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Engine Specific Info and Questions => IDI Engine => Topic started by: Ruby Doom on January 22, 2018, 04:00:43 pm
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I'd never heard of this, up to a couple of days ago, after I bought myself a Rabbit Truck.
Quick History: I used to run old 80's VW diesels, before I moved to the US, always missed them, finally bought myself one.
I've done head gasket jobs before, and had never heard of the stud idea, but I want this vehicle to last, the ones I've done previously, after a while you get to that stage where they won't start cold, unless you roll them down a hill, after they warm up, they run fine, and will work OK, unless you let them sit overnight. I used to park at the top of a hill. So, I'm quite prepared to believe that something got cocked up after I did the head change, and after a while I got some kind of leak.
This time round, I'm doing a semi-restore, in that I want it to last forever, even if it looks a bit old and patchy, so if there's a better way to do the head for longetivity, I'd like to do that.
It's an '82 btw, and has the 12mm star bolts.
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Studs can hold more boost and are reusable. A stock engine wont see an improvement really with studs over bolts assuming you use proper torque sequences. That being said the older blocks that use 11mm(i think) bolts are prone to cracking and pulling the threads out. In that circimstance a stud puts less pressure on the threads and can have more reliable results.
Hard starting is more of a compression issue. That can be caused by the head gasket but more often its worn rings or valves. A blown headgasket will have more symptoms then just low compression though.
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So no benefit on the heads that use the 12mm head stretch bolts? Just get a fresh set of bolts and go for it?
I'm going for longetivity, not performance, so there won't be any boosting the engine or tweaking the governor, or whatever these crazy kids are doing ;D
Are the torque sequences the same for studs? The extra turn after 1000 miles always freaked me out, one time I drove that in a week, just to get it over with.
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No studs goto like 125ft-lbs. Yeah just go with bolts and torque them properly.
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If you own an 82 now then you will be doing regular maintenance on it a lot anyway. So why not just get the 12 mm bolts and install? The 1000 mile twist is not that big of a deal. The bolts are designed to stretch that much, if you seat it down with the initial torque values then getting to 1000 miles should not be a worry.
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Head studs seem to loosen some as well. Every 20000 miles (for my 11mm 1.6l block) or so i back them off a quarter turn and then torque back to 105 ft/lb. They almost always have additional movement beyond the 1/4 backoff to tighten back to 105ft/lb.
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That seems to be an overwhelming NO for stud bolts then. Good, I can just go ahead as normal.
Thanks folks.
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Overwhelming NO? That's just silly. There is no downside to head studs other than the additional cost. If the stock fiber gasket is used, head studs will reduce the likelihood of head gasket failure even at stock boost pressures. The difference in cost is significantly less than the cost in parts/labor of a single head gasket change. The stock bolts will work but studs are definitely better than the bolts.
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So is there a better gasket than the stock fibre gasket?
Like I say, I'm just trying to build a bomb proof engine that will go for a long time.
I thought there was an issue with studs and putting the head back on with the manifolds attached, or did I misunderstand that?
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If you have hydraulic lifters and the block/head mating surfaces are confirmed flat, then the AAZ MLS gasket is better, IMO. If you have solid lifters, then there is not really a better option than the fiber gasket without some effort/risk. Plenty of threads on it already.
The ARP studs have an allen socket in the end of each. There is no issue with removing them in order to accommodate head removal/replacement with the manifolds in place.
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I have studs and I must say I like them. My situation may be somewhat unique, because last time I had the head off I stripped one of the holes in the block when I did the 1000 mile torque on the head bolts. I thought I would have to get a new block, but I put a heli-coil in and used studs instead. I got Raceware studs, which I think are even more expensive than ARP studs. With the Raceware studs you just screw them into the block hand tight. I thought maybe doing it that way would put less rotational stress on the heli-coil. Whether it does or not I can't say for sure, as I'm no engineer, but it made me feel better about it hehe. Anyway, they've been in there 5 years or so now, and I haven't had any problems. Plus they're re-usable, and since I live in the middle of nowhere, if I ever need new head bolts I have to order them, which usually always takes a week or so to get here. While that may not be an important selling point to some, I kind of like it.
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I thought there was an issue with studs and putting the head back on with the manifolds attached, or did I misunderstand that?
I do not have access to a garage so no chain hoist for me. I have to take the manifolds off in order to do the head work because I don't work out at a gym I am of less bulk than some other 60 year olds.
Replacing the head seems to be a problem for some. Alignment is the key and using the old bolts with the end cut off and a slot cut into them gives you 4 corner guides that allow you to lower the head right where it needs to go without and worry that you need to shift it a bit one way or the other.
When the gasket is covered with copper spray or Hylomar you are only given one set down so it needs to be exact. Struggling the head on with both manifolds connected just would not work for me. Others with better equipment do fine.
It does add to the total time to remove them and then reinstall when the project is concluding but honestly don't we all take them off anyway to do the work on the head? I don't remember seeing many pictures here of a head with the exhaust manifold attached unless it is some discussion of a turbo fix.
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On a non turbo car I would 100% go with stock bolts and the stock gasket. The odds of being in there again are very small assuming you don't over heat the engine or blow the timing belt. IMO, the fiber gasket (stock) is more forgiving to any imperfections in the head/block mating surface. The MLS gasket also lowers the compression ratio (very slightly) and since you are already worried about starting it's worth mentioning. Just make 100% sure that you order the correct thickness of gasket and you get the timing exact. Especially the cam timing. And the pump timing. And the crank timing ;-)
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On a non turbo car I would 100% go with stock bolts and the stock gasket. The odds of being in there again are very small assuming you don't over heat the engine or blow the timing belt. IMO, the fiber gasket (stock) is more forgiving to any imperfections in the head/block mating surface. The MLS gasket also lowers the compression ratio (very slightly) and since you are already worried about starting it's worth mentioning. Just make 100% sure that you order the correct thickness of gasket and you get the timing exact. Especially the cam timing. And the pump timing. And the crank timing ;-)
So you're saying I should watch the timing? ;D
Is there any advantage to the MLS, as lower compression and less forgiveness seem like bad things to me.
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The MLS gasket is much less likely to fail when running a turbo, especially if you are running higher than stock boost.
Considering yours is an '82 non-turbo engine, which would have solid lifters, the MLS gasket doesn't match your block/head and so the discussion is fairly academic.