After my HG install the gasket was flush with the block. RT, I wouldn't hesitate to get that thing out of there.
HG Internal Inspection?
- Thread starter Nomis
- Start date
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The amount of original head gasket protruding from the head/block interface area may not be a sure indication of imminent failure either. Especially since the replacement gasket has been "improved" by toyota. The size of the new gasket could be slightly different around the perimeter compared to the old. We would need samples of unused originals to compare with the "improved".
-Or you all could really be onto something. Not knowing really sucks.
-Or you all could really be onto something. Not knowing really sucks.
- Thread starter
- #23
A portion of the gasket is probably exposed from day one. I'm going to check mine tonight and see how much is exposed at the rear of the head.
I wouldn't worry too much unless you see a large amount of rounded gasket protruding out from the upper left portion of the head toward the firewall coupled with a discernable gap on the inside of the cylinder.
As Doug stated all this is speculative unless we have actual specs as to how much gasket is protruding back there from the original install - without that we may not have any correlation.
Maybe we should do a poll on how much gasket is protruding on each of our heads as a data point - i.e. - no external gasket protrusion, 1/16", 1/8", etc. ?
I wouldn't worry too much unless you see a large amount of rounded gasket protruding out from the upper left portion of the head toward the firewall coupled with a discernable gap on the inside of the cylinder.
As Doug stated all this is speculative unless we have actual specs as to how much gasket is protruding back there from the original install - without that we may not have any correlation.
Maybe we should do a poll on how much gasket is protruding on each of our heads as a data point - i.e. - no external gasket protrusion, 1/16", 1/8", etc. ?
Actually, the gasket protrusion could be a very good indicator. If it is uniformely protruding across the entire block one could surmise that the gasket was simply made with a bit of extra material. I categorically reject this, because an extra square inch of spendy gasket material simply wouldn't be wasted in this way and obviously gasket dimensions are extremely carefully defined.
If, however, the gasket protrudes in an irregular fashion, with an arc of material showing only at or near the center, then I think it's very bad news indeed. If it would be extremely unlikely a uniform extra rectangle of material sticks out, it would be beyond unlikely that an irregular amount would be designed to stick out.
My feeling? Any protrusion means the gasket has moved in that area, and it was not designed to stick out at all.
Raven - check out head/machine shops to find a good one in advance. Speak to the big domestic mechanics (as they are the bulk of the head work) and see where they take them.
DougM
If, however, the gasket protrudes in an irregular fashion, with an arc of material showing only at or near the center, then I think it's very bad news indeed. If it would be extremely unlikely a uniform extra rectangle of material sticks out, it would be beyond unlikely that an irregular amount would be designed to stick out.
My feeling? Any protrusion means the gasket has moved in that area, and it was not designed to stick out at all.
Raven - check out head/machine shops to find a good one in advance. Speak to the big domestic mechanics (as they are the bulk of the head work) and see where they take them.
DougM
The gasket is suppose to protrude in several places the around the perimeter where the head and block undulate, one of them is visible in this reposted pic attached on the right side below what looks like an oil hole, in these places the gasket has nice clean man made shapes, compare that to the shape at the top.
The gasket protrusion I am seeing at the back of the head almost looks like extruding RTV, like when you put way too much on an oil pan and tighten up the bolts, looks like a cross-section of rolling hills. I have two hills and some shorter sections near those.
I am going to try to get a pic.
Again looking at the picture attached and the impression line formed by the head I think the gasket was originally flush with the head in this area.
What I think this tells me is that my HG is structurally failing but I have no other definitive symptoms so it has not completely failed yet, what I don’t know is how long I have, 5 miles? 500 miles? 50K miles? I have no idea. I was worried about the HG before, now?
The timing is not good but I guess it could be worse, I have an S-load of crap to do to get my house on the market move to FL if it were to finally blow wile I was down there I may not have a work space, a bad situation, if it blows in the middle of the move wile I am unemployed even worse, don’t think I can risk that, as of right now my tools are not packed and I have a place to work., I should have knocked out the preemptive HG change last summer when I was seriously considering doing so,
In the mean time I need to get the 62 up to snuff and stop driving the 80,
Anybody got any ideas about a cheap (but good) straight edge long enough to check out the head? That and the valve tool are the only major tools I do not have for this job.
I would be very interested in others taking a look at their tucks, if there only a few protrudes out there I think my time is short,
Doug, I am hoping I will not need the services of a shop, IF the head is flat than the most I will do is clean it and possibly lap the valves, I had envisioned doing some other stuff like port and intake runner polishing but think this will wind up being paired down to the core job only.
If needed some buddies at work have recommended Dover Cylinder Head I will look into it more.
The gasket protrusion I am seeing at the back of the head almost looks like extruding RTV, like when you put way too much on an oil pan and tighten up the bolts, looks like a cross-section of rolling hills. I have two hills and some shorter sections near those.
I am going to try to get a pic.
Again looking at the picture attached and the impression line formed by the head I think the gasket was originally flush with the head in this area.
What I think this tells me is that my HG is structurally failing but I have no other definitive symptoms so it has not completely failed yet, what I don’t know is how long I have, 5 miles? 500 miles? 50K miles? I have no idea. I was worried about the HG before, now?
The timing is not good but I guess it could be worse, I have an S-load of crap to do to get my house on the market move to FL if it were to finally blow wile I was down there I may not have a work space, a bad situation, if it blows in the middle of the move wile I am unemployed even worse, don’t think I can risk that, as of right now my tools are not packed and I have a place to work., I should have knocked out the preemptive HG change last summer when I was seriously considering doing so,
In the mean time I need to get the 62 up to snuff and stop driving the 80,
Anybody got any ideas about a cheap (but good) straight edge long enough to check out the head? That and the valve tool are the only major tools I do not have for this job.
I would be very interested in others taking a look at their tucks, if there only a few protrudes out there I think my time is short,
Doug, I am hoping I will not need the services of a shop, IF the head is flat than the most I will do is clean it and possibly lap the valves, I had envisioned doing some other stuff like port and intake runner polishing but think this will wind up being paired down to the core job only.
If needed some buddies at work have recommended Dover Cylinder Head I will look into it more.
- Thread starter
- #26
Okay, I just got back from my '96 and I don't know how you saw back there RT? I tried to angle my quarter sized telescoping mirror and couldn't see anything but the back of the valve cover and some of the side of the head. I also tried to feel back there by hand and couldn't get my hand far enough down in there near the block / head interface area.
You just prompted me to go out in the garage and take a look at my collection of use head gaskets. As you can see in the picture above, there is an area at top right that is supposed to stick out. It's a light brown color from road dust and you can see the line of grime.
But from there across, the gasket should be perfectly straight across to the ear at upper left. So, the bulged area is indeed what you should be checking for.
Now I'm going to completely confuse the issue.
Neither of my failed gaskets exhibit protrusion - just the faintest arcing of the area this pictured one has that long arc of protrusion. So, clearly they can fail without having that protrusion as both mine did.
Kind of a bummer I know - just as a possible clue to imminent failure is considered, I show up with two that do not exhibit the trait. I also noted with odd fascination that my 93's fire ring actually moved TOWARD the cylinder back there while assuming the no-longer-round shape. I stacked them up and the 97 exhibits the expected elongation of the fire ring rearward, while the 93's has a protrusion toward the cylinder. Strange, no?
I guess it's the movement of the fire ring due to the loss of structure in the HG back there that's the problem. Whether that means the fire ring uniformely moves rearward as the above pictured one and my 97, or it gets pressed toward the center is due to a variety of factors. Whichever happens, there are areas of stress created in the gasket and the non metal part appears to crack as it is unable to bend like the metal layer. Then water and or cylinder gases begin to peck at these microscopic cracks and quickly widen them.
So Raven - where is the protusion on yours? Were you perhaps looking at the upper left area that's supposed to stick out, or indeed to you have material coming out from the center of the rear? And btw, that gasket is properly oriented as if it were laying on the block. So you'd be looking straight down at it and the red ring is the left rear of the block.
DougM
But from there across, the gasket should be perfectly straight across to the ear at upper left. So, the bulged area is indeed what you should be checking for.
Now I'm going to completely confuse the issue.
Neither of my failed gaskets exhibit protrusion - just the faintest arcing of the area this pictured one has that long arc of protrusion. So, clearly they can fail without having that protrusion as both mine did.
Kind of a bummer I know - just as a possible clue to imminent failure is considered, I show up with two that do not exhibit the trait. I also noted with odd fascination that my 93's fire ring actually moved TOWARD the cylinder back there while assuming the no-longer-round shape. I stacked them up and the 97 exhibits the expected elongation of the fire ring rearward, while the 93's has a protrusion toward the cylinder. Strange, no?
I guess it's the movement of the fire ring due to the loss of structure in the HG back there that's the problem. Whether that means the fire ring uniformely moves rearward as the above pictured one and my 97, or it gets pressed toward the center is due to a variety of factors. Whichever happens, there are areas of stress created in the gasket and the non metal part appears to crack as it is unable to bend like the metal layer. Then water and or cylinder gases begin to peck at these microscopic cracks and quickly widen them.
So Raven - where is the protusion on yours? Were you perhaps looking at the upper left area that's supposed to stick out, or indeed to you have material coming out from the center of the rear? And btw, that gasket is properly oriented as if it were laying on the block. So you'd be looking straight down at it and the red ring is the left rear of the block.
DougM
- Thread starter
- #28
Kind of off topic a bit but does anyone know when Toyota introduced the new style gasket? I just looked at a pick of the new style gasket and it looks like they redesigned the triangular shaped water passages that are prone to failure and replaced them with circular shaped water passages. Curious if some of the newer style gaskets made it on any of the production FJZ80's? Probably not, but one can wish.
I asked:
So I got a question about these blowing head gaskets.
Are they all, or the majority of them, blowing in the rear of the head? Like number 6 cylinder?
and Dan answered:
So there's a problem with cooling in number 6. Has anybody tried to find a cure for this?
The Hummer boys have a problem in the rear of the 6.5TD, similar to this, they have a fix where by they add a hose back there to increase the flow of coolant to the hot spot, no more gasket problems.
Sounds like this Toyota engine needs something like that. Anybody given any thought to this?
It doesn't surprise me there's a problem with #6, it's a long way back there, and the water has picked up a lot of heat by the time it gets there.
So I got a question about these blowing head gaskets.
Are they all, or the majority of them, blowing in the rear of the head? Like number 6 cylinder?
and Dan answered:
cruiserdan said:
So there's a problem with cooling in number 6. Has anybody tried to find a cure for this?
The Hummer boys have a problem in the rear of the 6.5TD, similar to this, they have a fix where by they add a hose back there to increase the flow of coolant to the hot spot, no more gasket problems.
Sounds like this Toyota engine needs something like that. Anybody given any thought to this?
It doesn't surprise me there's a problem with #6, it's a long way back there, and the water has picked up a lot of heat by the time it gets there.
Doug that does take some life out of it, well at least it worked for me, .....but oh wait that is not a good thing 
I was thinking they would all follow the same path but apparently not.
The protrusions I am seeing are at the back of the block similar to the picture I posted above but instead of a single arc I think I have two.
I wonder if on your 93 it pushed the ring out left and/or right instead of straight back, in the gasket I have (from a customer of Davids 80) the fire ring was pouched back and that caused one side to pull in, if the sides on yours were pushed out then the back could be pulled in.
Nomis getting an eye on this area is not easy, I had my Blue Point 2” round mirror with a very long stalk, I also tried from above for a wile with no success (mirror near the heater valve) from this position do not get side tracked by a rectangular flap hanging out of the valve cover gasket.
to get an eye on it I had to go from low, go to the passenger side and try to position the mirror roughly just above the transmission by passing it between the firewall and exhaust. Tilt it up looking at the back of the block. There are several wires and hoses in that area that make it difficult to see. if you see steel block move up , if you see aluminum of the head move down, when you find the split move across it, the further left you go (towards drivers side) the harder it is to see if you can make it from one side to the other without and extruded gasket you are good, one note the exhaust makes a similar aluminum/steel joint and side tracked me several times.
I am going to try to get a picture tomorrow, I don’t know how successful I will be. My home mirror is a Craftsman with a large rectangular mirror and a short stalk, don’t know if it will get in there or not, if it will it should give a better field of view.
This was talked about before I do not remember the details but the important part is new HG was post 1997 so no US 1FZ’s got the updated HG. Not only are the water ports stronger due to being round the fire ring is very much reinforced,
I showed a buddy of mine who specializes in composites these pictures and he was very surprised that carbon fiber in a HG, I wish I could remember the word he used but basically all the epoxies he is familiar with would basically plasticize and loose strength at these temperatures, and these are aerospace epoxies not surfboard stuff. Surely Toyota would use an epoxy that could hold up in these conditions right?
I was thinking they would all follow the same path but apparently not. The protrusions I am seeing are at the back of the block similar to the picture I posted above but instead of a single arc I think I have two.
I wonder if on your 93 it pushed the ring out left and/or right instead of straight back, in the gasket I have (from a customer of Davids 80) the fire ring was pouched back and that caused one side to pull in, if the sides on yours were pushed out then the back could be pulled in.
Nomis getting an eye on this area is not easy, I had my Blue Point 2” round mirror with a very long stalk, I also tried from above for a wile with no success (mirror near the heater valve) from this position do not get side tracked by a rectangular flap hanging out of the valve cover gasket.
to get an eye on it I had to go from low, go to the passenger side and try to position the mirror roughly just above the transmission by passing it between the firewall and exhaust. Tilt it up looking at the back of the block. There are several wires and hoses in that area that make it difficult to see. if you see steel block move up , if you see aluminum of the head move down, when you find the split move across it, the further left you go (towards drivers side) the harder it is to see if you can make it from one side to the other without and extruded gasket you are good, one note the exhaust makes a similar aluminum/steel joint and side tracked me several times.
I am going to try to get a picture tomorrow, I don’t know how successful I will be. My home mirror is a Craftsman with a large rectangular mirror and a short stalk, don’t know if it will get in there or not, if it will it should give a better field of view.
This was talked about before I do not remember the details but the important part is new HG was post 1997 so no US 1FZ’s got the updated HG. Not only are the water ports stronger due to being round the fire ring is very much reinforced,
I showed a buddy of mine who specializes in composites these pictures and he was very surprised that carbon fiber in a HG, I wish I could remember the word he used but basically all the epoxies he is familiar with would basically plasticize and loose strength at these temperatures, and these are aerospace epoxies not surfboard stuff. Surely Toyota would use an epoxy that could hold up in these conditions right?
lacruiser said:
Although there have been some overheats and subsequent head warpage and HG failure that is not usually the case on the 1fZ, many have failed with perfectly flat heads and no overheating,
Those three ports shown in the pic above are the largest water holes in the gasket. The rest range from near pin holes to about 3/6" round holes. Therefore the majority of the flow in the head should be from the #6 foreword to the 2 outlets at the front of the head witch makes sense.
I think it is the presence of the three large low strength shape holes in the gasket weakening it coupled with a thin fire ring that cause the failures but that is just from my examination of a failed gasket and looking at what Toyota did with the new gasket, on the new gasket the holes were made round instead of triangular (stronger) and the fire ring was reinforced.
Drawing of the original HG, besides the three large holes at the back the only other large holes are for oil and bolts, the rest of the water holes are tiny. The right side of the head gets more cooling because of the heat from the exhaust ports.
RT I have a straight edge I bought when I did my HG. No need to buy one.
Also a trick with the mirror, shine a flashlight onto the mirror along your line of site. This will illuminate the area you are viewing.
The round holes instead of the triangular holes is to slow down the coolant in the rear of the block to absorb more heat, thus controling the heat at the rear of the block(in theory).
I looked at the head to block and gasket interface today, and it would be real hard to see with a bore scope. You would have to drop the scope down then angle the camera back up some how to see the interface. The combustion chamber is more toward the middle of the cylinder. later robbie back to putitng a Head on a truck. I can look at the gaskets I have here and let you know about this buldge at the back. But it may be tomorrow before I get a chance to psot anything. later robbie
I looked at the head to block and gasket interface today, and it would be real hard to see with a bore scope. You would have to drop the scope down then angle the camera back up some how to see the interface. The combustion chamber is more toward the middle of the cylinder. later robbie back to putitng a Head on a truck. I can look at the gaskets I have here and let you know about this buldge at the back. But it may be tomorrow before I get a chance to psot anything. later robbie
landtank said:
Rick, that is very generous and quite helpful offer, I have been pricing them, they are not cheap. I will of course cover shipping from and back and will make sure it is well cared for.
Thank you
powderpig said:
I have heard this a few times and it never sits right with me. I have yet to directly compare the two gaskets but I'll take you word for it that the round hole produces a smaller opening, it would make sense that it does, but I am not sure that this restriction improves cooling of the head around #6.
If your goal was to get the water hotter a lower flow rate would deliver hotter water but that is not the goal, if the water at the surface of the head is warmer the flow of heat into the water is reduced and the temperature of the head increases.
The goal is to cool the head. For more cooling you would want warmed water to be replaced as quickly as possible to keep the water at the surface of the head as cool as possible, well controlled by the thermostat anyway as not to be to cold.
For instance when heat treating metals an agitated quench is considered a more aggressive quench that cools the metal faster than a static quench, the agitation removes heated water and replaced it with cooler water on the surface of the metal more quickly than convection alone.
That would be good stuff to know, besides my own trucks fate would be good to know if this is a decent troubleshooting aid, if a significant portion of failed head gaskets show this bulging maybe we have another troubleshooting aid in the arsenal.
Robbie I have a quick question for you, how long should it take for the bubbles in the bubble test to show up?
Near the end of my commute to work today I did some "spirited driving" including getting the R's up to about 4k pulling away from a couple lights, when I pulled into a parking spot I immediately popped the hood and opened the cap on the overflow making sure not to pull the tube out the fluid and revved the engine up, did it for about for about 30 seconds, I did not see any bubbles.
As I was walking in I thought maybe that was not long enough for bubbles to make their way from the heat to the overflow but maybe a 30 minute commute before hand would be enough time to collect bubble if they are they are being formed.
I'm not Robbie and I didn't stay at a Holiday Inn Express last night either, but the bubbles will quickly arrive at the rad top and thence the overflow. Technically speaking, bubbles have a very high surface area to mass ratio. As such, their movement will vary from the movement of the surrounding fluid very little, and their low inertia due to extremely low mass will further support this behavior.
Revving like you were doing would immediately detach any bubble that's lodged in pretty much any crevice. It's sounding good for you in terms of an imminent issue, but clearly this is a PM you need to schedule.
Regarding the bubbles, someone correct me if I'm wrong. At idle the cylinder pressure is the same as it is when you rev it. So if your engine is leaking cylinder pressure into the water jacket at idle, then it may take a while (meaning idling for many minutes) before the bubbles are worked along the water jacket and are entering the overflow. This assumes a full hot engine of course. If you rev it, you're simply making bubbles faster (more piston cycles per second = more bubbles per second produced) in a linear fashion.
So, if you pull up after running your truck and rev the engine and get no bubbles, I contend your engine is not pushing cylinder gases into the water jacket.
DougM
Revving like you were doing would immediately detach any bubble that's lodged in pretty much any crevice. It's sounding good for you in terms of an imminent issue, but clearly this is a PM you need to schedule.
Regarding the bubbles, someone correct me if I'm wrong. At idle the cylinder pressure is the same as it is when you rev it. So if your engine is leaking cylinder pressure into the water jacket at idle, then it may take a while (meaning idling for many minutes) before the bubbles are worked along the water jacket and are entering the overflow. This assumes a full hot engine of course. If you rev it, you're simply making bubbles faster (more piston cycles per second = more bubbles per second produced) in a linear fashion.
So, if you pull up after running your truck and rev the engine and get no bubbles, I contend your engine is not pushing cylinder gases into the water jacket.
DougM
IdahoDoug said:
That is what I am thinking; if I am making them they should have showed up after a drive even with a short rev. I am glad you agree.
I will have to keep an eye out for bubbles until I can get the 62 up and going,
I guess cylinder pressure would be slightly higher at no load high RPM rev than at idle but not by much. High RPM high load would get high cylinder pressure.
Yeah, I see what you're saying. I was thinking only of compression ratio. Under load - more fuel and more cylinder pressure though, as you note. Never thought of that - would be curious to know what the ratio of idle cylinder pressure to peak HP cylinder pressure is. You know - would it be 10% more or are we talking orders of magnitude? Interesting.
I just ordered a bunch of bicycle parts online and then came back to find you guys still awake. Didn't your mother ever tell you to "go to sleep"!??
DougM
I just ordered a bunch of bicycle parts online and then came back to find you guys still awake. Didn't your mother ever tell you to "go to sleep"!??
DougM
When I get home in a few hours I'll look for that straight edge. It was the longest one I could find.
I would agree with doug on the bubbles. Another test if you have a OBDII reader is to hook it up and watch you coolant temps. Drive it up a big hill and watch temps.
I looked at the gaskets I ahve and only one shows a slight bludge( I have 8). Some show slight seperation of the fire ring, other show jsut carbon build up and leaks to a coolant passage. #1 and #6 are the big winners for carbon build up on the fire rings.
To address the small hole, it is more about keeping the water longer around a area to get heat asorbation, verus trying to flow more coolant. I think it is a fine balance as to what is needed. It may be more of a problem keeping the cylinder temps down for proper combustion and not have predetation thus higher cylinder temps. Thus leading to cooler head. Happy engine. anyhow it is what toyota came up with to help fix the problem.
Some thing else I had written then lost by hitting the wrong key. I am sure I will remember soon. later robbie
I looked at the gaskets I ahve and only one shows a slight bludge( I have 8). Some show slight seperation of the fire ring, other show jsut carbon build up and leaks to a coolant passage. #1 and #6 are the big winners for carbon build up on the fire rings.
To address the small hole, it is more about keeping the water longer around a area to get heat asorbation, verus trying to flow more coolant. I think it is a fine balance as to what is needed. It may be more of a problem keeping the cylinder temps down for proper combustion and not have predetation thus higher cylinder temps. Thus leading to cooler head. Happy engine. anyhow it is what toyota came up with to help fix the problem.
Some thing else I had written then lost by hitting the wrong key. I am sure I will remember soon. later robbie