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Bent push rod?
Cargo Master
Joined: Apr 2004
Posts: 3,162
Likes: 1
From: Vilonia Arkansas
Originally Posted by Tenn01PSD350
What about bouncing up and down on the cam? Any possibility of lobe damage? Sorry, don't want to bing foul weather your way.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
It appears these valves can float, given enough R's, and the lifters are happy to oblige taking up the slack.
To what point can this happen? There must be mechanical stops on the lifters (snap rings?). Anyone know the lifter piston's range of travel?
Pop
To what point can this happen? There must be mechanical stops on the lifters (snap rings?). Anyone know the lifter piston's range of travel?
Pop
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
I have lifters laying around in the shop i can look at tomorrow Pop. 1996 i was asking this question not because of the lifter falling out of the bore (there is a retainer plate for them) however overextending the actual lifter itself. It is a hydraulic lifter, which means oil pressure keeps a constant valve lash on the rockers/push rods etc, and once you dont have a resistance for the oil to press against, the lifter could *possibly* just fill with oil and (pop?)
Cargo Master
Joined: Apr 2004
Posts: 3,162
Likes: 1
From: Vilonia Arkansas
I haven't had a lifter out of a 7.3 but I have had plenty of gas engine lifters out and apart in one fashion or another all had a mechanical stop of some kind. I don't think that there's enough oil press in the lifter to pop it apart unless it's really damaged bad.
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Originally Posted by 1996pwrstrk
I don't think that should be an issue either there was no pressure to cause any damage.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
They are roller lifters and held in alignment somehow so that they will not spin in the bore. All they will do is hop. If that little bit of bouncing on the lobe damaged anything, then the metallurgy needs to be improved.
Remember that the camshaft turns at 1/2 crankshaft speed, so even at 4k rpm, the cam is doing 2k. Not very fast.
If the valve isn't bent, put it back together and run with it.
Remember that the camshaft turns at 1/2 crankshaft speed, so even at 4k rpm, the cam is doing 2k. Not very fast.
If the valve isn't bent, put it back together and run with it.
Cargo Master
Joined: Apr 2004
Posts: 3,162
Likes: 1
From: Vilonia Arkansas
As soon as the parts come in thats the plan . I pulled out to pass someone in the ole 86 yesterday on the two lane and scared myself I really miss my truck.
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Brett Foote
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Originally Posted by 1996pwrstrk
As soon as the parts come in thats the plan . I pulled out to pass someone in the ole 86 yesterday on the two lane and scared myself I really miss my truck.
Cargo Master
Joined: Apr 2004
Posts: 3,162
Likes: 1
From: Vilonia Arkansas
As soon as I pressed on the go pedal and it went wahWAHHHHHHHHHHH and didn't really seem to pick up speed I knew. My pushrod is in but my rocker arm isn't but they expect it by the end of the day .I will have to get momma to pick it up so I can start first thing in the morning.
Last edited by 1996pwrstrk; Aug 21, 2007 at 11:17 AM.
Elder User
Joined: Oct 2006
Posts: 635
Likes: 0
From: New York
Wish I had read this sooner, some personal experiance may be relevant here. I broke a rocker bolt on the exhaust side while towing under load on a road trip that caused the engine to backfire through the intake, got that fixed, then later that trip broke the pushrod for the intake side. Removed both rockers for that bore, so the lifters were just sitting in their bore, and drove another 400 miles like that. And after that, removed the egine, camshaft and lifters and there was no obvious damage to the lifters, bores, or camshaft for that cylinder(8). So you should be just fine. I really wouldn't expect to find any permanent damage there.
I do know the OBS trucks had a TSB about the injector O-rings failing as you described, so that should put you back on the fast track.
I do know the OBS trucks had a TSB about the injector O-rings failing as you described, so that should put you back on the fast track.
Cargo Master
Joined: Apr 2004
Posts: 3,162
Likes: 1
From: Vilonia Arkansas
FN74 I wasn't really worried about the lifters or the cam since the time of the dirty deed it hasn't seen the high side of 1500 rpms and its only run about 15 mins. mostly at idle. I thank for your info makes me feel better.
Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
Just talked to Dave on the phone....I got to listen to the ol 7.3 purring like a kitten in his garage.
Congratulations on getting her back, I know it was killing you waiting on parts.
Congratulations on getting her back, I know it was killing you waiting on parts.