Bent valves and wiped cam?

[Ecomike]

I am posting this here, since the bulk of the engine experts are in this forum. And this a question about engines mostly!!

Any one know anything about the 2010 Jeep Liberty V-6 engines? Specifically!!!

Trying to figure what the rest of the story is. What started out as a head gasket job (coolant leak which alone seems nuts for a rig with no other leak and under 100 thousand miles), a week after the head gasket job was done by an engine shop, it ended up with 2 bent valves and 2 wiped lobes on the Cam shaft with no other possible cause or casualty than the timing chain adjusters being weak (or not adjusted well enough/properly, when the head was pulled?) and a week after doing the head gaskets they later replaced /repaired it with the 2 new valves and a good (they claim) used Cam shaft, and two new timing chain tensioners. It was done at an engine rebuilding firm...

<100,000 miles on the rig. They claim there was no piston damage. Yah, riiiight...I think they screwed up the head gasket job (and valve job they did while the head was off, that probably was not needed???), but how the hell do two valve stems get bent with out hitting and damaging the piston(s)?????

Still has a random misfire, but no CEL light now, and a miss at idle once it warms up (Runs fine on a cold start) and misses at 4000 rpm in park.

None of this makes any sense at all to me!!!! Pretty sure I am not getting the truth, or the whole story. My sons jeep, has 2-3 weeks of warranty left

I posted this on one lonely thread in the new liberty section, but like I said, most of the engine experts are here.

 

[lawsoncl]

Were the bent valves on the same side? I believe the tensioners are spring loaded with ratchet pawls. So the only thing you could screw up during reinstalling the tensioner is forcing the tensioner out too far or not resetting it so the tension is too tight. Or not properly releasing the pawl and pressing the the tensioner back in.

 

[Green Mesa XJ]

Oh there’s a KJ side now? I got a ping because I posted to that thread.

I don’t trust what the repair shop says. Tensioners and chain should have been fine unless the shop screwed up.

Random misfire with no CEL could be coils, wires (3 of them go from the coils if I have the year right.) and spark plugs. Injectors maybe, my f150 had bad injectors cause a miss like feeling with no CEL

Um there is something most 3.7 & 4.7 have where they feel like they miss at idle, drop rpm below 550 the spike up and settle down. Pretty much a known gremlin to jeep because Chrysler set the idle so low. All kind of things might feed in to it but a lot of us have replaced everything that in theory can cause it and it comes back. But this is only a at idle where it feels like it might stall but doesn’t.
If that’s the miss he might have nothing to worry about.


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[Ecomike]

Were the bent valves on the same side? I believe the tensioners are spring loaded with ratchet pawls. So the only thing you could screw up during reinstalling the tensioner is forcing the tensioner out too far or not resetting it so the tension is too tight. Or not properly releasing the pawl and pressing the the tensioner back in.

Yes it was just one side, as they replaced just the one Cam shaft that had wiped lobes. Intersting reply, thanks very much!!!! So does that answer how the valve stems got bent with out hitting and damaging the aluminum piston?

Could the hydraulic rocker (what ever its called) have gotten in the middle of the problem? They said it was nothing but the Can lobes wiped flat and 2 bent valves not closing that were the problem. Which happened a week after driving with the new head gaskets (as I understand so far)

 

[lawsoncl]

Yes it was just one side, as they replaced just the one Cam shaft that had wiped lobes. Intersting reply, thanks very much!!!! So does that answer how the valve stems got bent with out hitting and damaging the aluminum piston?

Could the hydraulic rocker (what ever its called) have gotten in the middle of the problem? They said it was nothing but the Can lobes wiped flat and 2 bent valves not closing that were the problem. Which happened a week after driving with the new head gaskets (as I understand so far)

I've seen valves hit the pistons and only leave a minor dent in the piston top. If the timing jumped a few teeth and was still running I would have expected more than two damaged valves?

I did see a bunch of posts about the powertech engines spitting out the rockers due to the lifters not pumping up or getting stuck. I suppose it's possible the rockers got out of place and bent the top of valves stems. You'd have to ask the shop if the valve was bent over inside the cylinder or bent over up in the head.

 

[Ecomike]

Even after all the physical engine repairs I posted, it is showing a pending code from random misfires. At least it was before they cleaned the fuel injectors. But I suspect, from what was said, cleaning the fuel injectors did not help. Have not been able to find out if the pending miss fire code is there or if the idle miss is still there. My main concern is how and why all the engine damaged happened. And what might go bump in the night next with Miss Liberty. I have already told him to buy an additional warranty and trade the damn thing before the engine blows up.

Spark plugs and coil packs are on the suspect miss cause list.

Oh there’s a KJ side now? I got a ping because I posted to that thread.

I don’t trust what the repair shop says. Tensioners and chain should have been fine unless the shop screwed up.

Random misfire with no CEL could be coils, wires (3 of them go from the coils if I have the year right.) and spark plugs. Injectors maybe, my f150 had bad injectors cause a miss like feeling with no CEL

Um there is something most 3.7 & 4.7 have where they feel like they miss at idle, drop rpm below 550 the spike up and settle down. Pretty much a known gremlin to jeep because Chrysler set the idle so low. All kind of things might feed in to it but a lot of us have replaced everything that in theory can cause it and it comes back. But this is only a at idle where it feels like it might stall but doesn’t.
If that’s the miss he might have nothing to worry about.


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[Ecomike]

I've seen valves hit the pistons and only leave a minor dent in the piston top. If the timing jumped a few teeth and was still running I would have expected more than two damaged valves?

I did see a bunch of posts about the powertech engines spitting out the rockers due to the lifters not pumping up or getting stuck. I suppose it's possible the rockers got out of place and bent the top of valves stems. You'd have to ask the shop if the valve was bent over inside the cylinder or bent over up in the head.

I doubt we can ever get that information from these clowns. But I will try. These places hate to let the mechanics talk to customers. And by know the mechanic(s) may not remember. They could not even tell me where the head gasket was leaking that they changed 2 weeks ago when all this started.

 

[Green Mesa XJ]

Did the insurance pick these clowns?


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[Ecomike]

The used jeep dealership he bought it from, where he bought the warranty also, picked the shop when they figured out it was internal (head gasket). The machine engine rebuilder shop has been in business maybe longer than I have been around, not a fly by night shop, but not the gold standard shop either (or at least they were not 30 years ago). But frankly there are so many bloody engines and rigs around now days, finding a quality expert is rare, crap shoot. From what little I have read the engine, the engine itself is not bullet proof like I am use too.

 

[Green Mesa XJ]

Normally the warranties are national companies. I’d try to call them with your claim number tell them you’re still have issues with with a repair. See if they’ll send you to another shop.

BTW 150 is not good compression for the 3.7, it’s specs are 170-225
I think the shop owner doesn’t know what the compression really is, if that 150 is legit it’s too low.

Also thinking about the miss he had earlier that could have been the headgasket.

3.7 is no where near the legendary 4.0(4.2), it is a decent motor but will not take the abuse a 4.0 will or any of the old iron head engines can. I was disappointed with our commander problems from the previous owners neglect, the gunk issue was something easily fixable in a 4.0 turned out to be a major headache with the 3.7.


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[Green Mesa XJ]

Do you know which cylinder(s) had the bent valves. What I would do is scope the cylinder to see if there is any damage.

I’ve got a question about this at a KJ forum, they’ve got some experts on this engine, hopefully they’ll know what is up with the shops claims.


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[Ecomike]

I doubt the service rep I had to interrogate even knew. He is a self admitted, non-mechanic. I suspect their forensic documentation is very lacking

I guess what I need help with is writing a list of questions we want answers to? So I can out them in writing to to the shop and dealership, and warranty company!!!

So lets start a list.

Which cyl #(s) and valves (intake or exhaust) were bent?

Was there any other part damage, or anything else loose, like a rocker, when the bent valves were found.

Where was the first head gasket leaking, where was the leaking coolant going?

Was the coolant and motor oil drained and replaced?

My issue is still the question of how 2 valves bent themselves??? And how the cam lobes got "wiped flat" with out the part in between, something called a hydraulic rocker (WTF is that anyway? I could not find a good image of what is lurking between the cam lob and the top of the valve shaft on line yet.)

 

[Green Mesa XJ]

Here is a very good reply from the KJ forum.

(Also make sure the shop used Chrysler HOAT coolant or Zerex G-05. )

Steel valve guide inserts and you only about 50% of the valve "stem" is inside that guide at any time so plenty easy to bend a valve without damaging the insert or head.

Just to add the only way to bent a valve is from mechanical damage,something let loose and caused the bend.It's not like a head gasket,seals,or any other gasket that just fails after time.Most likely cause was to much coolant in the oil caused lack of upper end lubrication and the cam lobes wore to much causing a rocker to fall off causing the bent valves.

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[Ecomike]

Here is a very good reply from the KJ forum.

(Also make sure the shop used Chrysler HOAT coolant or Zerex G-05. )
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Thanks. I never have trusted that junk. My son has been using the old school conventional green coolant since the leak started. No idea what was in it when he bought it.

I heard too many bad news war stories about those newer coolants. I/WE have been using the old green formula on my 2001 saturn since 2008, which has an aluminum head, now has 280,000 miles on it. Buy it is on its fifth Plastic POS radiator (Plastic fails, not the aluminum) since 2001, LOL. I know the Prior Owner....I replaced the OEM water pump for a front seal leak at 265,000 miles

Has the consensus changed the last 5-8 years on those newer coolants? Have they fixed the bad formulations they started with?

I have never ever had a head gasket fail in 45 years using the old school green stuff (Sodium Metasilicate and Ethylene Glycol formulations).

Even when or years after the rigs blew many hoses.

His jeep never had any external leaks we could find since he bought it!!

 

[Green Mesa XJ]

Prestone claims the new 50-50 green stuff is now formulated for all vehicles I think they removed silicates.

consensus is if the Jeep came HOAT keep it that way because mixing the fluid is bad and will eat up the cooling system. the green stuff seems to wear the seals differently if it was meant for HOAT. For Japanese cars the wrong coolant can cause premature water pump failure.

I’ve never experimented, for the jeep I put back the HOAT coolant, the Toyota I bought their coolant when I replaced the radiator, my ford truck when the shop swapped the engine out the flushed the coolant and used the supposed all in one new Preston instead of the golden color mopar stuff, it’s been fine for 3 years although if there some reaction I’ll probably not see it for another few years, still it was a reputable shop I doubt they use a coolant that would not be ok with the warranty. Still that’s trusting a shop.

I know some of the older GM were worse off with gm’s first attempt at a different coolant and better off with the old green stuff.

Newer cars seem to be damn sensitive.



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[CJR]

Ecomike,

Old school engineering dictates there must be clearance between valves and piston. Unfortunately, recent engines (i.e. Mitsubishi/Chrysler) use zero clearance between valve/piston. Eventually, thru thermal growth, etc. valves start hitting pistons which causes valve guide wear, bent valves, cracked pistons, cracked heads, etc. Years ago, I rebuilt/modified a 3.0L V-6 Mitsubishi engine out of a Plymouth Minivan that had zero valve/piston clearance. During fit-up I used modelling clay on the piston to check the valve/piston clearance and I discovered the zero clearance. Old engineering principles(i.e. GM and engineering practice) always had 0.080-0.1" valve/piston clearance to allow for the valve's thermal growth. My solution was to jnstall custom made thicker copper gaskets, measure the valve/piston clearance to insure I had the 0.08-0.1" valve/piston clearance and button it up. That engine now has about 50,000-75,000 miles on it and runs better than the original configuration.

Hope this helps.

Best regards,

CJR

 

[Ecomike]

CLR, thanks for the info.

Green Mesa,

I did a few hours of digging on line, and the coolant story today is a nightmare, of many different formulas, claiming blue skies, and Godzilla risks.... of switching, etc....

Way too much to repost and discuss here in this thread. What I do know is the coolant did not bend 2 valves 2-3 days after those clowns replaced the head gaskets. It was already using coolant (head gasket issue), before my son added the old silcate based formula. One thing I can not fathom is why they all call them "A" acid based formulas when the pH is highly alkaline, not acidic. There is no history on where the insane use of the word acid came from in the acronym formula names. The old formula had a pH 10.5-11, Highly basic, not acidic. But every web site on the planet now says the old formula was IAT, Inorganic Acid Technology, LMAFIA!!!!

All I know is adding bars-leaks fiber pellets and using the old high pH silicate formula has worked for 8-10 years on all my rigs with out draining!!! Only water pumps I ever killed where 2 cheap china bearing, 3 month old junk ones for AZ, LOL. Only radiators I ever lost/replaced, were due to POS plastic tanks in the last 40 years. My 85 Cherokee, diesel still has the OEM radiator in it, LOL.

So back on topic, how does a bent valve stem wipe the cam lobe when there is a hydraulic tappet between them?

 

[CJR]

Ecomike,

After posting my reply to you, I recalled that when I searched for zero-clearance valve/piston engine problems, Chrysler engines came up as being plagued with bent valves,worn valve guides, cracked pistons, cracked heads, etc. On pushrod engines, valve resistance (i.e. caused by piston contact and bending valves, valve guide wear, etc. ) is fed back by the pushrods to the cam lobes. After awhile, the cam lobes wear down excessively.

Best regards,

CJR

 

[Green Mesa XJ]

The post from the kJ seemed to think the damage to the cam was done while the oil was diluted with coolant.

Far as the coolant debate goes I’m not an evangelist for any of the new formulas, which ever coolant your son is going to run I’d say flush all the old stuff out until he’s only running one or the other. Mixing HOAT with regular antifreeze is supposed to cause a bad chemical reaction.




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[Ecomike]

Playing devils advocate, the coolant did not bend the valve.

Also they are assuming the coolant leaked on the cam shaft, which I seriously doubt since the head was not cracked. While I got no confirmation as to where the coolant leaked, my money is on a leak through the head gasket into the combustion chamber (causing the original miss fire) and out the exhaust, but I have no proof or confirmation where the head gasket was leaking.

In fact the head gasket leak was fixed the first time in the shop, and nothing else.

At that time they did what they called a valve job for extra $$$$ since they had the head off (sales pitch they did my on my son).

2-3 days later it had 2 bent valves and no compression on 2 cyls. I think they forked up the service work and its now a ticking time bomb.

The post from the kJ seemed to think the damage to the cam was done while the oil was diluted with coolant.

Far as the coolant debate goes I’m not an evangelist for any of the new formulas, which ever coolant your son is going to run I’d say flush all the old stuff out until he’s only running one or the other. Mixing HOAT with regular antifreeze is supposed to cause a bad chemical reaction.




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