3.7 head gasket failures.

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trail rated

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I'm taking apart the 3.7 for the second time in 2 months. Actually, I pulled off the timing chains a few hours ago..

Has anybody here had a head gasket fail so fast? We only overheated it once when the radiator side tank blew out (the temp gauge is a dummy gauge and doesn't show anything until the engine is really hot). But the head gasket failed 2 weeks after that so I don't think that caused it.

Also, the engine ran for over 600 miles with a bad head gasket (this is my fathers KJ and he was coming home from a business trip). When I removed the oil drain plug about a quart of water came out, I am worried that every time the engine was started the oil pump was picking up water instead of oil. I hope there isn't any damage that I don't know about.
 

tjkj2002

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I'm taking apart the 3.7 for the second time in 2 months. Actually, I pulled off the timing chains a few hours ago..

Has anybody here had a head gasket fail so fast? We only overheated it once when the radiator side tank blew out (the temp gauge is a dummy gauge and doesn't show anything until the engine is really hot). But the head gasket failed 2 weeks after that so I don't think that caused it.

Also, the engine ran for over 600 miles with a bad head gasket (this is my fathers KJ and he was coming home from a business trip). When I removed the oil drain plug about a quart of water came out, I am worried that every time the engine was started the oil pump was picking up water instead of oil. I hope there isn't any damage that I don't know about.
The overheating blew the gaskets,or at least weakened them where they failed soon after and the previous 600 mile trip with massive amounts of coolant in the oil without the proper fix had some play in it also .As far as driving 600 or so miles while leaking coolant into the engine is a very,very bad thing.Coolant is your engine bearings worst nightmare and will kill a set of bearings very fast.I'd be looking at a full rebuilt of that engine or it will continue to cause problems that will be big $$$ to fix each time.


I see problems like this(not on a KJ though) at least once a week at work,it can get expensive very fast.
 

trail rated

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The overheating blew the gaskets,or at least weakened them where they failed soon after and the previous 600 mile trip with massive amounts of coolant in the oil without the proper fix had some play in it also .As far as driving 600 or so miles while leaking coolant into the engine is a very,very bad thing.Coolant is your engine bearings worst nightmare and will kill a set of bearings very fast.I'd be looking at a full rebuilt of that engine or it will continue to cause problems that will be big $$$ to fix each time.


I see problems like this(not on a KJ though) at least once a week at work,it can get expensive very fast.

Crap... I'll replace the head gasket anyway and see what happens.
I don't know if it made a difference but it was running valvoline synthetic for the OCI.
 

Idaho08KK

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I haven't seen a headgasket fail yet on a 3.7L since they were introduced. Not to say it doesn't happen.:D

If there was a good amount of water in the oil and it was driven 600 miles, like tjkj said, the engine bearings could very well be damaged. Just installing a new head gasket may get you by for a while, but the engine could still end up failing in a short amount of time.
 

ShafferNY

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Don't click on that link. My McAfee picked up a trojan from that website and removed it.

I think your best bet is to look for a low milage replacement engine. Like everyone says, I'll bet the bearings aren't long for this world with that much coolant in the oil.
 

kb0nly

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Don't click on that link. My McAfee picked up a trojan from that website and removed it.

I think your best bet is to look for a low milage replacement engine. Like everyone says, I'll bet the bearings aren't long for this world with that much coolant in the oil.

No problem here on that website, McAfee is known to spew out a lot of false positives, one of the reasons why i hate it.

That would work good on the older Jeep as they did, but i couldn't imagine doing that swap on a KJ, could you imagine all the wiring and mechanical changes to make this work, yikes!! I'm not sure you could even make it work with most of the vehicles electronics as they are now.

You would be better off getting a CRD if you wanted diesel, although from what i can see they are scarce as hell. You can get a 3.7 long block from a few sources, or just pull the motor now before it gets worse and a light machining and new bearings and seals, along with new rings and such as well, will put it back on the road for a long time. Just don't overheat it again!
 

trail rated

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Ok, so I took off the head and as it turns out there is a crack at the #3 cyl. exhaust valve.

This KJ left a sour taste in my mouth, we might end up trading it in for a Ford or maybe another Jeep.
 

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ThunderbirdJunkie

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Ok, so I took off the head and as it turns out there is a crack at the #3 cyl. exhaust valve.

This KJ left a sour taste in my mouth, we might end up trading it in for a Ford or maybe another Jeep.

So wait

Because somebody let the KJ run overheated, and ruined a head (which will happen on ANY vehicle) you have a bad taste in your mouth?

It's not the KJ's fault that it was run for 600 miles with a FUBAR head. Sometimes the operator IS to blame...It would've happened on a 232 I6, or a Hemi, or a Viper V10, or ANYTHING.
 

kb0nly

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I was just going to say, don't blame the vehicle for operator error...

From what i have read online the 3.7 is nearly bullet proof unless you do something to mess it up. Driving 600 miles with a leaking head gasket or cracked head and overheating it qualifies as operator error.
 

ShafferNY

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So wait

Because somebody let the KJ run overheated, and ruined a head (which will happen on ANY vehicle) you have a bad taste in your mouth?

It's not the KJ's fault that it was run for 600 miles with a FUBAR head. Sometimes the operator IS to blame...It would've happened on a 232 I6, or a Hemi, or a Viper V10, or ANYTHING.

x2

I understand your frustration though.

My parents owned several Ford Escorts back in the '80s. The aluminum heads on those were disposable. If you blew a head gasket due to overheating, you might as well plan on replacing the cylinder head because nine times out of ten it was cracked. I think it's like that for aluminum heads on any engine. They just aren't as forgiving as good old cast iron heads.

Aluminum heads on my KJ are one of the things I'm not crazy about with it. As a result, I watch the temp gauge as much as I do the speedometer. Paranoid???? Maybe. :eek:

BTW, if you're thinking about replacing the cracked head with a used one from a salvage yard, remember there was a TSB on the '05 & '06 models that required replacing the valves and retainers or you might run into more problems.
 
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trail rated

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So wait

Because somebody let the KJ run overheated, and ruined a head (which will happen on ANY vehicle) you have a bad taste in your mouth?

It's not the KJ's fault that it was run for 600 miles with a FUBAR head. Sometimes the operator IS to blame...It would've happened on a 232 I6, or a Hemi, or a Viper V10, or ANYTHING.

Yes, but we shut the engine off immediately after we saw the temp gauge shoot up into the red zone. It's a jeep and Chrysler decided to not even use a real temp gauge in it, the 4.0 (242) I6 wouldn't of had any damage done by operating the engine at 250* for a few seconds. We drove 20 miles with a seized water pump on a 1990 4.0 XJ, thats in the FL summer heat. It was a beater so we didn't really care. Engine still ran fine after that, no increased oil consumption, odd noises, etc. It was still running like new at 300,000 miles when the transmission bell housing cracked.

We were waiting in line at a gas station in NY and briefly overheated the 4.0 in the WJ because of a failed E-fan (now upgraded to a clutch fan) and still has absolutely no problems.

But with the KJ you overheat it once and your screwed.
Anyway, it has been decided that the KJ is going to get a used head. I'm not sure if the coolant was from a cracked head as the dipstick never looked milky. I drained the oil half way through the disassembly so maybe water got into the engine as I was removing parts.

But yeah, the KJ is going to live, and it's getting a real temp gauge.
 

ThunderbirdJunkie

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the 4.0 (242) I6 wouldn't of had any damage done by operating the engine at 250* for a few seconds.

Funniest thing ThunderbirdJunkie has read all day.
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(rotflmao)(rotflmao)(rotflmao)(rotflmao)
(rotflmao)(rotflmao)(rotflmao)(rotflmao)

Sorry, but it's just that you wouldn't notice from every other orifice that's puking coolant, oil, and possibly even maple sap.

An engine doesn't operate at 250* for a few seconds. It has to GET THERE before it can operate at 250 for a few seconds.

You said it was shut off as soon as it was NOTICED...
The KJ goes DIIIIIIIIIIIIING when it gets hot...before it even GOES to the red. ThunderbirdJunkie knows this how?

Same way he hasn't had to replace a head on his KJ ;)

Moral of the story is don't let your engine overheat :D
 

trail rated

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I was just going to say, don't blame the vehicle for operator error...

From what i have read online the 3.7 is nearly bullet proof unless you do something to mess it up. Driving 600 miles with a leaking head gasket or cracked head and overheating it qualifies as operator error.

The engine was still running good with a cracked head, just a little bit of steam at start up and a small amount of coolant consumption (about 1/2 gallon every 400 miles). You would have never noticed that there was something wrong with the engine by just driving it, for all I know it could have been like that for longer than 600 miles. I found out that it was something with the head because the #3 spark plug was wet and the exhaust smelled sweet at start-up.
 

trail rated

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An engine doesn't operate at 250* for a few seconds. It has to GET THERE before it can operate at 250 for a few seconds.

You said it was shut off as soon as it was NOTICED...
The KJ goes DIIIIIIIIIIIIING when it gets hot...before it even GOES to the red. ThunderbirdJunkie knows this how?

Same way he hasn't had to replace a head on his KJ ;)

Moral of the story is don't let your engine overheat :D

With a blown radiator side tank the engine heats up quickly.

We were driving in the parking lot, all of the sudden I smelled coolant but didn't see any steam so I didn't think anything of it. About 15 seconds later as we were pulling into a parking space the temp gauge shot up, it didn't go up slowly. Within about 2 seconds the temp gauge went from normal (195) to hot (250). And yes, there was a warning chime.

Sorry, but it's just that you wouldn't notice from every other orifice that's puking coolant, oil, and possibly even maple sap.

The KJ, with it's 16 lb pressure cap, doesn't boil the coolant until 260*.
WJs, with their 18-20 lb caps, don't boil over until the coolant gets up to 266-272*.
 

tjkj2002

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Yes, but we shut the engine off immediately after we saw the temp gauge shoot up into the red zone. It's a jeep and Chrysler decided to not even use a real temp gauge in it, the 4.0 (242) I6 wouldn't of had any damage done by operating the engine at 250* for a few seconds. We drove 20 miles with a seized water pump on a 1990 4.0 XJ, thats in the FL summer heat. It was a beater so we didn't really care. Engine still ran fine after that, no increased oil consumption, odd noises, etc. It was still running like new at 300,000 miles when the transmission bell housing cracked.

We were waiting in line at a gas station in NY and briefly overheated the 4.0 in the WJ because of a failed E-fan (now upgraded to a clutch fan) and still has absolutely no problems.

But with the KJ you overheat it once and your screwed.
Anyway, it has been decided that the KJ is going to get a used head. I'm not sure if the coolant was from a cracked head as the dipstick never looked milky. I drained the oil half way through the disassembly so maybe water got into the engine as I was removing parts.

But yeah, the KJ is going to live, and it's getting a real temp gauge.
Almost 100% of all OEM temp gauges read the same as the KJ's.

Oh and there's a very big difference between a cast iron head/cast iron block compared to a aluminum head/cast iron block engines.Please don't compare the 2 since each has it's pro's and con's.
 

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