Hairline Cracks In Cylinder Head -- Advice Please! (1 Viewer)

[TomH]

So it seems the head cracks happen after having the head gasket done? Is that the consensus? And if so, why? Improper torque? Really curious because I've been thinking of having the head gasket done as PM.

Definitely not a post head gasket problem. If you are noticing the cracks after doing a head gasket then in my opinion the cracks were there when you pulled the head.

My LX450 was on the original head gasket and it was cracked.

Unfortunately it looks like I’m going to be a two time member of the cracked head club. I noticed a burning oil smell on my Land Cruiser last week so checked the obvious spot and sure enough there is an oil path right where the heads crack. I pulled the heat shields and lots of oil buildup on the exhaust manifold. I replaced the valve cover gasket last year so not likely leaking from the gasket. I cleaned it up and plan to check it again this weekend to confirm the cracks. The Land Cruiser is still on the original head gasket.

If it is cracked, and I'm pretty sure it is, I plan to take @Rifleman 's advice and try to fill the crack with some Loctite 270.

I’ve tried to come up with a reason why it is happening but I don’t have any good ideas. My LX450 came to me with cracks and I don’t have any PO history. I installed an Ultragauge as soon I got the truck and it never had a temperature problem. Would rarely get over 200 degrees.

I’ve had the Land Cruiser since 2003 and about 140K miles. Never had a temperature issue with this one either. I have seen temps as high as 217 when loaded down and towing the tent trailer but normal operation is always below 200.

 

[Brentbba]

Brings back bad memories. Blew a HG in Norcal and trailered the LC back to Socal and had the HG done. I'd asked the shop to have the head pressure tested when they sent it out for milling. Whether they did or not I don't know. Just a few thousand miles after the job I was still loosing coolant. Short story, took it to a better shop and they found a VERY VISIBLE crack in the head at the #6 cylinder head bolt. Did the first shop over torque, who knows. Second time around we replaced the head to, purchased from our friends at American Toyota Onur/Cruiserdan.

 

[TomH]

Here is what my Land Cruiser looks like about 150 miles after I cleaned it all up.

Here it is before cleaning. It looks like there is a crack there but certainly impossible to tell for sure.

 

[PFRELENG]

Figured I'd post the final video since it seems people are active on this thread.

Bring on the H8 comments



Lots more videos to come if people are interested in our channel.

 

[AJP]

Just to provide some of my very limited experience with these issues... for a while before my headgasket went south I noticed I was losing coolant ... then I blew the radiator. I wasnt able to be certain at first if it was the rad as the coolant was being blown to the back of the engine and seemed to be finding its way there under the hood liner,, which I accidently discovered was quite wet. So I was focussing on the rear of the engine where I could see drops of coolant .. but turned out to be the seal around the plastic upper housing of the rad that was leaking.

So I replaced the rad and all was good for a couple of months although I was still losing coolant - although much slower. BUT not long after I replaced the rad... lots of smoke on startup and very rough idle... the headgasket was toast. Later I realized that this sequence of events had all started with the headgasket on its way out..and the pressure the leaking gasket had introduced into the coolant had contributed to the failure of the rad.

I followed the FSM (and advice here) to replace the HG. My HG was clearly leaking at the no. 6 cylinder. I kept track of each head bolt and mic'd them as described in the FSM. I re-used all (as permitted in the FSM) except three which were replaced with three new bolts .. of the three that I replaced .. 2 were just barely within spec (but I didnt want to chance them) and the third was clearly out of spec (ie it was two thin -- and had been stretched).

It is noteworthy that the one headbolt that was out of spec was the the one that was located adjacent to the no.6 cylinder where the head gasket had failed. I do not know if this stretched head bolt is a 'cause' or 'effect' of the blown headgasket .... personally I am suspicious that because of its location at the rear of the block the bolt may be exposed to more heat that it was designed to accommodate and as a result it is 'yielding' too much during operation and the reduced clamping action on the head at that location is permitting the HG to fail. My advice is if you have a HG failure at the no.6 cyl location ...definitely replace this head bolt with a new one regardless of how it mics/measures out.

I can also 'buy' the likelihood of improper bolt removal (or torquing) sequence as a contributor to micro cracks in the head. I can also see two other factors that can contribute to those micro cracks 1) replacing the head on a block that is not flat -- according the FSM this is to be verified before replacing the head .. and 2) a head that has warped excessively and is replaced without milling. Incidentally the FSM advises replacing a head that is out of spec and does not advise milling... although a very minor amount of resurfacing seems to be acceptable.

 

[COYS]

People of repute (e.g. powderpig/Robbie) were observing cracks in the head at least as early as 2011 per this thread.

If one is to go through all the time and expense to replace the head gasket with engine out and back in, reasonable to decide whether the ~$1500 for a brand spanking new one is worth the squeeze while still avail at that.