I've recently had a built motor done for my '02 L and have gone through the break in miles my builder recommended. I won't bore you with all the details about my experiences up to this point, but I do have a question concerning it.

I took my truck into a local speed shop for some dyno tuning. While on the dyno, the truck developed a loud internal knock. I had the truck hauled back to my engine builder who is in a different State to tear into it and examine what the problem was with it. My engine builder called me yesterday and told me that #7 & #8 cylinder pistons were melted and damaged the bottom of the head at the #8 spark plug along with various other problems that result from this type of damage. The motor obviously will require a complete rebuild. In your opinion, what would of happened to cause such damage?

 

maybe the timing was too far advanced in your tune? just a thought..

 

Maybe you could find a ,very good low mileage ,used motor and have it built , locally in Phoenix, till you get things settled.

 

Hopefully Tim can assist you in this Kenny. I am very interested to see his input.

 

What was the A/F on the dyno run?

How many pulls did you do?

 

Well I wished I knew the answer to that question. I don't have all the information necessary to tell you. The reason for my post is to find out what would it take to cause this sort of damage. I'm intentionally not posting the engine builder or the shop who did the dyno so that I'm not accused of "flaming" and have the thread shut down.
If the vehicle was run lean as an example (and only as an example), how long would it take to cause a melt down?

 

Sorry to hear about this news......

First ? - Do you trust this shop?

Second ? - Have you asked them for #7 and #8 cylinder heads? If no proceed to the twilight zone. If yes have a second opinion drawn.

I asked a local shop recently - If I bought a built block from you and she went boom what would you do? He told me that they would tear down the engine and determine the cause - if it was detonation (melting heads) then it would be blamed on tune conditions, not engine build.

Sounds like this shop (whether they are right or wrong) is leaning that way to remove themselves from responsibility. And they may be perfectly straight, but there are always two sides of the coin - and I would be demanding both sides.

Get a second opinion on the cause and cover all your bases regarding the tune - your dyno should give a few of the missing pces.

Good Luck!


D-Day

 

If the timing was too far advanced, how long would it take at WOT to cause this sort of damage? Would it be something that a professional tuner would notice immediately and shut the truck down, let's say in a matter of a second or two? Would that be all that it would take to melt down a built motor to this degree?

Also, as an example, a 255 walbro pump fails at 3500 rpm, the tuner noticed immediately that the fuel pressure is at 34-35lbs. Would that cause this sort of damage?

 

No it wouldn't cause that much damage. It might fry a plug or two if they got out of it IMMEDIATELY. It sounds like they did multiple pulls on the dyno.

 

Thank you for your response Dan. The engine builder is the one who tore down the motor and gave me the damage report. The tuner has been my tuner for the last 4 years and I have trusted them up to this point. The information that I've received from my tuner does not match up to the damage caused to the motor which is the reason for my thread here. I'm trying to ascertain from those that know what would cause this type of thing. Rather than relying on my own information and over reacting I chose to run it past you guys.

 

hmmmm, very interesting. Thanks for your post.

 

Race engines are generally caveat emptor

 

I must admit, I had to look up the meaning:

Caveat emptor. Latin for "let the buyer beware." It refers to the sale of something of value, without a warranty from the seller.

My issue is not with the engine builder at all, he's been fantastic all the way through this ordeal. My issue is with what happened to the motor on the dyno and what would have caused this sort of damage.

 

could have been a bad injector or two which wouldnt indicate anything to the tuner via a datalog.

 

it leaned out at high rpm,,,maybe more then once

imho