Jeep 2.4 Engine Woes

[Tonyjustin]

Hello everyone. I have a problem of which I cannot find a reasonable explanation. I acquired a 2005 Wrangler with 214,000 miles and a 2.4L engine. It came to me with a blown head gasket and I thought I could replace that, along with the timing belt and water pump, and get it back on the road. Disclaimer: I am retired from the white collar world and therefore not a certified mechanic, but I feel capable to fix most things on my Jeeps.

The previous owner admitted it overheated when the head gasket blew but I didn’t ask how hot it got or how long he ran the engine in the overheated condition. When I did my diagnosis, it was evident coolant got into the oil. I performed a compression test and cylinders 1 and 4 showed approximately 180 PSI while 2 and 3 were 130 PSI. I should note this was a wet test.

When I disassembled the engine, the head measured out of spec for flatness so I sent it to the machine shop to be milled. I was also careful to loosen the head bolts in reverse sequence of the torque pattern and loosen them a quarter turn at a time until I could remove them by hand.

Upon reassembly, the engine had zero compression. I took everything apart again and discovered with the head fully assembled with rockers, lifters, and cams, I could fit a .010 feeler gauge between several of the valves and seats, regardless of the position of the cams. When I removed just the cams and inverted the head, the combustion chamber would hold rubbing alcohol for a reasonable amount of time. Installing the cams would inexplicably not allow the valves to seat. I had the cams properly oriented (intake to the intake side and exhaust to the exhaust side) but for the life of me, I cannot determine why installing the cams creates this condition.

Any advice, besides never mess with a 2.4 Jeep engine again? Thanks.

 

[macleanflood]

Your pushrods are too long now that you've removed material from the head. You can source a thicker head gasket to make up the difference or measure for shorter pushrods.

I think. I'll let more experienced folks have to say.

-Mac

 

[GoldenGorilla]

Not my area of expertise, but I believe the 2.4L is a DOHC motor, so no pushrod length issues should occur. It rides on a number of cam bearing journals. Any chance the camshaft bearings are missing? I have no idea how thick those bearings should be, but .010 would seem awfully thin. But I can't think of much else that would result in the cam pushing down the valve.

 

[Wildman]

Not my area of expertise, but I believe the 2.4L is a DOHC motor, so no pushrod length issues should occur. It rides on a number of cam bearing journals. Any chance the camshaft bearings are missing? I have no idea how thick those bearings should be, but .010 would seem awfully thin. But I can't think of much else that would result in the cam pushing down the valve.

View attachment 625074

You're correct that the 2.4 is a DOHC engine.

Hello everyone. I have a problem of which I cannot find a reasonable explanation. I acquired a 2005 Wrangler with 214,000 miles and a 2.4L engine. It came to me with a blown head gasket and I thought I could replace that, along with the timing belt and water pump, and get it back on the road. Disclaimer: I am retired from the white collar world and therefore not a certified mechanic, but I feel capable to fix most things on my Jeeps.

The previous owner admitted it overheated when the head gasket blew but I didn’t ask how hot it got or how long he ran the engine in the overheated condition. When I did my diagnosis, it was evident coolant got into the oil. I performed a compression test and cylinders 1 and 4 showed approximately 180 PSI while 2 and 3 were 130 PSI. I should note this was a wet test.

When I disassembled the engine, the head measured out of spec for flatness so I sent it to the machine shop to be milled. I was also careful to loosen the head bolts in reverse sequence of the torque pattern and loosen them a quarter turn at a time until I could remove them by hand.

Upon reassembly, the engine had zero compression. I took everything apart again and discovered with the head fully assembled with rockers, lifters, and cams, I could fit a .010 feeler gauge between several of the valves and seats, regardless of the position of the cams. When I removed just the cams and inverted the head, the combustion chamber would hold rubbing alcohol for a reasonable amount of time. Installing the cams would inexplicably not allow the valves to seat. I had the cams properly oriented (intake to the intake side and exhaust to the exhaust side) but for the life of me, I cannot determine why installing the cams creates this condition.

Any advice, besides never mess with a 2.4 Jeep engine again? Thanks.

Dp you have the cams timed correctly? I've never worked on the 2.4 so I'm not familiar with it. Have you looked at the FSM to see the proper way to setup the cams when reinstalling the head?

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/

 

[Tonyjustin]

Thanks for the feedback. You guys rock. I'll address all of the input in this reply. Yes, it is an overhead cam engine so no pushrods. I timed the cams but I don't think that was the problem. When I removed the head and the cams could move freely, I would turn them randomly until I was positive they were on the low point of the respective cam lobes for each cylinder. While I didn't specifically check the cam bearings neither camshaft appeared loose or sloppy in its final resting place in the head. End play was in spec. I also religiously followed the Mopar Shop Manual, even downloading it and printing out Section 9 that dealt exclusively with the engine and it's correlated assemblies. I also cross referenced with my Chilton's book, albeit the shop manual was far superior in detail and direction. I can't think I had any bent valves as all combustion chambers held alcohol with the cams out and the head inverted and leveled.

I have a theory and it may be a stretch. Is it possible that the head was warped and if the machine shop milled it incorrectly, as in not straightening the head before milling, the installation of the cams would cause the head to twist sufficiently to misalign the cam lobes to the valve tips? I'm pulling thoughts out of thin air as I would be mildly surprised the cams are strong enough to twist a head into misalignment. I just can't get past the fact that the engine held compression before disassembly but after milling the head, it could not.

 

[Wildman]

Thanks for the feedback. You guys rock. I'll address all of the input in this reply. Yes, it is an overhead cam engine so no pushrods. I timed the cams but I don't think that was the problem. When I removed the head and the cams could move freely, I would turn them randomly until I was positive they were on the low point of the respective cam lobes for each cylinder. While I didn't specifically check the cam bearings neither camshaft appeared loose or sloppy in its final resting place in the head. End play was in spec. I also religiously followed the Mopar Shop Manual, even downloading it and printing out Section 9 that dealt exclusively with the engine and it's correlated assemblies. I also cross referenced with my Chilton's book, albeit the shop manual was far superior in detail and direction. I can't think I had any bent valves as all combustion chambers held alcohol with the cams out and the head inverted and leveled.

I have a theory and it may be a stretch. Is it possible that the head was warped and if the machine shop milled it incorrectly, as in not straightening the head before milling, the installation of the cams would cause the head to twist sufficiently to misalign the cam lobes to the valve tips? I'm pulling thoughts out of thin air as I would be mildly surprised the cams are strong enough to twist a head into misalignment. I just can't get past the fact that the engine held compression before disassembly but after milling the head, it could not.

If the head was warped I don't think there is anyway to straighten it. But if it was warped enough to cause issues like keeping a valve open I'd think that would be enough to make it hard to spin the cams. Have you put a straight edge in the head surface? and then on the cam bearing lobes to see if it's straight?

If you're not sure of the work done by the machine shop it might be worth it to have another shop look at it. Or depending on cost what does a remanufactured head cost? That might be the quickest way to get it fixed.

 

[Tonyjustin]

Thanks Wildman. I like your idea of checking the head surface and then comparing it to the cam bearing saddles. In fact, I like it enough that I'm secretly pissed I didn't think of it sooner. Kidding. Maybe.

A loaded head (valves, springs, seats, and keepers) from Auto Zone is less than $500.00 delivered to my door. I'm likely to go that direction but I first want to make sure nothing else is wrong with the block or my procedure which will cause the same problem with the new head.

One more thought, the 2.4 is unique to the 2005 ad 2006 Wrangler. I'm told nothing else on the planet is compatible with that engine/make/model for those two years. At least not without a ton of modification and an ACME adaptor kit. It has Variable Valve Timing, which I freely admit I know very little about. It's possible the gremlin may lie in that area, but I'm reaching again.

 

[Wildman]

Thanks Wildman. I like your idea of checking the head surface and then comparing it to the cam bearing saddles. In fact, I like it enough that I'm secretly pissed I didn't think of it sooner. Kidding. Maybe.

A loaded head (valves, springs, seats, and keepers) from Auto Zone is less than $500.00 delivered to my door. I'm likely to go that direction but I first want to make sure nothing else is wrong with the block or my procedure which will cause the same problem with the new head.

One more thought, the 2.4 is unique to the 2005 ad 2006 Wrangler. I'm told nothing else on the planet is compatible with that engine/make/model for those two years. At least not without a ton of modification and an ACME adaptor kit. It has Variable Valve Timing, which I freely admit I know very little about. It's possible the gremlin may lie in that area, but I'm reaching again.

One more thought, Have you checked the flatness of the block with a straight edge?

And Yes I do believe that the 2.4 in your TJ is unique to it alone since the Neon uses a different block from what I understand. And I only know a little about this from reading a thread where someone added a turbo off a Neon to their TJ 2.4.

 

[Tonyjustin]

Yes, I checked the flatness of the block and it was OK. I’ll get around to your earlier suggestion this weekend. Thanks again for the help!

 

[Wildman]

Yes, I checked the flatness of the block and it was OK. I’ll get around to your earlier suggestion this weekend. Thanks again for the help!

Hope you get it figured out... Keep us posted..

Edit: And BTW Welcome to the Forum.