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Discussion Starter · #1 ·
In the process of replacing the head gasket on our 96. It failed on Tuesday with massive clouds of smoke out the tailpipe, with ~285K miles on the engine. Anyway, as long as we've owned the car, through a couple of different radiators, the coolant would always turn a rusty color not long after I would fill the system with 50/50 Prestone Green and distilled water.

Well today I found out why. I shined a light down through the coolant passages into the water jacket around the cylinders, and found tons of rusty gunk and actual pieces of debris all in and around the cylinder walls! I'm not really sure how to get the stuff out, if it's even possible, or if I should even worry about it. I'm thinking someone years ago before us may have used some type of radiator or block/gasket stop leak junk in the engine. But we've put nearly 200K miles on the car ourselves and it's never really been a problem before. What should I do?
 

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Hmmm. green is not proper coolant, it most likely has silicates, phosphates and borates. Which is not correct chemical make-up to prevent galvanic corrosion in cooling systems with dissimilar metals: iron-block + aluminium radiator. In fact, phosphates in green coolant will actually increase corrosion.

You can hot-tank block to clean out dis-solvable gunk which may be holding loose-pieces in there. I've actually seen the blades on water-pump break off from corrosion and disappear into coolant passages. Then with block upside-down, blast coolant-passages with compressed-air. Then use long-thin brushes to reach in and scrub passages. There are also long fuzzy pipe-cleaner type rods you use.

After rebuild, only use full-synthetic oil and Toyota pink coolant.
 

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Nah, someone probably poured in a ton of stopleak product and that's all the 'mud' left over from it. I've seen that shit before....


You'll need some tube and a good shop vac, start sucking it out and blasting water down through the jackets and rinsing again and sucking. Not sure if cleaners like Simple Green or Purple Power/Muscle will help but they're sure worth a shot!
 

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Mr Mojo Risin'
1993 Corolla DX
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I once had to clean out the block of a 3 cylinder geo that I can only describe as "a lagoon" due to some rocket scientist literally pouring a bottle of stop leak into it. What I will say from that experience is that generally when a car blows a head gasket at that high of mileage it's better to completely disassemble the engine and rebuild what's needed rather than just slap a head gasket on it and call it a day. When doing that you essentially revitalize just the top end of the engine which then puts a lot of stress on the still worn out bottom end (worn bearings, stuck rings, etc). So usually in short order the bottom end will over-pressure and then throw a rod or eat a piston skirt or whatever. Ask me how I know this? I did it.

So even if you just blow a head gasket you need to make sure the head isn't warped or even the block before just slapping it back together. You could potentially cause more harm that way. It's very important to deck the block and shave the head just a little if any warpage is present at all. The surfaces where the head/block meet need to be smooth and completely flat so the head gasket can do the "gasket" part correctly. So if the car overheated due to blocked coolant passages (which most certainly tells me it got hot enough) you need to look at the block/head before you put the new gasket on. Some people may say "don't overthink it" and it's true that you can just put the two tired halves back together and it most likely will work, just take your time and don't rush if you have to do it that way. Gunk like that hides in every crevice of the cooling system and getting any kind of blockage completely out is almost impossible with a garden hose and some chemicals. Like I said take your time and look at little signs (like pitting in the head) before slapping it back together. Haste makes waste. Can't tell you how many things I've half assed that came back to bite me

:gossip:
 

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Discussion Starter · #5 · (Edited)
Hmmm. green is not proper coolant, it most likely has silicates, phosphates and borates. Which is not correct chemical make-up to prevent galvanic corrosion in cooling systems with dissimilar metals: iron-block + aluminium radiator. In fact, phosphates in green coolant will actually increase corrosion.

You can hot-tank block to clean out dis-solvable gunk which may be holding loose-pieces in there. I've actually seen the blades on water-pump break off from corrosion and disappear into coolant passages. Then with block upside-down, blast coolant-passages with compressed-air. Then use long-thin brushes to reach in and scrub passages. There are also long fuzzy pipe-cleaner type rods you use.

After rebuild, only use full-synthetic oil and Toyota pink coolant.
The car's radiator is the same construction as my Honda's radiator, which I use Prestone green coolant in both. Prestone green is silcate, phosphate and borate-free, and is an ethylene-glycol coolant, just as the owner's manual specifies.
 

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Discussion Starter · #6 · (Edited)
I once had to clean out the block of a 3 cylinder geo that I can only describe as "a lagoon" due to some rocket scientist literally pouring a bottle of stop leak into it. What I will say from that experience is that generally when a car blows a head gasket at that high of mileage it's better to completely disassemble the engine and rebuild what's needed rather than just slap a head gasket on it and call it a day. When doing that you essentially revitalize just the top end of the engine which then puts a lot of stress on the still worn out bottom end (worn bearings, stuck rings, etc). So usually in short order the bottom end will over-pressure and then throw a rod or eat a piston skirt or whatever. Ask me how I know this? I did it.

So even if you just blow a head gasket you need to make sure the head isn't warped or even the block before just slapping it back together. You could potentially cause more harm that way. It's very important to deck the block and shave the head just a little if any warpage is present at all. The surfaces where the head/block meet need to be smooth and completely flat so the head gasket can do the "gasket" part correctly. So if the car overheated due to blocked coolant passages (which most certainly tells me it got hot enough) you need to look at the block/head before you put the new gasket on. Some people may say "don't overthink it" and it's true that you can just put the two tired halves back together and it most likely will work, just take your time and don't rush if you have to do it that way. Gunk like that hides in every crevice of the cooling system and getting any kind of blockage completely out is almost impossible with a garden hose and some chemicals. Like I said take your time and look at little signs (like pitting in the head) before slapping it back together. Haste makes waste. Can't tell you how many things I've half assed that came back to bite me

:gossip:
The car did not overheat. I had the head resurfaced on Thursday, but the machinist checked it when I dropped it off and said it wasn't warped at all.

Unfortunately the car has been down since Tuesday and I need to get it back on the road ASAP. I'll probably just have to leave the junk in the block and put it back together if there's no easy way to clean it out.
 

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Mr Mojo Risin'
1993 Corolla DX
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Make sure after you put it back together to keep your eye on the oil level as well as other vital fluids. As long as it's not warped and you can flush out most of the gunk it should go back together just fine. Expect a rebuild at some point though
 

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...the coolant would always turn a rusty color not long after I would fill the system with 50/50 Prestone Green and distilled water.
Could you clarify this? If you are using prediluted 50/50 coolant then you don't need to add distilled water.

While you have the head off it's a good opportunity to locate the block drain plug near the oil filter. Make sure you can remove it. After the engine is running you can do several flushes including taking the block drain out to try to get it cleaner before doing the final coolant fill. You can try some of those radiator flush products and follow the directions or use citric acid and make your own flush.
 

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Discussion Starter · #11 · (Edited)
Yes I removed the block drain bolt to uh.. drain the block :grin: I heard of it breaking off for some people, but I've had it out before so I removed it again without much issue. They really should have designed it like the Honda block drain plug - a stubby, hollow bolt with a 40mm thread that takes a 19mm socket. Pretty much impossible to break one of those.

I always buy Prestone concentrated coolant and mix it with a gallon of distilled water. The car takes around 6 quarts of coolant, and a gallon of concentrated coolant + water is way cheaper than 2 gallons of pre-mix.

At this point all I care about is being able to drive the car awhile longer until we can get rid of it and get something newer. My wife has had this car something like 15 years or so, and we're both sick of it, but she needs to be able to drive it before Wednesday when our son starts back to school. Car will be gone before it needs to be rebuilt, if I have anything to say about it.
 

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Discussion Starter · #13 · (Edited)


It's already partway back together. In this project I have replaced:

head gasket
head bolts
intake manifold gasket
exhaust manifold gasket
water pipe gasket
throttle body gasket
valve cover gasket
plug tube seals
valve cover bolt grommets
camshaft oil seal
distributor o-ring
distributor rotor
spark plugs
coolant
oil/filter
air filter
and lastly: brake master cylinder because it's been losing brake fluid for months despite replacing wheel cylinders, and last week the brake pedal started feeling spongy.

It's been a heck of a job. Tomorrow I'll be putting the camshafts back in with assembly lube, new fluids and hope to have it running.
 

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Did you replace the PCV valve grommet while you were replacing all the other rubber parts? I didn't see it on your list.
 

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Discussion Starter · #16 ·
Did you replace the PCV valve grommet while you were replacing all the other rubber parts? I didn't see it on your list.
It was replaced not too long ago, past couple of years I think. I replaced the PCV valve and the hose last winter when I cleaned out the sludge in the intake manifold and the clogged EGR pipe.

*edit* why aren't quotes showing up in my post? I hit the Quote button on your post @DrZ and the quoted post shows in the text box, but not in the actual post made after I finish.
 

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Discussion Starter · #18 ·
Everything is buttoned up, ready for new fluids. Crossing fingers that it starts up and runs okay, with no leaks. This part always makes me nervous!

I checked and re-checked and triple-checked the timing belt that everything lines up, and it does. I did not put on a new timing belt, although it's due for one at about 65K since I first put this one on. I want to run it awhile and make sure there aren't any leaks from the camshaft seal before I put on a new belt, just to ensure a new one doesn't get contaminated with oil. Although this current one has had some oily residue on it for who knows how long.
 

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Quotes are based on browsers. Mobile browsers seem to not show them. Desktop browsers do show them. I even turn off the mobile theme and mobile Chrome still won't show quotes while desktop Chrome does. Wierd...
 
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