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  #1  
Old December 5th, 2010, 12:18 PM
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Baird M. Gehring
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Unhappy Defender blows a pushrod :(

Hi all,
All last week I had my 4.0 apart installing a new head gasket set from proline. Got everything back together yesterday and took it around for a spin, everything was running very well for a while, even took it out on the freeway. Went out later in it to get take out and on the way home I heard a pow and noticed a trail of oil so I pulled over and discovered my engine had blown a pushrod out of the front of the oil pan. This is my first Rover, I love it, and I don't understand why this would happen after putting everything back together and doing everything by the book. Can anyone tell me what sort of damage I can expect? Will I need an entirely new engine or is it not that major of a problem?
-Baird
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  #2  
Old December 5th, 2010, 12:43 PM
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Originally Posted by BMGmotors View Post
Hi all,
All last week I had my 4.0 apart installing a new head gasket set from proline. Got everything back together yesterday and took it around for a spin, everything was running very well for a while, even took it out on the freeway. Went out later in it to get take out and on the way home I heard a pow and noticed a trail of oil so I pulled over and discovered my engine had blown a pushrod out of the front of the oil pan. This is my first Rover, I love it, and I don't understand why this would happen after putting everything back together and doing everything by the book. Can anyone tell me what sort of damage I can expect? Will I need an entirely new engine or is it not that major of a problem?
-Baird
I'm guessing you mean connecting rod?
Only a guess but when you did the head gaskets a lot of crap could fall down into the pan clogging up the oil pick up. If this happened it starved for oil and spun a rod bearing and tossed a rod.
I would plan on replacing the short block, or plan to turn the crank and resize the rods.

If it was a push rod I have no idea how it got there unless one fell down while putting it together. If that is the case you should be able to replace it and patch the pan.
I would love to see pictures.
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Old December 5th, 2010, 12:54 PM
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Quote:
Originally Posted by BMGmotors View Post
Hi all,
All last week I had my 4.0 apart installing a new head gasket set from proline. Got everything back together yesterday and took it around for a spin, everything was running very well for a while, even took it out on the freeway. Went out later in it to get take out and on the way home I heard a pow and noticed a trail of oil so I pulled over and discovered my engine had blown a pushrod out of the front of the oil pan. This is my first Rover, I love it, and I don't understand why this would happen after putting everything back together and doing everything by the book. Can anyone tell me what sort of damage I can expect? Will I need an entirely new engine or is it not that major of a problem?
-Baird
It really depends on why/how it got blown out, and what it hit along the way. It could be a simple as a a few valvetrain components and a new oil pan. Could also have screwed the block/crank/connecting rods too. This is just one of those problems that you'll need to start digging until you've found all the busted parts. I hate to say it Alice, but you may have to go pretty far down the looking glass this time. Be particularly on the lookout for large amounts of coolant or a lot of big metal shavings in the oil which would be indicators of greater problems. This may also be one of those cases where it's a good idea to cut open the oil filter and see what's in the filter elements.

First guess off the top of my head as to a cause would be loose chunks of stuff inside the engine got into the pushrod or lifter. However the good thing is that it came out the oil pan. Sometimes they come out the side of the block.

Not in any way knocking your work at all, (more adding this part as a friendly warning to future readers) but situations like these are why you need to be exceedingly paranoid about how clean you keep that upper valley when you open up an engine.

The good news is that you can keep the heads on most likely, as this kind of problem wouldn't have penetrated the cylinders at all. IIRC you can also leave the front cover on too, which saves a LOT of work right there. Just need to pull the intake manifold and oil pan for a good inspection. Hopefully.

-Hans

------ Follow up post added December 5th, 2010 01:01 PM ------

Quote:
Originally Posted by mud ruts View Post
I'm guessing you mean connecting rod?

If it was a push rod I have no idea how it got there unless one fell down while putting it together. If that is the case you should be able to replace it and patch the pan.
I would love to see pictures.

Yeah, if it's a con-rod it's engine time. I'm going under the hope that it really was just a pushrod.

It does happen from time to time to blow out a pushrod. Usually a lifter gets clogged and either loses pressure or over-pressurizes. That causes the pushrod to either bend or possibly get un-seated, and then it starts bouncing around, and who knows where it can go after that point. With that open valley, it's very possible for it to eventually find its way into the crankcase.

-Hans
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  #4  
Old December 5th, 2010, 01:47 PM
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well it seems my block is ruined
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Old December 5th, 2010, 02:04 PM
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well it seems my block is ruined
It was a connecting rod then? Damn.

It may or may not be rebuildable still, depending on the damage that was done. But realistically, a blown connecting rod at best means a full rebuild (scored cylinders, spun bearings, etc...) At worst it scraps the block (busted through the water jacket or side of the block. It's only that lucky 1% that get to just throw in a new rod/piston and drive away.

From the case of practicality, as our engines don't exactly have the parts availability/cost of a Chevy or Ford, your best option at this point in both time and money would be to find a good, used, low mile, replacement long block. Lots of 4.0 Disco's and RR's out there in the scrapyards these days, so shouldn't be too hard/expensive to track one down. Heck, you may stumble on a great deal for a 4.6.

-Hans
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  #6  
Old December 5th, 2010, 03:08 PM
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Depends on the severity of the fail. Luckily the rod went thru the pan and not the side of the block, so it may be savable. When rods go they can do a wide range of damage, not the least of which is bending the crankshaft, holing the block, ruining the piston bore and cracking internal webs. Usually rod failure is directly related to lubrication, or rather the lack of it. If the reason for replacing head gasket was to repair a coolant leak into the oil, that may be the initial cause. Coolant in the oil will eat the babbit off your bearing shells in short order, like an hour or so.
Your certainly going to have to take that lump out. A complete overhaul along with a possible sleeving of the bad piston bore will be in your future. I would go look for a good used longblock and just swap it in. An overhaul will be very costly.
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  #7  
Old December 6th, 2010, 01:05 PM
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I'm also in the middle of a top end rebuild. Has anyone tried replacing the crank bearings without taking the crankshaft out? I heard it can be done by dropping the oil pan and pushing them around & over?

Has anyone done this successfully?
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  #8  
Old December 6th, 2010, 09:08 PM
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Did it on my 2.25, no problems. Couldn't do the rear main but was able to do all the rod bearings and the two front crank bearings.


Quote:
Originally Posted by Streaky View Post
I'm also in the middle of a top end rebuild. Has anyone tried replacing the crank bearings without taking the crankshaft out? I heard it can be done by dropping the oil pan and pushing them around & over?

Has anyone done this successfully?
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  #9  
Old December 9th, 2010, 10:02 PM
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Baird M. Gehring
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for the record

I can't imagine that I let anything fall down into the valley during dis/re-assembly. I did everything according to my rover manual, replaced valve seals and cleaned the heads thoroughly while I had it all apart. Prior to doing all this I could smell coolant pretty bad in my exhaust and even could see it condensating on the end/inside of the tailpipe, no sign of coolant leak at all after the job was done. Still there's no chance that it could've been a cracked block from the beginning and once I got it all torqued down w/ new gaskets and all it just blew under pressure could it be? My rod didn't come out the bottom of the oil pan, just looks like the counterbalance or something hit and gashed the front/shallow bottom of the oil pan. I'll actually delve into it when I get some time. When I had the heads off I did notice the passenger side most forward cylinder appeared cleaner/less carbony than the others, this was the only cylinder that was cause for suspicion, no signs of leakage from the head gaskets themselves, only other indicator was deterioration of the very front passenger side valley-gasket water jacket. Coincidentally it appears that the pushrod/connecting rod failure/ or whatever it is, occured in the front of the engine. Anyways, I'm going to take off the oil pan to see what's up possibly this weekend but thought I'd add these minor details to see if anyone could further help deceifer this mystery.
Thanks,
Baird
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  #10  
Old December 11th, 2010, 01:30 AM
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Sorry, that really sucks.
So how many miles did you drive after the rebuild before it went? I'm wondering if the new gaskets actually sealed.? Did you hone/plane the heads before reinstalling? Pressure check? How many total miles?

Maybe it had too much pressure - from somewhere? Maybe the cam (lobes worn down?)?

I'm not a mechanic- just asking....
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  #11  
Old December 18th, 2010, 10:34 AM
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Took the passenger side head off this week, intake manifold, valley gasket and all. Found the camshaft broke straight off where the some of the lifters for the two front cylinders ride. Also took the broken connecting rod and piston out (turns out it did through a rod somehow) looks like it bent before it broke and spun around busting the crankcase and the side of the cylinder wall on the other side cause I can see straight through to the cylinder sleeve. Still don't know what caused all this. Is it possible the camshaft can just shear off on its own? Still no dropped/bent valves, although it does look like the broken rod/piston went up and hit one of the valves leaving a few gashes on the top of the piston. Anyways I'm getting a new 4.6 block and would just like to know what went wrong with this engine so I don't end up subjecting my new engine to the same initial problem/weakness.
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  #12  
Old December 18th, 2010, 04:16 PM
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Your description sounds like what happen to my first engine. On mine the "nose" if you will, snapped off from me keeping my foot on the gas pedal for over an hour while I was stuck in some water while I was off roading. Lasted for about 500 hundred miles or so before it went completely. The next day I went and replaced the oil in every area that took oil and also had a two cleanings if you will where they hook up a machine to pump some kind of cleaning solution through the oil system of the engine itself. Replace the oil filter as well of course. At the time when I was in the water all the engine related lights started to come on.
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Old December 18th, 2010, 09:11 PM
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There's a lot of things that can cause a connecting rod to fail. Oil starvation in the bearing. Metalurgical flaws or fatigue. Hydrolocked engine. Extreme RPM's or overheating. From your description, I'll say it was either an oil starvation or spun bearing most likely. Fatigue is possible, how many total miles were on the engine?

If it was a bearing starvation/spun bearing issue, that will be easy to identify. Pull the bearing caps for the busted rod and check the color. If it's silver, the bearing was likely still good. If it's worn to the copper or is wildly out of alignment, there's your cause. If you had a lot of coolant in the oil in the past, that thick cream colored paste that happens with water in the oil can rapidly wear out the bearings.... it's pretty damned abrasive. Then your bearing siezes up for even just a moment, and snap goes the rod. Cast iron connecting rods have great compression strength, but terrible shear strength.

As to the busted camshaft... my guess is that when things got jammed up in the cylinder and the valve got struck, it sent a shockwave along the valvetrain into the camshaft. Either that or theoretically the connecting rod could have struck the cam directly. Camshafts are made of, you guessed it, cast iron. The material is perfectly suited to the entire normal operating range of the engine, but a thrown rod is a very violent action as you've noticed.

It's also possible that this falls into the generic catagory of "shit happens". It happens sometimes, even if you do everything pefectly. Unless you're building a very high performance engine, there's no real reason to start shopping for high-po connecting rods or anything of that ilk. Just be meticulously clean with the engine, to the point of paranoia, and make sure the oil system is properly primed. Then follow a standard break-in procedure, and you should be fine.

-Hans
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Old December 18th, 2010, 10:29 PM
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what is the standard breaking in period for a new rover block? Should I have my heads checked?
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Old December 18th, 2010, 10:48 PM
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although it does look like the broken rod/piston went up and hit one of the valves leaving a few gashes on the top of the piston.
If it were mine... I would not spend the money on a 4.6 short block and not go through the heads as well especially if a piston came in contact with one of them.^^^

Are you getting a 4.6 w/ top hat liners?
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Old December 18th, 2010, 11:03 PM
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it's a genuine land rover 4.6 made around late 90s early 2000s, not an 03-04

------ Follow up post added December 19th, 2010 12:04 AM ------

no top hat liners
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Old December 18th, 2010, 11:48 PM
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what is the standard breaking in period for a new rover block? Should I have my heads checked?
In this case, I'd definitely have the heads checked. Not sure how/if they check aluminum heads for cracks, that damaged valve face makes me nervous.

Not sure what the recommended break in procedures are for this engine, been a while since I did a full engine build, so I don't want to give you bad info from old memories.

-Hans
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  #18  
Old December 18th, 2010, 11:53 PM
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Baird, could it be the oil screed became clogged somehow and that caused oil starvation at off idle rpm's?
just a thought.

if you are doing a new short block I suggest you get the heads checked again, explain to the machine shop what happened give them the whole picture so they know what to look for...
if the new short block does not come with a timing cover/oil pump, I would suggest you install a new one for piece of mind... do not reuse the old unit as there are metal shavings in it, even if you clean it you still dont know if that was the failure point of the old motor.
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  #19  
Old December 19th, 2010, 09:20 AM
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I'd bet that the initial damage was done before the new gaskets. The coolant leaking into that cylinder bent the rod (hydraulics) and shortly after (after you'd replaced the gasket) the rod broke. Generally the rod will brake the cam.
Not a wild ass guess as I have had several motors in the shop over the years that this has happened to and in these cases it was much more documentable. I have pulled bent rods out of motors that have had failed head gaskets and not yet broken, actually have a 200tdi that is in exactly the same shape. gasket leaked while motor was sitting and just trying to start the motor bent two rods.

Side note....you can hit a 35 foot ceiling (hard) with coolant being ejected from the injector hole of a diesel....glad nobody was looking.....just with the starter motor!
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