I have a 1993 Toyota Corolla with ~152K miles, which is using 1 quart of oil every 500-600 miles. Does blow some blue smoke out the tailpipe on startup and while on the road.
Took the car to the dealer. Did a dry/wet comp test which went like this: #1:170/220; #2:180/195; #3:180/215; #4:190/210. (These seem like pretty good compression to me – and the power is actually pretty good in the car.)
Dealer pulled the head off, noted some worn valve seals and some out-of-round wear in the cylinder, with a .001" measured out-of-round wear in 3 of the four cylinders.
Dealer’s “master technician” estimates that ~60% of my excess oil consumption is from worn valve seals and ~40% from the worn cylinders – he says that replacing the rings and valve seals will eliminate most of the oil consumption problem.
Anyone out there: I wouldn’t have thought that a mere .001" would contribute to this much excess oil consumption. Any comments?
Thanks.
Modern engines are built to pretty tight tolerance. Any more and you’d be losing compression, not just losing oil!
I’ll also mention that if the guy’s estimates are correct, just replacing the valve seals should bring the oil consumption back down to acceptable levels. I can’t imagine doing the rings is going to be cheap!
This is true, rice burners are sensative about theit oil seals
Is it pennywise and poundfoolish to have them just replace the seals without doing a full valve job with 152K miles?
Also, does replacing the rings, without reboring the cylinders given that out-of-round wear, fix the excess consumption caused by the cylinder wear…?
You can have very good compression and still burn oil past the rings. What happens is that over time the oil control rings (the lower one on each piston) will seize in the piston ring land (groove if you will) and will not wipe the oil from the cylinder wall on the piston downstroke.
This ring seizure can be caused by sludging of the oil, overheating episodes, and just plain old carbon deposits over time and this ring has very little effect on the compression.
My feeling is that this is the cause rather than the .001 of wear (assuming it is measured accurately) and the master tech SHOULD be aware that the oil control ring could be the problem.
If the rings are replaced you should be aware that the rod bearings, and preferably the main bearings also, must be replaced at the same time. One does not reuse bearings as failure may soon follow.
This also opens up the additional can of worms because this means the crankshaft journals should also be miked and if they’re out of spec the crank SHOULD be turned.
At 152k miles and with the head removed then what about the possibility of the cylinder head needing to be surfaced? At that mileage a valve job should be performed, not simply replace the seals.
The master tech mentioned is referring to what may be called a “minor overhaul” or an “in-car” overhaul. It can be done but it is not a proper, recommended procedure and the results for the long haul could be iffy.
JMHO to use as you see fit.
(And to bring up yet another point; just how does this master tech propose to eliminate this .001 out of round he claims is the problem?)
Do all that and you still have a 15 year old car with 152,000 miles on it. I have learned the hard way that it’s not always wise to sink a lot of money into an engine when the rest of the car is worn out. Maybe you could just live with the oil consumption for the next 100,000 miles or so.
I agree with you BLE – wouldn’t consider doing all that work in a car of this age – it’s only going to be used for 2-4K miles/year, as the extra car for our two teenage kids. I’d consider trying to live with the oil consumption, but I don’t want to have to be the one to remember to check it, and I don’t trust our kids to remember to do so – so the cost of reducing the oil consumption is in part to assure that the kids don’t destroy the engine by driving it with reduced oil pressure…
I think OK’s comment about the oil control rings may be on target – might be able to get the rings and valve job for close to 2K – which is also a lot to put into this car, but that’s cheaper than replacing it… it’s no longer an issue of “protecting the investment” – just a question of keeping a vehicle for our kids get around town!
The mechcnic is basically correct. My question would be how a very good car like a Corolla is this worn after 152,000 miles. The best solution, if you want a fix, is to find a good used engine from a wreck. Overhauling the engine is definitely not cost-effective, nor is installing a rebuilt unit.
I’m not suggesting for one minute that the OP go in and sink a small fortune into turning the crankshaft, bore cylinders, perform a valve job, etc., etc. (Basically a complete overhaul)
My point is that there is a proper way of doing things and a short cutting, half-axxxx method; the latter of which may work for a while or may not work for more than a week.
If the tech drops the rod caps, reuses the bearings (which are now disturbed from the original positions), and the engine is knocking 500 miles later who is going to the blame for this?
If the cylinder head is reinstalled with new seals only and a head gasket pops 500 miles later due to the cylinder head surface being distorted (simply loosening the head bolts can do this), then who will the finger be pointed at?
If the new set of rings do not seat properly into an egged bore (which a hone will not cure), who will be cursed?
What the OP could consider (and I’d even consider it on my own car) is to add a can or two of SeaFoam to the engine oil and see if this helps to free up the oil rings. Maybe even removing the spark plugs, pour some SF into the cylinders, reinstall the plugs, and allow it to soak overnight would help. (And of course, do not crank the engine over the next day without removing the plugs, disabling the coil, and placing a few rags over the plug holes to catch any SF that is blown out. Cranking it over with liquid in the cylinders could cause a hydrolock.)
Too late now but no way I would have pulled the head on an engine with that mileage. Just no good place to stop. Do the seals and have to mill the head, do the valve job without the overhaul and oil usage will increase. Can’t do the rings without the bearings, then why not do the other parts. Just no good answer except put a used engine in, or check flatness of the head and do the seals and be done with it.
I question the technique of checking the cylinder taper/out of round with the pistons still in.I can’t imagine a mechanic that would give you any kind of warranty or even a fiqure in regards to oil usage.What kind of oil consumption figure would you accept after rings and valve seals.I would give no warranty unless a total rebuild along with all required machine work was performed.Find a low mileage engine and replace.