Putting my head back on today, should the head bolts be lubed or oiled? if so , what can I use to lube them?
Head bolts lubed or not?
- Thread starter Chris TQS
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They come out the packet with a oily coating on them, and i've always just nailed them in like that.
Putting any liquids down there risks cracking the block from hydraulic pressure.
Putting any liquids down there risks cracking the block from hydraulic pressure.
Yep, no need to oil them really however you can use wd40 oil or similar to spray a light mist if they were out of the box for too long ! Lay them on some kitchen paper towels to soak any excess lubricant...
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The more my paranoid little brain think about it, the more this sounds like a realistic possibility... It's not something I've ever head of before though. How likely do you think this is and is it something you've seen before?
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Just found some interesting reading here actually - http://www.enginebuildermag.com/2005/07/perfect-engine-sealing-starts-with-proper-head-bolt-use/
It goes into quite a lot of detail regarding head bolt use, but there are two quotes in particular that are relevant here:
"As a rule, the threads and underside of the head on most standard automotive head bolts should be lubricated with motor oil before the bolts are installed. The torque values specified by the engine manufacturer are typically based on oiled threads and fasteners – not dry fasteners"
and
"Installing head bolts dry can lead to trouble because the increased friction in the threads can reduce clamping force up to 25 percent or more at the same indicated torque reading."
It goes into quite a lot of detail regarding head bolt use, but there are two quotes in particular that are relevant here:
"As a rule, the threads and underside of the head on most standard automotive head bolts should be lubricated with motor oil before the bolts are installed. The torque values specified by the engine manufacturer are typically based on oiled threads and fasteners – not dry fasteners"
and
"Installing head bolts dry can lead to trouble because the increased friction in the threads can reduce clamping force up to 25 percent or more at the same indicated torque reading."
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Its a valid concern usually if coolant or oil spills down the bolt hole when you remove the head, and isnt removed before the new head goes on. Liquid is incompressable, and the bolt advancing down the hole creates massive hydraulic pressure.
Clearly a minimal amount of oil on the threads and head surface shouldnt be a problem.
The point about torque settings is valid, but thats very likely why the bolts on these engines are angle tightened. The first torque value is very low, where the frictional difference is small, and then the angle tightening stages dont care about thread oiling.
I cleaned out the bolt holes with brake cleaner and then blow them out with an air line. I used a small amount of engine oil as the bolts seem dry to me.
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i used ARP torque lube on the heads of my bolts, purely for better accuracy with torque readings. Provided the tool is also calibrated
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So my paranoid little brain has been at it again, and decided to look at a picture I took when the head came off...
As you can see, one bolt hole literally FULL of oil
which I almost certainly didn't do anything about when fitting the head...I've only done 80 or so miles on the engine and it seems fine. I suppose it would manifest with similar symptoms of head gasket failure if at all? . . If not as actual HG failure.
Can't believe I didn't think of this at the time, it seems so obvious! I recall one of the bolts feeling a big "squidgy" and tight as I was winding it in by hand as well. . . I hate to admit it, but I've got a feeling I might have to think about preparing the spare block I have in the garage
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Hmm not ideal!
Not really sure what to suggest. You might get away with simply removing the bolt, cleaning out the oil and refitting the bolt?
Not really sure what to suggest. You might get away with simply removing the bolt, cleaning out the oil and refitting the bolt?
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Yea, as bodge as it sounds, apart from having the whole engine apart (AGAIN!), this could be my best/only option... I will be keeping hold of my spare block just in case though!
On another note she seems to be running very well at the mo... Just embarrassed a Boxter running only actuator pressure
