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What causes bent pushrods? #4561247
11/01/17 12:18 PM
11/01/17 12:18 PM
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
My dad has a 1999 Fleetwood Flair 30H RV that he bought 2years ago, around 76k miles. It has the Chevy 454 engine. In August he moved up to Oregon and drove it up there towing his FJ Cruiser, 4 mpg crzy . In August before the journey he changed the oil, plugs, wires, cap, rotor, etc. On the journey it set a CEL for running lean (or rich? Can't remember) and it also has had a crack in the exhaust manifold, we thought it might be that.

It's been running fine, except last week he said it wouldn't go over 10 mph, had a rough idle, and when giving it throttle it stumbles and bangs on the passenger side.

He took it to an RV mechanic who said it had 3 bent pushrods and it runs fine now after the repair.

How do push rods get bent? I'm not that internal-engine-savvy.


2015 Hyundai Sonata 2.4L 88k Motorcraft Synthetic Blend 5w30 & OEM
2000 Toyota Camry 2.2L 231k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: What causes bent pushrods? [Re: Nick1994] #4561251
11/01/17 12:24 PM
11/01/17 12:24 PM
Joined: Aug 2003
Posts: 11,013
Buffalo, NY
JTK Offline
JTK  Offline
Joined: Aug 2003
Posts: 11,013
Buffalo, NY
A hydraulic lash adjuster (lifter) that sticks all the way extended can bend a pushrod.


2017 Ram 1500 4x4, 3.6L. 2016 Nissan Quest SV (Babe magnet IV)
Re: What causes bent pushrods? [Re: Nick1994] #4561252
11/01/17 12:25 PM
11/01/17 12:25 PM
Joined: May 2009
Posts: 12,283
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline
Joined: May 2009
Posts: 12,283
N.H, U.S.A.
overrevving usually.


2014 Nissan Rogue S CVT, OC#10 47272mi-QSUD10W30+5w20 Toughguard Filter; '17 Subaru Crosstrek CVT OC#2 ?? mi-SOA/Idemitsu 0w20 + SOA Filter
Re: What causes bent pushrods? [Re: Nick1994] #4561256
11/01/17 12:27 PM
11/01/17 12:27 PM
Joined: May 2009
Posts: 12,283
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline
Joined: May 2009
Posts: 12,283
N.H, U.S.A.
He need to get a old Suzuki Samurai or a Smart for a tow behind. That FJ is a fat piglet.


2014 Nissan Rogue S CVT, OC#10 47272mi-QSUD10W30+5w20 Toughguard Filter; '17 Subaru Crosstrek CVT OC#2 ?? mi-SOA/Idemitsu 0w20 + SOA Filter
Re: What causes bent pushrods? [Re: Nick1994] #4561257
11/01/17 12:29 PM
11/01/17 12:29 PM
Joined: Jun 2003
Posts: 17,815
Deplorable in apple valley, ca
Chris142 Offline
Chris142  Offline
Joined: Jun 2003
Posts: 17,815
Deplorable in apple valley, ca
Overrevving. All that weight pushing it down a hill usually.


02 Wrangler carlube 5w30
87 F250 traveler 15w40
07 fjcruiser Chevron 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: What causes bent pushrods? [Re: Nick1994] #4561258
11/01/17 12:30 PM
11/01/17 12:30 PM
Joined: Sep 2015
Posts: 6,075
Kalifornia Kollective
BrocLuno Offline
BrocLuno  Offline
Joined: Sep 2015
Posts: 6,075
Kalifornia Kollective
Bad lifter as stated above ..

Or, it is the rocker arm not having enough slot clearance so that the arm stops moving and the cam/lifter does not. So if this engine ever had a cam change (?) and they did not install "long slot rockers", it might be close to the limits ... An over rev and lifters pumped up will put it over the limit.

Or, it could be piston/valve interference due to a worn timing chain (long shot), timing jumped one tooth (also long shot, but still needs worn chain), or piston/valves set too close and carbon build-up has closed the gap (best probability) ...

I would not drive it until I found out why?

Find a tune-up shop with a bore scope and have them look in the cylinders. If it's carbon-ed up, get it cleaned (various ways). If it not carboned up, then it's mechanical ...


Last edited by BrocLuno; 11/01/17 12:33 PM.

Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.
Re: What causes bent pushrods? [Re: Chris142] #4561259
11/01/17 12:32 PM
11/01/17 12:32 PM
Joined: Jan 2008
Posts: 10,968
OH
SatinSilver Offline
SatinSilver  Offline
Joined: Jan 2008
Posts: 10,968
OH
That's like towing a 4Runner behind it as far as weight goes. Yikes!

Re: What causes bent pushrods? [Re: ARCOgraphite] #4561260
11/01/17 12:32 PM
11/01/17 12:32 PM
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Originally Posted By: Chris142
Overrevving. All that weight pushing it down a hill usually.
It took a lot of throttle to get it up the mountains to Oregon from Arizona, not sure what else he could have done. Also, it ran fine when he'd drive it around town occasionally the past couple months, he said it was all of a sudden. He doesn't drive like a race car driver so I don't think he was redlining it around town.

Originally Posted By: ARCOgraphite
He need to get a old Suzuki Samurai or a Smart for a tow behind. That FJ is a fat piglet.
He was moving, wasn't for a vacation. It was a flat tow too with a tow bar so no trailer weight.


2015 Hyundai Sonata 2.4L 88k Motorcraft Synthetic Blend 5w30 & OEM
2000 Toyota Camry 2.2L 231k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: What causes bent pushrods? [Re: Nick1994] #4561261
11/01/17 12:32 PM
11/01/17 12:32 PM
Joined: May 2012
Posts: 5,666
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline
Joined: May 2012
Posts: 5,666
Fort Lauderdale, FL
As I said in the other thread, BBC engines are not exactly happy with high sustained rpms. Most of the time when we see BBCS with bent pushrods, it's either broken or soft valve springs that allowed pushrods to escape their position and be rammed into a new position after escaping the rocker, or collapsed lifters allowing the same.

When we do the marine versions, we almost always replace the valve springs with something aftermarket that will take the beating, unless preserving a crate engine warranty.

Collapsed lifters are nowhere near as common as broken or soft valve springs.


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: What causes bent pushrods? [Re: Nick1994] #4561277
11/01/17 12:57 PM
11/01/17 12:57 PM
Joined: Sep 2015
Posts: 6,075
Kalifornia Kollective
BrocLuno Offline
BrocLuno  Offline
Joined: Sep 2015
Posts: 6,075
Kalifornia Kollective
Well, I assumed that broken valve springs were not the issue because the OP did not relay that info from the mechanic?? But maybe we don't have the whole story ...


Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.
Re: What causes bent pushrods? [Re: Nick1994] #4561279
11/01/17 12:58 PM
11/01/17 12:58 PM
Joined: Oct 2005
Posts: 7,094
Colorado
Kuato Offline
Kuato  Offline
Joined: Oct 2005
Posts: 7,094
Colorado
Credit to Chevy's 454 for operating that long with several bent pushrods! Yeah at high rpm you get valve float (valves stay open) and when they're in the way of the piston or other parts....well something's got to give.


Thick vs Thin test: 15k / 43k miles complete
Re: What causes bent pushrods? [Re: Nick1994] #4561357
11/01/17 03:00 PM
11/01/17 03:00 PM
Joined: Nov 2008
Posts: 9,288
Phoenix
dishdude Offline
dishdude  Offline
Joined: Nov 2008
Posts: 9,288
Phoenix
.

Last edited by dishdude; 11/01/17 03:02 PM.

2018 Challenger SRT 392 PUP 0w-40 Wix 57899XP
2018 GTI
Re: What causes bent pushrods? [Re: Nick1994] #4561386
11/01/17 03:51 PM
11/01/17 03:51 PM
Joined: Dec 2004
Posts: 426
Dayton,Ohio
ShotGun429 Offline
ShotGun429  Offline
Joined: Dec 2004
Posts: 426
Dayton,Ohio
heavy towing up a mountain (heat) can take out the oil film on the valve guides,Cast iron guides, steel valves, hangs them (valves) open off the valve seat, and Piston hits said valves and you end up with Bent pushrods, Just replacing pushrods may not fix your issue long term.

Re: What causes bent pushrods? [Re: BrocLuno] #4561406
11/01/17 04:16 PM
11/01/17 04:16 PM
Joined: May 2012
Posts: 5,666
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline
Joined: May 2012
Posts: 5,666
Fort Lauderdale, FL
Originally Posted By: BrocLuno
Well, I assumed that broken valve springs were not the issue because the OP did not relay that info from the mechanic?? But maybe we don't have the whole story ...


I didn't get that impression either, just passing along info.

Multiple bent pushrods definitely makes me think of valve float due to collapsed or semi-collapsed lifters.

Part of me even wonders if low oil pressure allowed the lifters to leak down enough to set a few pushrods free.

Not an easy one to hit dead on unless you're the mechanic who was on that engine.


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: What causes bent pushrods? [Re: DoubleWasp] #4561503
11/01/17 06:00 PM
11/01/17 06:00 PM
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Originally Posted By: DoubleWasp
Originally Posted By: BrocLuno
Well, I assumed that broken valve springs were not the issue because the OP did not relay that info from the mechanic?? But maybe we don't have the whole story ...


I didn't get that impression either, just passing along info.

Multiple bent pushrods definitely makes me think of valve float due to collapsed or semi-collapsed lifters.

Part of me even wonders if low oil pressure allowed the lifters to leak down enough to set a few pushrods free.

Not an easy one to hit dead on unless you're the mechanic who was on that engine.
I posted all the info I got from my dad, sorry if it wasn't enough.

I believe the gauge reads good oil pressure too, he filled with 10w40 MaxLife before the journey.


2015 Hyundai Sonata 2.4L 88k Motorcraft Synthetic Blend 5w30 & OEM
2000 Toyota Camry 2.2L 231k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
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