302 failure - any opinions???

[Julian West]

I have an SVO 302 & after some over enthusiastic revving on a track day, ie 7000 rpm for a *very* short moment (oops!) & hitting 6500 a few times, the engine developed a serious 'clatter'.... doesn't sound like a big end or a main bearing, just a 'clatter'.....

I made the following checks....

visual check of the valve springs - all OK

removed & inspected hydraulic roller lifters - all OK

removed & checked pushrods for straightness - all OK

carried out a leakdown test, all cylinders within 8-12% - all OK

Next I drained the oil & pulled the sump off & found flakes of metal in the oil.... Would anyone care to guess what the problem might be?? I guess I'm gonna have to pull the engine out for a bottom end rebuild, however with the leakdown test showing such good results I'm wondering what the problem might be....???

Any opinions gratefully received!

[Joe T]

That looks like bearing material to me, although that is quite a lot of material, big end or main bearing are normally the main culprits, does the 302 have a thrust bearing on the crank like smaller Ford engines?
Could it be a small end bearing if its just a clatter? inspection of bottom end will answer your question really.

Good Luck

Joe T

[Keith Hardy]

Holy Moly! That is fubar-ed

I would say spun bearing for sure, looks like it spat out a main for the amount of metal there...

[Doc Watson]

Complete the bottom end inspection.. possibly a mains bearing has torn up, I initially though about residual swarf from production but some of the pieces are big!

Anybody else?

[Big-Foot]

Last time I saw shrapnel like that is was from a cracked crankshaft that ate up the main/thrust bearing...
Part of it looks like an oil-ring expander, but since there are no larger chunks of aluminum, I guess I'd rule that out...

[Ian K]

That was my first thought as well - a main bearing.

Ian

[StanJ]

Julian, does the sound you are hearing have two distinct, focused "knocks" per crankshaft revolution? The bearing backing material shown in the photo, along with the general heat coloring of the carnage looks like a rod bearing to me...I'd strongly suspect #s 1 and 5 in a wet-sump Ford with an unmodified oiling system. Do either one of those cylinders happen to be the 12% leaker?

[Ross Nicol]

Julian
If your hoping to re-use the crank don't run the motor.That is bearing material and the most most likely cause is low oil pressure and in turn caused by corner surge at the track.I found after tearing my motor down with the same material in the sump that 2 big ends had no shells at all and this caused knocking as you are describing.You'll need to pull the crank out and have it and all the rods checked, so pistons out too I'm afraid.
All I can say is been there done that! Was your oil light coming on as you were cornering or have you an oil pressure gauge, I use a light to attract my attention to the gauge and this works for me.
Ross

[Steve C]

An "accusump" (I run a Canton) is good insurance for those who are not running a dry sump.

Steve

[Jim Downard]

I'd say rod bearing by the looks of how thin some of the pieces are, and it appears that I can make out a few skid marks on another.
BANG! $$$$$$$$$$
Hate when that happens.
I had a buddies small block Chevy go once and he had about 7 pieces of camshaft plus one rod in the oil pan. Man, THAT was ugly, no fugly.

[Jac Mac]

I'm with Stan J, numbers 1-5 rod brgs- your in for at least a new crank & two rods, good chance the one in it is bent if not cracked as well. DONT just throw a new crank and a couple of rods at it, those two cyls will also have some scratch marks from the debris that got thrown at them and with some possible skirt damage on the pistons.
You need to have serious look at your sump & pickup/baffles-gates etc if your going to make the trackdays a regular thing! Fit an additional oil line from filter block to rear of main oil gallery as well.

[Julian West]

Gentlemen,

Thank you all for your replies, interesting reading for sure..... The noise was definately not a 'knock', it didn't 'sound' like a main or a big end.

I run a genuine GT40 sump with the correct wings & trap doors, the in car video showerd oil pressure at a fairly regular 40 psi, altho I'll watch the vid again to be sure. I could smell oil when it happened.

Will keep you all posted.

Regds,

[Paul Thompson 'Hooligan']

Looks like bearing material to me too.

I'm also with Ross here, fit a pressure switch to a bright warning light as it will get your attention real quick for low pressure.

Also - in our experience, capilliary oil pressure gauges seem to be be slow to respond, we noticed oil pressure dropping on cornering from the data logging system/warning lights long before seing it on a gauge.

When a drysump belt was thrown at Lydden hill sprint a few years back, it took me less than a second to lift and shut off from the light coming on as pressure dropped below 30 psi. As it happened at about 70mph in a corner at 6000+rpm it probably saved the motor too.

Hope it works out ok.

[Andy Green]

Hi Julian,
I’d mainly concur was has previously been said.
If you fit a dash warning light, connect it to a pressure switch that trips about 20 psi. Normal switches are around 7-8psi and if it comes on during surge conditions, it will be too late. Also use a high intensity LED (Maplin do a nice 25mm cluster LED) which aren’t intrusive when mounted on the dash, but when illuminated you won’t miss it.

Normal oil pressure gauges aren’t accurate enough to pick up any minor dips in oil pressure caused by oil surge. My friend’s race engine had a period of running the big-end bearings, however he had a Pi dash-logger fitted and we were able to look at the oil pressure prior to the failure. The pressure had been dropping momentarily (less than 0.5 sec) and under the mechanical high loads, it was enough for the hydro-dynamic oil film to collapse and metal-metal contact to be made. One this happens, the bearing fails in a matter of seconds. We ended up curing the problem with wider bearings and a dry sump system.

You may have the best oil pan available, but it’s no good if you have oil hang-up in the valley & cylinder head. I’m no expert on these engines, perhaps someone else can add to this part.

You will need a complete engine strip & rebuild to ensure that there is no bearing swarf in any of the oil galleries.

Regards
Andy

[Paul Thompson 'Hooligan']

Further to my last post - I'd recommend the adjustable type of pressure switch - available from 'Demon Thieves' among others.

Low Pressure Switch | Spares & Accessories | Demon Tweeks Motorsport, Motorcycle, Modifying, Parts and Accessories

We had it set to about 30psi - and with the dry sump system, it only came on when motor was really hot at idle, 1500rpm and it was off again.

[Frank Catt]

Julian, whatever else you do, if you even think the crank is reusable ( which I doubt ) then get the crank crack tested, its essential because the next time it could be an even bigger bang and a whole new engine.

[Jac Mac]

Julian, there is another 'cause' that can lead to this type of failure & its not oil surge related.
If your 302 still has pressed pins and it experiences any or a combination of the following conditions it will fail the rod bearings.-- High RPM leanout, Detonation, over advanced ignition, fuel quality, coolant temparature shocking, air locks in cooling system, sticking thermostat, heat range of spark plugs. --- If any of these are likely particularly in a track day situation with short warm up etc or your first time out the piston pin can partially seize in the pin bore, this in turn creates extra load/heat at the rod brg and if use is continued bearing failure or rod breakage results.- Why #1-5?, being at the front they experience any 'cold' coolant from the radiator first and due to the fireing order/air flow dynamics in the intake manifold #5 is known to be the 'lean prone' cylinder in Fords, now if the piston has expanded from any of the above conditions and the cylinder suddenly gets hit by a dollop of cold coolant it literally shrinks to the point where there is a seizure of the piston which is enough to cause the pin & rod bearing oil film to fail & start this destructive path.

Moral of the story-- look very closely at the piston pins/skirts for any sign of galling or overheating on teardown.

Jac Mac

[Howard Jones]

Main bearings. Gonna be a complete rebuild I'm afraid. I hope you can save the crank and block. Those bearing halves/shells came completely apart it looks like. Do you know the status of the balance job on that motor? It might have ate itself up by being out of balance at sustained high revs.

I got away with a new crank and a rebuild when mine looked like that but I did save the block, rods, and pistons with a line-bore and oversize bearings.

Those Fords are tough little buggers. It could be worse, a rod could have let go, or it could be a Por$$$$che.

Sorry to see what happened but now you can rebuild it your-way with a bunch of cool new parts and a complete balance. You know you wanted to anyway, right.

[Julian West]

Gentlemen,

thank you all for the informative replies & thabk you to those that have helped me with pms. A quick inspection this morning revealed it's no 4 big end.

Jac Mac, thx for the extra info. The failure was toward the end of a 30 minute track session, looking at the video again very carefully it looks like oil pressure was just over 40 psi at the start of the session, but very slowly decreased over the 30 minute period. It's hard to see but it looks like oil pressure was around 35 psi at the time of failure.

Thinking back, there are some pretty long corners at Silverstone & whilst I was was marvelling at the amount of grip I had & enjoying some lateral G, I wonder if oil pressure was dropping momentarily (based on what some of you have said).

Anyhow looks like I'll be busy in the workshop for a while now. Frank, thx for the tip, I doubt very much if I'll re-use anything that looks even slightly iffy, the cost of the parts vs the fittingwork involved = a no-brainer!!

Jac Mac do you have any more info regard ing your comment on fitting an additional oil line from filter block to rear of main oil gallery??? Presumably you fit a take off behind the oil filter, but where do you tap into the main gallery??

Paul/Ross re the oil light, do you fit a tee in the block where the capilliary guage currently is & fit the electric switch in the tee?? thx for the links!

Regds to all,