Just need an honest opinion

jared_bortel · August 5, 2008

Had a truck in the shop for a straight forward head gasket repair. Pretty cut and dried big old pain in the ass. B/S extra wiring ofr the service box and all the shit on it made it foolish to even try and pull cab. Performed head repair and test drove about 40 mi. Returned vehicle to customer and he drove it for about 300mi over the past day and a half. Truck hydrolocks on I-95 at 65 mph. Injector #8 leaked down and hydrolocked cylinder. Hold down bolt came out tight and bottom

o oring and copper washer are gone. I know beyond any reasonable doubt that i torqued injector fully to 24ft/lb spec. Upon removal I find alot of visible wear on head of bolt as if it had been excessivly handled. Run oasis again and remember that previous history at other dealers involed #8 injector replacement three time already. I have a few spare holddowns in my nut and bolt collection and I started checking them. Compared to the four spares I have the one I removed from this truck was .025" longer. I doubt for some reason that this is my issue and point of failure but i must raise an eyebrow none the less. BTW the other four that i had spare were about .007" max difference in the range of them.

Keith Browning · August 5, 2008

If this engine has a history of multiple injector problems in the same cylinder you need to inspect and replace the hold down clamp but more importantly the injector cup. Once an injector loosens to the extent that the copper gasket is pounded away the cup is beat up as well and cannot provide a good sealing surface. #8 too! Whoo Whee! That sucks in chassis but it can be done.

Jim Warman · August 6, 2008

Just a word of advice on doing the cup in frame.... we had a claim kicked back because we couldn't supply the old head bolts and gasket...

Keith Browning · August 6, 2008

Just a word of advice on doing the cup in frame.... we had a claim kicked back because we couldn't supply the old head bolts and gasket...

Kind of ironic since he already had the heads off. This is where the honesty part comes in. He should have thought of all this when he had the heads off and was inspecting all of his parts. (not a personal dig - just an observation) Unfortunately Jim is right because the workshop manual states that you must remove the cylinder head to replace injector cups. This can be done in chassis and it is done that way more frequently than you think. The problems are that the process creates metal shavings and the lack of access space prohibits the use of a slide hammer for the rear cylinders. I have creative workarounds for both. Lastly, you need to ensure all antifreeze and fuel that spills into the cylinder is removed before starting the engine.

jared_bortel · August 7, 2008

I agree that the injector cup would be cause for concern but I forgot to mention that the head was replaced with the head gasket repair so theoretically it's relatively fresh. I got lucky and manual compression test showed 380 psi across the whole bank. Rolled the dice and put it back together with a new inj and hold down and double checked the torque on all four on that bank. I raped that truck for 30 mi. and it went fine so I shipped it out. I was just wondering the plausability of my little theory. Thanks guys.

Keith Browning · August 7, 2008

So this is a theoretical question about the engine before you repaired it or has it returned after the customer took the vehicle after you released it?

Tony302600 · August 7, 2008

This has happened to me from another shop, changed the hold down and injector and shipped it...ok...

jared_bortel · August 7, 2008

Simply put I have very little doubt about the cause of this failure being the injector hold down. I was just wondering what everybody's opinion on my findings with the injector hold down bolt length and whether this this evidence is substantial enough to support my conclusion.

Bruce Amacker · August 7, 2008

Simply put I have very little doubt about the cause of this failure being the injector hold down. I was just wondering what everybody's opinion on my findings with the injector hold down bolt length and whether this this evidence is substantial enough to support my conclusion.

Yes, without a doubt. You were wise to measure the length of the bolts.

One of the coolest clinics I ever attended was a fastener class put on by Parts Associates Inc. PAI is our hardware distributor- the guy who come out and fills all of the little screw trays and nut/bolt bins. The class showed how important torquing is, and how an over torqued bolt does not have the "clamp load" that a properly torqued bolt does. This class had a neat widget that sat on a tabletop and measured clamp load. First the guy would install and properly torque a bolt, measure the clamp load, and write it down. Then he would over torque the bolt 10-20% and wow!, watch the clamp load fall down. Then he would loosen the bolt and retorque it, but it would never reach the clamp load it reached when it was new and properly torqued. He could loosen and retorque that bolt 10 times and it would reach the same clamp load each time, but as soon as it was overtorqed, the clamp load fell off. A true lesson in fasteners I'll never forget.

PS High end race cars do not get the rod bolts torqued- they get tightened to about .006" longer than standard. That's why torque specs are sometimes very wide- like 60-90ft/lb. They are actually looking for the proper stretch of the fastener, not the torque.

PPS IH has a "thread gauge" that is used to check the head bolts on DT engines that were torque-to-yield. They can be re-used if they pass the thread gauge, but few do.

Good Luck!

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Shlep · August 8, 2008

PPS IH has a "thread gauge" that is used to check the head bolts on DT engines that were torque-to-yield. They can be re-used if they pass the thread gauge, but few do.

Good Luck!

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Good thing Ford doesn't know about that gauge or they would modify it and say none of the bolts have to be changed /forums/images/%%GRAEMLIN_URL%%/flamethrower.gif /forums/images/%%GRAEMLIN_URL%%/ford.gif

Bruce Amacker · August 8, 2008

Good thing Ford doesn't know about that gauge or they would modify it and say none of the bolts have to be changed /forums/images/%%GRAEMLIN_URL%%/flamethrower.gif /forums/images/%%GRAEMLIN_URL%%/ford.gif

Sshhhhh. The walls have ears.

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