4.7 (NOT HO) WJ #2 Piston Damage Opinion Needed - JeepForum.com
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Unread 07-02-2013, 04:39 PM   #1
MikesBean
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4.7 (NOT HO) WJ #2 Piston Damage Opinion Needed

Hello All!

I need your opinion! ( I will try to put up pics ) I see the site has some issues...

4.7 WJ missing terrible..#2 cylinder no compression.
Pulled head today! Valve seat ring just hanging around so the valve would not shut.
So..the piston is gouged with a smile face groove pretty good gouge and a lighter one to the side probably where the seat smacked it some also...

WHAT TO DO?

Opinion so far from machine shop, mechanic or two....clean it up with wire wheel to remove sharp edges....put a head on and go... MY mechanic really good guy does not like that idea? He may opt for new piston $$$...

MY CALL IS CLEAN IT UP A LITTLE AND GET THE HEAD ON!!!

Just so anyone my see this: The head will come from
ODESSA*CYLINDERHEAD ON EBAY....OVER 7000 GOOD REVIEWS $390 delivered! Two year warranty! Complete with all the parts remained and a new casting with the valve seat issue corrected!!!!

SO....WHAT DO YOU TOP GUN GUYS GOTTA SAY?

683284862_o.jpg   683284983_o.jpg  
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Unread 07-02-2013, 04:48 PM   #2
wickedwj99
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What I would do is put a new piston in and get a new head on. If you just put a head you risk blowing the rest of the motor from unknown issues that could be hiding.
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Unread 07-02-2013, 05:13 PM   #3
99gcl532
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I bet a new head would be just fine.
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Unread 07-02-2013, 05:18 PM   #4
Krom
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The correct way would be to change the piston, but that opens up a can of worms. Once the piston is out, you should change them all. Then you should change the bearings, and have the rods recon'd, crank may need a grind or polish, should do the other head, water pump... etc, etc, etc....

Unless you have the $ to rebuild the engine, I'd just sand the sharp edge off the piston, have a machine shop do the head and valves, and run it
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Unread 07-02-2013, 05:51 PM   #5
MeanGreenZJ
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Too bad that you have another crap cylinder head that can do the same thing on the other side of the engine.
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Unread 07-02-2013, 06:13 PM   #6
MikesBean
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Please look at the issue with the pics please...Looking for your best input on the one question...

THE #2 PISTON....WHAT DO YOU THINK? ANY EXPERIENCE? WOULD YOU REPLACE IT OR ADD THE HEAD AND SEE HOW IT PERFORMS?

This Jeep had the heads ground and new gaskets July 2011. This issue happened less than 10,000 miles after that service. It was running strong and driving well until #2 valve issue. I will replace the head with new casting from Odessa with reman loaded parts. If the other side drops a seat fix it too.
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Unread 07-02-2013, 06:50 PM   #7
coopdc78
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I'd agree. Clean the piston up and go.. Honestly does not look too bad.. What's the worst that can happen..
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Unread 07-02-2013, 07:17 PM   #8
Double E
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This is the single best images of a dropped valve seat I've seen in my years here. Congrats on shutting it down before it took out the engine: Scored cylinder wall, parts pushed through the cylinder, etc. You are the lucky man today.

Agree... get the new head, have the shop tack the seats in place on the new one and also the head on the other side ....soon. Maybe not right away if cash is low...but labor while it's apart is less now.

The rest of the engine (bottom end) is not normally at issue if the seats are good.

Question...did this event follow an overheat situation?
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Unread 07-02-2013, 07:27 PM   #9
multmigs
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God damn I hope you went out and bought some powerball tickets after that mess... I had the same thing happen and took out my entire motor at 60mpg when the rest of the junk went flying around the inside of the block after the piston exploded....
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Unread 07-02-2013, 07:44 PM   #10
MikesBean
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Thanks Double E!

No overheat except two years ago and 10,000 miles ago. National service company (they are the car company...but they don't make cars ) screwed up a radiator install. Then tried to fix it with stop leak.....I took them to the mat for $5000 to get it all fixed on my own... No valve work done then, just shaved them and put on with all new timing gear... Jeep has run great since then until this issue....now has 125,000 miles and is maintained well using Mobile 1 synthetic. Mechanic says it looks good...no sludge at all.

New head from Odessa on eBay has them made to NOT have seat issues.....they got lots if business and over 7k reviews....
I called and talked several times and also sent those pics to them....Waiting on some feedback also on the piston issue...
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Unread 07-02-2013, 09:44 PM   #11
65Mustangs
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Quote:
Originally Posted by MikesBean
Hello All!

I need your opinion! ( I will try to put up pics ) I see the site has some issues...

4.7 WJ missing terrible..#2 cylinder no compression.
Pulled head today! Valve seat ring just hanging around so the valve would not shut.
So..the piston is gouged with a smile face groove pretty good gouge and a lighter one to the side probably where the seat smacked it some also...

WHAT TO DO?

Opinion so far from machine shop, mechanic or two....clean it up with wire wheel to remove sharp edges....put a head on and go... MY mechanic really good guy does not like that idea? He may opt for new piston $$$...

MY CALL IS CLEAN IT UP A LITTLE AND GET THE HEAD ON!!!

Just so anyone my see this: The head will come from
ODESSA*CYLINDERHEAD ON EBAY....OVER 7000 GOOD REVIEWS $390 delivered! Two year warranty! Complete with all the parts remained and a new casting with the valve seat issue corrected!!!!

SO....WHAT DO YOU TOP GUN GUYS GOTTA SAY?
Looks like you were lucky, and the damage in minimal. No point changing the piston unless you're going to replace all the bearings. But bearings and rings are cheap.

My $0.02 (experience talking) at a minimum, pull the other head and have it inspected / valve seats replaced. This is not expensive, and once it happens to one side, it WILL happen to the other.

At that point IF you have the funds, replace cylinder #2 ONLY, replace ALL the main bearings, rings and the oil pump. Maybe $100 in parts and a couple hrs labor. This will basically give you a "rebuilt" motor at a fraction of the cost. This is "best case" besides a complete rebuild.

If money is tight, put a new head on the damaged side, and start saving your pennies, because odds are you will need to do the other side at some point in the future. At that point, just do a complete rebuild.

For what its worth, I drove around with a "clicking" trans for 7,500 miles after my motor issues (see my thread for details) until I saved up the CASH to rebuild it. Don't finance repairs beyond the minimum to get you back on the road, fix it, save up, then improve it. Again just my $0.02. YMMV.

GOOD LUCK!!
And remember, keep it rubber side down!
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Unread 07-02-2013, 10:02 PM   #12
C101Commando
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I'd replace the dented piston. It's aluminum and it's been hit, cracks around the impact are very possible and difficult to see. At a minimum bring that piston up to the top and clean/inspect the thing best you can.. maybe coat with dykem blue dye and then steel wool it clean to see cracks, like a poor mans magnaflux..
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Unread 07-02-2013, 10:18 PM   #13
MikesBean
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Thanks to all you Top Gun Guys out there!
Keep em' coming.
The info from each of you is outstanding!
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Unread 07-03-2013, 12:54 PM   #14
Jeeples
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That right there folks is why it's important not to overheat aluminum headed engines. Often times there can be a significant lapse in time between overheating and dropping a valve seat. I second what a lot of people here are mentioning, just clean up the piston top a bit to prevent hot spotting and you should be good to go.

However, since you mentioned that no valve work was done to the heads after the overheat event, I would really suggest having them rebuilt or having reman'd ones installed. There's a good chance you may drop the seat on another cylinder.
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Unread 07-05-2013, 03:55 PM   #15
MikesBean
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Thanks Jeeples!!! I appreciate your response! It seems spot on....I am going to try and get the two heads not just the passenger problem side. It was the problem side 8,000 miles ago almost two years to the month when heads were ground and put back.... It was running soooooo sweet......NOTE: FYI Replaced all 4 O2 sensors 6 months before this event and the gas mileage went up from about 12 to 18 in town!....Used Denso since I found out they make the OEM sensor.. Bought one from the dealer and the other three on Amazon way less!!!!

UPDATE: Denso O2 Sensors were right at $31-33 each delivered with my prime account....

Last edited by MikesBean; 07-05-2013 at 04:12 PM..
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