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Discussion Starter · #1 · (Edited)
My hood insulation is in pretty bad shape. I was planning on removing it anyway, just adds weight and removes engine sounds anyway.

However, I noticed a UK "contains asbestos" sticker, like this:

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It looks like fiberglass, but asbestos and fiberglass look and behave very similar, so I'm kind of worried of both leaving the fraying material in and removing it myself.

Can anyone here confirm what the insulation is made from? And if it's not asbestos, does anyone know which parts are? Brake pads? Gaskets?
 

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If your worried, just wear a respirator and remove it carefully and seal in a plastic bag.

Most asbestos was banned by the early 1980s, so even if there is 1% asbestos in that insulation there is about a 99.9999% chance you will die of old age before a small exposure like that would give you any lung trouble. People who die of mesothelioma were exposed to high levels of asbestos materials day in and day out sometimes for decades.

You would be shocked how many asbestos containing materials are used in construction of older buildings that people are around everyday of their lives and don't know about it (i.e. drywall, joint compound, mastics, popcorn ceiling, floor tile, etc.)
 

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asbestos has not been used in Japan for longer than the US. Definitely not in vehicles.
It could also be mineral wool which is fire retardant (under hood insulation).
In the trunk, it is acetal butyl based insulation for sound not for temperature. Dry ice and remove.
 
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I"m confused. You use "trunk, bonnet, and hood" Are you speaking of the panel over your engine? I think yes except you then used trunk. That sticker - I have never seen it on any vehicle's underhood insulation. Are you saying it's on YOUR insulation? Finally, if there is some in your insulation, it must be a crazy small amount because once its dangers were known, I cannot see Toyota or any automaker allowing you to drive around where the hood insulation is vibrating, aging and shedding particles mere inches in front of the vehicle's interior air source. So that sticker may be in the spirit of overzealous regulations such as those we see here in the US now. We laugh at things like a box of water glasses purchased in California, each bearing a sticker "This product is known by the State of California to cause cancer. Do not eat it or prepare food in it....etc" Have any of you in California seen the actual sticker on car windows that says "This product is ...California....."? It's nutty. So perhaps over in your country they were nutty 30 years ago when the Supra was built and it had to leave the assembly line with that sticker despite having zero asbestos because it was a regulation. I'm with the others - almost unthinkable that insulation has asbestos in it.

If you're removing it, lay plastic over the entire engine bay, wet down the insulation and pull it off wet and sloppy so there are near zero airborne particles, and wear a respirator.
 

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You'd be surprised. In 1989 the 5th court overturned an EPA ban of asbestos in the following products:
brake drum linings, automotive transmission components, gaskets, and other friction parts, as well as in the production and use of roof coatings, brake blocks, paper, pipe, and shingles made with asbestos.

It turns out cheap aftermarket pads from china often contain asbestos. California, which are idaho man loves to mock, banned asbestos brake pads in 2015 (less than 0.1% by weight of asbestos, cadmium, chromium, lead, or mercury as of January 1, 2015) but I;m sure asbestos pads are available in Idaho if you need them.

I doubt there is any OEM asbestos in the Supra, but they could be there in aftermarket parts..
 

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Wow, did not know there was any pushback anywhere on asbestos. Have things stayed that way since 1989? I wonder if US based private companies of those products overturned chose to remove it anyhow due to their legal staff saying "Uh, your insurer, your liability policy, and all your bonds will be cancelled if you continue to use it. And none of the national chains will carry it."?

As for Idaho, yes we can still get things up here that are not available in California - that's true. I bring a case of "real" brake cleaner down to my '66 Chevy Nova buddy whenever I come down. Mostly, these days we are just pissed off that Fortune Magazine rated our town the #1 Real Estate market in the USA a couple weeks ago. Time to build a wall, perhaps....
 

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Discussion Starter · #7 ·
I"m confused. You use "trunk, bonnet, and hood" Are you speaking of the panel over your engine? I think yes except you then used trunk. That sticker - I have never seen it on any vehicle's underhood insulation.
Sorry, I've corrected that. That was a typo - I meant hood, not trunk. I'm talking about the insulation above the engine bay.

You'd be surprised. In 1989 the 5th court overturned an EPA ban of asbestos in the following products:
brake drum linings, automotive transmission components, gaskets, and other friction parts, as well as in the production and use of roof coatings, brake blocks, paper, pipe, and shingles made with asbestos.
Yep, not just in the US. In my country, asbestos rooftop shingles were extremely common until they were banned in 1998 as well. Before then, was commonly used in piping, including ventilation and HVAC shafts - even though the dangers of fraying asbestos were well documented by then. It's crazy.

I read online that the headgasket problem of the 7M-GTE was actually caused by the asbestos ban in Japan. Prior to the ban, Toyota was planning on using a head gasket containing asbestos, but they had to change it last minute because of the ban. Because of the last-minute change, they had no time to validate the torque settings for the different compression characteristics of the new replacement gasket.
 

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Interesting. So yeah, I'd lay plastic over the engine just to keep it from getting wet, then wet the remaining hood fiber and pull it off wet. There may be a half-hearted water layer on it that you'll want to kinda gently shred while spraying water on it perhaps with a short handled tined garden implement or something else that will plow furrows through that possible layer. Heck, when you rip chunks off, have another plastic layer on the engine and when done just wrap the upper layer around the soggy remains and toss it into the trash. Head's up the insulation also helps prevent the hood paint from getting overbaked, so you may find replacing it functional. I'm replacing the insulation for one of my other cars with a reflective foil product that's self sticking. I've had it sitting in the closet for 4 years and haven't gotten around to pulling the old one off.

On the spate of head gaskets that's exactly correct. Not only was the forced hasty new HG material an issue for holding torque but it also degraded prematurely as happened on the 1FZFE LandCruiser straight 6. They lasted a mere 180,000 miles (heh) and showed breakdown despite excellent coolant changes by me since new.

Just a week ago I torqued my 7MGE head back on with a new gasket at 72ft-lbs (vs original spec at 50 something.
 

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I can see that perhaps the lack of asbestos in the head gasket adds to the problem. The current sealing material breaks down on the exhaust side, but not the intake side, so it's related to heat. But, the underlying structure of the gasket is also not strong enough. The thin little pieces of brass on the exhaust side buckle, letting the cylinder rings distort towards the exhaust side. That buckling also means the coolant sealing rings fail. Higher torque on the head bolts will not fix this problem as the gasket itself is failing.
 

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Asterix,

Interested in discussing this if you want to start a new thread, but here's my reaction:

I can see that perhaps the lack of asbestos in the head gasket adds to the problem. The current sealing material breaks down on the exhaust side, but not the intake side, so it's related to heat.
Yes, asbestos handles heat well and the new composition did not. Curious what you mean by "current" material?
But, the underlying structure of the gasket is also not strong enough. The thin little pieces of brass on the exhaust side buckle, letting the cylinder rings distort towards the exhaust side.
In a clamped product, it resists buckling because the space is filled and compressed. When the encapsulating material is lost because it breaks down with heat, the inner metal layer can now buckle as it has space to do so.
That buckling also means the coolant sealing rings fail.
Higher torque on the head bolts will not fix this problem as the gasket itself is failing.
Agree if the head gasket is failing. Hopefully in the intervening 30 years since those gov't-rushed parts, they have figured out the material. If the material does not degrade and disappear, reducing clamping pressure further, hot gases cannot get in behind the compression ring and quickly erode more material. The compression ring is supposed to stop the direct contact of hot gases on the material behind it. So, the higher clamping forces will contribute to fixing this problem if at a lower clamping force, hot gases and added head movement would degrade the HG at an unacceptably high rate. All HG sustain wear - especially on a straight 6 - but if the life is acceptable then all is good.
 

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The issue with the cooling rings collapsing is unlikely to be caused by the gasket material failing. It is weekly supported by the center "post" and relies on clamping pressure to keep it intact. The image below shows the fire ring deforming in turn causing the coolant ring to deform. There is very little gasket material in that area to provide any real support. Its all from clamping pressure.

260522
 

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Hmm, no - I think my new one had material there over the copper that looks to have been eroded away to bare (thinner) copper in that photo. Do they come with bare copper on the post?

Edit: just went to check other HG I have and agree there is little structural support provided by material there if you try to bend it in your hands. But the important point that if the copper is not properly kept under proper clamping pressure by the presence of even that little layer of material, then coolant incursion, hot gases etc can happen and continue to erode the material that was clamping it even further. Then the copper has room to distort. The instant it distorts from its structurally strong straight, the battle is lost and the firing ring does not have the structure of that post behind it, supporting it from pushing away from the cylinder. I have no idea where the pictured gasket came from, or what conditions it endured, but any, repeat ANY loss of material of a head gasket takes the clamping pressure at that spot to essentially zero, right? I don't care if the loss of material was as thin as a human hair - the head and block are literally NOT clamping at all at that spot. For a HG, that is a very bad thing to have happen.
 

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Well yes. True. Which is why the critical spots are formed using metal rings that are thicker than the base squishy material. That concentrates the forces around the critical sealing areas.
Stock
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MLS
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Hmm, I think we're straying from the OP's thread and even from the asbestos topic. The fire ring failure looks to me like a severe preignition type of failure, an overheat, or a loss of clamping pressure, or some combination. I have confidence that a straight copper post (uncoated) can handle the conditions its designed for. I also have confidence that a user can modify an engine (higher power) capable of destroying a stock, or stock construction head gasket and that changing conditions due to age and use can also cause failure because at the end of the day, a HG is a wear item. Any idea what lead to that fire ring failure?
 

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That is the standard failure mode of all 7M head gaskets including my own. It is not from preignition or anything else abnormal on a stock 7M.

Examining the head and block will show grooves forming from these rings moving around that ultimately leads to a loss of clamping pressure as the grooves grow bigger. Why the rings start to move to begin with is generally acknowledged to be due to undertorqued bolts which is another way to say the clamping pressure is inadequate. QED
 

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Hmm. Do you have a feel if these were failures at the original 58? ft-lbs clamping from the factory? Are they still happening with the 14lb-ft higher head bolt torque? I heard or read somewhere that the rings begin to vibrate up and down gently slapping the head and block when they get some space. Yeah, I've seen those circular grooves as well.... bummer to deal with..
 

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I do not have any data to support whether the 72 ft-lbs spec eliminates the issue completely. Under stock boost it might. The 7M gasket is similar to the 5M gasket. The 5M has no generally recognized issues at the original 58 ft-lbs so cylinder pressure seems to play a role as both 5M and 7M have the same cylinder bore size. Also note that there was a p/n chnage (11115-42021 )to the oem gasket. I have read that this change for 91/92 solved the BHG issue, but again I have no data to support it.
 

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Like 3p showed in post #11, that little copper/brass bridge/post buckles. My latest failure has all 6 buckled up into the space in the head. That bridge has no support from above - it's not clamped at all - only the coolant ring is clamped and that's not enough. I will say it did not help me at all that my block deck was a little low all along the exhaust side, but we're talking 0.001".

The original factory gasket in my '88 NA lasted 180k, somehow. The failure was not long after the car overheated because of a clogged radiator. The 2nd one lasted 40k, with stock bolts torqued to 72ft-lb (IIRC). The 3rd gasket lasted 60k with ARP bolts torqued to at least 75ft-lb, and retorqued after some time. That's one data point saying upping the torque does not fix the problem. That's why I point to the gasket design as the actual problem. It's too weak and just can't take the aluminum head/iron block mismatch.

I can only speak for a gasket bought from Toyota in 2005, but I really doubt they've changed the design at all since then.

An MLS gasket fixes this problem completely, and Toyota knows it, as they used an MLS gasket in the 2JZ. There's a steel core that looks way stronger in the problem area. The outer layers are springy to handle the thermal expansion differences between the iron block and aluminum head.

If they ever show up, I will be using ARP's undercut studs this time, torqued to ARP's recommended 90ft-lb.

A head gasket is not a wear item in my book. This car is famous for it failing, unlike just about every other car. I'd rather not change it again as 3 times is too many.
 
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