Valve guide oil seal question...

Worn (or decomposed) valve guide seals dont always tattle with a puff of smoke on a cold start. Depends on the engine itself and design, as well as the degree of oil leakage.

But they OFTEN betray the problem by the blue oil smoke puff on cold startup.

I have had cars that behaved like they had worn seals, but really never used any significant oil.

A friend of mine had a Honda that ate the seals after he drove the car on the Autobahn and overheated it. It began to use oil. We pulled the rubber seals and they crumbled like popcorn. Replacing them fixed the problem - for a while.

It is my belief, and I am sure it will be challenged, that most oil consumption problems either stem from leaks, or from worn oil control rings/cylinder wall issues.

"hls" wrote in news:_OXEi.53181$ snipped-for-privacy@newssvr29.news.prodigy.net:

That's my thinking too, but I wanted input from the knowledgeable people here.

I've been told that worn valve guide oil seals can cause excessive oil consumption in-and-of themselves, while at the same time NOT causing a puff of smoke on startup.

Worn out valve stem seals usually create a puff of smoke on acceleration after prolonged idling. On a cold start, the exhaust system is generally cold enough that you don't get the puff of smoke.

And valve seals are the most likely cause of high oil consumption.

How are worn bearings the most likely cause of high oil consumption. Unless you are talking about front and rear bearings so loose the crankshaft bangs the seals out.

A little bit of oil can make a lot of smoke.

Always and never are always known to never happen.

But worn valve seals usually do exhibit that behaviour.

And valve seals are another cause of high oil consumption.

A little bit of oil can make a lot of smoke.

Always and never are always known to never happen.

But worn valve seals usually do exhibit that behaviour.

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Hey, Tegger, I read all the responses and was afraid something important was gonna be missed, but it was finally covered--by John S. Main bearing wear does cause high oil "loss" esp. on certain engines, Chev V-8 small-block for ex., when they wear (and it doesn't take all that much) and let the crank fall down and "wallop" the rear main seal so as to cause too much clearance around the crank. Can cause high oil "leakage", which results in high oil "consumption". Thanks, John S, for mentioning that unkind scenario. s

Tegger wrote in news:Xns99A669AF7C621tegger@207.14.116.130:

So many replies to this thread I don't know where to start. I therefore reply to my original post.

The reason I asked the original question has to do with a weird observation with my engine, which happens to be a Honda product and has almost 300K miles. I change my oil every 2500 miles without fail, and have done so since the warranty ran out in 1994.

For the longest time the engine used no oil that I could see. Then suddenly it started using oil at about the rate of 2500 miles per quart. It stayed this way for several years. Then summer 2006 it dropped precipitously, to about 1500 mi/qt, and as low as 1200 mi/qt at the very height of summer.

The car does NOT leak oil, so it's surely being burned.

I tried different viscosities, different brands, in an attempt to improve matters. Even tried Mobil-1 0W-40. Nothing I tried had any effect of any kind on consumption.

But now, about a year or so later, my consumption has DECREASED. It's now running at around 1800 mi/qt. My measuring method is very precise, so I know these are accurate numbers.

Other than something to do with valve guide oil seals, I cannot fathom how this engine is burning LESS oil than it was a year ago. WTF is going on?

I considered fuel in the oil, but the oil doesn't smell like it has significant gas in it, and my fuel mileage has remained steady for more than a decade (28-30mpg). The car is driven great distances at a time, so it can't be water building up.

Thoughts, anyone?

If the oil consumption increased that much, rapidly, then something broke. My guess would be that an oil ring expander collapsed. That would allow more oil burning. Then as the oil burned carbon started to build up and that slowly caused the ring groove to fill with carbon to the point it acted like an oil control ring.

Some more oil being drawn past worn guides and seals and your burning oil.

If you want to find out do a leak down test on each cylinder.

Tegger wrote in news:Xns99A8C9E1CCD6Ategger@207.14.116.130:

In case there is anyone actually interested in my "very precise" measuring method...

My engine's dipstick spans 14mm between upper and lower marks. This 14mm span represents one liter, or about 1.057 US quarts.

I printed out an accurate scale showing the 14mm span. marking the millimeters.

1) Change oil and filter. 2) Drive car at least a half-hour, so oil is good and hot. 3) Park car in particular location. 4) After car has sat /overnight/, pull dipstick, wipe off, reinsert ALL the way, record oil level. Measure against millimeter scale to see where level is relative to upper mark. Repeat a few times to be certain. 5) Drive 1000 miles. 6) Make sure last drive is as per step 2. 7) Repeat Step 3, making sure car is parked exactly the same way as it was for the first check. 8) Check oil level as Step 4, but placing the upper mark of your scale where the oil level was the first time you performed Step 4. 9) Calculate consumption.

Example from this last change:

1000 mile level down about 7.5mm from original level. This corresponds to 0.5357 liter, or 0.5661 US quart. 1000/0.5661 = 1766 miles per quart.

"Steve W." wrote in news:fc7c51$fjq$ snipped-for-privacy@aioe.org:

I would never have thought of that.

If carbon is acting as a control ring, is there any harm in just letting it stay that way?

And so I will. What should I expect on the leakdown test?

With that much mileage, and with sudden onset, my guess is that you have broken a couple of rings. Each oil control ring that breaks kicks the consumption up in a pretty big step. Consumption might go back down a little as the crack in the ring plugs with some blow-by sludge, but its hard to say.

Well with 300K on it, it would depend on what the rest of the vehicle is like and if you want to spend the money on a rebuild.

Well with a cold engine you will likely find at least one cylinder reading higher than the rest. Listen at the oil fill when you are checking them and you will hear the air going past the rings.

"Steve W." wrote in news:fc9445$9co$ snipped-for-privacy@aioe.org:

There's no rust on the body, so fixing the engine is a possibility.

My concern is primarily that a rebuild may not be worth the effort if a broken ring has damaged the bore. I'm only allowed a .010" overbore.

Thanks.

The car runs just fine. It idles quite smoothly and has good power at all speeds. I'll get the test done at some point, but it's not a panic right now.

If you're getting more than 1000 miles per quart, I wouldn't worry too much about it. Failed oil rings don't usually hurt the bore too much- a failed COMPRESSION ring will, but you'll KNOW if one of them goes (sudden drop in power).

Only .010 overbore allowed? Stupid disposable engines. But then, anything can be sleeved, but it sure does make it less economically appealing.

Steve wrote in news:2MmdneSUwedjGXTbnZ2dnUVZ snipped-for-privacy@texas.net:

That's my thought too. So long as oil consumption and emissions are manageable, I'm just going to keep on as usual.

What Honda did here was to embed a 3mm thick iron sleeve in 3mm of aluminum. Take too much off the iron and...

I found out (just out of curiosity) that a new Honda short block is about $3,000 Cdn. With a new head and all related parts, it would cost about $5,000 to be on-the-road with a brand new engine.

I hope mine goes a few more years.

What would be involved to drive across the border and pick up a good used engine (if you can find one cheaply enough)? Would you be allowed to bring it back and use it, or would taxes and government regulations be the death of it?

"hls" wrote in news:OVAHi.9740$ snipped-for-privacy@newssvr23.news.prodigy.net:

Car parts cross the border pound-of-flesh free. Except for shipping...