Overtorque headbolts? or replace 1 by 1 (like bentley says)

[jcsomerset]

I think i've isolated the slow oil leak to the exhaust side of the engine between head and block - this annoys me since dad and I did the head job less than a year ago - so the head gasket is nearly new - and we performed the replacement job per bentley and haynes specs (we've got both manuals) after I got the head remanufactured (bought car with busted timing belt and head)


the question is - can I overtorque the head bolts a 1/4 or 1/8 turn to try to stop said oil leak - or is it better to buy a new set of headbolts and replace them 1 at the time per bentley specs...

lastly - does anyone have a better torqueing suggestion for the torx head bolts than 23 ft/lbs then 1/4 turn then 1/4 turn? is there a ft/lb rating for each successive 1/4 turn.

THanks in advance - i really, really don't want to do another head job on this car - they are such a PITA!

[jcsomerset]

If I have to tear the engine down again - I'm liable to go get a 2.8 crank off of an e and make a stroker.

[Jordan]

overtightening the bolts will not stop the leak.

You will need to pull the head, clean both mating surfaces, check for trueness, then put a new headgasket in.

you need alot more then a eta crank to make a stroker.

[jcsomerset]

That's not really what I wanted to hear - but a truth I was probably denying -

the mating surfaces were cleaned very well before the initial install/ reassembly (scraped and brushed)- but we didnt' check for trueness of the block surface - it's kind of hard to warp a cast iron block - but i suppose it's possible -

with an '89 i engine- from what I understand (and have read)- I don't need much more than an eta crank for a stroker (and rods; I forgot Rods; just edited this in) - maybe some larger injectors - remapped ECU - but as far as mechanicals/hardware go - i'm not far off..

I'll probably live with the leak for a while - perhaps a long while.. I haven't made up my mind yet.

[kansas-ix]

but we didnt' check for trueness of the block surface - it's kind of hard to warp a cast iron block - but i suppose it's possible -

yeah thats b/c it would be your Aluminum head that would be warped.

[Axxe]

Are you sure it isn't just the valve cover? If the head was loose I would think you would loose power and leak coolant.

[jcsomerset]

the head was remanufactured - it was true - done by a local machine shop that's probably the one of the best in the south (performance combustion; if anyone cares). 2 rocker arm bosses were cracked and re-welded; the head was completely dissasembled; cleaned; cooked, checked for "trueness" and had all new exhaust valves(as those were bent by PO who didn't know what a timing belt was - much less that it ever needed changing. ) ; guides; and at least 1 new rocker arm (as one had been cracked in 2)

so the head was (and is) straight

- it could be the valve cover - I know those are notorious for leaking; and I'm due for a valve adjustment; but am fairly sure i've got some weeping between the block and head. If so I will probably just live with it for a while. I'm not in the mood to do another head gasket job within a years time - maybe this coming fall - if I get motivated or it blows itself up between now and then.

[Madhatter]

You cant use any other method other than angle tightening. The bolts are torque to yield and that is the way you have to do it. Change to metric blues if you dont want to.

[jcsomerset]

You cant use any other method other than angle tightening. The bolts are torque to yield and that is the way you have to do it. Change to metric blues if you dont want to.

Forgive my ignorance - what are the metric blues? a brand of HEad bolts?

[mikeedler]

if your head was redone, it is probably leaking from the doghouse shaped gaskets on the front and rear of the head. they are at the ends of the rod that the rocker arms are mounted to. try the valve cover gasket at the same time.

[Madhatter]

You cant use any other method other than angle tightening. The bolts are torque to yield and that is the way you have to do it. Change to metric blues if you dont want to.

Forgive my ignorance - what are the metric blues? a brand of HEad bolts?

yeap, very popular in the turbo community. They arent torque to yield bolts so you dont have the issue of angle tightening.

Metric Blue - grade 12.9 head bolts http://www.mcmaster.com/
Part Number 91303A306 $9.60 per Pack of 5. you will need 3 packs of 5.
also, use the washers from your old head bolts.



Material
Class 12.9 Blue-Coated Alloy Steel
Head Style
Standard
Drive Style
Hex Socket
System of Measurement
Metric

Thread Size
M10
Length
150 mm
Hex Key Size
8 mm
Thread Style
Standard Right Handed
Thread Length
Partially Threaded

[jcsomerset]

So I can get these Metric Blues and torque the hell out of them? is that the basic Gist of it? anyone have a suggestion as to ft/lb rating on these suckers?

Obviously - 3 serial torquings would be warranted - but i like this idea much better - more precise IMO with a ft/lb reading than 23 ft/lbs then 90 degrees then 90 degrees.. that's just inexact science from my point of view..

[matt325is]

I have the metric blue bolts. Since I had replace my head gasket not 500 miles before, I kept the gasket, and replaced just the head bolts with the new ones. I did them 1 by 1, in the correct torquing pattern. I torqued to 30ft-lbs, then 40, 50, 60, 65. These bolts do not stretch like stock bolts, so they can hold a lot more cylinder pressure (in FI applications).

I blew a head gasket before because my stock bolts stretched (and did not happen again). I now have around 300 miles on the new head bolts, and so far so good. Also, make sure you lightly oil the new bolts, and use the washers from your stock head bolts (as the Metric blue's dont come with washers).

By the way, make VERY sure there is no oil in the block threads. I snapped a bolt because it could not go down anymore (oil cant compress).



matt

[jcsomerset]

I have the metric blue bolts. Since I had replace my head gasket not 500 miles before, I kept the gasket, and replaced just the head bolts with the new ones. I did them 1 by 1, in the correct torquing pattern. I torqued to 30ft-lbs, then 40, 50, 60, 65. These bolts do not stretch like stock bolts, so they can hold a lot more cylinder pressure (in FI applications).

I blew a head gasket before because my stock bolts stretched (and did not happen again). I now have around 300 miles on the new head bolts, and so far so good. Also, make sure you lightly oil the new bolts, and use the washers from your stock head bolts (as the Metric blue's dont come with washers).

By the way, make VERY sure there is no oil in the block threads. I snapped a bolt because it could not go down anymore (oil cant compress).


matt

So you replaced them Per Bentley - to 30 lbs (all 12) then the serial tighenings?

[matt325is]

No, I did one at a time. I took 1 out, put the new bolt in, torqued to 30, then 40,50... Then move on to the next bolt, and do the same sequence of torques. then move on to the next bolt and so on.

matt