catastrophic bummer

[3929R]

No catastrophic bummer but I'm still befuddled as to what happened.

I did a hot compression test- a very consistent 150 on all 4! I'm at roughly 4,500' elevation and I believe that 150 equates to 170 at sea level. The manual calls for 160 or higher. Given the consistency I did not re-test with a shot of oil in each cylinder. Should I?

I visually checked the carb dash pots and they still have oil. Coolant level in the swirl pot is fine. I didn't check the brake fluid but my servos are removed and the brake system is no longer connected to the engine (the picture earlier in this thread with the red valve/cam cover is not my engine).

I drained the oil and it looked great. No chunks, shimmer, shine, nor any notable pollution. Likewise the oil filter looked fine, though I did not cut it apart.

The only thing I've found a miss was the oil level was over full before I drained it. I would guesstimate about 1/2 quart, but maybe it could have been as much as a quart. Could this alone have caused my sudden symptoms but nothing else before?

Even before draining the oil (when still over filled) the engine was no longer blowing smoke when I warmed it up for the compression test. Now the exhaust shows a bit at start up up nothing noticeable when warmed up. It starts right up and runs great. I feel like Chicken Little! But dang it blew a big cloud of smoke!

TCS4605R said: "There is a rubber 'tube' that connects the head to the block.  The tube is located on the right hand side of the engine in front of the mechanical fuel pump.  If it gets clogged up, oil cannot drain from the head back into the engine sump.  This excess oil could then be sucked into the combustion chambers via the intake valve stems and cause a lot of smoke.  Have you taken the cam cover off?  You should be able to poke a long skinny screwdriver or welding rod down the tube and touch the bottom of the sump pan."

I started to remove the cam/valve cover but it seems to be glued on tight with gasket sealer. My thought was to use a thin putty knife to break the seal/gasket. My putty knives were not at my garage, I didn't have a new gasket at hand, and I wasn't sure this was the best approach. 

I haven't driven it yet, mainly because I was trapped in the garage by construction materials in the driveway.

Any thoughts would be appreciated.

[EuropaTC]

Hi Mark,

We all have different attitudes to what's acceptable or not in terms of guideline specs, and for me getting a consistent 150 across all 4 would be good enough even if it's not technically within the tolerance given in the manual.

More important to me would be that it's a marker against which I could judge future deterioration rather than an absolute "it's not in spec, it's knackered" type of thing. Heck, my compression gauge might be +/- 5% out and I have no way of knowing. So I tend to look for uneven compressions  -  150,120,120,150 for example, which could indicate a blow between 2 & 3.  Or 150,150,150,110 where the last one has a valve or gasket problem.

If you have a serious valve/piston ring problem then there will be big differences, far more than 10 or 20psi from spec.   Even if your 150psi is 100% accurate, that just indicates an engine with normal wear and tear to me, nothing to start raiding the piggy bank for just yet.  I'd probably re-test myself with oil in the bores just to complete the picture, but I'll bet you're at 170/180/OMGthat'shigh  with oil gumming up the bottom end   

I re-read the original post and for some reason I'm wondering if it wasn't just a plug fouling or missing a beat as you coasted to a stop at the lights ? The stutter when you started could  have simply been a temporarily over rich mixture with unburnt fuel in one or more cylinders and once that cleared everything came back on line.

I don't have a sensible reason why that should happen other than a plug nearing the end of it's useful life.  I'm aware it sounds very optimistic and overly convenient but we seem to be knocking out the usual causes for smoky engines. Especially as it doesn't seem to be recurring, which you would get with valve/bore wear. I'm told high oil levels can cause burning but again, that wouldn't be a single event,  it would be all the time.

Given the engine sounds ok I would be tempted to give it an oil & plug change and drive it with a careful eye on oil usage/pressure for the next few miles. Oh, and carry a mobile phone/credit card at all times !   

Brian

[BDA]

I think Brian, as usual, might have this figured out. It's probably time to look into plugs, wires, and distributor cap, but Brian's probably right that a plug is the most likely culprit. Do you know how old those parts are?

Your compression is fine - actually, I'd say great! I compression is important, but the consistencey is probably just as important. Doing a test with a squirt of oil just to get a baseline for both wet and dry is a good idea.

Since you've run the engine since your "catastrophe" you probably won't be able to read the plugs very well, but you might want to look for anything out of the ordinary from one plug to the next. The insulator should be a dark tan color and be dry. Obviously, nothing should be broken, bent, or otherwise mangled on it.

[3929R]

The plugs have less than 1,000 miles on them. The car runs rich and the plugs tend to be more black than brown when I've checked them in the past. When I removed them for the cold compression test they were blackish. #1 plug was also a bit wet. I assumed this was a result not the cause of the problem?

The compression is consistent but I think it is also well within spec (high enough) when adjusted for my elevation above sea level. I am at roughly 4,500 feet above sea level and from what I've read on-line that gives an altitude/elevation factor of 0.88. That is why I said my 150 equates to 170 at sea-level (150/0.88=170).

[BDA]

I don't think there is anything about your compression to worry about. Black is not necessarily bad. Someone might need to correct me but at idle speed, they may end up black because the mixture is rich. I used to cut the engine while at full throttle and coast into the pits to read the plugs when I was racing. The wetness should be checked out. Is it wet with oil or gasoline. Given your compression, I might guess gasoline so maybe that plug isn't firing all the time. What kind of wires do you have? How is your distributor cap and rotor, points and condenser? If all those check out, I'd start to drive it in larger and larger concentric circles - with your cell phone!

[TCS4605R]

You say the plugs only have 1000 miles on them.  I have had plugs that were bad 'out of the box' - try a new set of plugs next time you fire it up.  How many miles do you have on the plug wires.  My wife's 1991 Miata has gone thru at least (4) sets of plug wires - the old ones worked great at low RPM, but gave up at higher RPM.  It is either spark or fuel - I think it is spark related.

Tom
74 TCS - 4605R

[EuropaTC]

Hi Mark,

Following on the spark plug idea, although they are relatively new it might just be that if they are always running black you've managed to get enough fouling on the insulator to cause one or more to break down or stutter every now and then ?

There has been a lot of debate on the Elan forum regarding plug selection for our engines and the general view seems to be that the Lotus recommendation of Champion N7Y is too cold for your average driver these days. (maybe we all used to drive around on the red line in the 60s ?     )

Anyway I decided to try a hotter plug as both the Elan & Europa run rich with dark plugs and I changed to NGK BP6ES, which I think are roughly equivalent to Champion N9Y. I don't do enough mileage to shout "Eureka !!!" but having had them in both cars for a couple of years now, I do think they are more suited to my driving as they appear to run cleaner. Some folks seem to use BP5ES which are even hotter and I might give them a shot next time. (NGK and Champion helpfully use opposite numbering systems from hot to cold which confuses me no end)

Brian
 

[3929R]

Thanks again for all the replies, thoughts, and ideas.

I drove the car today and she ran just fine. I swapped the number 1 plug for the number 4 plug just to see if the same plug would be a bit wet in a different cylinder or if the #1 cylinder would be a bit wet with a different plug. After my drive all four plugs looked about the same and were a bit blacker than I believe they should be. I would guess I'm running rich because of my elevation, ~4,500 feet.

My plug wires appear to be in good shape. I do have a new set that I was waiting to install when I put in my new distributor and pointless ignition. Maybe I'll move that project up on the to do list.

I've been running Bosch WR7DC+ spark plugs, which are equivalent to NGK BP6 and Champion N9Y. I think I'll  try a hotter plug and see how they look.

I'm still not sure what caused my smoke plume. Maybe spark failed in the #1 cylinder??? In this case I'm happy you can call me Chicken Little.

[jbcollier]

If you tend to putter around, by all means try a hotter plug.  However, flat out you may well run into problems with pre-ignition due to overheating plugs.  Just something to remember if you ever find yourself charging up a long hill flat out.

[Bainford]

I have a very strong suspicion that the smoking issue was caused by over filling the sump with engine oil.

[4129R]

That happened to my diesel land Cruiser. The diesel was leaking into the sump, the oil/diesel filled up without me checking, first thing I knew was serious quantities of blue smoke out of the exhaust so the lorry behind had to stop, he couldn't see the road. The only way to stop the engine was to stall it in first gear with the brakes full on.

I have seen that happen to others.

Oil smoke is very worrying, and can be very expensive.