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Yeah, that's not how the rad cap works. You might be thinking of the thermostat which is 188 degrees. The rad cap has a pressure rating. The OEM cap on a 22RE is 13psi.
no, as the radiator gets hotter the pressure inside the radiator changes, so there will be a specific temp range associated with a 13psi radiator cap, when it bleeds off at 13psi... for instance, water expands by about 4% when it goes from room temp to boiling temp.
"A change in pressure of 1 psi results in a 3-degree change in temperature” say Cochran, “If your engine calls for a 15 PSI cap, but the one that is actually on the radiator is only holding to 7 PSI, you can see engine temperatures 27 degrees higher than you should." https://usradiator.com/its-all-the-s...X-J-enhwMb3xTQ
temp-induced pressure changes are why a crack would only manifest itself as a problem in certain circumstances, but as you've indicated with statements like "I am losing coolant BEFORE the engine gets hot", it's difficult to attribute this to high radiator temps.
Last edited by osv; Sep 23, 2024 at 09:20 AM.
Reason: text showing up in black!
no, as the radiator gets hotter the pressure inside the radiator changes, so there will be a specific temp range associated with a 13psi radiator cap, when it bleeds off at 13psi... for instance, water expands by about 4% when it goes from room temp to boiling temp.
"A change in pressure of 1 psi results in a 3-degree change in temperature” say Cochran, “If your engine calls for a 15 PSI cap, but the one that is actually on the radiator is only holding to 7 PSI, you can see engine temperatures 27 degrees higher than you should." https://usradiator.com/its-all-the-s...X-J-enhwMb3xTQ
temp-induced pressure changes are why a crack would only manifest itself as a problem in certain circumstances, but as you've indicated with statements like "I am losing coolant BEFORE the engine gets hot", it's difficult to attribute this to high radiator temps.
Ahh. I see what you mean. I agree. I don't think I have the brain power to articulate it back but it makes sense. Pressure and temp are directly related basically. The function of the cap is correlated to pressure and pressure is correlated to temp.
So, does this mean my engine is running hot? I would think so.
Like Millball, i can only think of something related to the head. You might try a leakdown test to see if that offers anything, but if having the engine at operating temp is essential this might be tough to do. I'd highly recommend the test before pulling the head, though.
If the issue was at the block/head mating surface the headgasket should have signs of failure once the head is pulled. But I'd also think the block test would have shown that.
At freeway speeds enough air is being forced through the radiator that fan blade and fan clutch essentially freewheel. But considering what you're going through I'd probably would have put news ones on, too. Kudos for getting oem grade.
Toyota did have that special thermostat for the 22R# that addressed temperature overshoot (that small hole you drilled was sorta replicating that) but that condition was very specific, and oddly random. Only a minor percentage of 22R's did that. And that was weird (typically flaws in 22R design affected the vast majority, not a select few). The temp overshoot would happen when a cold engine was heating up. There would be a delay in the thermostat opening, creating the temp gauge to go up to about 3/4 before the thermostat fully opened and the temp needle would drop to normal. Once thrmostat fully opened the vehicle's gauge and cooling system behaved properly. But that initial spike during warm up was alarming to those paying attention. Vehicles with overshoot did it when vehicle was still pretty new, or not at all. It wasn't something that showed up years later.
The leakdown test is about the most informative test you can run in this situation, it can narrow your focus quite a bit if you're lucky.
The tricky thing will be analyzing the head if you pull it. I've found most machine shops not that great in scrutinizing. They recommend the resurfacing and possible valve job, while condemning the head pretty much kills their machine job.I can't tell you how many times we sent heads out for inspection, they got resurfaced and shipped back to us, only for our tech to find a hairline crack. So if you do pull the head I think taking an orbital sander with some wet/dry paper and cleaning up the head surface and doing your own inspection would be worthwhile. I'd probably really look over the valve seats where that spring broke. Most 22R head cracks that I saw were in the combustion area around the valve seats, not so much the mating surface. But right now everthing is on the table.
I'll ponder this as I walk the dog now.
I agree. Everything is on the table. Human error. Faulty parts. Target focus.
I agree with your sentiment about machine shops. Well, shops in general. Sometimes I bring the tuff questions and money only to leave with less money and easy answers.
A leak down test is about the only one I haven't performed. I have arranged to borrow one and will try that this week.
I found this simple article to follow. https://www.mobil.com/en/lubricants/...%20plug%20hole.
I've had a crack in a 22RE head before. I hope it was my old truck but I can't remember. It was between the valve at the seat where two seats are closest. That time it had overheated bigly! Either way, I need to do a thorough inspection.
I'm also going to try cleaning the block galley via the bung near the bell housing. It's free and should take <30 minutes.
Right now a a new long block sounds might appealing. I want to go smash around in the woods and given the problems I'm having it would almost give a 100% solution. Plus I have a lot of block deck pitting. It gives me anxiety. https://sunwestautoinc.com/product-c...yota/3-toyota/
Have you had the engine fully rebuilt (new rings, bearings, and seals) or are you just doing the head? If you are going to rebuild the engine I would take the block to a machine shop and have them magnaflux the block. To verify that there are no cracks in the cylinder walls. The reason I mentioned this is because there is coolant that flows around the cylinders. A cheap way to do it is a cylinder leak down test you will want to do this at 100 psi or more if there is a crack you should see it in the coolant as bubbles. I would also do this when the engine is hot so the rings seal properly. Sometimes when the engine is running it can be hard to tell if there are bubbles coming out of the radiator
Copy that. Thanks man. I have never had the engine rebuilt. I bought the truck with 170k and it has 320k now. I believe the head gasket has only failed the one time. I checked compression recently and it was holding at 170psi in all cylinders.
I'm not sure if i'd do a full rebuild or remanufactured engine with core exchange.
Last edited by ethanfurniss; Sep 23, 2024 at 10:18 AM.
The only two things that could push coolant out the overflow like that (that I can think of) is a combustion leak into the cooling system, or the water/coolant just getting too hot, expanding, and displacing water.
But the block test does a pretty good job on the 22R# for detecting combustion leaks. Nothing is infalliable, but still, it was a pretty reliable test for that engine. Which makes me ponder on whether there might be a restriction somewhere in the system thats increasing the temp..
My dad used to service restaurant equipment, and he had these long springs to remove lime deposits from the copper tubing on the big commercial coffee makers. Might be worth trying to run one of those down the various cooling passages in the block and head and see what you might find. You can get them on Amazon pretty cheap, just use "deliming springs" in the search.
Using high quality parts during this testing is adviseable, and it sounds like you've done that. Once replaced, i think you can rule that component out.
From what I understand, the temp gauge was showing overheat, it was just thought that the rising temp was due to low water from being pushed out the overflow. Maybe the running hot and water loss events are occurring at the same time.
The pressure of the cooling system correlates to the boiling point of water. For example at 17 psi the boiling point of water is 255 F. 13 psi is around 235 F. If the engine is passing test that prove no combustion gas is in the coolant then I would suspect the engine is actually overheating and making steam therfore pushing the coolant out of system. And your temperature gauge is reacting too slow to what is really happening. With the radiator cap on can you monitor the upper and lower radiator hose temperature and can you tell when the thermostat opens?
Two different thing scan be happening
1. Too much coolant flow not giving the coolant enough time to absorb or release heat.
2. Not enough flow / no flow.
Can all so try removing thermostat and flushing with a hose top to bottom and bottom to top to verify you are actually getting flow through the block. The coolant holes in the head gasket are very small and can clog with debris.
Have you checked the engine timing (verify the crank pulley hasn't spun) and make sure its set correctly.
Last edited by superex87; Sep 25, 2024 at 04:13 PM.
A couple of things have happen since my last post.
I took my wife on a date in the truck.
I passed Oregon DEQ with flying colors.
I installed an OEM drivers side mirror.
I replaced my Chinese headlights with more Chinese headlights.
I removed a bung in the block and flushed a significant amount of crud out of the block.
I drove 60 miles at 70mph WITHOUT OVERHEATING.
All in that order.
This is huge but may be a red herring.
Aside from stoking my wife out, buying really expensive stickers, having a mirror what stays adjusted, and having headlights that work I MAY have fixed the problem we're discussing today.
The truck had previously steamed out and overheated in under 20 miles.
Ill now start using the truck for day trips with hopes to gain the confidence to drive more than 60 miles from the house.
Ill do my best to keep this thread up to date.
The photo is NOT MY WIFE. Ha. Its my dog Eddy on said 60 mile drive. Trash Not gold panning After headlights amd before mirror
Last edited by ethanfurniss; Oct 15, 2024 at 09:00 PM.
The problem persists.
I drove about 60 miles away to go dirt biking. It wasn't all at 70 because of traffic and mountain roads but the radiator was a couple inches low when I got there. I noticed the wheel well and undercarriage was wet from the overflow puking. I topped it off on the way back and it warmed up a little about 10 miles from home when I was waiting in traffic for a bridge. I goosed it a little and it cooled off and stayed at normal temp for the rest of the drive.
So, I have not made any significant gains.
I can do a head gasket again but at this point I'm leaning towards replacing the motor with a second hand one. That way I'll have double the parts to troubleshoot with. Reman long blocks are reasonably priced as well.
so the temp gauge wasn't showing overheating? i don't see where it was mentioned.
was the water in the radiator over the fins? on my truck the normal water level is at least an inch or so under the bottom of the radiator cap.
first your truck worked fine for a 60 mile drive, then a few days later lost some water, why would that be? its weird
Thanks for reading the update.
No. For either drive it didnt over heat. It got what I'd say is a little warm on the second.
Fine for the first 60 mile drive. Yes-ish. There was some coolant on the edge of the airbox that day but i was hoping it was because the rad was topped off and the overflow was still full to the top. I didnt check the undercarriage. However, after each 60 mile drive (first drive last weekend and to and from dirt biking) the rad was about a quart+ low.
I agree that it's weird. On so many levels IMHO. Weird that i haven't found the problem and weird that i had a marginal gain from flushing the block.
quoting that link: Long straw goes to the radiator and the other hole is the vent/overflow for the catch tank.
Hooking it up backwards with the vent (non straw) side connected to the rad will push coolant up that straw and out of the catch tank as soon as the system pressurizes.
quoting that link: Long straw goes to the radiator and the other hole is the vent/overflow for the catch tank.
Hooking it up backwards with the vent (non straw) side connected to the rad will push coolant up that straw and out of the catch tank as soon as the system pressurizes.
That is a prudent thing to bring up. I have read that thread several times over the years and I did second guess myself on its installation this week too.
If you haven't pulled the cooling system drain cock at the left rear of the block it would be a good idea. That passage seems to accumulate crud. I doubt it'll change anything, but good to clean out.
If your temp gauge is staying under 3/4 and you're losing water/coolant than i'd have to think a small crack in the head is the most likely culprit. Only happening at higher speeds/rpms may bear this out.
One swan song you could try is adding sodium silicate to the system. Maybe about 1 cup's worth. It has the ability to seal hairline cracks in hot surfaces. It's not a permanent fix, but if it effects a change (you stop losing water) than you'll have a better idea of what you're dealing with. The engine has to be at full operating temp for the silicate to start working. Silicates can be hard on seals, namely the waterpump,but if it does slow or stop your water loss you'll have a better idea what to focus on.
If you haven't pulled the cooling system drain cock at the left rear of the block it would be a good idea. That passage seems to accumulate crud. I doubt it'll change anything, but good to clean out.
If your temp gauge is staying under 3/4 and you're losing water/coolant than i'd have to think a small crack in the head is the most likely culprit. Only happening at higher speeds/rpms may bear this out.
One swan song you could try is adding sodium silicate to the system. Maybe about 1 cup's worth. It has the ability to seal hairline cracks in hot surfaces. It's not a permanent fix, but if it effects a change (you stop losing water) than you'll have a better idea of what you're dealing with. The engine has to be at full operating temp for the silicate to start working. Silicates can be hard on seals, namely the waterpump,but if it does slow or stop your water loss you'll have a better idea what to focus on.
Thank you for the suggestion. That is what the post from 10-15-2024 above is about. I did remove some gunk and saw some gains. The problem persists however. It may have been a coincidence.
My temp gauge stays right at the 45% mark across it's range. Left of center. Until the coolant is low.
I am losing coolant but it's due to an over pressurization of the cooling system. I can't rule out that a cracked head is causing this but the coolant isn't going into the oil, the combustion chamber or externally. Combustion gasses are not going into the cooling system either.
The over pressurization is manifested at all times. At idle in the driveway all the way to smashing the freeway at 70mph. It seems the coolant only wants to exit the system (out the coolant overflow) at sustained freeway speeds.
Borrow an Inspection camera/boroscope from the parts store tool loan. Many can see 90 degree(or more) try and look for something around/between the valve seats.
Maybe it is just pulling in air, and not even pressurizing. Did you check/replace the little coolant hoses under the intake?
Because at your point I replaced the entire engine with an OEM crate one I was lucky to get. I replaced the radiator as well. It was done.
I learned to use red Toyota coolant. Has used "anything" and then just water.
I replaced the head twice and it always returned just as you described it.
Deck the head and inspect the surfaces. Pitting.
Deck the block. That's what I didn't do. Pull the cables at the computer. lay it on the block and go for it
Sep 23, 2024 | 09:18 AM
