914runnerswap

Hey guys, new to the site, mostly just browse to get answers but i need some help on this one.

REcently my father in law and I pulled a 3.o out of my 89 pu and put it into a 91 4runner. didnt do any real engine disassembly as we didnt want to get into that much work. Got everything put back in and barring a few minor leaks that can be expected from the swap with a 210000 engine, after about 5 days i got to work and noticed the lower radiator hose was completely off the radiator. naturally, it overheated and i put more coolant in, Could the thermostat be the problem? its and aftermarket radiator so maybe that? any input would be greatly appreciated thanks

spudrunner

Could be a stuck thermostat or the hose may have just been loose.

AH64ID

A normal cooling system operates under pressure. So it would take overheating first to blow a hose off of radiator. My guess is its the wrong hose or wasnt tightned in the swap...

InternetRoadkill

Cooling systems normally operate with 10 or 12 pounds of pressure on them. That's nowhere near enough to blow a hose off unless it was already loose. Also, the radiator cap has a pressure relief feature on it to keep this sort of thing from happening.

Make sure your clamps are tight.

4runnerx3

sometimes a blown headgasket can let the engine pump pressure into the cooling system.

Babypig

Yep, exactly what happened to mine.

914runnerswap

ouch, that could have been one of the last things i was looking to hear. i will replace the thermostat and tighten all the clamps and see if that does the trick. if not, looks like i might be taking it somewhere. any way I can tell if the headgasket is blown on my own? didn't know if there were any signs to look for or what to look at. thanks guys

mt_goat

Look for coolant in the oil or oil in the coolant or coolant out the tail pipe (white smoke)

A compression test may tell you too.

spudrunner

Check the radiator cap also. Make sure it's the right application. Start with the simple things first.

lee

yeah get a new cap as well

4runnerx3

Check the radiator overflow/reservoir tank, if you see bubbles while its running you have a blown gasket.

MMA_Alex

you're not gunna get enough pressure out of the stock cap to blow off a hose. If the pressure goes up its released (spring mechanism in the cap). You're sure you got the bottom hose back on right, and properly clamped after you swapped the engine over?

914runnerswap

Did some investigating, and read my haynes troubleshooting. It said the drivebelt being loose could cause the engine to overheat. I looked and the power steering belt was not tight at all, maybe an overlook im not sure. Is that connected to the drivebelt? Figured that could be the cause bc i have never had any problems with the thermostat before now.

mt_goat

They must be talking about the drive belt that drives the cooling fan. If you have AC there will be 3 different drive belts.

AH64ID

Those are all drive belts... the P/S one, on a 22RE anyways, is the same one as the water pump... not sure on 3.slow. It causes it to overheat since the waterpump isnt working well... But my guess is you overheated from the hose falling off, no coolant= hot motor..

mt_goat

It's different on the 3VZ, the water pump is not driven off a drive belt, what the fan comes off of does look like a water pump though (some call it a fake water pump), but if you look at from the back side you'll see it just a bearing in a housing. IIRC the timing belt drives the water pump. But if the fanbelt was too loose it could cause the fan to slip on the belt and spin slower, but I think it would make a lot of noise if that was the case.