|
|
 Cracked heads?
#877628
03/27/08 05:41 AM
|
Joined: May 2006
Posts: 709
OP
Rock Warrior
|
I dropped off my heads the other day at the machine shop. He pressure tested them and one has a crack in it. He said I need to get a new one from a junk yard. I thought you could fix cracks? Do I really need a new one? How do I know the one at the yard is any good?
1989 Montero 4dr V6 3.0l
|
|
|
Re: Cracked heads?
[Re: 89montero]
#877629
03/27/08 11:30 AM
|
Joined: Sep 2006
Posts: 2,712
Roll Me Over
|
You can't fix the crack for what it cost to get a used head.
Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in Spring1989
95 Montero SR 3.8 DOHC Only one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Then a Gen2 SR with full coil independent suspension.
|
|
|
Re: Cracked heads?
[Re: OldColt]
#877630
03/27/08 05:09 PM
|
Joined: Jan 2001
Posts: 13,649
Web Wheeler
|
Ditto Charlie.
You can look for obvious cracks, usually between the valves, or radiating away from the valve seat (although I once had a Starion head crack in the exhaust port). Or you could buy a cheap crack dye test kit and a u/v light source, or the machine shop can pressure test (mandatory anyway). Get a crack warranty (guaranteed rebuildable without welding) on the used head and all you'll be out is time and gas if it is bad.
Not responsible for advice not taken...
|
|
|
Re: Cracked heads?
[Re: fasteddy]
#877631
03/27/08 07:12 PM
|
Joined: May 2007
Posts: 570
Rock Warrior
|
Get a crack warranty (guaranteed rebuildable without welding) on the used head and all you'll be out is time and gas if it is bad. Cant weld on a aluminum head anyway <img src="/forums/images/graemlins/shame.gif" alt="" />. You cant fix internal cracks on aluminum heads due to you cant magnaflex them. The normal cracks show up around the valve seats. If you get one from the junk yard, have it checked for crackes to. You have to remember theres a reason its in there.
Last edited by LandRaider; 03/27/08 07:21 PM.
|
|
|
Re: Cracked heads?
[Re: 93montero_sr]
#877632
03/27/08 07:21 PM
|
Joined: Jul 2005
Posts: 2,088
Body Damage is Cool
|
My question is wouldn't have there been some kind of sign that the head was cracked before taking it off?
88 Raider(Red):160k-Reman'd 2.6-5spd-Weber-SW Hubs-34x9.5 TSL-OffRd Pkg-1"Tbar-2"BL-CB 88 Raider(Silver):No 2.6/Bad KM145 Parts/Project 88 Montero(Brown):No 2.6,4.88s Parts/Project [b]4X4 STICKERS,SHIRTS,ETC: 4WD Stickers AT COST.[b]
|
|
|
Re: Cracked heads?
[Re: DRaider90]
#877633
03/27/08 07:38 PM
|
Joined: May 2007
Posts: 570
Rock Warrior
|
Water in the oil. White smoke(steem)coming out the tail pipe. Or it could of cracked when being unbolted for the block if not taken of in the correct order.
93 montero sr 3 inch body lift 31x11.50 super swamper ltb, 2 8inch 130 watt pro comp off road lights, 2 55w lights on the rear bumper, rear air locker, magnaflow exhaust muffler,superwinch manual hubs,15x8 black rock crawlers (steel)
|
|
|
Re: Cracked heads?
[Re: 93montero_sr]
#877634
03/27/08 10:20 PM
|
Joined: Sep 2006
Posts: 2,712
Roll Me Over
|
Cant weld on a aluminum head anyway And why can't you weld an aluminum head? And a crack in the exhaust port on a Starion head, that would be #4 cly. Hottest spot on that engine. Damn hard spot to reach to weld.
Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in Spring1989
95 Montero SR 3.8 DOHC Only one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Then a Gen2 SR with full coil independent suspension.
|
|
|
Re: Cracked heads?
[Re: OldColt]
#877635
03/27/08 10:33 PM
|
Joined: May 2007
Posts: 570
Rock Warrior
|
If you were to attemp to weld on a aluminum head make sure you have a good TIG welder,pre heat the head till it gets hot and clean the hell out it.And make sure you have a real steady hand. <img src="/forums/images/graemlins/kewl.gif" alt="" />
93 montero sr 3 inch body lift 31x11.50 super swamper ltb, 2 8inch 130 watt pro comp off road lights, 2 55w lights on the rear bumper, rear air locker, magnaflow exhaust muffler,superwinch manual hubs,15x8 black rock crawlers (steel)
|
|
|
Re: Cracked heads?
[Re: 93montero_sr]
#877636
03/28/08 01:44 AM
|
Joined: Jan 2001
Posts: 13,649
Web Wheeler
|
I've seen it done on a 2.6 head, and it ran for 100K. Cut out the valve seats, heated it at 500 in the oven overnight in a jig to reduce the warp and straighten the cam bore, and welded it the next day while still hot. The welder was an artist with the TIG. Almost didn't have to grind the weld smooth. No fix, no pay warranty, and they'd give me a new core if it failed, so I tried it. I liked it. $150 to do it. He ground it out and just built it back up. Magic stuff...
Not responsible for advice not taken...
|
|
|
Re: Cracked heads?
[Re: 93montero_sr]
#877637
03/28/08 02:11 AM
|
Joined: May 2006
Posts: 709
OP
Rock Warrior
|
If you get one from the junk yard, have it checked for cracks to. You have to remember there's a reason its in there. Yeah that's what I'm worried about. I'll spend my afternoon ripping the head out only to find it's cracked too. Oh well, good thing is my local "pull-a-part" charges $26 for the heads. Thanks for your help
Last edited by 89montero; 03/29/08 04:09 AM.
1989 Montero 4dr V6 3.0l
|
|
|
|
