Plug Failure, or Bottom End trouble ?

[richardcox_lotus]

Dear All. Out for a run this evening - Sprint running v sweetly until.....(you know what's coming).... slight ting noise, like a stone hitting the car. Less than 1 mile later, not running quite so smooth, less than 1/2 a mile after that (and only 1 mile from home too), bang. Lots of smoke out of exhaust. Engine Stopped.

Current state of play after tow home:

Level of oil much higher on dipstick
No obvious holes in block
No oil slick on road
Small water loss (Maybe half an inch in rad)
Engine won't turn over

and.....

No 3 Spark plug looks like this (See pics).

Obviously this is going to be......expensive.

But my thoughts are:

Bottom end failure somewhere - peering down the bores, it does look as if the pistons in 1 & 3 are higher than normal - could this result in the piston hitting the plug ?

Plug Failure on # 3. (Remnants of plug are on top of piston). If this was the case I would have thought it may still run on 3 cylinders. But if so, why has the oil level changed ?

Even a numpty like me can tell it's an engine-out job. I'm curious as to what may have caused it.

[memini55]

Could be any number of things. I had a strange one last summer on a freshly rebuilt motor it dropped a valve seat and it broke into pieces and hammered plug as yours look. I pulled the carbs and exhuast manifold and shined a light down each plug and looked in ports and found one that had lots of light and looked down port with light and could see no seat left.
The parts had the motor locked.
If you have more than one cylinder with trouble may be something else.

Not Good!
Mark

[rgh0]

Yes could be a range of things - ingested something in through carbies, dropped valve or valve seat, broken piston, rod or rod bolt.

You will find out when you pull the head off

I hope its not to expensive a rebuild. I had a rod bolt fail on a racing engine at 8000 rpm a few years ago and the only thing on the engine that did not need repair or repacement was the cam and front timing cover!

When the rod bolt failed it made a clicking noise for about 5 seconds until the second bolt on the rod failed and the rod then destoyed the rest of the engine.

cheers
Rohan

[ElanSeries2]

I had a similar rod bolt failure to the one you describe, Rohan (fortunately on an A-Series, not a Twin cam). It clicked, or clapped, for several seconds before letting go in a big way. The hole in the block made diagnosis slightly easier for me than you, Richard.

I have to agree with Rohan - either the car has ingested something through the carbs (unlikely if you have an air filter, and haven't been messing with the carbs/filter recently), or you've dropped a valve guide or broken a valve head, which has jammed the motor. With either of these, you may find you can turn the motor backwards. Alternatively, you could have broken a rod or rod bolt, which will have made one hell of a mess in the crank-case.

I suppose there's a remote chance you had an oil pressure problem/pump failure, which led to a cam seizure. You'd need to take off the cam cover and the sump to make more progress on your diagnosis. I'd be prepared to find lots of debris in the sump... Sorry!

[Famous Frank]

My heart goes out to you. That's an icky feeling when somehting like this happens, .............but it always could be worse. I don't think you'll know what the problem is until you take it apart. On the bright side, use this as a wonderful training exercise, take lots of pics and share the news with the rest of us nuts on this wonderful forum.

As a matter of reference, I had a twincam motor in my older S2 that I took out of the car to remove the dry sump the previous owner had installed. The car was occasionally used for autocross events and also street driven. Occasionally, it would see 7000 rpm. When I removed the pan I thought it might be a good idea to look at the bearings. The engine had been professionally rebuilt 4000 miles earlier. WHAT TO MY SURPRISE..!!!..........all the rod bolts were hardly snug. It took 10 to 12 lb ft of torque to loosen the rod bolts. WHY IS THAT YOU SAY? All the rod bolts had stretched. Many twincam rod bolts are now 40 years old and may have been torqued and stretched many times. My suggestion, spend the money and buy NEW "ARP" Rod Bolts. They are worth every penny!

http://www.arp-bolts.com/

[hatman]

Water level low, oil level high, engine won't turn over? Head gasket failed, water drawn into bore and hydraulicked it perhaps?

[denicholls2]

Water level low, oil level high, engine won't turn over? Head gasket failed, water drawn into bore and hydraulicked it perhaps?

Water's unlikely to do the physical damage you see here. In my own experience on a Spitfire, inhaled puddle-water caused instant failure via a bent connecting rod. I don't think a head gasket failure would be likely to produce more water than the engine could dispose of, though. And if it got sucked in, it could be pushed back out the same hole.

Good suggestions here. How much would a bearing cap lying in the sump contribute to the oil level?

Very bad news, I'm afraid.

[richardcox_lotus]

Yeah, I did have thoughts on that, have to wait & see though. My engine man won't be able to fit me in before end of June, & I don't have the facilities to remove it fom the car at home. I was thinking of draining the sump rather than have an oil/water mix slowly rotting away any good components.

Looks like my plans for a long summer holiday are out the window.....back to work we go.............

[memini55]

Most certainly drain everything out if you are not going to get to the tear down for a couple months. Been to the engine shop and saw a boat motor which sat for two months after it sucked muddy water and it had major rust everywhere. You might drain out everything and flush it out with diesel fuel and then dump some oil back in to hold rust to minimum.

Wish we all had better news
Mark

[richardcox_lotus]

Having a look at things this morning (best I can). Undid the sump plug & drained 2 litres of coolant from the sump, followed by another 3-4 litres of oil (Had obviously settled). Have drained about 2 litres of coolant from the rad. Not really much mayonnaise. No shrapnel came out the sump with the fluid, & couldn't see anything when pocking a torch into the hole.

More info when I get it.

[billwill]

If it is a 2-seater Elan, you should be able to get the sump off from underneath. Not sure about a Plus 2.


Not easy, but possible

[JJDraper]

Before you take the engine out, I suggest taking the head off, even before the sump. This will give an instant diagnosis (probably!) and make the engin easier to get out, if indeed you need to do so. You should be able to get the head off in an hour or so, thereby wasting less time worrying as to what else may have gone amiss. I am puzzled as to how so much coolant could have got into the sump in such a short time, but it may have been brewing before the noise you heard, which could have been the final straw. My bet is on a valve seat, followed by a valve head...

You have my sympathies, but the quicker you tear it down, the quicker you can get it back on the road!

Jeremy

[tower of strength]

The mystery of the "magic" oil level of many a Twink (applies to most twin webbered engines by the way) is over fueling and poor ring sealing, check your sump oil for petrol (it'll be very thin and stink of petrol, even when cold). I couldn't under stand why my old 130 used to burn and leak oil, but never needed to be topped up between oil changes!!

The plug damage can only be caused by impact,a foreign body would be the favourite culprit, be it a nut/washer/screw ingested or a piece of broken valve/valve seat. For the piston to have done that damage, it must have become strangely deformed to reach, unless the plug was too long in the first place and it would have happened on start up, the car running on 3 cylinders only since the plug was installed.

Good luck with the investigation, fingers n toes crossed that theres not too much damage

Mark

[rgh0]

Another engine failure I had when racing was when I dropped a valve head. This smashed the head and the top of the piston so the sump filled with coolant from the head water jacket. Engine kept running though and I drove back to the pits with lots of steam coming out of the exhaust. it happily kept running on 3 pistons and the shell of the 4th - demonstrates the strength of forged pistons, rods and steel crank

Actually a relatively cheap rebuild that time - just weld up the head and re-machine the combuston chamber, new valves and 1 new piston.

cheers
Rohan

[richardcox_lotus]

Time for an update. Cylinder head came off on Friday. Valve damage to #2.

Unfortunately though, there has been a failure in the block. Essentially the sidewall of #2 has caved in, taking everything else with it. Reason ?? - Open to conjecture ! - Never raced; Never rebored.

So now I need a new block (And probably head). Have asked at "www.unobtamium.com" so am now asking here instead.

Alternatively, if anyone has a tired old engine that they no longer desire & that needs rebuilding, please let me know (This will be going into the "needed" section as well).

Oh, and if anyone has a winning, but uncashed lottery ticket, can I have that as well

Richard