How I Spent My Weekend

[Cowracer]

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This picture should say it all

http://www.gatewaydata.com/truck/Headoff1.JPG


Yes, that is my brand spanking new motor.

What happend, you ask?

Well, the thing would not start last thursday. Locked solid. I have a boat that had bad manifolds that would fill the cyl with water after you stopped, so I have seen that symptom before. It sure seemed like it "hydraulic-ed" to me, so I figured I would pull glow plugs out to see what was up.

As luck would have it the first one was #1 and the plug was followed by a stream of coolant. (Insert MUCH foul language here). I checked the engine oil, and there was no trace of coolant in the oil, and later, when I drained the coolant, there was no trace of oil in the coolant. I called Jamie Advant and advised him of the problem.

Jamie said that he can't remember the last time they had a head gasket problem, but we agreed that the head would have to come off. Jamie immediatly started the process of sending up new gaskets and head bolts. I agreed to pull the head, and if it was a head gasket, then Jamie and I would settle up later on my labor.

When I pulled the intake off, I shone a light down the #1 intake runner and the SOB was full of coolant on top of a closed intake valve. WTF!!! :confused: I couldn't see how a blown head gasket would get coolant ON TOP of a valve.

But, I proceeded with the teardown, hoping to see a big chunk out of the head gasket. Sure enough, the head gasket was in good shape with no obvious coolant tracks to the cyl. Again, I called Jamie an we agreed that the problem HAD to be in the head. Jamie said he would be shipping me up a new head.

We talked some more, and decided to have me punch out the intake valve and inspect the runner. We were both dying to know what would cause this.

What I found was a small hole in the casting of the intake runner.

http://www.gatewaydata.com/truck/Hole1.JPG
Seen from the valve seat

http://www.gatewaydata.com/truck/Hole2.JPG
seen from the intake port

http://www.gatewaydata.com/truck/Hole3.JPG
Closeup from intake port.

This hole was letting coolant under pressure into the intake runner.

I would like to add that the truck ran (strong) for a week before this happend with NO problems. I don't think that this hole was caused by anything the Diesel Depot did or didnt do. I also dont think that any amount of testing could have forseen this problem. Jamie Avant is standing by his product, and he is taking the proper steps to make it right by me. Which is a damn sight better than GM did with the FSD's.

I should have the new head by friday, and I should have The Big Blue Truck back on the road by the first of August.

Some times I don't know whether to laugh or cry...

Tim

[jeffscarstrucks]

Sorry to hear about your problem! It is good to know that your guy is standing behind you and he is lucky to be dealing with a customer with the skills to work with him. I wonder if the head that they used came from a core engine that was blown up violently; parts really go every where when that happens (speaking from experience). I guess that unless they track the parts from the time they come in then it would be hard to know. Does it look like a pourous cavity from the casting process. I've seen that in some race heads buy they have ported to the point where they where thin. I don't mean to ramble; just thinking out loud on your situation. Good Luck, JEFF

[Kennedy]

I always recommend pressure testing all heads and blocks when rebuilding. The shop that I use has engrained this in me a long time ago...

[ 07-26-2005, 07:01 AM: Message edited by: kennedy ]

[Billman]

Would it be worth checking for a bent rod?

Sorry to hear Cowracer.

[MTTwister]

"Would it be worth checking for a bent rod?"

? - Would that be easily done by verifying Piston height in the block - without tearing it down any further?

[Cowracer]

Originally posted by jeffscarstrucks:
Sorry to hear about your problem! It is good to know that your guy is standing behind you and he is lucky to be dealing with a customer with the skills to work with him. I wonder if the head that they used came from a core engine that was blown up violently; parts really go every where when that happens (speaking from experience). I guess that unless they track the parts from the time they come in then it would be hard to know. Does it look like a pourous cavity from the casting process. I've seen that in some race heads buy they have ported to the point where they where thin. I don't mean to ramble; just thinking out loud on your situation. Good Luck, JEFF Jeff, these heads were not ported. It looks like a defect in the casting, no cracks or "nicks" just a small (1/32") hole


Originally posted by kennedy:
I always recommend pressure testing all heads and blocks when rebuilding. The shop that I use has engrained this in me a long time ago... The heads and block were pressure tested, and passed. Like I said, I even went a week with no problems. Just one of those things that makes anyone who builds engines shudder.


Originally posted by Billman:
Would it be worth checking for a bent rod?

Sorry to hear Cowracer. I dont think the rods are hurt. I locked my 4.3 in my boat about 6 times till I figured out what the problem was. The starter didnt generate enough torque to hurt the rods. I know, diesel starters have more torque, but then again the rods are stouter. I should be OK.

Tim

[tom.mcinerney]

Unbelievable. Casting defect, huh? Probably OK seal until some heat/pressure/vibes opened. I would check the piston height with feelers/depth gage.

Such events fully justify both tears and laughter. I've certainly enjoyed your approach to the project. And will the new head be shipped painted? [almost impossible].

The mechanical/NA VW engines would develop small cracks in the aluminum heads, which eventually leaked coolant, depressing starting capability.

[markrinker]

Unreal. Where do all these casting flaws originate?

[BrentN]

Casting flaws in general can come for many reasons.
1. The design of the component may not lend itself to flowing metal very well and you may not get even fill or that area of the design may be thinner than it should be or a core was shifted, causing wall thicknesses to change.
2. Metal when liquid as it rounds a corner in a mold will impart high amounts of heat into the tool or the sand medium- This heat can cause this portion of the mold to cool slower than the rest of the part. If the cooling rate deep inside a part is significantly slower or faster that the rest, then a residual stress concentration can be formed.

There are a lot of details that go into casting a part whether it is a sand casting or a die casting.

I see a lot of aluminum die cast parts that we will expose a lot of porosity on, especially if we take a slight surface cut. The fact is, the porosity is always there, its just whether you see it. Another saying in the business, "a good casting is the fortunate arrangement of porosity, a bad casting is the unfortunate arrangement of porosity"

I wouldnt get too worked up over it, as it doesnt sound like this particular failure is very common on our heads. You just got unlucky. Of course, something could have changed at the foundry that pours these heads and your experience is the taste of things to come-I hope not.

I also own a Fiero. When it was being built, the 2.5L head would always crack in the same spot in certain years..GM fixed it, but it wasnt just limited to the Fiero, every 2.5L had the flaw, most would open up under higher heat conditions. Which of course the Fiero produced. But when at the junkyard looking for a replacement head, there where dozens that came off of other GM models that used that engine. Crap Happens. Hopefully Avant relays the info to GEP...It may be nothing, but it may serve to help the rest of us when we need to replace our engines or for all the Humvees that are still getting them.