Head Gasket Evaluation

[landandsea]

Boom,

My guess is that a more likely scenario would be coolant in the oil. That would cause the oil to appear milky.

I've had that unfortunate experience over the years - not the 80 though. Never had oil in the coolant.

Ed

 

[landandsea]

[quote author=landtank link=board=2;threadid=13534;start=msg128007#msg128007 date=1080438341]I
I removed my valve cover and both cams and checked the torque setting of the head bolts after driving the truck for a week. [/quote]

Rick,

A mechanic told me that re-torquing the head after a run in period was essential to doing the job properly. He also said that the proper way to re-torque is to first loosen the bolt and then torque it to the proper setting. He made the point that not loosening the bolt first doesn't give accurate readings.

I've done it his way ever since.

Ed

 

[landtank]

Well if you read the manual the torqueing proceedure is kinda strange to say the least. You basically torque the bolts to 29 ftlbs and then give them 2 sequencial 1/4 turns. No final torque value ???.

My old gasket looked like it had been crushed by the head during install which would seem normal. I just wanted to confirm that after a few drive cycles the torque was still near what I'm used to seeing and somewhat uniform.

 

[Lars]

[quote author=landandsea link=board=2;threadid=13534;start=msg128478#msg128478 date=1080529547]
Rick,

A mechanic told me that re-torquing the head after a run in period was essential to doing the job properly. He also said that the proper way to re-torque is to first loosen the bolt and then torque it to the proper setting. He made the point that not loosening the bolt first doesn't give accurate readings.

I've done it his way ever since.

Ed
[/quote]


Hmmmm..... I dont see anyone buying a brand new vehicle then opening it up a few weeks later to retorque the head bolts. Isnt it pretty much the same scenerio? Just a thought.

Robbie.... if you read this - how many 1fz's have you seen with a 2nd blown gasket?

 

[landandsea]

Rick,

I haven't read the manual. The procedure you described would have to rely on very strict manufacturing tolerances of the bolts and the head. To end up with the correct tightness every time using that procedure seems unlikely - too many variables. (maybe that's why someone mentioned, in a thread, that headbolts shouldn't be re-used)

Lars,
Good point. Who knows what the actual assembly at the factory is like? I would imagine a very high level of precision. Probably not something we could duplicate in our garages. Or even in a high end type of shop. Thus the re-torquing recommendation.

I remember the mechanic telling me that the only time a head gets properly re-torqued is when a mechanic works on his own engine.

Ed

 

[Scamper]

IIRC, it was Dan who mentioned that the head bolts are a kind of one-use elastic bolt (or something like that). I would think that trying to loosen and retorque this kind of bolt would not be a good idea.

But I too remember that the rule of thumb for HGs was to retorque the head after so many miles. I think that may be specific to old cast iron heads, but be old shcool now with the newer materials, etc.

Tom

 

[robbie]

I have seen only 2 HG failing after a new style HG was installed. Both these was do to improper HG troqueing, both only got the 1st pass of the 90 degree turn. One was done at a dealership (new short block installed), the other was from TAP's rebuilder. Both lasted over 30k miles before problems showed up.
Most engines head are torqued by Robots any more, doing the whole head pattern at the same time. Even new plants are installing pistons by robots. I think a cleaner enviroment is what the factory can offer over most shops or home garages. Excatness is then in the integerty of each person. Most shops would be out of business if the mechanic does not take care in every step of every process. The statement that mechanics only do right by them selfs is not right, if it was right then shops would not stay in business.

As for retorqueing you can do more harm some times by doing this, you could deform the HG by over squishing the HG. If coolant is not drained You could allow coolant to creep under the gasket if you do not drain the coolant out before retorqueing the HG. Todays materials are designed for One time torqueing usless it it stated in there FSM.

 

[landandsea]

Robbie,

I didn't mean to imply that the job isn't done right if the head isn't re-torqued. I think it's more of a "good, better, best" type of comparison.

You also mention "oversquishing" the HG. Is there a chance that re-torquing could do this if original torquing procedure is followed correctly?

Scamper brings up a good point, also. Maybe so-called single use bolts shouldn't be re-torqued.

I think this is good stuff to discuss since many of our trucks are getting to the point of head gasket issues. I have 142k miles, some of them have been abusive. So I'm thinking of head gasket replacement as PM and doing it myself. I've been thinking about a blower also, so I'd want to freshen up the old motor anyway before putting a blower on.

Thanks for the thoughts on re-torquing.

Ed