Engine seized!

[SiahNyde]

Rolling through the parking lot of a local grocery store when all the sudden I hear a loud clank and the engine dies. I pull off to the side and try to crank it, nothing. starter engages but doesn't turn over. Triple A tows me home where I promptly remove the belt and free spin all accesories except the crank. About an hour and a half later I go out and crank it over. 2 or 3 flops and it's siezed again, and I can't move it with the crank pulley. judging by the way it was siezed, then later it cranked a little but siezed back up, I was thinking hydrolock? what does this sound like to you guys, any idea? I'm gunna tear into once we clear out some space in the garage, but could deffinately go for some advice/experience!!

I drive a 1999 mustang gt that is procharged, has custom blower cams, is forged, still has stock heads, and blueprinted and balance engine.

Thanks!!

 

[bhuff30]

Very interesting situation. You mentioned a loud clank, and then the engine locking up and also stated that you have a procharger. I am thinking you tossed a rod, which seems a bit unusual at idle (was idle or you were playing around?).

I don't think hydrolocking is very likely. You didn't mention anything about driving through water. If it was coolant, then it would be more likely to fill the engine while parked, then you try to start it and bend/break a rod.

You'll just have to take it apart to see for sure. But I'm betting on a broken connecting rod that was fatigued from power/rpms.

 

[trombonedemon]

Its possible that the rod is bent so much that the actual piston is bottomed out at an angle.

 

[SiahNyde]

is a bent rod very likely? I have forged connecting rods, and i was just coasting. I had been driving the car harder than normal that day though. I was confused as to why it, for lack of a better phrase, loosened up after a while?

 

[trinity_gt]

Why did you mention hydrolocking? Was there a large puddle involved and do you have a low-hanging intake?

 

[SiahNyde]

We thought maybe hydrolocking from a blown head gasket. I didn't notice any puddles and don't really know the symptoms, i just figured that if it was rods or whatever, it wouldn't have been totally siezed then been able to crank it over a few times a little later

 

[Maxpowers]

There's any number of reasons this may have happened. One of which is not that it was hydro locked on coolant. Truth is that you wont know until you tear into it.

The worst thing you can do in a situation like that is attempt to turn the motor over again. There will most likely be much more damage now.

 

[trinity_gt]

Sounds like you broke a rod though it seems to have chosen an odd time to go. Still, you said earlier you'd ridden the car hard and put it away wet, so to speak, so perhaps there was a latent failure that occurred then but did not manifest itself until now.

Remember to take pics...

 

[mogs01gt]

Do you have an oil pressure gauge? Might have snap the teeth on the oil pump earlier that day.

 

[SiahNyde]

I had driven it harder than i had in a while, but not as hard as it was on the dyno, or other instances. we did rebuild the oil pump instead of buying a new one, perhaps that caused an issue. I guess I'm just going to have to tear into it and cross my fingers that it's not too expensive...i'm still paying on my original build parts! stay tuned and i'll update when i get a chance

 

[GDawg]

Definitely take pics to share...

 

[SiahNyde]

I started going over the engine today and noticed something right away. Under the oil filler cap there was a large build up of a white substanance, reminiscient of oil/coolant/water all mixed together.
Blown headgasket, no?

 

[trombonedemon]

Thats just the blowby gasses not venting properly. That won't cause your engine to lockup unless the oil is completely fried. Have you torn apart the engine yet?

 

[merc123]

Headgasket wouldn't cause lock down either.

 

[SiahNyde]

Haven't been in for a while, but finally got into the stang and here's what I found:

left side had a rocker(?) laying down at the bottom of the head with a small crack in it.

Right side was sporting 3 rockers dislodged and 1 wedged quite nicely between the cam and the hydraulic lifter. this was one that had fallen into the bottom, 3 of the 4 had cracks.

 

[SiahNyde]

Got the timing chain cover off and boy did we hit the mother load ----

Timing mark on the cam compared to the timing mark on the chain.

The remnants of the guide...

those chains are sinched tighter than a gnat's ass!

Early next week we'll be pulling the heads and checking for piston damage. Since they're forged, they might have stood a chance. valve/heads/cams on the other hand...

Any recomendations on where to go from here?

 

[Winters98GT]

Hopefully, the shortblock is all good. You can pick up heads for 150-200 bucks, and slap them on. I'd replace all the guides, chains, etc. if that is it.

I think for the motor to stop like that, you still might have something wrong with the shortblock. Normally, if you break something in the valvetrain, you can hear it and the motor is still turning a bit. Not a mechanic by any stretch, but I've blown the valvetrain on 2-2v's, which ended up taking out the motor, but not like you are talking about. Good luck!

 

[mr-mike]

looks like that motor saw some heavy beat downs I would try to find a running late model 4.6 maybe hit in the rear this was an easy swap you never said how many miles ? gas prices will make picking up V8 trucks & cars easy like the last time .......good luck

 

[SiahNyde]

We were conidering a shortblock swap, the other thing is that I spent a substantial amount of cash on forging the bottomo end. I've got a cobra crank and forged h-beam rod and forged -21cc dishtop pistons, so I don't want to just toss that. the car has about 130k but we rebuild the entire engine about 2k ago. the valve train was the only part we didn't do some upgrading to.

 

[usaf_branham]

you built the bottom end but didnt replace the chains and guides?