R

Redman

New Member
I last posted in Jun, with various engine problems that appeared to have been resolved by helicoiling a "failed/loose" head bolt, plus skim / new gasket on LHS only. [The focus of the diagnosis had been lack of compression on No 5 cylinder.]

All has been well for a month or so, but on longish (150km) run at weekend, symptoms returned: limped home as carefully as I could (late at night / rain / etc!). On inspecting engine bay, oil is sprayed everywhere on the left side (from driving point of view), and pulling the spark plugs it does look as if No 5 cylinder is failing again - others look OK.

Is this likely to be another head bolt / head gasket fail? I ask since the presence of so much oil everywhere is new to me.

And how likely is it that it is the helicoil insert that has failed?

Suggestions, before I head off to the local workshop and pay another wadge of cash to get on the road?

Redman [V8 Auto / 2000 / Recon Block and Heads 18 months ago, and much work since!]
 
depends on where oil came from (out the dip stick could be blocked engine breather on long run) helicoils if done right shouldnt fail
 
Have just been out to run afresh over things, and look at the crankcase breather (which on searching does seem to be a bit of an issue). Now see that exhaust is spraying oil out ...............

Would a blown head gasket do this?

Thanks

Redman
 
Correction! Not oil coming out of exhaust, but oily water / vapour.

I assume head gasket failure number three. Given that had the head skimmed last time, and that a reputable LR Main Workshop (I certainly trust the head mechanic, who took a personal interest in the helicoiling etc) did all the work, is there something else that could be the cause of such repeated failure?

And I'm still puzzled by the oil all over the engine bay. Is a blocked breather enough to blow a gasket? And if so why only the LHS and not RHS?

Redman
 
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often skimmed heads go again if skimmed to make straight after warping depending on how hot theyve been too hot and aluminum "relaxes" and will move readily again under slightest temp rise ,early 3.9 before serpentine belt where prone to lh side due to water pump,later depending on weakest point, blocked breather wouldnt blow a gasket but would invert valley gasket and push seals out or enough to leak bad need more info
 
OK: LR Workshop still feel problem is helicoil and will only recommend new block: frankly not a sensible option on a Year 2000 vehicle!

I've stripped out the LH cylinder head myself, with following results:

Gasket is, as expected, failed (badly burned through) - in pretty much the same spot again; focus is thus again on No 5 cylinder and nearby Head Bolt. Difficult to be absolutely sure, but my impression on releasing bolts was that the helicoiled bolt was not as torqued up as the others. [How to test?]

Inside of Rocker Casing (plus all over visible internals) is what looks like heavily carbonised/burned oil. One of the Tappet Rods (?) on No 5 - I think the exhaust valve - also shows heavy deposits half way down it.

Anyone able to advise further? Also: any way to "test" the helicoil; and if suspect can I simply extract and replace, or do I need to go to something bigger (Timesert?)

Redman
 
if helicoil is still tightly in place not stripped holding thread,then should have been fine ,over heated heads can move ,check with straight edge ,poorly injectors can burn head compoments .pistons etc rare but ive seen it, the beauty of helicoil type is that through wedge effect between threads force is transmitted outwards as well as up as in std thread which is what strips it ,reason why helicoil type are often used in ali castings,the only other consideration is that bolt hole cant be too big
 
Update - after rather more careful study.

LR Workshop helicoiled 2 of the bolt threads on the LH side - Numbers 10 and 8 if removing in Rave order ie above No 5 Cylinder. Gasket has failed badly (completely burned through) between these 2 bolts, and No 5 cylinder head is fully carboned up.

Helicoil on 10 seems to extend about 1/2 way down length of bolt / hole; and on 8 about 1/3 the way down. Should the helicoil not run almost the entire length of the bolt in order to function fully? Did LR know what they were doing?

And if I now remove the existing helicoils and replace, how long a helicoil should I actually use?

Appreciate any quick replies - am trying desperately to get back on road this week.

Redman
 
Will get head checked again asap, but by my way of thinking if the helicoils are a reasonably obvious potential source of failure, then I should look at ensuring they are 100% right before tearing into everything else. Or not?
 
Your prompt replies very much appreciated!

Bolts seem to screw in/out easily into the inserts, though the very top of the one in "No 8" broke off when I was doing so - only using finger power. Otherwise they seem OK though I have not torqued them up again yet.

Any views on length of insert? Browsing throws up two main points: first that anything over 2 x Diameter of bolt is not adding any strength (seems counter-intuitive, but there you go); second that should go for longest insert possible (but would this mean double stacking the inserts, with the attendant risks of the lower one shifting / threads fouling?)

Redman
 
Head polished and tested - incl valve guides checked (which are OK - presumably eliminates them as an issue). Now just need to sort out helicoils.

I'd still be v interested in views on how long an insert is needed for a head bolt. Current ones (ie which failed) are 1.5D only - I can't quite believe the LR workshop ever thought that would be enough. Should be able to get 3D - is this sufficient?

Alternative is to use 2 x insert in each one - but then if anything happens and there is an insert failure, I assume it will be well nigh impossible to get the lower one out? Anyone tried this?

Redman
 
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