How do I determine if the problem is upper or lower end?
I did a compression check and it was 150psi across all
4 cyl. Where do I start looking?

The engine was great until it jumped time, broke valves and dented pistons. The head was replaced along with all gaskets and we smoothed out the pistons.

I can literally drive 30 minutes and it will be one quart low, all smoke out the exhaust, no leaks.

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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans, Jamex Springs.

http://www.sethirdgen.org/octride.htm

JM,

At this rate, the car will have to have a second gas tank just for oil.

Since the compression is respectable, I'd guess the rings are not completely gone. Is it possible that the oil for the head/OHC is getting into the chambers? A gasket mismatch, perhaps? Minute cracks in the head from the oil passages to the chambers?

It's also possible that the PCV system is allowing excessive oil to be drawn through the vent system and through the intake. Does the rate of consumption change if the PCV is disabled?

A good place to start would be to check all of the spark plugs to determine if the problem is general or localized in one or two cylinders. If the problem is only in a cylinder or two, it doesn't look good. At that point, whatever the problem is, it will require some tear-down.

Cross your fingers and hope it's a screwed up PCV or misaligned gasket.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

I don't know, will try tommarrow.
Three of the four plugs are dry and slightly black. One plug is very wet and black...now what?



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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans, Jamex Springs.

http://www.sethirdgen.org/octride.htm

Well you got LOTS of oil going into that that one cylinder then. Check the seals on the valves, check the cylinder walls for deep scratches, or most then likely a bad gasket somewhere. Take the head off and have a look.

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92 Z28 L98 350
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Ported stock heads, XR270HR-10 cam, TES headers, Crane AFPR, Flowmaster catback, MSD ignition components.
Best ET 13.5@105 mph
"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)
Click here to see my car at Truspeed.org

Check out TruSpeed at http://www.truspeed.org
Check out the Bin Archive at http://www.truspeed.org/bins.html

JM,

If this is the same cylinder that had the worst valve kiss-off problem, the damage is probably not yet repaired.

The wet, black plug is probably oil fouling, so the search should concentrate there. If you're lucky you might have a bad valve guide on the replacement head. If it is a reman, I wouldn't be too surprized. The common failure mode for OHC engines is valve interference when the timing belt finally lets go, and bent valves and guide damage aren't that uncommon. A reman head might have had a guide reamed straight and knurled as a "repair". If it weren't such a PITA on an OHC engine, you could remove the valve spring and check the valve stem for side clearance. Still, that's a LOT of oil to be sucking past a valve guide.

You might also have a leak in the oil supply passages to the OHC journals and lash adjusters. Study a design schematic of the engine and determine where the oil supply to the head is routed. If it is adjacent to the problem cylinder, you might have a head gasket sealing issue. If you suspect that, you could retorque the head bolts to see if the symptoms change.

If you're not so lucky, the valve interference you experience may have distorted the piston top a little more than you presumed. Even though compression is good, oil control may be completely screwed on that one hole. That would be getting you into the lower half of the engine, and deeper into your wallet.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

That was our first thought but the badly damaged one was the #3 piston and the oil-fouled one is the #4 piston.
I know it's a lot of oil to go past the valve seal but is it possable? I mean what's the most oil that could pass a valve seal even if the seal was missing? 1 quart a day?

The oil passage comes straight up the middle between the #2 and #3 pistons. #3 piston was damaged but it is not oil fouling, #4 piston IS oil fouling.
My wallet is empty from the reman head, gasket kits, timing chain/adjuster kit and timing cover case with intergrated oil pump. Total coat with me doing the work is a little over $700. That hurts.
Next import that throughs a chain/belt gets launched off a cliff without thinking twice

Thanks Vader!


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans, Jamex Springs.

http://www.sethirdgen.org/octride.htm

JM,

Just for squats and giggles, you should check the PCV system. I've seen some engines that have the PCV fitting route to one intake runner instead of the carb/TB base (1970's Ford 2.3L comes to mind). If the PCV were sucking a lot of sump oil, it could all end up in one cylinder. Coupled with a few leaking valve guides/seals, it could account for a lot of oil in a short time.

How did the cylinder walls appear when the head was removed? I would guess that any ring damage and wall scuffing would have been fairly apparent, but am curious in general.

Is there any unusual noise when running the engine? A rod knock or piston skirt dragging are pretty distinct noises. It's possible that you did more damage to the piston than you originally thought, like cracking a pin boss, ring land, etc. The cold compression check might still be good, but higher forces could be flexing the piston around when the engine is running.

It's still possible that there is something wrong with the head, like a crack that is allowing oil from a journal or lash adjuster to flow into the chamber or into one of the valve ports. A crack from an oil gallery to an intake port would yield a good compression test but a lot of oil consumption. I know that the GM 2.2 DOHC (Saturn) has some very tight tolerances in the head castings due to the complexity of lubrication, ports, coolant passages, and valve train layouts. A little crack could go a long way. Your engine might be similar in design and have very thin castings as well.

I hope you find it, or at least get some cool videos of it going over the cliff...

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

Throw it in the trash where it belongs and buy a 3rd gen. Then put valve guide seals on it.

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"So many Mustangs, so little time..."

The car in question is a 1992 nissan Stanza XE, 157k miles. I know where it belongs but before I can sell it to get my fix money back(I'm not lookin for profit) I need to fix the smoking/burning problem.

As for buying a 3rd gen, check my sig......
or this older site. http://sethirdgen.org/octride.htm



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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans, Jamex Springs.

http://www.sethirdgen.org/octride.htm

Sorry (NOT!!!) I just had to yank on you a little bit.

I'd be inclined to suspect that the head you got is FUBAR. Get another head from the junkyard, it should fix the problem. I doubt there's any kind of a ring or other bottom end problem.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited January 01, 2001).]

I'm still planning on trying disabling the PCV, then changing the valve seals on that #4 piston, re-torque the head and then change the head gasket again before it goes over the cliff(digital camera I promise).

Cylinder wall were great even with 157k miles on this 1992 Nissan Stanza.

No unusual noises untill the tell-tail ticking when it gets low on oil after 2 days.

The head is a reman and is warrented for 30 days or 30 minutes whichever comes first.

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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans, Jamex Springs.
http://www.sethirdgen.org/octride.htm

[This message has been edited by John Millican (edited January 01, 2001).]

edited

[This message has been edited by John Millican (edited January 01, 2001).]

JM,

Just in case, you might want to call the supplier of the reman head and warn them that you think you might have a problem. That should give then time to get another one on hand so that after you exhaust all other possibilities you can excersise your warranty.

Even if the problems don't completely disappear, any doubts about the head can be removed. I would even pressure them for a new gasket set, since the loss of the gaskets would be due to the suspect head, not your negligence.

Changing the head again can't be any fun, especially on a Sentra, but it might give you a car to sell or run instead of scrap out.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

Maybe the car just doesnt like you. Or it could be a racial thing