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Head gasket leaking after engine rebuild.


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#1 1974CJ5

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Posted 06 December 2010 - 12:50 PM

I have recently rebuilt the engine in my 87 2.5 MJ because of a broken piston ring on cylinder 2. Everything worked awesome, except my head gasket is leaking a bit under the back right corner against the firewall. I had the head resurfaced, no warping detected, block was professionally cleaned, used a felpro gasket installed dry. After this problem began I starting reading in a haynes manual that composite gaskets shouldn't be used. Well the only gasket I can find is the same felpro gasket covering 85-2001 jeep 2.5 engines. The haynes manual says that 87's should only have a stamped metal head gasket that should be sealed with copper sealant.

Does the felpro gasket supersede this? What do you guys think? Should I be looking for a different gasket or is there another problem?

Note: I cannot detect any white smoke in exhaust or coolant in oil (yet). I am reasonably sure that it isnt the freeze out plug on the back of the head.
87 mj 2.5 2wd ax4 d35
85 xj 2.5 d30/d35 a904 np207
74 cj5 5.0(304) d30/d44 t15 dana20
2006 tj 2.4 d30/d35 nsg370 np231
2009 kk---who cares.

#2 streetjeep2.5

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Posted 06 December 2010 - 01:15 PM

I have recently rebuilt the engine in my 87 2.5 MJ because of a broken piston ring on cylinder 2. Everything worked awesome, except my head gasket is leaking a bit under the back right corner against the firewall. I had the head resurfaced, no warping detected, block was professionally cleaned, used a felpro gasket installed dry. After this problem began I starting reading in a haynes manual that composite gaskets shouldn't be used. Well the only gasket I can find is the same felpro gasket covering 85-2001 jeep 2.5 engines. The haynes manual says that 87's should only have a stamped metal head gasket that should be sealed with copper sealant.

Does the felpro gasket supersede this? What do you guys think? Should I be looking for a different gasket or is there another problem?

Note: I cannot detect any white smoke in exhaust or coolant in oil (yet). I am reasonably sure that it isnt the freeze out plug on the back of the head.

One head bolt, and I forget which, is supposed to be torqued less than the rest. I think it's a corner one. Did that happen? Also, first time the head off? If not, they say you should not loosen and torque again the head bolts more than once. If this is a second time, you may have a weak head bolt there. I should be following that advice also, but I used my head bolts a second time. We will see.
Doug

#3 airspeed

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Posted 06 December 2010 - 01:43 PM

I just changed the head on my 2.5 about 6k miles ago, no problems so far. I guess I broke all the rules, felpro gasket no sealant, reused the head bolts, same torque at all locations. I did notice that there was a "This side up" on the head gasket.

Rick
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#4 Geonovast

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Posted 06 December 2010 - 01:51 PM

Leaking what?

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#5 jimoshel

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Posted 06 December 2010 - 01:52 PM

Left front head bolt needs less torque, 75ftpds than the rest. 85ftpds.

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#6 1974CJ5

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Posted 06 December 2010 - 01:55 PM

Bolt number 8 (in tightening sequence) gets 75 pounds, and the rest get 85 pounds. bolt 8 however is on the driver side of the engine closest to the fan. Maybe I should just replace the head bolts and see what happens.... thoughts? As far as I know it was the first time the head was off, but I have no guarantees.

Leaking what?

coolant down block.
87 mj 2.5 2wd ax4 d35
85 xj 2.5 d30/d35 a904 np207
74 cj5 5.0(304) d30/d44 t15 dana20
2006 tj 2.4 d30/d35 nsg370 np231
2009 kk---who cares.

#7 Cheech

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Posted 06 December 2010 - 05:52 PM

Just remember: There are two different torque values depending on which gasket type is used. There is a value for using the stamped steel gasket and one for using the composite type. If using the composite type the value is up around 100.
1986 2.5 NP 207 LWB Auto 4x4

#8 mnkyboy

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Posted 06 December 2010 - 08:30 PM

Make sure there is nothing in the bolt holes,I've seen guys throw the bolts in without cleaning the holes and get false torque readings.

I would also replace the bolts or at least mesure them for strech.
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#9 1974CJ5

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Posted 06 December 2010 - 09:50 PM

Just remember: There are two different torque values depending on which gasket type is used. There is a value for using the stamped steel gasket and one for using the composite type. If using the composite type the value is up around 100.


So basically you are saying using the torque values for the composite gasket listed in the haynes manual for the felpro aftermarket gasket?

Do you think there is any value in me searching out the stamped steel version of the gasket? I am assuming I would have to go to the jeep dealer for this.

Make sure there is nothing in the bolt holes,I've seen guys throw the bolts in without cleaning the holes and get false torque readings.

I would also replace the bolts or at least mesure them for strech.


I just ordered some headbolts today, so I hope that helps. I did check the bolt holes very very well, and blew them out with comp. air several time before installation, the head was professionally cleaned also.

Do you guys think I should use gasket shellack on the head gasket when I re-do :fs1: it?
87 mj 2.5 2wd ax4 d35
85 xj 2.5 d30/d35 a904 np207
74 cj5 5.0(304) d30/d44 t15 dana20
2006 tj 2.4 d30/d35 nsg370 np231
2009 kk---who cares.

#10 Cheech

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Posted 06 December 2010 - 10:55 PM

Yes, I would recommend using the torque values for the composite gasket. I started a topic about the torque values when I replaced the gaskets in my 86. Basically, we came to the conclusion that the different values listed in the Haynes for the different years was based upon the gasket type used and not a difference in the block itself. I torqued mine to the higher amount, can't really remember the exact number, but it was over 100 and have had no problems.
If you think about it, it makes sense that you want the higher amount because you need to crush that composite gasket to make it seal. With the steel gasket, it is the sealant that does the sealing.
I would recommend just using the composite style, I doubt the other style is still made. My gasket set from Carquest (victor reize gaskets) came with the composite.
1986 2.5 NP 207 LWB Auto 4x4

#11 1974CJ5

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Posted 07 December 2010 - 07:24 PM

I started a topic about the torque values when I replaced the gaskets in my 86. Basically, we came to the conclusion that the different values listed in the Haynes for the different years was based upon the gasket type used and not a difference in the block itself. I torqued mine to the higher amount, can't really remember the exact number, but it was over 100 and have had no problems.


Sweet! thanks for clearing that up. I will do just that then when my new head bolts arrive. Seriously hope this is last time I have to get into this head for a while.
87 mj 2.5 2wd ax4 d35
85 xj 2.5 d30/d35 a904 np207
74 cj5 5.0(304) d30/d44 t15 dana20
2006 tj 2.4 d30/d35 nsg370 np231
2009 kk---who cares.

#12 mjtjnj

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Posted 07 December 2010 - 11:08 PM

That's funny (not really), I have the same problem. I had my 2.5 professionally rebuilt and assembled it. Got it back and the valve stem seals were improperly installed, so I removed the head, and the machine shop fixed it. I put it back on. I used the FSM in putting the new Felpro head gasket and head on. Torqued, I believe to 85 (except #8 at 80). Leaking back corner - driver's side. Took it to a mechanic, and he said there was an update -- for the composite gaskets -- that said 115 ft/lbs (105 for #8), so he re-torqued them. He went to pressure test it, and my heater core exploded! LOL - had a new one anyway. So I'm holding my breath that the block or head aren't cracked, and that the builder decked the head properly, etc. Sucks.



Keep me posted!

Tom