Problem: I ran my jeep overheated (i really don't need any responses saying this was dumb. I'm well aware. I was in the middle of nowhere, with no heat and in the middle of the night. I did, however, have and use a gallon of antifreeze.)

Once I got it home, I let it cool and had diagnosed the cause of the overheating (busted radiator) I restarted it.

It ran very rough and backfired out of the TOP of the motor. It has a fairly useless valve cover gasket and smoke came out from a leak in the VCG.

After disabling the fuel pump and the spark, I ran a compression test.

Compression Test Results:
1: 120
2: 130
3: 0
4: 110
5: 140
6: 0

Any ideas, fellas?

 

prolly a head gasket blown at those two cylinders, if you got a little know how and a time you can do it, the worst part ive found so far (im in the middle of one) is gettin the lower exhaust manifold bolts on

 

could be a headgasket, it could have cracked the head, or you may have overheated/melted the exhaust valves, although i dont know if thats the most likely option. i would just get a new motor myself. cause if you ran it that hot theres a good chance you did warp the head.

 

I would guess that it is the head gasket too. I would just replace the head gasket and bring the head to a shop and have them check it out.

 

Head is going to have to come off.

When removed, take it to a reputable machine shop that specializes in this type of work.

They can do a thorough check of the head for straightness, cracks (magnaflux testing) etc. and the internals on that head.

Then install a new headgasket with a verified head.

You do NOT want to just replace the headgasket without having a shop checking that head over!

 

X2

 

you would get a new motor!!?? seriously!!?? just cause you warp a head dont mean you need a new motor, it just needs you need to get your old head leveled or worst case a new head but def not a new motor

 

Well what do you expect when people who know less then the OP try and give advice? Obviously he knows nothing about diagnosing a motor and deciding if its worth pulling or not.

Just to point this out..
Motor worth swapping in from a JY: $500
Buying an engine lift to do the job: $200
engine leveler to make your life ALOT easier: $50
Beer and pizza for 2-3 days of friends helping: $50

Thats around $800 just to swap the motor, minimum. Ask me how I know.

Or you could pull the head off
Tq wrench from walmart: Free, return it when your done. **** Walmart.
Head work at machine shop (for me, NAPA): $175 for crack check and plane
Head gasket $35
Being able to see if your rings are bad :free
Opportunity to have the valves cleaned up : free
Exh / intake gasket : $13 at NAPA

So lets compare. 800 bucks to swap the motor, or 215 to pull the head off, inspect the rings for play, then if that checks out (free so far) have the work done and buy the gaskets. I left out Coolant and oil costs because they are involved in both processes. Head gasket job roughly 6-10 hours labor with 1 man. Motor swap roughly 20 hours labor (Took me and 2 friends 3 days to be 100% done

Yup. Great suggestion. Deff. Swap the motor....


TJ hit the nail right on the head.

 

Compression not too bad except for those 2 cylinders so I would say something def wrong with head or gasket. With 0 compression my guess would be stuck valves. At any rate you are going to need to pull the head and have it rebuilt.

 

Here is some info on how to perform a compression test and how to interpret the readings you get. This info is from the compression tester I purchased.Hope these instructions help you to determine the condition of your head and head gasket.

8. Crank the engine for at least four compression strokes or until the pressure reading stops rising on the gauge.

Test Results

1. On a normal cylinder, the gauge needle should travel up-scale on each compression stroke until it reaches a peak value. All cylinders should indicate a pressure that is within the vehicle manufacturer's specifications, and the reading should not vary more than 10% from cylinder to cylinder.

2. If the needle fails to travel up-scale as described in Step 1, or if it remains at the same value for several strokes and then starts to climb,the cylinder has a sticking valve.

3. If the compression reading is considerably higher than the vehicle manufacturer's specification, it indicates carbon buildup in the cylinder.

4. If a reading on two adjacent cylinders is 20 pounds (or more) lower than the other cylinders, a defective head gasket is indicated. Water (coolant) and/or oil may be found in the two cylinders under these conditions.

5. If the readings are low or vary widely between cylinders, pour a teaspoon of clear S.A.E. grade 30 oil into each cylinder and retest. If the readings increase considerably, the fault may be due to poorly seated or worn piston rings. If the readings remain about the same, the valves and/or associated components are likely the cause.

 

Thanks a lot for the input, guys. I've got the coolant drained, and i'm on my way to get a fuel line removal tool to get the fuel line off the intake. I'm pretty mechanically inclined, so I'm not too worried about this job. Besides, I have another vehicle to get me around while I work on this one.
My guess is stuck valves too, but this does give me an opportunity to see what's going on in there and clean things up.
The intake was black and greasy on the inside and i'll bet the injectors could use a good cleaning too.

 

Not trying to hijack this thread but, Does this indicate a stuck intake valve?

I just ask because the jeep I just purchased wont start and was sold to me because of an over heating issue and running rough, like a bad head gasket or something. I haven't done my compression test or really had time to work on it at all yet but the intake on mine is pretty nasty.

 

intakes just get dirty like that from years of use just clean it out. when you get motor running go out and buy seafoam from a auto store and ask for instructing on how to properly use it. fore warning when you do it whatever vehicle you do it to will sound likes it going to die and smoke no worries its normal haha.

 

Thanks. I have used seafoam before and realize that the intake will get dirty for use but was just asking because the op had mentioned stuck valve and dirty intake, I think i just read it wrong my bad.
Once I get it going I will run some seafoam through a few tanks of gas..enough about me though lol I dont want to hijack Beat-up Sport's thread..
Thanks

 

yeah for sure good luck.