3.7 Head Gasket

bgcarl01 · **Posted:** Sun Apr 13, 2014 8:38 am

I have been told by not less than 5 people in the past three months that I am driving around in a ticking time bomb of an engine about ready to throw a head gasket apparently at the drop of a hat. 2 mechanics, 1 rebuild guy, and 2 friends have all commented on how the 3.7 is notorious for head-gasket issues. I spend a lot of times on message boards and info sites, and the issues I come up with on the 3.7 are dropping valve seats. The CRD shows up quite a bit for head-gasket changes, but not the 3.7. So, with this lovely group of 3.7 drivers, who thinks this has merit or is just rubbish?

streetglideok · **Posted:** Sun Apr 13, 2014 10:37 am

Plenty of armchair mechanics out there. I remember once where everyone in this little hamlet in Wisconsin thought it was stupid to own a diesel, that the things would never start when it got below 40*. Now all of them own one. That said, there will never be a shortage of people on the negative nancy wagon. The vast majority, aside from Ford 5.4L and 3.8L engines, failed due to a thermal event, that is they were allowed to run hotter than designed. It does not matter what you drive, all engines do not respond well to overheating. A lot of your Asian and Bavarian imports are very intolerant of overheating as well. If you take care of your vehicle, its a non-issue. Weakest link is the electric cooling fan system, and that is where most of the trouble comes from. I do hear some people say " I have never overheated my jeep but the valve seats/headgaskets went bad". I'm not your momma, so you don't need to lie to me, lol. When you press them, truth comes out, it ran hotter than it normally did, but not in the red. The red zone on the gauge is almost an arbitrary thing.

Of the heads I have pulled, I did pull a 3.7L once for a broken valve spring. I pulled a few 4.0L heads for head gasket or valve issues. I've pulled a few BMW heads, and Subaru heads, and I lost count of Ford and GM heads. We see a lot of KJs and KKs where I am now, and if it was such a menace, I would be doing them a lot. Instead, I seem to be doing a lot of Subaru and BMW head pulls. Wonder why I don't hear people cry what piles those things are?

lfhoward · **Posted:** Mon Apr 14, 2014 12:57 pm

I've been on this board since 2011 and I think I've only heard of about 2 dropped valve seats in all that time and maybe one head gasket. The 3.7 tends to run a bit noisier than some and it drinks gas like Kool-Aid but it seems to be a pretty reliable power plant all in all.

Bmxer524 · **Posted:** Mon Apr 14, 2014 6:00 pm

lfhoward wrote:

I've been on this board since 2011 and I think I've only heard of about 2 dropped valve seats in all that time and maybe one head gasket. The 3.7 tends to run a bit noisier than some and it drinks gas like Kool-Aid but it seems to be a pretty reliable power plant all in all.

Didn't Troy just drop a valve seat?

Anyways, the 3.7 is pretty bulletproof. Problems seem to be few and far in between. Pretty sure the 4.0 I6s were known for head problems. I know 00-01 XJs were big time known for it. And I think the old JK's 3.8 was known for problems too.

lfhoward · **Posted:** Mon Apr 14, 2014 8:56 pm

Bmxer524 wrote:

lfhoward wrote:

I've been on this board since 2011 and I think I've only heard of about 2 dropped valve seats in all that time and maybe one head gasket. The 3.7 tends to run a bit noisier than some and it drinks gas like Kool-Aid but it seems to be a pretty reliable power plant all in all.

Didn't Troy just drop a valve seat?

Anyways, the 3.7 is pretty bulletproof. Problems seem to be few and far in between. Pretty sure the 4.0 I6s were known for head problems. I know 00-01 XJs were big time known for it. And I think the old JK's 3.8 was known for problems too.

You're right. Troy was one of the two I could remember who had their 3.7 drop a valve seat. But if I had to guess who wheels their KJ the hardest out of everyone on the forum, I think I would come up with Troy and his orange Gila Monster. :JEEPIN:

The other person I was thinking of was TwoBobsKJ, IIRC. He performed a heart transplant on his KJ using a donor 3.7 from a Dodge Dakota. Bob wrote the best engine swap how-to I've seen for the KJ. His write up is over on JeepKJ.com.

bgcarl01 · **Posted:** Thu Apr 17, 2014 2:44 pm

Good to hear. I actually picked up the Libby due to so many of them being on the road. (I like junkyard parts down the road.) And the reliability that I was hearing about. Just seemed odd to be hearing the rumors lately.

dieselenthusiast · **Posted:** Sat May 03, 2014 2:01 am

Based on my used oil analysis, the 3.7L runs hot. And according to my most recent UOA, the oil seems to hold up better when swapping from Amsoil 5W20/5W30 to Amsoil 10W30.

KJWildman · **Posted:** Sat May 24, 2014 12:14 am

Another of the problem areas are the radiators. They seem to developed cracks at the upper driver's side, which could cause overheating and blown head gaskets.

Sent from my Z796C using Tapatalk

Function > Form · **Posted:** Tue Jun 10, 2014 10:22 am

streetglideok wrote:

We see a lot of KJs and KKs where I am now, and if it was such a menace, I would be doing them a lot. Instead, I seem to be doing a lot of Subaru and BMW head pulls. Wonder why I don't hear people cry what piles those things are?

Hey SGok, people do cry about Sube 2.5L non-turbo engines. They have a major HG reliability issue, especially around the first few years that they were introduced ~2000. That community has been crying to Subaru for years!

Only 'major issues' that I've had are the usual: the psgr side valve cover leaks and smells like a blown out candle when it drips on the ex.manifold, driveshaft head done (boot torn, sounded like a major racket under there...jingling, clanking, etc especially in 4lo), new rad - mine kicked it almost right after buying it - doesn't overheat though.

bgcarl01 · **Posted:** Mon Jun 29, 2015 10:50 am

Figured I would revive this old thread i started. The last two weeks been noticing air in the coolant system, and losing coolant slowly. Also misfires on cylinders 3 and 6 and also multiple randoms. I guess I created my own karma! Took in this morning, they can see coolant leaking into the top of the piston areas with camera. Cross your fingers the heads are okay. Getting it fixed as I own it in 3 more payments. Figure I can't find something I like more for only a couple grand if the heads are cracked a grand if they're not.

3.7 Head Gasket

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