18_YotaLuv

Ok, my friend has a 1990 4runner, 22re, 5speed. No engine mods besides general maintance. He would drive it for about 2 or 3 minutes and it would start to overheat. He parked it for the night. Next morning, he started it and let it run for about 5 min and it started to go over that half way point and then shut it off not wanting to chance anything. What should he be looking for?? I need to knw of any possible things, and also where or how to check? Also how much to fix/repair. Thanx alot, and srry bout the long post, jus trying to put in all the info possible.

Thanx

khany2002

If it overheats that fast, that would suggest there is no coolant flow. Check your belts to make sure your water pump is running, and I presume your fan clutch is locking up and running (although even if it was not running, it would take longer than 2 minutes to overheat).

More likely, start it, feel the upper rad hose while looking at the gauge. If the upper rad hose stays cold, there is a blockage, an air pocket or no coolant flow.

If the upper rad hose is hot, feel the lower rad hose. If it's hot, your rad is not cooling. Feel your rad for hot spots and cold spots, which would identify blockage points. You could then try flushing the rad or replace as necessary.

Of course, this goes under the assumption you've checked to see there is sufficient coolant and the general running condition of the vehicle is OK.

Also, after 2 minutes, are you getting warm heat from the vents?

If the engine is still feeling cold, look at the gauge, it could be faulty.

18_YotaLuv

Ok, ill defiantly try that thanx! And if their is a blockage, how would i get that out? And the engine is in great shape, and runs perfect. And he doesnt ever use his heater hah so idk, ill check it for him. My cousin said something bout maybe cracked heads? Is that possible?

xxxtreme22r

cracked head is possible, but there would be a huge power loss on the motor. To me that sounds like more like a sticking thermostat or a bad water pump. I would start with the thermostat. And make sure it actually has coolant. Could possibly be the water temp sender for the gauge as well, but not sure if it would cause symptoms like that.

85gijunk4x4

like said before, could be no coolant, faulty or sticking thermostat, bad fan or clogged coolant hoses. id start off by checking the coolent level, if the level is good, let the engine run and fell the hoses for coolant flow, if the coolent is flowing it could be your thermostat sticking, or opining/closing when its not supposed to. like said before, if could also just be a bad guage and/or sending unit. you could find out by letting the temp go up, and turning on your heater, if the heat is pretty hot (and since toyota heaters blow hot to begin with, im guessing it would be unbearably hot if it was overheating) its a coolent problem, but if it feels normal, and the engine doesnt seem to be hot, it could be a bad guage reading. another good indicator of a bad guage is that the guage moves drastically (from low to high temp, or high to low temp) within seconds, as an engine cant heat up or cool donw that quick.

18_YotaLuv

Ok, how could u check the thermostat or water pump??

18_YotaLuv

And thanx, this all helps alot. But from reading and stuff, since its heating up within minutes im thinkin more of a bad gauge. Cause it doesnt drive any different and sounds good. but ill defiantly do the heater thing and chack the coolents, thermostat and water pump. Thanx guys!

xxxtreme22r

you might be able to feel the coolant flow through the hoses, but the easiest way to do it is to take the rad cap off. But be very careful taking if off when it's hot, because that thing will blow coolant all over the place including on yourself if it really is over heating. I would take it off when it's on the cooler side and then run the engine till it gets hot. If you see no flow then either the water pump isn't pumping fluid (assuming the belt is on the water pump) the thermostat is sticking or there is a blockage in the lines which is highly unlikely.

85gijunk4x4

water pump= feel for coolent flow, listen to hear if the water pump is making any weird noises or whining etc. check your belts to make sure theyre not slipping. look at the water pump while the engine is running and make sure the water pump pulley is turning.

thermostat= im not too sure, but pull it out and look at it. if its all corroded or rusty looking, or even just old, it could be at fault. what i would do to check the water pump and thermostat, is pour coolent into the overflow while the engine is not running and cooled off. start the engine and after a few minites the thermostat should open and suck the coolent into the coolent system. if the coolent gets sucked in right away the water pump is good, but the thermostat may be stuck open.

xxxtreme22r

ya know what, I should know this but I don't, but would a bad rad cap cause overheating? Only thing a bad cap would cause that I can think of is boiling coolant, but that doesn't necc mean overheating by the gauge reading, if you follow me.

85gijunk4x4

never thought of that before, but come to think of it, a bad radiator cap means bad suction, bad suction means no pressure, no pressure means no flow (i think lol )

xxxtreme22r

not sure on the suction part maybe to and from the overflow, but I don't see that playing apart in the coolant system in general unless it's completely fubar and pulling in air into the radiator, but then he would have a coolant leak there as well once the fluid warms up and pressurizes the system. Afterall you have coolant flow when the cap is off. But if the rad cap isn't holding proper pressure it will lead to boiling coolant, just have not had that experience with any of my vehicles nor any when working for years in oil change places to know what the effects are on the gauge itself.

85gijunk4x4

lol yeah idk, im just throwing stuff out there...

never had an overheating problem before, so ive never actually solved one, so im just thinking of things i would do if i were in his shoes lol. thats about all the advice ive got for now, but ill keep thinking

18_YotaLuv

Well ill check that to then! Hahah Thanx alot tho guys!! Keep the seggestions coming tho, anything helps. Im lost when it comes to cooling and electrical. haha