lifter tick, or rod knock. I pull the oil dipstick and... it's completely dry. Whoops. Bought the closest viscosity I could get in the middle of the mountains and put 4(!) quarts in before it reached the max mark. Started and ran fine (and quietly). I desperately wanted to pull the drain plug and look for shiny bits, but I was in a very inaccessible location and I couldn't even have gotten a tow truck there. I held my breath and drove it 9 hours home. It burned about half a quart over that time. I had friends behind me on the tail and they said my car never smelled or looked smokey.

So, 4 quarts burned in maybe 800 miles, no smoke out the tailpipe or any other otherwise suspicious symptoms. Could bad valve seals explain this? If I pull the valve cover, will I be able to visibly tell what's wrong? Is the pressure too high? Could the OPRV be malfunctioning and the high pressure is forcing oil out? The engine has no external leaks. Coolant looks as fresh as the day it went in, no milkshake on the oil cap.

harveyf

Bad valve stem seals would exhibit as white smoke out the exhaust on de-acceleration. The negative pressure in the combustion chamber due to the engine braking effect sucks the oil past the valve guide seals into the cylinder and then it burns. So that does not sound like your problem.

To me, 4 quarts of oil in 800 miles would show as smoke if it is getting by the rings or something like that. Although if you haven't already, I would get it warmed up and take it out and run it near redline, maybe up a hill to put some load on it, and check the rearview mirror carefully for oil smoke. Also get off the throttle suddenly as described above and check for smoke.

Check the block carefully for signs of leaks/spillage. Fresh oil doesn't necessarily show up unless you are looking for it would a good light. When you get done with your above test run, park it over something like a white towel etc. and see if you get some drainage.

harveyf

And it is very strange that you weren't flashing the oil pressure idiot light on your dash if you were running the Dragon 4 quarts low. Is it possible you started out overfilled somehow?

mikehayes

Harvey, there was certainly lots of engine braking happening in low gears at high revs on the tail, so that stood out to me when you mentioned negative pressure. It had occurred to me also. I'm fairly confident I had it filled right to the top line, but it's possible I misread the dipstick I suppose. I was shocked the idiot light never came on either. The last time I saw it go on, the 8V engine was still in the car. I assume it still works, but I don't know a safe way to test it. I park on a very clean concrete driveway/garage and check underneath most days and have yet to see a drop, but I can do some tests and double check.

jhowell371

Leaky valve seals will usually show up on startup after sitting overnight. The oil runs down the valve stems into the combustion chambers. Have someone watch the tail pipe for bluish smoke when you fire it up. High RPM off throttle deceleration is the most likely explanation for your high oil consumption under race track conditions with valve seals of unknown quality. I'm kind of surprised you didn't do a preflight before your high speed work. You may have lost a quart or so just getting there on a barely broken in engine. Glad it's OK.

thomasmryan

It is possible your oil control rings haven't seated on the cylinder bores or ring lands yet. The 318 curves might have sloshed a minimal amount up on the bore walls to where it wasn't visible in the exhaust but still being consumed. The hair pin corners not so much as the downhill bends where you're at threshold braking and all the oil goes to the front of the motor.

harveyf

A couple of things come to mind.
1. Certainly worth checking to see if the idiot light comes on when you do a "pre-start" i.e. ignition on, car not yet started. That basically confirms that the light will come on when the sensor has zero pressure. Oil pressure gauge should also show zero.
2. I would get it well warmed up and dump the oil and filter. Let it drain for an hour or so. Then I would refill with the correct amount of oil as specified in the workshop manual, start the engine to get the new filter filled, turn it off, wait a few minutes, and check the dipstick. See if the level on the dip stick makes sense.

I only bring all this up because how far the dipstick extends into the pan can be corrupted, for lack of a better word. I did some experiments on my new track car engine before I put it all together to see how everything lined up. For instance, if the dipstick tube is not seated in the hole in the oil pan where it resides, it can hold the dipstick artificially high, thus leading to overfilling. Also, the pan on the later cars, the one with the oil level sensor built in, holds about a quart more than the earlier pan. So my point is there are plausible reasons that you may have either underfilled or overfilled. Ergo do the little experiment I described above to get a baseline. Don't blindly trust the dipstick.

And yes, your rings may not have sealed.

My track car will suck down a quart of oil after 1 day of track work (typically [4] 25 minute sessions for a DE) so your Dragon Quest could be expected to use some oil. But 4 quarts is surprising.

A little bit of a long shot but I've been meaning to post a caution to folks about the baffle in the oil pan. It has a hollow region. On most of the older ones in my pile of parts, the plastic tabs, that allow them to assemble the piece during manufacture, are broken. It struck me that if the cover were loose, the baffle hollow region could collect oil rather than letting it drain back to the pan. But again, maybe a quart, not 4 quarts! Also, the new baffles have the cover held on with screws.

I'm sure you will keep a close eye on things for a while

mikehayes

Yes, there's no doubt it was a serious oversight on my part. Lesson learned for the future.

mikehayes

Good to know. Will do. I did your tests last night. Got it nice and hot, took it up to about 6k in 2nd, and let off hard while looking in the mirror. Not a hint of smoke, visually or smellably (for lack of a better word). I do notice the new engine has some exhaust burbles when letting off that the previous engine never did. I don't think that's related though, unless oil could be burning in the exhaust like gas would.

Noahs944

These engines burn oil... especially when driven hard.
If you are bored & have time, you can remove exhaust manifold & check for oil at 1 exhaust port. This indicates a problem with one cylinder.
Did you break in you rings correctly? Did you orientate the oil control piston rings correctly?
You said using .5 quart in 9 hours of normal driving. This sounds good to me. About the same as my car.

harveyf

If you can take it to redline and not see anything in the rearview mirror, I think you've ruled out the really expensive stuff

You may still have a leak or something.

BTW, that 20-50 Valvoline racing is what I like to run.

Did you start out with non-synthetic? Hopefully yes, if you were seating new rings.

jhowell371

Forgot to ask, how was the oil consumption on the trip home?

Tiger03447

When you had the guy check over the head, did he do a valve spring check? Sometimes a weak valve spring will give a quirky idle. Check it with a vacuum gauge, if the needle jumps around on a regular basis, that could be an issue, but not 4 quarts worth. what do the plugs look like? If they are all oily, the rings may not yet be seated.

mikehayes

As mentioned, I run 20W50 VR1 also. Currently it has about 2 quarts of burnt VR1 mixed with 4 quarts of 10W40 "Havoline" haha. I did wonder if maybe the 20W50 was too viscous for a brand new engine that could presumably generate higher oil pressures. I certainly feels less encumbered with the thinner oil in it.

mikehayes

As mentioned, about .5 quarts after 9 hours of continuous highway driving.