Should I try to start it or just rebuild?

[BoldUlysses]

Here's the deal. On March 11, 2004, my 240Z caught on fire.

On the way to lunch, the undersized CarQuest replacement battery, which I had stupidly tethered to the battery tray with a bungee cord, slipped forward off the tray and impacted the oil filter, puncturing it. I saw the ammeter go crazy and smelled burning, so I immediately turned in to a side road and shut the car off. I popped the hood and discovered a spark from the battery had caught some of the oil mist on fire. I found a rag and quickly beat it out.

I should have just had the car towed. However, like an idiot, I tried to at least nurse it to the parts place. I coasted it down the hill and came to a stop at the light at the bottom of the hill. When the left turn arrow went green, I started the car and gingerly drove it about half a mile before it started going *chug chug chug* I immediately turned into a parking lot and stopped the car. I then walked the remaining half mile to the parts place, bought oil and a filter, walked back to the car, put them on and drove the car home, where I took an alternate car to work.

I drained the oil from the Z that evening. Weirdly, I don't remember seeing any filings or metal. But after an oil change I tried to start it, and it would start, but the engine would cycle between racing and bogging, racing and bogging. I chalked that up to what had happened, but...I decided to replace the points at the same time I drained the oil, and I had had some issues tuning the SUs. And I never warmed the engine up all the way.

The car hasn't been run since. Here's my question: Should I just go ahead and rebuild it, or try to start it? I'd obviously drain and replace the gas as well as the rubber fuel lines, fresh oil, new plugs, adjust the valves, etc etc. And probably send the carbs back to ZTherapy to have them replace the seals on the sides of the bearings—I had been getting a vacuum leak through there.

What would you do?

[Healey Z]

Assume for a moment that the long block is toast and it will need to be replaced or rebuilt. On the new motor, you would still want to do fresh plugs and have ZTherapy do the seals. I would go ahead and do those two things and give the current motor a try. The only other cost to give the current motor a shot is some gas, oil and some time.

It doesn't look like there is much $ to lose by giving the current motor a shot and a lot of $$$$ to gain, if it is in fact usable.

[BoldUlysses]

That's a good point. I would have to do that stuff anyway. What else would you do re:trying to start it? Squirt a teaspoon of MMO into spark plug holes? I guess I gotta get a battery too.

Is there any way to gauge the condition of the bearings without totally tearing down the engine? Say, dropping the oil pan and removing a main or rod bearing cap or two or three? Ill-advised?

[Healey Z]

If it were my motor, I wouldn't spend the time and effort to crack the motor open unless I had strong evidence that it is a problem; nothing you have said so far makes me believe you have spun a bearing.

I would see if I could get the motor started in the garage and keep an eye on the oil pressure and listen for sounds. If that checked out in the garage, then take it out on the road at all different speeds and look for a nice long hill to gradually accelerate up. The motor will tell you what it needs if you give it a chance and listen to it.

Edited January 20, 2012 by Healey Z

[BoldUlysses]

If it were my motor, I wouldn't spend the time and effort to crack the motor open unless I had strong evidence that it is a problem; nothing you have said so far makes me believe you have spun a bearing.

I would see if I could get the motor started in the garage and keep an eye on the oil pressure and listen for sounds. If that checked out in the garage, then take it out on the road at all different speeds and look for a nice long hill to gradually accelerate up. The motor will tell you what it needs if you give it a chance and listen to it.

I know just the hill.

What does a spun bearing sound like? High-pitched? Or does it manifest itself more as particles in the oil?

Like I said, the engine did start to *chug chug chug* before I shut it off after running it w/o oil pressure for a minute or so. What else could have caused that change in behavior other than the engine eating itself?

Thanks so much for your input. I really hope this engine is save-able without a rebuild.

[ZohanIsBack]

A couple different things can cause the symptoms you are talking about. The first thing that comes to mind is something electrical. You DID have a car fire and it did involve the battery, after all. Any number of things could be damaged, but that's what fuses are for. I would more bet on something pulled loose by the battery when it went down. Maybe not, but just one idea. The other thing it could be is damaged internals. Most often that will come along with savings in the oil, but they can be hard to spot sometimes, especially if you did it in a garage without tons of light.

A spun bearing most often presents itself in the form of rod knock caused by the loose fit of the piston rod on the crank. You'll also probably loose some oil pressure as well. Hard to say, but a minute without oil.....that can get risky. I agree with Healey though. No reason to start dumping money into it.

Good luck!

[BoldUlysses]

Thanks for the input! I will check the wiring harness. There isn't a whole lot on that side of the engine for the battery to hit before it got to the oil filter, so I doubt it pulled something loose, but I'll check just in case.

I'm definitely going to try to start it! Pulled the SUs off last night to send to ZTherapy.

All fuel and hydraulic rubber lines are going to be replaced, among many other things.

Any suggestions as to how to clean out the fuel lines? I'll search too.

Thanks again.

[madkaw]

How much oil did you loose or how much did you wind up putting back in after your incident ?

Ruining your battery will cause running issues without sufficient charge to your ignition. Grounding problems will also effect engine performance. Do all you can before deciding to crack open your engine

[BoldUlysses]

I don't remember. Chalk everything that happened that day up to the "young, stupid" me. Nowadays I would never do that in a million years. 'Course, neither would anyone, I suppose. Hindsight is 20-20, heh.

Will do everything I can. Sending out the carbs today; gonna drop the fuel tank in the next week or so.

[5150 will]

I haven't seen it mentioned yet, but did you check the spark plugs and wires when ? I would think it would be very possible that the battery flying forward would hit/break/crack at least one spark plug on the way to the oil filter. Or at least pull a wire or two loose. I would doubt you did any major damage to the internals driving as far as you did. That being said, I'm with everyone else on getting what you have going and see where you are from there. Sounds like you're on your way.

[BoldUlysses]

All the spark plug wires and boots are intact. I haven't check the plugs themselves, though, for cracks or breaks. Will do that tonight. I think they're okay, though.

Here's a question: Is there any chance I had at least some oil pressure during my 3/4 mile drive? The corner of the battery punched a pea-sized gash in the oil filter; at that point, does all the oil just come straight out the filter? Is the pressure totally gone? I'm not totally familiar with the oil's path through the engine after it gets picked up in the sump and goes the through the pump.

[Zed Head]

Pea-sized is pretty big. All oil passes through the filter unless enough pressure builds up to open the bypass valve. With a hole in the filter there's no pressure to push it through the bypass. How much oil did you put back in with the new filter?

The odds are not in your favor.