Why did my engine die?

Patty · Postby **Patty** » Tue Mar 10, 2009 11:17 pm

Ok so apparently my engine is dead. Short story - a friend had it at MDTC recently, it started to lose power and knock after 7 or so laps so he limps off the track and it stops dead there. Pulled out the dipstick and showed no oil. Yes, I'm a bad man. :oops:

The most recent history I've had wrt engine oil was late last year when I stopped hard at a set of lights the pressure gauge/idiot light would drop to 0 momentarily and climb back up to it's usual spot. As weeks went by it happened more frequently such that even normal stopping at lights would make it drop so I checked the dipstick and showed low engine oil. Car never overheated though.

I topped up the oil again and the problem stops (~mid Jan this year), took it to Marulan late Jan, threw it around the track for overall about 70laps, no probs, no overheat, no pressure gauge dip, drive home. In between then and last weekend I drive it casually about once every 2 weeks. Fast forward to last weekend and we have dead engine as per my opening paragraph.

What I would like to ask you guys is what could have happened to my engine oil? Surely if it leaked I would see the puddle on my garage floor. I've had a car with worn valve stem seals and it billows smoke when I start it. You would only notice a small puff of smoke when you pull away harder than normal in the mexy.

Is it normal to lose that much engine oil for the amount of driving I described (i.e. was I or my friend ignorant)? Or could there have been some mechanical problem? Car had only done <95,000kms and less than 10,000kms in the last 1.5 years when I've had it

Anyway, we're going to get another engine and swap it over. It wouldn't be a bad time to start learning more about our little car. :mrgreen:

Patty · Postby **Patty** » Tue Mar 10, 2009 11:28 pm

Oh, I've already been told I should always check the fluids before I track it. So..yeah obviously I know now. :lol:

ampz · Postby **ampz** » Wed Mar 11, 2009 11:26 am

Cars will burn oil at the track, although not at such a high rate that you would need to pour a litre in before/after a session (unless you have a turbo that needs a rebuild). :oops:

The reason being, the oil thins down from the overfueling of the sustained WOT periods (Wide Open Throttle). Overfueling is normal when you are at wot, it helps to keep the pistons cool avoiding magical holes. The downside is that with the thinner (now more combustible oil) is that with normal driving, instead of the oil staying on the piston walls and resisting the urge to ignite (and therefore be scraped better off the walls by the piston rings) it will burn off especially in daily driving situations (short trips are notorious).

During normal driving conditions (not at a race track) the extra time it takes for the engine to come to temp and all the respective metal pieces (pistons, piston rings) to expand and tighten the tolerances, oil will seep through and be burnt off,. In such a new car the tolerances are obviously tighter. Smoke screens are often difficult to see. But as a rule of thumb, I change the oil after track days, flush a little of the brake fluid from the calipers and clutch slave cylinder and in extreme cases, change the power steering and radiator fluids if they've boiled (they will have changed to a darker colour, p/s fluid smells like varnish once boiled).

Good luck with the new engine.
Cheers
Nuno

bruce · Postby **bruce** » Wed Mar 11, 2009 11:30 am

Patty wrote: threw it around the track for overall about 70laps, no probs, no overheat, no pressure gauge dip, drive home. In between then and last weekend I drive it casually about once every 2 weeks. Fast forward to last weekend and we have dead engine as per my opening paragraph.

Did you check the oil after all those laps? If not, there's your problem - you went onto the track again with little or no oil.

Patty · Postby **Patty** » Wed Mar 11, 2009 1:28 pm

bruce wrote:
Patty wrote: threw it around the track for overall about 70laps, no probs, no overheat, no pressure gauge dip, drive home. In between then and last weekend I drive it casually about once every 2 weeks. Fast forward to last weekend and we have dead engine as per my opening paragraph.

Did you check the oil after all those laps? If not, there's your problem - you went onto the track again with little or no oil.

No, I didn't plan on having the mexy at the track again. Was waiting for 95,000 to click around to do the service then. Sigh.

Thanks for the run down Nuno. I feel so stoopid that all this could have been easily avoided.

bruce · Postby **bruce** » Wed Mar 11, 2009 2:20 pm

I can't believe you did 70 laps on a track and failed to check the oil before/during/after?
Then you failed to check the oil before you went on the track again?
Ten bucks of oil would've saved all this expense.

Just hand your keys over and make for the door !

silvermiata · Postby **silvermiata** » Wed Mar 11, 2009 4:42 pm

this sucks.. sorry to hear it happened.. never say it won't happen to me...

daffyflyer · Postby **daffyflyer** » Wed Mar 11, 2009 4:49 pm

bruce wrote:
Patty wrote: threw it around the track for overall about 70laps, no probs, no overheat, no pressure gauge dip, drive home. In between then and last weekend I drive it casually about once every 2 weeks. Fast forward to last weekend and we have dead engine as per my opening paragraph.

Did you check the oil after all those laps? If not, there's your problem - you went onto the track again with little or no oil.

Yeah, what kind of idiot would do that... oh... yeah.. me :oops:

Do what Im doing and "fix" it by building a cammy, high compression motor of doom :mrgreen:

Patty · Postby **Patty** » Wed Mar 11, 2009 5:32 pm

I did hand over the keys actually. I was some 150kms away when said motor turfed it.

Did I mention they were 70 teeny laps? :roll:

Thanks daffyflyer, make me feel a little less failed. :lol:

Hellmun · Postby **Hellmun** » Wed Mar 11, 2009 6:15 pm

Well I run penrite Sin 10 in my car..and I've never topped it up between oil changes and I still leave it about 5000-7000km's and it's only dríven on, to or from a racetrack. I check it before I leave for a track day, I check it when I arrive at the trackday and usually before I leave as well though. So it's a good lesson for people. Double check your fluids when driving a car hard!

When I ran the Royal Purple 10W50 oil though I actually changed it at 3000km's because I ran out of oil to top it up with. Not sure how much thicker the SIN 10 gets...but it lasts and the engine feels great to me.

Patty · Postby **Patty** » Sat Mar 14, 2009 7:00 pm

We've started pulling bits off the motor. We intend on swapping in a 2nd hand low kms motor (~<60k kms best we found so far).

In your opinions how much will I be able to sell it for afterwards? I was actually thinking of listing it for ~$13.5k until this happened. People have told me now that it's not worth more than 7-8k. If I was to list it right after it's all sorted with ~3months warranty on motor, how much would you pay for it now? If u must know, it was in good mechanical condition, good condition inside/out, no logs prior to when I purchased it 1.5yrs ago, bought at 86k kms, serviced again at 90k kms, died just before 95k kms, always garaged, new soft top on insurance just prior to when I bought it.

Patty · Postby **Patty** » Sun Mar 15, 2009 2:54 pm

So adding further to my life lessons we've tried to jack the car up on the chassis rail/frame rail (i don't know what the proper name for it is) and squashed the hollow section. Now the pic below is NOT my car but pretend the big crack is not there and instead a squashed bit from a hydraulic jack, roughly in the middle of the length.
pic for reference

Now, I intend to get it assessed once I can drive it to Mania but, tired of being reassured by people who don't care about the car like I do, how bad is damage done to this hollow section? What could happen if I don't repair it?

Mr Morlock · Postby **Mr Morlock** » Sun Mar 15, 2009 10:29 pm

not sure what Graeme meant by FM rails ( I am sure it is obvious to others) A hole like that has got to seriously challenge the strength of the section and is a point for corrosion to set in. I tend to be somewhat pessimistic and believe that it would not pass a RWC and I would think it was a priority to seek some advice on fixing it.

Patty · Postby **Patty** » Sun Mar 15, 2009 11:22 pm

Thanks Graeme. Puts my mind at ease a little. Will post a pic of what it looks like when I get a camera...not that you can't imagine what a squashed hollow section looks like.

Mr Mortlock, my rails don't have a crack in it. I just borrowed the pic to show which piece I squished, and I think he's talking about a FlyinMiata frame rail.

Haha if I seriously considered all the suggestions I've been given by the time I finish this jobby I'll have a BPT motor, racing cams, FM rail (why not just go the full butterfly brace), and well, thats it actually but I'm sure I'll get more advice as I break stuff. :lol: