engine help

[kev711]

so the other night my water pump and thermostat both decided to go bad at the same time. i didn't know my 98 tj was over heating and it shut down on me on the highway, got a tow home and put in a new water pump and thermostat. now the engine is running crappy, not much power and i'm getting a missfire reading on cylinder one. i changed the spark plug and wire...no difference.......any advice??? shot head gasket, ring??

[kev711]

well the verdict on the compression test is all are reading 150psi except cylinder one which is reading 28psi....sucks!!

[ct67_72]

yep, probably head gasket.

[kev711]

yep, probably head gasket.

how would i know if it's just the head gasket?

[clean4drxj]

how would i know if it's just the head gasket?

There might be some bubbles in the coolant overflow tank, it make eat coolant(oil would look milky), and a few other obvious telltale signs.

[ct67_72]

the best way is to do a leakdown test. This should point to the right area. You can also check for bubbling in the coolant like Tom said, sometimes its hard to tell that though. There are also analyzers to check for exhaust gas in the cooling system.
I happen to have both.......

[ct67_72]

also if you have a compressor and a compression tester, you can make a makeshift leakdown tester. Especially when the compression is that low.
remove the gague from the hose of the compression tester and install an air line fitting. scres it into the cyliner and fill it with air. The cylinder will have to be TDC compression stroke, and listen for air escaping and watch the radiator for air bubbles. I have a feeling with compression that low it will be pretty obvious, oh and pull the oil cap and listen for air, if its pressurizing the crank case.

[kev711]

also if you have a compressor and a compression tester, you can make a makeshift leakdown tester. Especially when the compression is that low.
remove the gague from the hose of the compression tester and install an air line fitting. scres it into the cyliner and fill it with air. The cylinder will have to be TDC compression stroke, and listen for air escaping and watch the radiator for air bubbles. I have a feeling with compression that low it will be pretty obvious, oh and pull the oil cap and listen for air, if its pressurizing the crank case.

i've heard of that! looks like i'll be trying that for the first time in the morning.

[kev711]

well, got my hands on a good head, put it on but the rod for cyl 4 wasn't put in the right spot but didn't know it, turned on the engine and it bent. took off the head, put in a new rod in cyl 4 and got running again but now it's not running that great. did a compression test and cyl 1-3 @150 and cyl 4 @ 130......any ideas??

[kev711]

and will do damage to the engine if i drive it the way it is???

[clean4drxj]

To be off only slightly could be a number of things from a slightly bent valve, valve seal.. ect
I have to assume that you got the correct pushrod(year and engine size)?

[kev711]

yup, got the correct pushrod in. one guy said i might have bent a valve so i'll have to replace a valve but that's way out of my league

[DizzDizz]

yup, got the correct pushrod in. one guy said i might have bent a valve so i'll have to replace a valve but that's way out of my league

replacing valves isnt really that bad as long as you have a valve spring compressor. other than that its pretty simple. i would say i wouldnt drive it cause if the valves is bent who knows if its gonna mess anything else up. if you dont want to attempt it. i have one of the best machineist on speed dial basically and i can give you his number. but he isnt cheap.

[kev711]

so i decided to give it a shot and just drive it on the highway for about 40 miles. when i got to my destination, i noticed the engine sat at idle really nice and had plenty of power..well as much as you're going to get from a 4 banger. today i did another compression test and tada!!!! all 4 squirrels we kickin at 150psi! i guess i had a stuck valve in 4.....so happy

[tjramplebump]

you lucked out man...just keep an eye at your temp or for any irregularity's and you should be alright...