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 Re: New Clearwater head causes compression psi to go through the roof
[Re: weebur]
#923319
01/07/09 01:19 AM
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Joined: Dec 2002
Posts: 120
OP
Wheeler
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I blew the edge off #4 exhaust valve 200 miles from home. I limped home and ordered a new casting w/o jet valves from Clearwater. Resumed the trip and put on 1,000 miles or so then checked the compression pressure yesterday. Old head ran 145-160psi with the new head 2-4 cylinders are at 186 and #1 is at 198psi. The FSM says it should be 170. I ran each test 4X with a good/accurate gauge. Anything to be concerned about?
It seems to be running OK except for a rattle/knock under light load that's in the lower end, probably #3 cylinder, but that was there before I replaced the head. Well I couldn't believe that the compression ratio on the 2.6 was 7:1 so I pulled up all of the TSB's online along with repair data and engine specs. According to that source the compression ratio on the 2.6 (non-turbo) is 8.7:1 and 7:1 on the turbo engine. Anyway, tomorrow I'll start replacing all three timing chain guides and see if the rattle is from noisy chains. Also, there is a TSB that increases the head bolt torque to 80 ft/lbs. on the 2.6, FYI.
'97 Jeep Cherokee XJ, Country, Black/Gray Leather, 4.0L, 4WD Command-Track, AW-4 Auto, 3.55:1 Gears, PowerTrax No-Slip Locker, Hi Country Tow Brackets, Spectre Air Filter, 235X75R15 Goodyear Wranglers, 126K miles
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Re: New Clearwater head causes compression psi to go through the roof
[Re: weebur]
#923320
01/08/09 09:22 PM
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Joined: Apr 2008
Posts: 441
Mudrunner
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Maybe the block has been milled down that would up the compression as well
1997 Montero LS with a motor swap a 1990 V6 12valve ported heads full 2.5in Ex I run stock tire size for Daily use, off road have 33x12.5 working on going trubo.
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Re: New Clearwater head causes compression psi to go through the roof
[Re: TainterRacing]
#923321
01/11/09 06:25 AM
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Joined: Dec 2002
Posts: 120
OP
Wheeler
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Maybe the block has been milled down that would up the compression as well That's a good point. I know some work was done on it before I got my hands on it, but I don't know exactly what was done.
'97 Jeep Cherokee XJ, Country, Black/Gray Leather, 4.0L, 4WD Command-Track, AW-4 Auto, 3.55:1 Gears, PowerTrax No-Slip Locker, Hi Country Tow Brackets, Spectre Air Filter, 235X75R15 Goodyear Wranglers, 126K miles
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