Flatlander engine demise discovered!!!

[Dsl_Dog_Treat]

Well I had a break in shop action Sunday and decided to get the engine torn down and discovered that #7 piston is totally *****'ed due to the wrist pin overheating.
Removing the rod from the piston, as shown in the pics, the rod, wrist pin and piston crowns haver all been subjected to excessive heat.

Fearing my hunch was becoming more evident now, I put the piston cooling jet alignment tools on and confirmed my hunch.
As shown in the last pic, the alignment dowel is off to the side and putting pressure on the opening thus being was out of alignment.
#8 piston also had a scorched crown as well and cooling jet alignment was off as well.

The cooling jets on this 6.9 are the bolt on ones and probably on a stock biuld, this "may" be get ya by but seeing the EGT's that we do, I wouldn't chance it.

But shaving .060" off the tops of a Mahle hardened anodized piston isn't going to provide a long engine life when running high temps in these engines.

Sooooo, there's your dog catcher TSB engine building tip for the day.

I've been able to get ahold of Ken to get the final build specs, since Ken did the build, and round up the necessaries, 2 new pistons shaved, balanced and ceramic coated all to get it back to breathing fire.

Now to get some manifolds in the works to mount a few Holsets on top of them.

 

[icanfixall]

Thanks for the updates. Have you removed the cooling jets and looked for partical blockage in them yet. Good to find the reasons but sad too. How far off were the alignment on these cylinders and the alignment tool I thought was to be used on the press in jets only. How would a bolt in jet get out of alingment..

 

[Dsl_Dog_Treat]

Thanks for the updates. Have you removed the cooling jets and looked for partical blockage in them yet. Good to find the reasons but sad too. How far off were the alignment on these cylinders and the alignment tool I thought was to be used on the press in jets only. How would a bolt in jet get out of alingment..

I haven't removed the suspect jets yet Gary.

No telling how they got out of alignement but the pic shows how far off #7 was as it was the worst.

 

[subway]

i thought that the EGT's were real low on the engine when i was running, now we have an idea of how important the cooling jets are.

 

[Dsl_Dog_Treat]

i thought that the EGT's were real low on the engine when i was running, now we have an idea of how important the cooling jets are.

Exactly!!!

And wether it be stock piston or aftemarket design, IMHO it will make no difference after seeing how burnt the crown was on #7 with LOW egt's!

 

[icanfixall]

oldmrbill had a cooling jet plug up and that wasted a piston fast. Because I have a temp gauge in my oil pan I can tell you the oil usually is about 10 degrees above the coolant temp.. Untill your pulling a grade loaded or not. Then you will see temp excursions in the 260 degree area.. Run without coolant like I did pulling a termendous grade in so ca and the temps pass 330... Then pistons swell and the engine slows to a stop no matter how much peddle you give it.. Also there is a racket from the lifters being fed some thinn hot oil... Yeah... That was my worst day right there....

 

[Darrin Tosh]

You just wanted to show off your Cooling Jet tool!

Yea that piston is Scorched! Good find there Ron.

 

[icanfixall]

Ron... What does the pin bushing look like or the oil hole alingment. Are the rod bearings worn on one side more than the other. Surely that cooling jet is way off proper direction. I wonder is someone installing the pistons hit it and didn't feel it was a big deal...

 

[Dsl_Dog_Treat]

Gary the pin bushing is smoked also. Pic doesn't really do it justice.
I haven't removed the bushing yet as I'm not sure I want to use that rod since is took on some serious heat.
Rod bearing was evenly worn but appears to have been contaminated as it has a score in the material.


Darrin of course! Who wouldn't want to show off their tool to a group of unsupervised adults!

 

[hesutton]

Ron, Thanks for giving me a preview on Sunday. It makes me nervous to see some of the damage you've found. Makes you wonder what else Ken or his crew may have "overlooked" during teardown, reassembly? I'd be sure to pull the main and rod caps to make sure the other bearings aren't *****. You can't be too careful in keeping them spotless. Any trash on the journals or the bearsing will haunt the engine for the rest of it's service life.

I know we talked about this Sunday, but I really think someone () bent those jets during the teardown or during the assembly. With that much aluminum taken off the crown and little cooling from the jets, it's no surprise the pistons you looked at show heat damage. The heat transfer from combustion is an issue (dispite the ceramic coated crown).

Too bad there aren't more piston options. It'd be nice if there were pistons with 20 or 30k lower compression heights rather than just 10K pistons from Mahle.

Can't wait to see more stuff from this 6.9.

Heath

 

[wanabebig]

Ron, go figure you would be one to get a blue engine from another member. On another note, i'd love to know the deminsions of the plate, where the wholes are at, and all. That would be a pretty handy little plate to have when rebuilding one of these motors.

Jim

 

[Darrin Tosh]

Ron, go figure you would be one to get a blue engine from another member,
Jim

 

[icanfixall]

I was wondering when someone was going to bring up the blue engine..;p Funny how things like that work out sometimes... What was the make on those pistons Ron and were they large pin or small pin.
The rod bushing can be machined outlower for the pin fit by about .006 so that will drop the piston down in the cylinder that much plus.. If its a 7.3 piston it can be a lower comp piston thats already .010 lower. So overall you will have a piston thats dropped .016 before you mill the tops any. I only know of one person that has cut the bushing like this and he has 80,000 trouble free miles on his engine....

 

[Dsl_Dog_Treat]

Well that took a whole 10 posts to surface.
Jim I'm gonna try to something about that.

Heath, I learned that the ceramic coating had been removed on version 2 when the pistons were shaved.
They will be on this version but not sure if it would have saved the crowns or just prolonged the inevitable.
Not sure about how the cooling jet got bumped but I can't really point fingers at this point.
Speaking with Ken yesterday, I'm gonna have him get the pistons shaved and rematched with the good ones and have him ceramic coat the pistons as he's familiar with this build and believes this was the first of its kind.
I'm excited about this build.

 

[hesutton]

Gary, You can also get the 6.9 pistons with the 0.010 lower compression height pin placement, just like the 7.3's. Mahle number is 144111 for the standard size. It has a 6.64cc Ricardo combustion cup.

Heath