Difference between a cracked head and a blown HG

WillRadford · 04-05-2007, 12:34 PM

Im going to look at a 4runner with a blown HG that a guy is selling for $1050 after work today. He said to me he thinks it either has a blown HG or a cracked head.

I know with a blown HG Im going to see the white smoke out the exhaust and a lack of power. What type of things would I notice if it were a cracked head? How would a head even crack? Overheating? Wouldn't a cracked head be pretty noisy? Wouldn't it be pretty obvious if the head was cracked? I don't think the guy I talked to knew what he was talking about. What can you guys tell me on this?

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dcg9381 · 04-05-2007, 12:37 PM

There isn't a good way to tell a cracked head from a HG issue without pulling the head. Cracks can be so small, they're almost impossible to see, even if you know where you're looking... That's why shops pressure test.

Vehicles with blown HGs can run fine... Best way to see how bad it is w/o disassembly is a leak down test..

80W90 · 04-05-2007, 12:39 PM

for that price i would buy it regardless of the reason

kmcc78240 · 04-05-2007, 12:40 PM

I do not know I am sure someone will chime in. But a HG can be replaced and the heads machined down. A cracked head you would need a new head for the engine.you will not intil you take of the head though.

WillRadford · 04-05-2007, 12:40 PM

Ya, the body looks pretty good. 212k miles. i found a new head on ebay for $300. Is that a reasonable price? It didn't have any of the valves or anyhting in it but the cracked head would have all of that. I could have it all swapped over.

rdlsz24 · 04-05-2007, 12:54 PM

Heads are cheap. If that is all that is wrong with it, go for it. Go with a head from engnbldr.

Forgot to mention that you can pull the head and have it inspected for cracks, milled, etc, but that will most likely be over $100 right there so you could just put that towards a new one. The only downside to a new head is it can cause your bottom end to go out from the new increase in compression.

Rob

WillRadford · 04-05-2007, 01:05 PM

Well, if I buy it, pull the heads and find out that the HG was blown, then there doesn't seem to be any reason to buy a new head. I'd just get the one I pulled cleaned up, milled and the valves reground. It seems super unlikely that the head would crack AND the HG would blow.

UncleBob · 04-05-2007, 01:47 PM

Quote:

Originally Posted by WillRadford

It seems super unlikely that the head would crack AND the HG would blow.

No, very likely. Blown HG would be the cause of the cracked/warped head.

I guess it all depends on how long it was driven with a bad head gaskets. If it lost all it's coolant and overheated, you can bet the head is toast. If the previous owner killed the engine and towed it home as soon as they saw smoke, it may be ok.

In this kind of deal, plan for the worst (full engine rebuild) and hope for the best (head gasket).

keithguts · 04-05-2007, 01:54 PM

what year runner are we talking about, and what engine?

surf4runner · 04-05-2007, 02:58 PM

Quote:

Originally Posted by UncleBob

No, very likely. Blown HG would be the cause of the cracked/warped head.

or a cracked head would cause the HG to fail...

the HG can fail w/o a cracked head, it may warp if overheated though.

the heads comin off, so have it checked before you buy a new one.

1994runner · 04-05-2007, 03:46 PM

Once the heads are removed, have them pressure tested and resurfaced. There is no way to be certain while the engine is together. A good machinist might be able to weld it if it does have a crack

justinking060310 · 04-05-2007, 04:03 PM

I paid 900 for a 95 4Runner that is beautiful and had a blown HG -- so I would agree that it sounds like a good deal. Always plan for the worst - If your counting pennies it might not be the best project, but if you have the money, tools, and time it is a good project. And i have lots of extra parts you will need

I would pop the oil drain plug and see what comes out. If it's a HG, you should get coolant coming out before oil. The toyota dealer pulled the oil filter for inspection to figure out there was a HG failure on mine as well... Not exactly sure what they looked at thou.

Kat

TC22RE · 04-05-2007, 04:21 PM

I would be careful replacing a completely rebuilt head on a block with high miles... you may end up stressing the bottom end too much... just a thought, may be a good idea to rebuild the bottom end while you're at it and have a new motor...

04-05-2007, 12:37 PM	#2 (permalink)
dcg9381 Registered User Join Date: Jun 2006 Location: austin, tx Posts: 1,825	There isn't a good way to tell a cracked head from a HG issue without pulling the head. Cracks can be so small, they're almost impossible to see, even if you know where you're looking... That's why shops pressure test. Vehicles with blown HGs can run fine... Best way to see how bad it is w/o disassembly is a leak down test.. __________________ http://www.22REturbo.net

04-05-2007, 12:54 PM	#6 (permalink)
rdlsz24 Registered User Join Date: Sep 2005 Location: Pecatonica, IL Posts: 1,483	Heads are cheap. If that is all that is wrong with it, go for it. Go with a head from engnbldr. Forgot to mention that you can pull the head and have it inspected for cracks, milled, etc, but that will most likely be over $100 right there so you could just put that towards a new one. The only downside to a new head is it can cause your bottom end to go out from the new increase in compression. Rob __________________ 1988 Xtra Cab Pickup ('94 22RE; 4x4; 5spd) Rancho lift w/ 33x12.5x15 tires & 5.29s Last edited by rdlsz24; 04-05-2007 at 12:56 PM.

04-05-2007, 01:54 PM	#9 (permalink)
keithguts Registered User Join Date: Aug 2006 Location: Bay Shore, NY Posts: 1,422	what year runner are we talking about, and what engine? __________________ IF YOU DON'T DRIVE A TOYOTA, TEST DRIVE ONE TODAY! MY PICS 95 4runner 3.0 auto 4x4 My Rig My Rig RangerMan Enjoy

04-05-2007, 04:03 PM	#12 (permalink)
justinking060310 Registered User Join Date: Dec 2006 Location: Virginina Beach Posts: 626	I paid 900 for a 95 4Runner that is beautiful and had a blown HG -- so I would agree that it sounds like a good deal. Always plan for the worst - If your counting pennies it might not be the best project, but if you have the money, tools, and time it is a good project. And i have lots of extra parts you will need I would pop the oil drain plug and see what comes out. If it's a HG, you should get coolant coming out before oil. The toyota dealer pulled the oil filter for inspection to figure out there was a HG failure on mine as well... Not exactly sure what they looked at thou. Kat __________________ 95 4runner 2wd 3.0 v6 Downey headers (dont buy them) Downey 2 1/2" full exhaust/Carsound cat Weasy2k cams/ENGNBLDR's o/s valves ported and polished heads/intake New project- 94 4runner V6 4x4 A/T 3" 4Crawler BL on order 33x12.5 BFG A/T's on 15x8 Cragar Black Steel Wheels 90 4runner 4x4 3vze Auto parting out - let me know if you need anything! 85 4runner, SFA, 22re, 5speed parting out

04-05-2007, 04:21 PM	#13 (permalink)
TC22RE Registered User Join Date: Sep 2006 Location: New Mexico Posts: 100	I would be careful replacing a completely rebuilt head on a block with high miles... you may end up stressing the bottom end too much... just a thought, may be a good idea to rebuild the bottom end while you're at it and have a new motor... __________________ '94 Single Cab 4x4 Pickup Turbocharged/Modified 22RE SDS EFI System Std 5spd 31x10.50 BFG's

04-05-2007, 12:39 PM	#3 (permalink)
80W90 Registered User Join Date: Apr 2007 Location: Cascade Mountains, SW-WA Posts: 255	for that price i would buy it regardless of the reason

04-05-2007, 12:40 PM	#5 (permalink)
WillRadford Contributing Member Join Date: Jun 2006 Location: Bountiful, UT Posts: 154	Ya, the body looks pretty good. 212k miles. i found a new head on ebay for $300. Is that a reasonable price? It didn't have any of the valves or anyhting in it but the cracked head would have all of that. I could have it all swapped over.

04-05-2007, 01:05 PM	#7 (permalink)
WillRadford Contributing Member Join Date: Jun 2006 Location: Bountiful, UT Posts: 154	Well, if I buy it, pull the heads and find out that the HG was blown, then there doesn't seem to be any reason to buy a new head. I'd just get the one I pulled cleaned up, milled and the valves reground. It seems super unlikely that the head would crack AND the HG would blow.

04-05-2007, 03:46 PM	#11 (permalink)
1994runner Registered User Join Date: Jan 2007 Location: Eastern Iowa Posts: 90	Once the heads are removed, have them pressure tested and resurfaced. There is no way to be certain while the engine is together. A good machinist might be able to weld it if it does have a crack

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