Title says it all.. My coolant is boiling..

After driving on the freeway, 20ish miles round trip doing 65ish, I got home and noticed my coolant was bubbling and making noise so I checked it.. It was boiling.. It was not steaming or overflowing out the cap and I didn't notice any different smells..

My gauges don't read accurate because of my charge light issue, so I don't know if it read super hot, but obviously I have an issue!

Anyone have any experience with what causes this? Or any ideas?
I have a feeling my head gasket is going belly up.. Maybe this is my excuse to build a motor for my truck

 

Radiator or cap could be leaking. Or the tubes off the front cover for the water. Any water leak will make it act like that. Or a sticky thermostat. How's the oil look on the stick and the inside of the oil cap?

 

Yea def check that radiator cap and all hoses big and small .....some rare cases the water pump perpeler comes loose from its driveshaft and just sits there and doesn't spin ..I have never seen this on any r series motor so I doubt it ...

 

I have a brand new 13psi cap on it, only a week or 2 old. My old one was leaking so I replaced it.

As far as I know I'm not leaking any out of the hoses, but it could be mixing, I'll have to check when I get a chance.

 

I've had water leaks haunt me on Toyotas. Always been the worst battle. The bottom of the intake manifold has a steel plate crossing water to the back for the factory aqua-choke. They can leak. The port between the 2 and 3 intake runners can leak. They will all be hardly visable or wet but when it's running and under pressure and load, it finds its way out. I thought you did a heater core recently, you may have tweaked and leaked a water line some place. I would say get an aftermarket water temp gauge and add it in. There's usually a free port on the thermostats housing to use. I run duals on the 78. Factory and aftermarket gauge. One on each side of the thermostat.

 

The intake gasket could also be bad. Allowing water right into an intake port when it warms up. Check these things and hopefully you solve it.

 

Would mixing oil and water cause The water to boil?

 

If its mixing the two there's only a few places it could happen. Usually either te head gasket or the front cover gasket. If that's the case you're losing the water and its getting hot. Might wanna plan for a new head gasket just in case. The felpro permatorque is only $18 at autozone.

 

I might just do all the gaskets to be sure.. Head gasket, intake, front cover, might as well just do the timing chain and guides.. I have nearly all the gaskets already (planned ahead) I'd rather not have to do all this stuff though...

I'm pretty confident it isn't a leaking hose, no wet spots anywhere

 

I tried to get it to repeat what it was doing, and couldn't get it to boil.. Drove the same distance and speed and it wasn't even slowly bubbling!

Maybe I just had an air bubble? Or something that worked itself out..
Some days I hate my life.

 

i'm currently trying to track this down
looks like the previous owner used rtv on the plate and it's starting to weep....

 

I have found 2 good solutions for that crossover plate if using a weber. My first fix was to drill out and retap each hole one size larger and install set screws. Basically a stud with a female Allen head at one end. Install the studs, use RTV and seal the plate down. Use fat washers and nuts. With the box end of a wrench you can hold the stud while tightening the nut to reduce the risk of stripping the stud back out. Reason for larger studs is a few of my holes pulled the threads out with the stock bolts.

My next fix was on another intake. Make a piece of aluminum plate that fits the crossover hole just below the thermostat inside its housing. Sort of an oval shape. I got mine to fit, then hit it with a hammer and chisel to bow its shape downward for more surface area on the seat. The I mixed up some jb weld. Put a thick layer down, then the plate. I put a small piece of aluminum scrap on top to not glue my clamp down. The next day I added a layer on the bottom side. The day after I added one more layer inside. So it's thick as hell. I've used jB weld inside stock valve covers and had them never fail. I trust it for water. Never had a problem. The way I did that intake, the entire plate can be removed. No more hot water below the plenum. It actually lets the passage underneath act as cooling fins. I noticed much cooler intake temps by hand. Also, you don't need a big ugly plug at that 3/4"ish fitting between the #3 and 4 intake runners. I have pics and more details on both these mods if anybody is interested.

 

I'm getting super pissed off about my truck right now! So far it has boiled 3 times, but today it was a lot more.. It has only done this when driving on the freeway about 3200rpm for decent distances, but it doesn't always do it.

I've narrowed down my thoughts to either a head gasket issue, a failing water pump somehow, or a slowly getting blocked radiator.. If I do a head gasket I'll put my ported head on and get a cam for it

I really want a new radiator, preferably all aluminum.. What years are exact bolt in for a 1977?

 

I have always run 90-95 4runner radiators. The 4 cyl version will take stock rad hoses. The V6 version is a bit bigger. I had to extend my lower hose with exhaust tubing about 6" on the verticle section next to the alternator. The bolt spacing is correct on width, but the height of upper to lower bolt is off a bit. I usually use the top rad hole and drill a new lower. That worked for the all aluminum tig welded style. When I swapped to the plastic tank style I had to run the lower holes with new uppers. I don't run a fan shroud and it only hits about 170 cruising the freeway on a warm day. I have a 180 thermostat.

The reason I went from all aluminum to plastic and aluminum was the first one broke. My jack slipped from the frame horn and hit the radiator tweaking and leaking it. They were 120 vs 70 when I replaced it and so I cheaped out and ran the half plastic kind. Haven't had any issues with it yet but it's just ugly. I plan to get another tig welded style. Eventually ill have electric fans on it. Hope that helps.

 

I never was a fan of the old single core brass ones. All my Toyotas have run on the warm side with them. Much cooler temps with an aluminum type. Winter time you might want a 195 thermostat to keep some heat in the block. So you can feed it to the heater core. I ran a 180 and had weak heat.

 

So any 90-95 4runner radiator will work? Probably a lot easier getting an aluminum one for it then one for the 70's trucks.. Do you know if the shroud would work? Maybe redo the bracket but that's easy

Will newer pickup radiators work? Like the 80's trucks

Do you have a 2 core?

 

I don't know the core count on my current one. Old was a 2 core. eBay is where to get them. Search direct fit. Pickups from the 80s will work too. Did an 88 aluminum replacement on a 78. Any car that I have that gets a ba radiator I replace them with those.

And you don't need the shroud. It just helps guide the air. The material change allows heat to exchange away so much faster its not an issue. For safety sake, go ahead and make one work. Or swap to some junkyard electric Taurus fans or something similar.

And if you're afraid of hitting your fingers on the plastic fan, don't worry. It doesn't hurt that bad. It's happened to me a few times. Sure was happy it wasn't a metal flex fan though or id have less fingernails to chew on.

 

I found a 2 core all aluminum one for a 4 runner for $96.. I'll probably buy it later this week.

I have hit the fan a couple times.. I always expect to be missing a finger, but nope it's still there.. Haha

 

I'm going to be making a trip to the junkyard this weekend to look if different year trucks radiators will be a direct bolt in, or at least how far off it will be. Hopefully something will be a perfect fit.

 

Try a 4th gen. 3rd gens are direct swap I think. I wanted a bigger radiator though so I have a 95 v6 copy.