3VZ 4Runners - you guys have any experience with head studs?

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insightbrewery

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Hey guys, so I have a potential customer flip-flopping as to whether to sink money into his unicorn '94 4Runner (V6 4WD manual). It's got a blown head gasket, which as you are aware is a known issue on the 3VZ. It also failed smog due to high emissions and timing being advanced by 10 degrees. Since it's an EFI engine, I'm guessing that the 140K-old TB has stretched.

Normally, I'd get the Toyota overhaul gasket kit, but on a quick Googling I saw that LCE sells a top-end kit that has MLS gaskets and head studs to replace the stock head bolts. They claim it fixes the 3VZ head gasket issue for good.

Any of you have any experience with this? I also would only resurface the heads, not the block...so was contemplating using head studs with stock graphite gaskets or a Fel-Pro PermaTorqueMLS (if available).

Thanks as usual.
 
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71Corolla

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I don't have any experience with that engine, but I know the HG problem is not head bolt related they hold up fine the composite gasket simply goes bad same as they do on all iron block/aluminum head engines eventually. Studs are always better except knowing the correct torque values to me it's a guess since the original design doesn't use them.

tldr; I'd say you are going to be the guinea pig if you go with the studs and MLS gasket set.
 
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insightbrewery

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Hm. Let's see if the guy bites, I quoted nearly $2k and I bet he's not going to want to drop that into that old a truck. That's what I figured on the head studs, I guess the MLS gasket does the real work. I'll call the company now, I really don't think he'd go for resurfacing the block.

I don't have any experience with that engine, but I know the HG problem is not head bolt related they hold up fine the composite gasket simply goes bad same as they do on all iron block/aluminum head engines eventually. Studs are always better except knowing the correct torque values to me it's a guess since the original design doesn't use them.

tldr; I'd say you are going to be the guinea pig if you go with the studs and MLS gasket set.
 
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71Corolla

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I guess the MLS gasket does the real work. I'll call the company now, I really don't think he'd go for resurfacing the block.
Have you ever used a MLS gasket without machining the block? Every engine I've worked on the iron block had some witness marks from the original HG and sometimes pitting I'm wondering if this will be an issue.
 
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insightbrewery

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Yeah, I have, but only Fel-Pro's PermaTorque MLS which has a coating to deal with "up to 80 RA" finishes.

I called the company, they confirmed that it's the MLS gasket and rerouting the coolant crossover with their headers that bulletproofs the engine, not the studs (icing on the cake). Welp, standard composite gasket job it is. If he wants to go through with it, that is.

Have you ever used a MLS gasket without machining the block? Every engine I've worked on the iron block had some witness marks from the original HG and sometimes pitting I'm wondering if this will be an issue.
 
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insightbrewery

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Dunno, but here's my thoughts:

1. I hate Fel-Pro. Federal Mogul products in general nowadays, except for Moog which is sadly dropping in quality as well
2. I used the gen4 5S-FE MLS from Fel-Pro on my '95, and only resurfaced the head, but cleaned and checked the block. No coolant loss, but I would see black dots (like carbon dust) in the coolant reservoir...not sure if residual, or not, because it never got darker. Maybe it was leaking, probably not.

Makes me wonder how long that coating lasts.
 
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