Bent valves and wiped cam?

[Ecomike]

If, as I think, the two coolants operate at 2 different pHs, that is likely the case, however the jeep dealership he bought it from was not even using synthetic oil on the oil changes.:smsoap: So WTF knows what coolant they were using? It was used Jeep dealership.

If the pH of old style coolant drops from 10.5-11 down to under a pH of 10, it will precipitate a glass film on the heat exchange surfaces. :hang:

I have yet to find the operating pH on the newer coolants.

Easy enough to test with a pH meter, a glass beaker, stir rod, and watch to see if anything precipitates when they are mixed.

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]

So why did only two valve stems get bent? If it jumped time, wouldn't more of them have been damaged?

I read that the valve seats are sintered steel, pressed into the Aluminum head, and they are known to come loose and cause the loss of compression!!! Perhaps wiped lobes and bent valves as well? But the machine shop should have caught that!!!

 

[trippled]

Have you actually seen the head? From what you describe it sounds like the valves stuck in the guide. If it went long enough I suppose it could maybe cause the cam to go flat and if they eventually hung open could have hit the piston and bent the valve. But without anyone seeing anything it's pretty unlikely you will get a definitive answer. Yes, pretty much everything now is an interference engine. If a valve hangs open when it shouldn't it's probably gonna bend.

Coolant probably won't do it. You don't get synthetic unless you pay more for it. Put the coolant in it that's supposed to be in it.

 

[Vanimal]

a wiped cam will not bend valves as a direct result. A wiped cam decreases valve travel, so it would be LESS likely to bend. Also, unless the valve broke off and was floating around the cyl, i highly doubt it damaged the pistons enough to matter whatsoever.
However, if the cam is wiped, all that metal went somewhere, and that somewhere is in your bearings. That motor will have a significantly shorter lifespan IMO.

 

[Green Mesa XJ]

Whatever happened with this engine?


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[Ecomike]

Whatever happened with this engine?

He drives it in limp mode, meaning he shifts to neutral at a stop light and bumps the idle up with his foot. It has a pending random miss fire I think using a scanner. Rough idle, so he is shopping for a replacement.

 

[Green Mesa XJ]

Damn. Something is majorly screwed up .
Is the warranty not going to fix it?


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[Ecomike]

Warranty is about to expire, and we agreed it was not worth the risk of keeping it, so no attempt has been made to fix the last issue (may just be a spark coil or plug, or it made coolant damage to the O2 sensor(s) and or Cat converters). Also the dash gas take level is not working right now, Tank is empty at 1/2 full reading on the dash, which may not be a warranty item.

Looking for reliable quality design rig now. Found a 99 Diesel XJ I think on Craigs??? $1500, but way too little real info, waiting for seller to call back

 

[Green Mesa XJ]

I hate dealing with these warranty companies but I’d push them on getting the vehicle at least drivable so it can be sold.


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[Ecomike]

If he buys a rig from the same folks, he will stick them with the problem and push for an extra break on the deal/cost.

I hate dealing with these warranty companies but I’d push them on getting the vehicle at least drivable so it can be sold.


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[Green Mesa XJ]

If he buys a rig from the same folks, he will stick them with the problem and push for an extra break on the deal/cost.

If he can I guess that fine. I’d hat for your son to lose money because he’s stuck with a lemon. Is it a local warranty through the place he bought it? Kind of odd, but I could see a smaller local dealer try to make the profit on a selling warranties. If it’s a local deal make them see their repairs made it undrivable. If it’s national company keep on them until they replace the engine. Even after it expires as long as you reported the issues they still have to fix it.

Seems like new jeeps engines management systems are so complex once the have gremlins you keep fighting. Same thing for these aluminum head overhead cam engines. Once they overheat or drop a valve unless the repairs are done right it comes back to haunt. I’ve seen so many post from people who pick up a cheap KJ don’t realize these engines are still very expensive and trying to piecemeal a repair will not work.

I’d be curious to see service history for that KK, my guess is the dealer bought it with a engine problem and tried to patch it. Aside from a factory lemon there is no reason any low milage engine should fail like this.



BTW as your son is shopping around keep in mind any Chrysler product from the late 90s to 2012 with a 4.7 or 3.7 are the same engine as his KK has now. And oil changes are the life’s blood of these newer engines.


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[Ecomike]

It just threw a P0128 code, interesting, but not yet, by itself a clear bit of info.

" P0128 JEEP
Description
Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.
Symptoms- CEL
Possible causes
- Insufficient warm up time
- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty MAP sensor
- Engine coolant temperature sensor harness is open or shorted
- Engine coolant temperature sensor circuit poor electrical connection
- Faulty engine coolant temperature sensor When is the code detected?

Coolant temperature does not reach predicted engine coolant temperature within specific time

Tech notes
If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem."

If he can I guess that fine. I’d hat for your son to lose money because he’s stuck with a lemon. Is it a local warranty through the place he bought it? Kind of odd, but I could see a smaller local dealer try to make the profit on a selling warranties. If it’s a local deal make them see their repairs made it undrivable. If it’s national company keep on them until they replace the engine. Even after it expires as long as you reported the issues they still have to fix it.

Seems like new jeeps engines management systems are so complex once the have gremlins you keep fighting. Same thing for these aluminum head overhead cam engines. Once they overheat or drop a valve unless the repairs are done right it comes back to haunt. I’ve seen so many post from people who pick up a cheap KJ don’t realize these engines are still very expensive and trying to piecemeal a repair will not work.

I’d be curious to see service history for that KK, my guess is the dealer bought it with a engine problem and tried to patch it. Aside from a factory lemon there is no reason any low milage engine should fail like this.



BTW as your son is shopping around keep in mind any Chrysler product from the late 90s to 2012 with a 4.7 or 3.7 are the same engine as his KK has now. And oil changes are the life’s blood of these newer engines.


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[Green Mesa XJ]

Damn that’s weird.

One thing about the 3.7 mopar on the thermostat, I don’t think there’s a good after market brand yet. Or the shop didn’t connect the temp sensor or broke it. It’s in the middle of the engine under the alternator, or in about the area.


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[Ecomike]

From the prior post data on the PO128 code:

"Coolant temperature does not reach predicted engine coolant temperature within specific time

Tech notes
If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem."

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Thinking about the junk, metal shavings from the wiped CAM after those yahoos dorked up the head gasket job, maybe got into the T-state and it stuck open??? And I bet they did not even replace the T-stat, or they used cheap chinese one.

So far the coolant level looks OK.

 

[Green Mesa XJ]

Nah, the coolant I doubt would get the metal shaving, oil pump and bearings that’s another story.

Is it at least running correctly otherwise?


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