Rebuilt engine, Drinking oil...

[91Caprice9c1]

94 1L 5-spd. Bored 0.030 over, valve job, new valve seals, new pistons, rings, etc. Rebuilt from the ground up. Machine work done by a reputable shop, Assembly done by me, a reputable builder. Car runs like a top, compression is perfect, 210 across the board. At highway speeds 60+mph, a HUGE plume of smoke emits from the exhaust. It is caused by oil from the pcv system finding its way through the intake. New PCV valve, free flowing fresh air inlet tube, and free flowing pcv to intake tube. This much so far I know for a fact, so why is this happening?
The only thing I can think of, is that the aftermarket PCV valve is insufficient. I wouldn't be surprised at this, as last week I had to cut my own TB gasket because the aftermarket ones I acquired (3 different gaskets) allowed a sizeable vacuum leak at the mating between the TB and the intake manifold. Any ideas before I try a pcv valve from the dealer? I maintain a fleet of 20 of these cars, and this is the second car to have this problem. The other one is high mileage and I haven't gotten to inspecting the pcv system - But for all intensive purposes this engine is practically brand new!

-MechanicMatt

[Rpg0]

Matt, I'm kinda stumped on your 3qts a week... I wouldn't think that PCV would pass that much in a week. But as you stated, 210# in all 3 cylinders, rebuilt head and new rings. I have to assume the rings were fitted and installed properly being a fresh .030 over?

Funny story, My wife bought a van many years ago, I took it back to the mechanic found on the door sticker for some service and he kinda freaked out when I pulled up. After I started talking with him he pulls out a 6" stack of service records for the thing(no wonder he freaked eh ! Lol), the last one being where the previous owner had noticed low oil... and refilled it, it goes low again, refilled again... then calls the mechanic as they hear the engine knocking at a light nearby. They pull it into the garage and it's low on oil again. No leaks, no oil smoke. The Engine was toast. When they started to disassemble it they pulled off the valve covers and they were full of oil. All of the oil passages going back to the oil pan were completely closed off with sludge. Before this they never serviced the engine all of the service was to the inside electrical, brakes, driveshaft, rearend and transmission. This was during a period of 3 years and he figured they never changed the oil or filter just added oil. So we reaped the benefit of a new factory engine with darn near a new van from a dealer as they got it on a trade-in.

Not saying this is what's wrong, but seems kind of unusual with it being a fresh rebuld and all.

Good Luck,
RPG0

[91Caprice9c1]

Well, I haven't actually measured the rate of consumption. I'm just trying to figure out why the pcv system is sending oil into the intake. I think I read somewhere that there is a problem in the heads of these cars with oil draining which might lead to a pooling of oil in the head eventually pouring it into the head?

[99Metro]

Supposedly there is a little brass oil pressure reducer (orifice) that goes between the head and the block and mounts in the block. I am certainly no expert, but I would think that if that was missing, you'd have excessive amount of oil going to the top the cam/valve cover area and be causing what you see. I did rebuilt my motor a couple months ago, but due to a block issue, ended up installing a JDM myself for cheap.

just my 2 cents

[idmetro]

91Caprice;
I was reading an interesting post on the teamswift board: http://www.teamswift.net/viewtopic.php?t=27274 Have you checked your oil pressure? Perhaps you are having a similar condition with very high oil pressure causing you grief by pumping oil into the head faster than it can drain??? There's another post over there regarding modifying the head gasket to insure that oil is freely able to drain back from the head http://www.teamswift.net/viewtopic.p...asc&highlight= Maybe one of these issues will apply. Please let us know when you find a solution.

[99Metro]

Here is what I found on the restrictor:

Cylinder Head Oil Restrictor On
1989-95 GM 1.0L Engines

Beware of some confusion on the cylinder head oil restrictor used on 1989-95 GM 1.0L engines. This engine uses hydraulic lash compensators in the cylinder head and the restrictor is used to control the amount of oil directed toward them. The confusion has been the correct location of the restrictor. Apparently some engines have it installed into the cylinder head and some in the cylinder block.

Regardless if the restrictor is screwed into the block or head, it also prevents excessive amounts of oil into the cylinder head area. If the oil control plug (restrictor) is not installed, the additional oil may overwhelm the PCV system and cause oil consumption.

When properly installed, this restrictor, Part #96051574, also acts as an anti-drainback valve and prevents lifter noise at start-up. This engine is made for GM by Suzuki and they also offer this restrictor under Part #11112-73001.

Here is the direct link:
http://www.rebuiltautoengines.com/suzuki-articles.html

[91Caprice9c1]

Very interesting! Thank you guys for the information, gotta love these forums man. It may be a while before I post back with any findings as a few other geos have more pressing issues at the moment. But I will definitely let you guys know what works for me eventually. Thanks again!

-MechanicMatt

[idmetro]

Matt;
Good luck on your quest. With 20 Metros under your care I'll bet you have learned a bunch about these cars and we look forward to hearing how you've solved various issues that have come up.

[91Caprice9c1]

Well gentlemen, as promised, I'm back to report my findings with regards to my Metro with the fresh engine rebuild that was drinking oil like no other. After a slue of more urgent repairs on my fleet, I finally had time to take a closer look at said problem child. As it turns out, it was the aftermarket head gasket's inability to drain oil from the head back to the crankcase that was creating my problem. My solution, which has been covered by other forum members, was to use the old gasket as a template to cut larger drain holes in the new head gasket. The impressions left in the old gaskset allowed me to transfer the necessary size and shape holes to the new one using a cutting wheel on a die grinder. That simple! No more smoke at sustained high speeds, no more oil consumption through the intake PERIOD! After putting the poor metro through the ringer on the freeway, I parked it in the service area, popped the hood, removed the top half of the air filter housing, to discover an absolutely DRY air filter, DRY bottom half of housing, and DRY Throttle body. Thanks again for everyone's input.
-Matt

[idmetro]

Matt;
That's AWESOME! Thanks for the update, I'm sure it will save a lot of time and effort not to mention frustration.

[dookeye]

Greetings everyone, this is my first post here.

I have owned a Sprint and a Metro XFI previously,
and just bought a 92 Metro recently.

I am posting here because my Metro has a similar problem:
It is burning a great deal of oil, it goes through at least a quart every 100 miles; I have tried using thicker oils and a viscosity increasing oil additive and they are not effective.
It is definitely burning it, as it puts out constant bluish smoke.

The odometer reads 73K, and I tend to believe that it is 173K on the engine.
I do not believe this engine has been rebuilt or had major work done.
I just did a compression check, and all three cylinders registered solid readings of about 195.

I have pulled the PCV and it seems to work as it should.
There was some oil in the top of the throttle body when I first bought the car, but I tend to think this may be because the previous owner had overfilled the oil; it appeared to be close to a quart high.

With the solid compression ratings, I think I can rule out a problem with the rings and also with the valves and valve guides. My thinking has been that most likely I have one or more of the valve seals that have failed; due to the amount of oil consumption, I would guess that one has completely failed: like fell apart basically.

However from what I have read here, I am keeping in mind other possibilities, like the head gasket, and also I have read here about an oil pressure regulator? valve? that is mounted either in the block or head. I was wondering just exactly what would happen if this was not working? would the top of the head fill up with oil? and would the oil then back up through the PCV system and into the top of the throttle body?

I am going to start tearing it apart today, so I will let you all know what I see as I go, any suggestions or guidance would be greatly appreciated.

I am also going to replace the timing belt while I am at it, since I don't know when or if it has been replaced in the past, do Metros usually require anything else replaced along with the belt, like a tensioner or guide or something?

[91Caprice9c1]

Originally Posted by dookeye

With the solid compression ratings, I think I can rule out a problem with the rings and also with the valves and valve guides. My thinking has been that most likely I have one or more of the valve seals that have failed; due to the amount of oil consumption, I would guess that one has completely failed: like fell apart basically.

However from what I have read here, I am keeping in mind other possibilities, like the head gasket, and also I have read here about an oil pressure regulator? valve? that is mounted either in the block or head. I was wondering just exactly what would happen if this was not working? would the top of the head fill up with oil? and would the oil then back up through the PCV system and into the top of the throttle body?

Extremely worn valve seals are definitely a possiblity to keep in mind, and I would look into these first. Since the time when I originally started this post, I have rebuilt 4 more metro engines. And along with the experience have gained the following insight: There is an oil control check valve that limits the amount of oil pumped into the head from the block. With the head and (head) gasket removed it should be clearly visible mounted in the block around the number 1 cylinder (if memory serves true). Now, the head gaskets are designed with this check valve in mind, and the drainback holes cut into it are small enough to keep adequate oil in the head for lubricaiton. When I first assembled the engine associated with this post, I had not included that check valve during assembly. This basically resulted in way too much oil going to the head, which the gasket was not designed to drain. Now I have on purpose built two engines this way, (without the checkvalve) but of course enlarged the drainback holes in the head gasket to compensate, and they appear to run much stronger than the other three engines I built WITH the checkvalve and un-modified head gaskets. None of the engines to date, drink oil through the PCV system.

Originally Posted by dookeye

I am also going to replace the timing belt while I am at it, since I don't know when or if it has been replaced in the past, do Metros usually require anything else replaced along with the belt, like a tensioner or guide or something?

No. Typically, just the belt is adequate.

MechanicMatt

[dookeye]

thanks much for the response and clarification,

None of the engines to date, drink oil through the PCV system.

yeah, it didn't seem likely that that much oil could be running all the way back through the throttle body.

There is an oil control check valve that limits the amount of oil pumped into the head from the block.

I'm guessing that if this valve fails, it will fail open?
interesting modification that you did, doing away with the valve entirely= one less thing to go wrong.

How often have you encountered head gaskets that have gone bad with Metros? I have not seen much anecdotal evidence of this which again steers me towards suspecting valve seals on my car.

[91Caprice9c1]

Originally Posted by dookeye

yeah, it didn't seem likely that that much oil could be running all the way back through the throttle body.

On the contrary, that is exactly what was happening in my case. Because I left out the check valve, and hadn't yet figured to motify the head gasket, oil was backing up in the head and flooding through the PCV system and into the thottle body where it then became part of the combustion process, and blew huge plumes of smoke out the tail pipe.

Originally Posted by dookeye

I'm guessing that if this valve fails, it will fail open?

The only way for this valve to fail is if it clogs or if its not there at all. If it clogs, the head looses lubrication. If its not there, too much oil will shoot into the head.

Originally Posted by dookeye

How often have you encountered head gaskets that have gone bad with Metros? I have not seen much anecdotal evidence of this which again steers me towards suspecting valve seals on my car.

[/quote]
The only times I have seen head gaskets go bad on metros is with either old age, or overheating - the general causes of head gasket failure (in non-high performance vehicles at least). Aluminum is much more prone to failure through excessive heat cycling (than cast iron). An aluminum head, or an aluminum block for that matter has a given number of heat cycles it can endure throughout it's service life, until it becomes too soft to maintain a flat surface with the head gasket. At this point in it's life, the head and block become insalvageable, even machine work will only temporarily restore it's use. I could go on, but the point is, a head gasket does not just fail, and if it does, it usually will not cause oil consumption into the combustion chamber, at least not until long after it starts to manifest in other disturbing symptoms; such as coolant in the oil, oil in the coolant, water consumption into the cylinder, and compression loss across adjacent cylinders.

What I meant to suggest earlier, is that perhaps someone had assembled your engine incorrectly, as I had, by not installing the check valve into the block before installing the head. And seeings how your compression is strong, and a blown head gasket will not cause oil consumption as a solitary symptom, you are left with either A) the engine is assembled improperly B) you have bad valve seals C) your oil pump is over pressurizing the system (stuck pressure relief valve you mentioned earlier) and not dumping off excess oil back into the pan, or D) the oil drainback holes in the head gasket have become clogged with oil sludge from old age.

Also note, that when i said that none of the engines drink oil to date, i was refering to the engines after I had figure out the relationship between the check valve and the drainback holes. No checkvalve means you must enlarge the drainback holes. If you do not enlarge the drainback holes, you must install the chekcvalve. If you have no checkvalve, and un-modified drainback holes in the head gasket, you will get oil through the throttle body via the PCV system. I apologise if I'm a bit scattered, i really am trying to clarify lol its a bit late.

MechanicMatt

[dookeye]

no you have been very informative,
just some normal slight misunderstanding on my part because of my ignorance.

It boils down to I guess the valve seals still being the likely culprit; I am just curious if it will be easy to tell if the seals are shot when I pull off springs/lifters, I have not run across a procedure to test them in my manual yet, I suppose I will be able to see gaps between the seals and valve shaft, or damage to the seals.