Cracked 4.6 Block.....AGAIN

[05moneypit]

Figured I would give the guys on S197 a crack at this one.....go ahead beat me up over it....I've worked in a mill for 30 years, not much phases me.

I am either cursed, unlucky or dumbest phucker on the planet.

This is the second time this has happened to me. Here is the thread from the last one. http://www.yellowbullet.com/forum/sh...od+motor+water

This was a fresh build. NVH block (06 block), standard bore (honed .002 over), 3.80 stroker 10.3:1 CR race gas only. I also went to the waste gate deal to control boost even though I only run race fuel.

Started the motor for the first time last Sunday. No issues with the motor on initial start. Played with some tunes at idle but the car never left my garage till today. Finished up a few other things and took it for a road test today. Running the same tune as last year but limited boost(waste gate set-up) to 15psi on the new motor. Made one pull(2nd gear) and looked fine other than the tune showing very fat at 6k (9.9 afr) so I got out of it and headed home, before I got half way back (less than 1 mile) it started to get hot (220*) on a 160* stat. Pulled it in the garage and there was water dripping on the floor.

I went to a mid plate on this build, still running stock motor mount with poly bushing but the plate is supporting block more than the mounts.

Zoom in on the pics, the crack is in the same area as my last block except on cyl 1,2,3 now instead of just 4.

A buddy said to much cylinder pressure but I'm only running 15* of spark and the crack is below the top of the piston.

Would the excessive rich spot in the tune cause this?

Hell I only drove the damn thing less than 3 miles!!!!!!!!!!!!!

WTF AM I DOING WRONG??????




__________________

 

[lethe]

Damn man that sucks. Sorry to see that happen to you after 3 miles. I don't have an answer to your question.

 

[DVEST8R]

Im baffled

 

[TexasBlownV8]

Damn sorry to hear this. There's got to be some serious stress to have caused 2 blocks to do this.

 

[5.0Shocker]

While I'm baffled as well, what engine mounts are installed? Poly or solid? Sorry to see this happen.

Sent from Ammo HQ

 

[skwerl]

I'm scared to death of working my ass off building a motor and having this happen. I'll spend a few more dollars and get a Ford Racing Aluminator shortblock instead.

 

[dysan]

Damn dude..that sucks. My current engine is the same compression as yours but with a 3.750 stroke and .010 over pistons. I'm curious if you somehow hydro-locked a cylinder and the pressure caused it. Did you have your injectors checked after your last failure? I guess you'll see when you take the heads off and look at the pistons.

 

[05moneypit]

I had the injectors cleaned and flowed (Feb 2011) before my last failure. I highly doubt it hydrauliced since it will still running fine. It filled the oil with water just like last time so the crack is through into the oil return passages.

The only thing I can think is I had a huge air pocket in coolant system, I really doubt that though because I run an electric pump and have a bleeder system set up because I know how hard it can be to fill the coolant system on these engines......but I guess anything is possible at this point.

I was trying to figure out last night how to save a screen shot of the data log from that road test to post it. It did start to heat up pretty quick once I got it out on the road even though I wasn't hammering it.

Lee

 

[ethic1]

Not sure if I read that wrong, but Why would you go with the same tune that blew the motor last time? Seems like you are getting detonation on a large scale.... The blocks have been shown to handle tons of power, so there has to be something going on? Failed fuel pump, intermittent injector failure, bad fuel..?

 

[weather man]

If you have the log. Ask LITO if he could review it. To go down that fast, think he would spot tune issue.

 

[stkjock]

is this the crack?

 

[05moneypit]

Not sure if I read that wrong, but Why would you go with the same tune that blew the motor last time? Seems like you are getting detonation on a large scale.... The blocks have been shown to handle tons of power, so there has to be something going on? Failed fuel pump, intermittent injector failure, bad fuel..?

This was my "base" tune, 660rwhp. Open loop. Commanded lambda of .80 to 6K then .78 above that. 15* spark (race fuel only) total and boost was limited to 15psi and I never got it above 6K rpm. As I said in the first post the only thing I saw was it started going extremely rich about 5800 and I was out of it by 6K.

This is the same rotating assembly that came from my last block. There were no signs of detonation on the last block either.

I know these blocks will hold a ton of power. I evidently did something horribly wrong in the assembly or maybe I filled a cylinder with fuel from a bad injector?

I'm in the process of pulling it back out right now. Going to send the injectors out again and have them tested. I will post some pictures when I get it apart.

Lee

 

[05moneypit]

No above that. Right through the drain plug, its about 5-6 inches long.

is this the crack?

 

[stkjock]

ah, really hard to see

 

[MexGT]

That sucks, hard to say what is wrong without knowing every detail in hand.

 

[05yellowgt]

I had to modify my thermostat when we went to an electric water pump. Meziere said that the electric pump wouldn't always produce enough pressure to flow through the stock thermostat so they suggested to drill a few holes on the outside rim of the thermostat to allow more flow through it. The car was started for the first time to get it on the rollers. The we saw the motor getting hot and caught it before anything got out of control.

I don't know if this is a common thing or not but i wanted to add some thoughts.

 

[Taxman]

wow man that sucks. I'm sub'd just to see what the hell caused it.

 

[908ssp]

I had to modify my thermostat when we went to an electric water pump. Meziere said that the electric pump wouldn't always produce enough pressure to flow through the stock thermostat so they suggested to drill a few holes on the outside rim of the thermostat to allow more flow through it. The car was started for the first time to get it on the rollers. The we saw the motor getting hot and caught it before anything got out of control.

I don't know if this is a common thing or not but i wanted to add some thoughts.

I removed my thermostate and replaced it with a electronic temerature controller which regulates the pump. It runs for 10 sec at 6 volts and then off for 30 seconds. As the engine warms up the pump runs more often and once it runs continuously the voltage rises. It does take longer for the engine to warm up and if the air temperature is really cold the engine runs much cooler than it did before. I also have a larger than stock radiator.

 

[19COBRA93]

What's that spot I circled? That appears to be where the crack starts.

The only things I can think of that would cause this would be incorrectly torqued heads, or some sort of motor mount stress. Whatever it is, I think it's something you're doing. I've never seen this before, and for it to happen back to back to you is unheard of. You've got to find the common denominator that was the same between both motors, but different from what everyone else is doing.

 

[Redrocket06]

Sorry to hear about your troubles, you are living every mans build nightmare.

Could the way the motor is supported have anything to do with it? The direction the crack runs, could it be caused by lack of motor support alowing too much engine twist? Not rotation assembly rotation, but actual engine twist when you wot?