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Dec 20, 2014
Wilmington, NC
Ok guys, it seems like people make a big deal out of these motors blowing head gaskets. I'm wondering how many miles you have driven before your head gasket blew? Or maybe you're still going...?

Me --> 185k and running fine (knock on wood)
Ive seen them happen all over the board but the majority seem to happen in the 100-200k range. Usually started by an overheating incident
Its all about maintenance. Some guys on the forum have well over 300k on oem HG. Best is to monitor temps with scangauge or other brand.
A lot of engines run great in 200*+ range BUT over time this will deteriorate the Hg. And you won't know it's running that hot without monitoring. It should run at 190 ish normally. This will promote long life of the HG.
Also, in terms of the HG "blowing" that doesn't seem to be typical for us either. I was suspicious of mine when I purchased it at 173,000 mi., but I knew everything to check on the inspection like bubbles in coolant, coolant condition, color of coolant, condensation on oil cap, chocolate oil, debris in overflow reservoir, steam in exhaust, etc. The LC ran (and runs) very smoothly, and passed smog with no problems. But, the PO was a smart guy and he wasn't positive about the HG (he had done the PHH and axle seals). Hmm. The all-metal radiator had a weep. Hmm. I bought it for our Baja casita commute, and with summertime temps plus idling border waits I couldn't wait to see what would happen. So, a Blackstone oil analysis was in order. How easy is that? $25, briefly pull the drain plug, and $25.
Report came back quickly, sure enough, I was getting coolant past the HG. Blackstone responded to my inquiry with advice too. They said the amount of leakage, while definite and measurable, wasn't severe and that it could probably be operated with frequent oil changes. No promises of course, or if it might fail more catastrophically! On the plus side the many other measures of my truck's oil were very good which indicated I had an engine in good health otherwise.
The top end job on my engine was a great experience for me. My confidence and pleasure in the rig is greater than I ever intended it to be too! It has become my DD while my 2013 VW GTI languishes in the garage. As my children are approaching driving age I really want to get another 80 Series when I can afford it.
244ish in my 3fe
Just under 251,000 for me in my 97 lx450 and still running strong!
Here is my take on head gasket failures. I used to work for Fel-Pro doing head gasket design in a former lifetime so I do have some experience in this area.

A head gasket will last a very long time if it has adequate clamping force on it AND the head and the block move together. By move together, I mean when they heat and cool they expand at the same rate. Engines with poor clamping force just suck because you really can’t increase the clamp force. Changing from stock head bolts to high strength studs, (like ARP) can help but usually not much. Fortunately the 2F and 1FZ engines have decent size fasteners and thick enough surfaces so that the clamp stress isn’t a problem.

A straight 6 design is worse than a V8 or an I4 because it is longer. When the engine heats up, thermal expansion will make the head and the block physically longer, the longer the engine, the more thermal growth will take place. On a 2F where the head and the block are cast iron, they both grow at the same rate so there is no relative movement between the two. On a 1FZ with an aluminum head, the head expands more than the block creating a scrubbing motion when the thing heats up and cools off. 1FZ HG failures frequently show damaged combustion seal rings on the outside ends of cylinders 1 and 6. This is where the scrub is greatest.

At Fel-Pro we would run all types of engines on dynamometers with computer controlled test cycles. The systems were plumbed so that a valve could switch the cooling water from hot to cold to simulate thermal cycling of the engine. We could force a failure of the HG on the dyno that was very similar to the mode of failure in the 1FZ HG.

What this means is that it doesn’t matter how many miles you have on your 80, what matters is how many heating cycles you have and how severe the cycles are. If you live in Fargo, ND and make a lot of short trips, your HG may leak at 100k. If you live in Florida and drive 150 miles a day, your HG may last 500k miles.

When the HG does fail, it may be slightly compromised for a long time before a catastrophic failure. A small crack in the combustion seal will allow some hot exhaust gas into the area of the soft gasket material, (graphite in this case.) Depending on the size of the crack, the combustion gas may take a long time to erode the soft material. Eventually the high pressure gas will blow out material and then blow the coolant out of the cooling jacket causing a severe overheat. Before this happens, some combustion gas is making its way into the cooling jacket. Maybe you engine is running a bit hot? Maybe you’ve just spent a bunch of time replacing you fan clutch but the engine still runs hot. Maybe you have a minor leak in the head gasket.

Think your high mile HG isn’t leaking? Have a buddy hold the engine at 3000 rpm while you look inside the coolant overflow bottle. Watch it for at least 4 minutes after the engine is warmed up. If you see a bubble in the coolant every 30 seconds or less, your HG is leaking. It might stay like that for a long time, or it might decide to clear out the cooling system on your next camping trip.

Sorry-was quoted too-This regarding causes
I changed mine at 145K, but on inspection was still good to go.

Nevertheless, it's a time bomb. It will fail at some point, especially if run hot. These trucks are all close to 20 years old. It's OK to change the head gasket. Replace yours now if it worries you.

Remember that overheats kill more 80s than rust.

Change the radiator and thermostat every 100K, and fix the HG when it fails. No big deal. 80s aren't quite immortal, but close.
233k on my 3FE. Just did the "bubble" test today, all good.

I've thought about changing my oil more frequently but instead I just leak it out. :)
Mine is still good @ 150k. I think the most important thing is cooling system maintenance. Making sure you flush the entire system on a regular basis and keep good toyota coolant in the system. As well as a proper working thermostat. Most of the muppets that owned your 80 before you did, did nothing to service the cooling system. They thought if the overflow tank is full all is well. They do not understand that coolant degrades over time and looses it's properites.

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