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Discussion Starter #1
So all winter I've been picking away at the 7M, and now it's a completely stripped block. Follow along as I rebuild it with tools most of you have around your garages. This is a regular rebuild of a 124k engine that blew a head gasket 20 years ago and the car was then parked near Mt. Rainier in Washington state south of Seattle until we bought it in 2018 and trailered it home. Plan is for it to roll by Memorial Day. I'm not a pro, but have a long career in the automotive field at corporate and have restored a dozen cars or so.

The engine block had water/coolant in a cylinder and another had rust blisters on the cylinder walls from the valves being open and 20 years of heat cycles. It was seized due to the rings, and I determined to take my time and free it up. I soaked all cylinders with Kroil for months. Gently popped it free, used Naval Jelly to dissolve the cylinder rust, then took 6 bore measurements in each cylinder per the book and it looks to have been very well treated because the cylinders are all square, and hardly worn. it's a small thing, but I want a numbers matching car when it's all said and done.

I decked the block where the fire rings had made some dents, using a slab of marble and sandpaper, finishing at 220 grit and leaving a surface finish appropriate to a plain jane aftermarket HG. It's part of a complete engine seal kit I ordered from Rock Auto. For a total of $380 with shipping I also ordered a timing belt kit with water pump, Clevite rings, full bearings, accessory belts, new hoses, motor mounts and a few other little things. Add in a thread chaser to clean up the head bolt holes, a can of black gloss paint to make the block and oil pan pretty again, the sandpaper and a few things, I'l probably be under $500 and it should be pretty fresh and even look good.

There should be some pictures now that I've got the painted block in the stand, and I hope you enjoy. These are terrific cars even stock and it's worth reminding ourselves while there are a lot of expensive mods that can be done, at the end of the day this is a Toyota and a lot can be done for the dollar.
 

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man sounds a lot like my home brew rebuild 10 years ago. I started with a rod knock motor --reman crank shipped to your door back then was ~100$ !! I put nippon turbo pistons (japan oem ~also $100 bakc then), rockauto bearings / flepro layered mhg and arp studs

has taken a beating the last few years, 12+ psi / 6k rpm every single time I drive it. got my money out of the garage rebuild for sure :)

if I could do it over again I would of used oem toyota lip seals (cams/front main) as the felpro stuff all blew out over time.

and the cheepo rockauto water pump, that lasted all of 15 min. but they warrantied it, and my used spare I slapped on is still not leaking

wtg for the pics :)
 

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sounds almost like what i'm doing. had a BHG between 4 and 5. was just going to slap a HG on it as cheap as i could just to drive around until i'm ready to JZ swap it.
well started taking it apart yesterday and one thing turned into another. seems like some hack did a HG on it before and did a horrible job and thats why it blew again.
theres heavy intentions in the head from the fire rings so i'm going to have it decked now. everything was coated in fipg so i'm replacing all of the seals. timing belt was cracked so doing that and w/p. t-stat was stuck open so doing that.
there goes my cheap rebuild lol.
hoping this is the worst of it because i dont feel like spending another cent on it.
good luck with the build.
 

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started taking it apart yesterday and one thing turned into another. seems like some hack did a HG on it before and did a horrible job and thats why it blew again.
Maybe check the head for flatness with a strait edge.
Chase the threads in the block, rusty, or crudded up threads won't torque correctly.
Repeated gasket failures may have a different root cause than just a cursed engine due to the fact the head bolts were not torqued correctly at the factory when it was first built.
Why does an engine go 100k before popping a head gasket, then starts popping the repeatedly ?
Because something isn't being addressed that should have been, or people/shops don't no that the factory torque spec.s are wrong.
 

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my guess is it was because the the head had the indents from the fire rings making it not seal as well. thats why im getting it re-surfaced.
also running ARP's, did not want to cheap out there.
 

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Discussion Starter #6
So today I learned a valuable lesson worth passing along to anyone replacing a head gasket that has blown. This afternoon I spent a pleasant few hours out in the sunshine at a folding table removing the old rings and cleaning up the pistons. I used a piece of the top ring (easy to snap these iron rings, the 2nd ring is steel and won't snap cleanly) to clean out the ring grooves. Not much cleanup needed as the engine seems to have been well maintained.

I heated the pistons with a heat gun and tapped out the wrist pins, which I'll be replacing along with their bushings in the connecting rod. I cleaned out all the oil passages of the first one, and the oil passages behind the oil control rings had an odd feel. The wire didn't bottom cleanly. So I turned it in the sun so I could see and it was full of carbon. The carbon that comes off pistons and valves when you blow a head gasket due to the steam cleaning effect.

So passing the tip along to others to clean these very important passages out thoroughly. On two of the cylinders, I had to use a small drill bit to clean them as the wire wasn't cutting it. Then two of them required me to actually DRILL the crud out - I couldn't do it spinning the bit by hand. I guess it's wise to wonder where that carbon goes when you blow a head gasket, and this is one spot. Probably why my wrist pins don't look so hot and will be replaced.

So today's task was getting the pistons ready for reassembly and I also wanted a look at the pins and bushings in case I needed to order something. Which I do. Here's a shot of the black carbon getting pushed out of the oil feed hole that's supposed to lube the wrist pins/bushings:
249898
 

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Discussion Starter #7
Well I'm at $481 today, so the 500 mark is definitely not going to happen by the time I add a few more things. I added new pistons/piston pins and crank bushings for the pins today for $101. On the good side, there will be nearly nothing used here except the crank and connecting rods and the oil pump (which I've yet to measure for tolerance). Bummer because the price for the pins before the world apparently ran out of them was $7.81 each. So I guess another way of looking at it is I'm paying about $17 each but they come with free pistons and bushings!
 

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sounds too good to be true, new pistons for $101. beware of china pistons, they are garbage and known to crack ring lands

NPR brand (japan) sets are $170 on fleabay these days. I have been punishing a set of those for quite a while with my setup...so far so good. these are the only ones I know of that are not forged and known to (maybe) be as good as oem.
 

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Discussion Starter #9
Thanks. I will check them over carefully. My original pistons are fine, so I will be able to use the piston pins and my originals if the fit is there. It will be very interesting to compare them side by side of course. So any input on the lands - were these failures on built 7M's and/or Turbos? Mine will be a pedestrian stocker driven on premium fuel in the fat part of the torque curve vs you young whippersnappers and your valve-floating RPMs!
 

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haha I can't get much into float, oem computer cuts me off around 6500. I like that fat part of the torque curve too, 4,000 rpm ...just prefer a turbo ramming air into the 7m

but yeah im interested in the comparison oem vs china piston. if you could weigh them / mic them even better. but I suspect the real issues are internal metal flaws you cant see from the outside.
 

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Discussion Starter #11
I'll take a look at them with a mic and I will also weigh them. I have a buddy with a machine shop so perhaps I can get him to weigh in on the metallurgy if he has a technique to do so. I have another acquaintance with an aerospace shop but less accessible there.
 

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Discussion Starter #12
ghnftgre, welcome to the madness - great first post. Yes, I will be doing all the details and explaining them here.
 

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IdahoDoug

on the pistons, an ultrasonic cleaner will take care of that carbon in those holes without issues because if that is in those holes, those passages are completely clogged.

I run a dual frequency 180 watt unit here.
 

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Discussion Starter #16
I got them clean but that's a good suggestion. Hmm. Maybe i can get them even cleaner - anyone have a soaking parts cleaner they like for aluminum pistons?
 

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Harbor Freight, their inexpensive ultrasonic cleaner and buy some citrus cleaner (i use the Zep Citrus stuff, works great especially in the ultrasonic bath) and clean away. It will not harm the aluminum. Do not use the Purple industrial degreasers as that stuff is caustic to Aluminum AND skin!
 

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+1 on the harbor freight ultrasonic cleaner. but....get the protection plan. I had mine fail ~6 months, but I did do prob 500 cycles in it.

word of caution. I remember when I brought the cleaner home I was like honey let me clean your glasses in this machine before I get it tainted with oil. Id seen a cool youtube and tons of crap comes off glasses that look clean. well, the thing ripped the paint off her glasses and she was not so pleased.
 

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Discussion Starter #19
Wups! Sounds like me - from hero to zero in 45 seconds. Looks like FedEx just arrived with my pistons. That was quick. The connecting rod bushings are not due for a couple days though, so not able to move forward yet.
 

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Discussion Starter #20
Well, at first glance I'm impressed with the pistons, and they're from Taiwan, which is preferable to China by a mile. I'll try fitting the new pins in my original pistons first at 140 degrees and if they fit well, I'll use them. But I will do some weighing and measuring as well, to preserve the equal balance that Toyota originally aimed for in original assembly.

Doug
 
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