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Smoking like a chimney - but only sometimes

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I've been noticing an unpleasant problem with my 6 as I drive it more. There are some quite long steep hills where I live (it's a river valley). I have to go down them in 2nd using both engine and brakes to keep the speed down. At the bottom when I stop - still on the incline - the car is smoking like crazy - blue oil smoke. 100 yards further down the road (on the level) it isn't.

I figure it's oil getting in through the top end somehow (swag though) due to the incline, but I also noticed it last night when I came to a halt after I'd been accelerating uphill. I did a couple of runs to try to see what was going on - If I kept the revs below 2500 it didn't smoke, above 4k it smoked for a minute or so then back to normal.

Caveat - the car is new (to me). It is running a little rich, but not grossly so, and it indicates 63k on the odo, which with the old titles I have seems reasonable, so it's not a totally knackered engine - it pulls fine w/o smoking.

I haven't done a compression test, but I can't see how it's the rings - I'd expect it to smoke all the time. It's not overfilled with oil and the oil pressure is fine (>50 at all times).

I'm confused as to what it can be. Anyone ever see this? Or care to hazard a guess?

/ubbthreads/images/graemlins/confused.gif
 
Compression test will tell for sure. Sears has testers for around 25 bucks and it's a good investment.

I'd vote valve guides.

Run a compression test and then put a tablespoon of oil in the spark plug hole and run it again (the infamous "wet test". If there is a noticeable improvement in compression then it is the rings. If it remains the same then you're looking at something in the valve train. Probably you'll find one cyl. that is much worse than the others and that will be your culprit.
 
/ubbthreads/images/graemlins/iagree.gif Only way to figure it out is with a compression tester, and valve guides would be my bet too.
 
Drove up to Sears. Bought the gadget, ran the test. Here's the (averaged) #s, but I need a little help interpreting just how bad they are. Forgive the dots, it was the only way I could find to line the columns up.

From the search I did, it looked like the consensus was that 120 was ok, so it looks like #2 is low. Anyone care to hazard a guess as to how long before a rebuild will be necessary?

Cyl...Dry PSI..Oil PSI
1.....130........145
2.....110........145
3.....130........152
4.....120........148
5.....125........190 (!)
6.....130........175

Two points -
1. If you never did a compression test before (like me), a turkey baster was a great way to get the oil into the hole rather than onto the exhaust manifold.
2. If you live in a townhouse development (also like me), don't fire the car up right afterwards to clean it out when the neighbour's kids are playing outside. They nearly called the fire brigade...

Thanks in advance, Alan
 
well... so much for the valve guide idea. The extra oil in the holes forces down the sides of the piston and helps make a better seal. In english... you've got too much clearance in the piston/ring/walls...

But you knew that...

How long before you need to rebuild it? Tough to say. How long do you want to keep the mosquito population under control in NY ??? If it's smoking now it isn't going to get better. You could put a quart of "Motor Honey" in it and cut down the smoke for a week or two at a time.

Problem is that if oil is going up then unburnt fuel is going down so you're going to make a mixture of fuel and oil that is not going to do your bearings any favors.

Sorry that this is your early introduction to this car but at least you caught it before things went really wrong and you ended up throwing a rod through the block.

Others may point in a different direction but if it were mine and nothing sounds like it's knocking in the bottom end I'd milk it gingerly for a few more local runs until fall.

Once it's apart you're in for the typical "might-as-well" stuff and should probably have all the bearings checked at least if not replaced, head rebuilt, block re-bored, new pistons, etc etc etc.

Good Luck and welcome to the Forum!
 
At which point it gets to the "might-as-well put a V8 in there" stage...

Actually it's not smoking much at all - really only on hills like I said before. It's not burning much oil either - in 300 miles under a pint. I've had new cars that got though more than that in their first 300 miles. (A lot more actually, and mobil 1 was much more expensive now I think about it).

Thanks for the advice, I think I'll just keep an eye on it for now. If it starts using oil egregiously I'll do something about it. If not I'll figure out whether to rebuild or bastardize it over the winter.

At least its not rusty (yet)...
/ubbthreads/images/graemlins/driving.gif /ubbthreads/images/graemlins/england.gif
 
True that the compression is a little uneven, & maybe a bit low.
That does not explain why the problem only happens on a hill. I suspect that more than the normal amount of oil collects in one end of the top end, when going up or down hill, due to less drainback holes being available. This floods the valve guides which may have less than optimum sealing. I wouldn't worry too much about it until it gets much worse. In the mean time, plan on an overhaul when time & finances permit.

When doing a wet compression check, only a very small amount of oil, about two cc's, is needed & it should be exactly the same amount in each cylinder. The combustion chambers are very small & even a little oil can raise the compression ratio & gage readings. This was probably the case with cylinders number 3, 5, & 6. Especially # 5.
D
 
My advise is to drive and enjoy , there is little harm in some smoke and the rings might loosen up a little(I think some are stuck like the oil scrapers). But long term you will want to freshen it up, so start a slush fund!!
MD(mad dog)
 
The smoke sounds like valve guides to me. Are you using 30+ oil? Thin oil will amplify the problem. What crank case ventilation system are you using? Make sure the PCV is working properly (if you have one). A simple and quick test for valve guides is to back the car down from moderately high RPM's, then WOT. If a cloud develops, its valve guides allowing oil to pass through to the cylinders. I know a few people that re-do the head with a re seat of the valves, knurl the guides (rather than replace them) and resurface the heads with out putting new rod bearings and main bearings and RINGS only to find it should have been done and would cost a little over $100 in parts for the additional work. Drive it and enjoy until you just want to freshen up the engine
 
This may sound stupid (its my specialty) but I would change the oil and make sure you have the correct amount of oil in the engine. The smoking on the hill puzzles me too.
 
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