This H23 engine was rebuilt about 25k miles ago and has burned oil since I got it from the builder (1qt/200 miles). Originally I thought it was a problem with the head since the rebuild was focused on the bottom end. I started by replacing all the valve stem seals but nothing changed. After doing some research I thought that even with new stem seals, worn guides could still cause oil consumption. I pulled the head, got a valve job, new exhaust guides, and seals all around. After putting the head back on the oil consumption continued. The seals put in by the machine shop don't appear to be from the dealer because both sides have silver springs and I know the exhaust should have a black spring. Leak-down numbers are strong: 5% or less on all cylinders.
My questions are:
Could non-OEM stem seals possibly be the problem?
Do all these signs point at faulty oil rings?
Why would compression rings be fine but not the oil rings (if any one is thinking break-in problem)?
Jese christ man, that is blown-motor umbers right there. But your engien being newly rebuilt is a really interesting situation.
I'd say it was the rings, but if the leakdown test came back good, I don't see what the issue could be. Could you try OEM valve seals? Why didn't oyu in the first or second place?
When I did the valve seal replacement myself the first time I did use OEM valve seals but the problem persisted. I am unsure as to the brand of valve seals the machine shop used after they pressed in new exhaust guides. As stated in the original post, the leak down numbers are strong but I know this only indicates the condition of the valve-to-seat seal and the compression rings.....tells nothing about oil rings and guides/seals.
On another forum, one guy suggested using supertech viton valve seals b/c they are much better than OEM? I questioned him on it but didn't have a good reason.
What are people's opinion on this scenario:
I can consistently get the motor to smoke by going down a steep hill in gear and 0% throttle. It does NOT smoke on the way down the hill but when I get the bottom and begin the give the engine throttle to go up the other side, big plume of smoke. I have heard different opinions about this symptom. Some argue the high vacuum pulls oil past the valve seals....some argue it pulls oil past the oil rings. Any experience?
No experience, but I have to say, it sounds like the rings are bad, and if the leakdown test doesn't test the oil rings, then that is a possible red flag. Man, this is a ****ty situation to be stuck in. It's gonna either cost you a bunch, or you're gonna keep eating oil like mad...
I am almost convinced that it is the oil rings but I don't understand how the engine builder could have installed the compression rings properly and then screwed up the oil rings.
I can't remember if the H23's have a silicone impregnated aluminum bore like some of the H22's, but if it does and it is not honed to a proper finish, then you will have this problem. If the machine shop honed and finished the bores to the degree as cast iron bores your more than likely gonna have oil consumption problems
As for it being the seals, the O.E ones are good, but some aftermarket ones are crap and will give oil issues, but this does not sound like your case as you have changed the seals twice. How where the valve guides?
The exhaust guides had to be replaced but the intakes were in good shape. When the engine was rebuilt it was sleeved and honed by darton. Other internals include JE 9.0:1 pistons, and crower billet rods. I talked with one machinist and he said part of the problem may be related to the very low tension oil rings that come with performance pistons?
low tension oil rings should not cause the amount of oil consumption that you are having. A lot of people are running JE pistons or other forged performance pistons with the ring package given and don't have major oil issues that you have.
another problem may be the ring gap alignment. If the gaps are or close to being aligned, then you will get oil consumption.
And one more consideration, broken ring land. if they caught a ring when inserting the pistons, it could have broken a ring land. depending on the land that is broken, you may get a good compression and leak down readings but have the oil issues that your having.
Either way, your doing more damage by driving it. Rip that sucker apart and get it fixed before it costs you more money.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
