Hi peeps!
92 sport 2 door 4.0 stick

my XJ has 204,xxx on it so i was considering a head rebuild vs a new motor and checked the compression to give me an idea of what direction to go in.
im posting the results to see what you all think. evidently if you rebuild the head with bad or weak rings you will cause further damage. i have searched all around and it seems that stock compression should be between 120-150 psi. that seems like a wide range to me.

# dry wet
1-146 170
2-150 160
3-148 161
4-151 180
5-150 158
6-146 158

so far all i can think of is
1. carbon build up
2. the motor has been replaced by the P.O. and its fine leave it alone
3. the rings arent seating correctly/oil didnt spread wet test again

so im gonna wet test again and compare the numbers

what do you all think?
cheers!

 

wet retest results are
1-165
2-161
3-170
4-187
5-169
6-170

 

sounds pretty high honestly. by wet testing you mean what? you put oil down the spark plug holes to seal up the rings? how reliable is your pressure tester?

 

yeah oil and yes its reliable seems a bit high to me as well

 

Run it.

 

Did you have the engine warm and all other plugs out when you did your test?

 

Reasons it may be showing a little high:

Too many pulses - 1st pulse should be 90% or more of the final value.
2nd pulse 95%
3rd pulse final value.
pulsing too many times will keep driving it up.

Wet -One cylinder at a time:
a teaspoon of oil max.
Rotate engine 4 or 5 turns to spread it around evenly.
Then 2 or 3 pulses.

Compression gauges aren't very accurate, the relationship is the important thing.

I'd run with it.

 

numbers seem a little high but the good news is they seem pretty close to each other. thats the important part is that they arent too far off from each other. id run it. save your money for the other issues that are bount to come soon lol

 

did engine cold with all plugs out thanks for the info so far guys

 

Run it. You only have 5 psi difference. That is well within the parameters for an engine. Why did you feel it necessary to do a compression test?

 

Spec is about 150psi dry, I believe. You're golden

 

Mdnov, only because of the mileage, we just did the head on a buddys and the power he has is amazing compared to mine so i was thinking of redoing my head.

thanks austin!

 

What did they do when they did the head? Did they do a 3 degree valve job and use the hardened valve seats? Did they do any porting? Just curious.