Power Stroke!%#@$&*^(
 

Ok gearheads who here knows anything about 7.3L Ford Power Stroke diesels. I have a customer with a 97 7.3L and it keeps bending pushrods. Exhaust pushrods and even broke a rocker arm once. Ive scoured some ford forums and had a friend look for TSB's and have found nothing.
I know the driver of this thing abuses it so I suspect an overspeed condition but the last time it happened (a couple of hours ago) I dont think he had the opportunity to really trash it.
Any of you guys run into this problem?

Unless he has dorked with the IP speed govenor I don't think overspped would be a problem. Has the block and head ever been milled such as for a rebuild or due to a head gasket failure? If too much was milled it is possible the pushrods are now too long. I believe this motor also has hydaulic cam followers. Is the oil pressure within proper range? I wonder if too high of oil pressure, say from the a bad bypass flow not opening causing problems with the hydraulic lifters?

TimK

Does any PERFORMANCE MODS ON THE ENGINE? With TODAYS electronically CONTROLLED Diesels, more hp is just a plug in! Does he have an ehxaust brake? The performance mods could change his engine governed speed. He could be over-revving it. If the ehxaust brake restricts too much and the guy didn't have heavier ehxaust valve springs installed, A valve can stay hung open and get hit by the piston. This was an issue with earlier, 12valve Cummins diesels in Dodge trucks.
This guy sounds like he just hasn't suffered enough in the pocketbook yet to take his RIGHT foot off the floorboard!!!

No exhaust brake on this truck. But it has an exhaust back pressure regulator. It closes a flap in the exhaust to aid in warm up. It's stock. It has happened on the same exhaust valve 3 times. I'm beginning to wonder if its a weak valve spring.

I don't think it's particularly applicable to this situation, as it sounds like you have a problem specific to one valve, but remember, either electrical or mechanical, a governer only affects the speed you can power the engine up to. If equipped with a manual transmission, one can always over-rev an engine by downshifting incorrectly.

I've seen several engines, both gas and diesel, destroyed in this manner. And each time the customer said "I thought the computer/governer would keep it from over-revving". Apparently they were under the impression that new control systems were not only able to control aspects of the vehicles engine and other systems, but able to control the laws of physics as well. While some new systems almost seem like it, flirt with the idea of it, none have managed to defy physics yet.

MV

I bent a few pushrods and broke a couple of rocker arms, but it was the combination of too much fuel. I was using injectors that were 30% rich ( and timed wrong I might add) and propane. I really think the problem that I had was the injection duration was too long, thus, the fuel was burning longer than it should have in the cycle. It did it during a down shift to pass at 65MPH....

It did make lots of noise......

I just re read my post. It's just the exhaust pushrod on number 8 that does it. I'm gonna pull the valve spring and have a look. Maybe sticking in the guide or a broken valve spring.

I was going to suggest a sticking valve. I had old fuel in my Travco 413 and it caused a lot of intake valves to stick. Bent a whole bunch of pushrods and took a lot of work to loosen up the valves.
Could be the valve is slightly bent, sticking in the guide.

my first thought was over reving.

my scout four cylinder had been used to push snow. when i got it it was running kindof rough and upon investigation all the pushrods were bent as hell.

pushing snow in the low range it is pretty easy to get carried away if you are trying to make money.

tom w

Sorry, I don't know the answer.
 

That's why they call them PowerJokes! :D

I pulled the spring from the affected valve and it moves smooth. Guide to stem clearance was .001 inch. I wonder if it's too tight. Max clearance is supposed to be .0055 thats a huge difference and way too loose for a gas engine.

Look for oil problem on rocker arm
 

I used to own a engine shop and some time ago we had a customer 7.3 that ford kept replacing a bent push rod. Every time it was the same one I think the 3rd time they even replace the lifters not sure but either way the problem was no oil up the push rod the rocker arm would get hot and stick and bend a push rod or 2

I think I figured it out! No 8 exhaust valve was sticking just a bit. You could just feel it a little by hand with the spring removed. I pulled the exhaust manifold and looked at the stem and could see metal transfer from the guide to the stem. Instead of pulling the head I polished the stem through the exhaust port with crocus cloth. I think it should work. Only time will tell.

it is worth a try.

tom w